Solid State Guitar Amp Forum | DIY Guitar Amplifiers

Solid State Amplifiers => Amplifier Discussion => Topic started by: THChrist on December 28, 2010, 11:02:15 PM

Title: KMG SS Poweramps
Post by: THChrist on December 28, 2010, 11:02:15 PM
Hello everybody.

It's been a while since my last visit. I've been investigating about some tube preamps, since i've been wanting to have a multiple preamp with lots of modes and shinny lights.

But I'm also lookin for a poweramp to use my preamp. I've been considering lots of poweramps: Chips (TDA/LM), transistors (ála Randall), 5w Single Ended (AX84), 20w SE, 20w Push-pull, etc.

Today I was checkin' my bookmarks and found this site i visit a couple of months ago: http://milas.spb.ru/~kmg/index_en.html

He's an active member of freestompboxes, and has some pretty interesting stuff. Guy knows his biz. And they were two projects: a Fet Micro poweramp for recording (and or practice); and some Fet poweramps. And a Celestion V30 Simulator. Three projects, like I said.

I just wanna know if anyone at this forum is familiar with those projects, if someone has build 'em and have any opinion.

The Micro PA looks pretty interesting. Is a kind o' transistorized version of a Marshall PA, includes OT, V30 Speaker Sim and Speaker Saturation Simulator.


Here are the links:

Micro PA
http://milas.spb.ru/~kmg/microfetpa_en.html

Fet PA
http://milas.spb.ru/~kmg/fetpa_en.html

http://www.freestompboxes.org/viewtopic.php?f=2&t=9487
http://www.freestompboxes.org/viewtopic.php?f=13&t=8582
Title: Re: KMG SS Poweramps
Post by: J M Fahey on December 29, 2010, 05:31:52 AM
 Hi tchrist.
Those are interesting ideas, very experimental and quite far from a finished product.
Not bad as a concept, but the waveforms he shows are SS type :(, not tube type, so the main object of getting so complex and expensive (just ask for a quotation on his output transformers) is not achieved.
No te rompas la cabeza contra una pared.
Just build a tried and true chip amp, from 5 to 150W; *or* a real tube one; again from 5W to 100W, and experiment with the preamp, stomp boxes, etc.
Good luck.
Title: Re: KMG SS Poweramps
Post by: teemuk on December 29, 2010, 07:34:19 AM
I don't know... to me at least the MicroPA output looks pretty much like one coming from a generic tube amp: somewhat rounding up on the clipping onset and it even features the same type of crossover/blocking distortion mechanism due to shifting bias point. But, I think those scoped waveforms are either from running to a resistive load or the amplifier's response stays fairly linear regardless of load impedance. So the mechanism where amp's gain interacts with a reactive load is not showing up in there. Otherwise, it pretty much nails the "PP tube power amp thing".
Title: Re: KMG SS Poweramps
Post by: phatt on December 29, 2010, 07:52:50 AM
Hello tchrist,
Not sure where your heading but I agree with JM Fahey's last post. 8|
That stuff is Way to complex for little benifit as a tube power stage will still be better.

I did have a listen to the clip, Turning the knobs did little to effect any real change in sound.
Also a servere lack of bass but that's a matter of taste.

A note on tube preamps ,, it's a dog chase tail thing as the real benifit of Valves is in the power stage not in the preamp stages.
So if you want to throw money at something then build a Valve power stage and leave all the tricky complex preamp stuff for SS. Cheaper and Easier to fault find for the hobby types.
These days anything with an AX7 inside a preamp will sell.
IME, Complex valve preamps are no better than what can be done with transistor/chip circuits.
Sure if money is no object then go nuts but the cost is significantly higher with Valves.
Phil.
Title: Re: KMG SS Poweramps
Post by: THChrist on December 29, 2010, 12:30:50 PM
Thanx everybody.

Well, the Fet PA looks interesting and the clips got me thinkin' about 'em. What i wanna do is a series of modules, pretty much like those old modular stereo systems you used to put one over the other.

I cannot afford expensive preamps, rack effects or tube amps. But near to chinatown we have a place called "Paruro". Blocks and blocks invaded by stores and galleries dedicated to sell and/or make electronic components. In example, the power transformer, winded by hand, can cost me ~US$20.

Hi tchrist.
Those are interesting ideas, very experimental and quite far from a finished product.
Not bad as a concept, but the waveforms he shows are SS type :(, not tube type, so the main object of getting so complex and expensive (just ask for a quotation on his output transformers) is not achieved.
No te rompas la cabeza contra una pared.
Just build a tried and true chip amp, from 5 to 150W; *or* a real tube one; again from 5W to 100W, and experiment with the preamp, stomp boxes, etc.
Good luck.

Hello tchrist,
Not sure where your heading but I agree with JM Fahey's last post. 8|
That stuff is Way to complex for little benifit as a tube power stage will still be better.

I did have a listen to the clip, Turning the knobs did little to effect any real change in sound.
Also a servere lack of bass but that's a matter of taste.

A note on tube preamps ,, it's a dog chase tail thing as the real benifit of Valves is in the power stage not in the preamp stages.
So if you want to throw money at something then build a Valve power stage and leave all the tricky complex preamp stuff for SS. Cheaper and Easier to fault find for the hobby types.
These days anything with an AX7 inside a preamp will sell.
IME, Complex valve preamps are no better than what can be done with transistor/chip circuits.
Sure if money is no object then go nuts but the cost is significantly higher with Valves.
Phil.

I know it is too complex (but I'm in denial)  and with half the effort/components I could build a small chip amp. The knobs where almost useless; and I know most of the "valve" sound comes from the powertubes. But I hear it telling me "build me, c'mon..."

I saw lots of youtube videos with DIY JCM800 preamps (only) and they sounded good. And I was expecting some kind of PA to get me closer to tube sound. There are some guys who built those JCM800 2203-style preamps and used chipamps. They sounded good, but there was something missing.

I don't know... to me at least the MicroPA output looks pretty much like one coming from a generic tube amp: somewhat rounding up on the clipping onset and it even features the same type of crossover/blocking distortion mechanism due to shifting bias point. But, I think those scoped waveforms are either from running to a resistive load or the amplifier's response stays fairly linear regardless of load impedance. So the mechanism where amp's gain interacts with a reactive load is not showing up in there. Otherwise, it pretty much nails the "PP tube power amp thing".

Now, your opinion kinda clashes with Fahey's and Phil's. And somehow, feeds my obssession. Could you tell me more about it? I see the values of the micro PA and they're pretty Marshall to me (470ohm, 10k, 4k7 tail resistor, 220k bias splitter, etc), but the structure is slightly different. And while the 5w Fet PA uses the same structure as a Marshall, it has different values. Do you have any sugestion or explanation for that?

Thank you to all three, and please, excuse my lame english and my OCD. And happy new year to all of you.

Title: Re: KMG SS Poweramps
Post by: J M Fahey on December 29, 2010, 04:10:16 PM
Hi tchrist.
I'm not "clashing" with our friend teemu's opinion (far from it), because I simply didn't even *look* at the "small" Fet amp, just went straight to the "big" one, where I saw no curve bending, bias shifting, etc. at all, at least in the scope images posted by the author.
All I saw there is a little top rounding, *very* easy to get by far simpler means.
And the "tube artifacts" are generated in a far better way by the excellent Transtube circuit.
Maybe driving a real world speaker things change.
Differences of  *opinion*?
Sometimes yes, and that's good, or the World would be quite boring.
If you can get that transformer wound for such a low price, and build the amplifier, go for it, and post results here.
Happy Xmas and New Year to everybody, y felices fiestas para ti.


Title: Re: KMG SS Poweramps
Post by: THChrist on December 29, 2010, 04:21:47 PM
Hi tchrist.
I'm not "clashing" with our friend teemu's opinion (far from it), because I simply didn't even *look* at the "small" Fet amp, just went straight to the "big" one, where I saw no curve bending, bias shifting, etc. at all, at least in the scope images posted by the author.
All I saw there is a little top rounding, *very* easy to get by far simpler means.
And the "tube artifacts" are generated in a far better way by the excellent Transtube circuit.
Maybe driving a real world speaker things change.
Differences of  *opinion*?
Sometimes yes, and that's good, or the World would be quite boring.
If you can get that transformer wound for such a low price, and build the amplifier, go for it, and post results here.
Happy Xmas and New Year to everybody, y felices fiestas para ti.




I didn't mean "clash" in a bad way. Differences of opinion are mandatory in order to evolve. For what i know, the designer of the small PA wounded his own TF (if you look at the page for the small amps, you'll see there are few windings). I respect everyone's opinion and i take in consideration that english is not our first language (at least to both of us and Teemu, don't know if Phil's 1st language is english)

I just asked the guy who designed for some info. It looks like this 2011 I'll need money, so I better start selling my body, ha ha.

Que planes para año nuevo?
Title: Re: KMG SS Poweramps
Post by: phatt on January 01, 2011, 09:11:22 AM
Hi THChrist,
            Well if all you really want to do is play the guitar then you can waste so many years trying to perfect an amp (Glass or Sand) you may forget how to play the instrument by the time you finish.

I make a personal point of not bothering very much with *One Off* builds/sites that claim or even imply they found the holy grail circuit.
Unless they have evidence of there inventions being used by live working musicians or have built quite a few.

The amount of times I've got excited over circuits at home only to find in real world working situations they never deliver.  :'(

Want to see my shed full of land fill circuits (spare parts bin now) ;D

In close to 30 years of messing with circuits only 3 or 4 of my inventions are worth a mention. (All posted here I should Add, check under schematics) I would not be so cruel as to post circuits that I knew had possible shortcomings.

You mentioned power tube sound so here is a little trick I did many years ago you might wish to try which will open your eyes about powertube sound.

I simply took a small little 20 watt SS Amp and wired a series lamp limiter into the Mains power cord which produces quite convincing power amp compression.

Caveat; The Amp circuit needs to be very simplistic for this to work.
i.e no onboard digital FX and fancy switching circuitry.

You loose some wattage but the saggy compressed sound is very reminicant of tube power stages.

At times I wish I'd kept that litte amp it was so much fun for small gigs,, as I
needed no pedals,, just a straight rock sound with nice rattle and comp when driven hard.
The draw back, just like early small valve amps they sound great but only at one Volume level.

IMO the difference between a good or bad amp (Any type) can be mostly put down to
tone shaping. i.e how and where in the circuit these tricks are implimented can make
a massive difference.
Just hanging the Marshall value resistors off a semi conductor wired up the same way
shows little understanding of how to make good amplification.

I won't mention names but a lot of fet preamp circuits have become so popular because they use close to exact values as those used on some famous Valve circuits and again they are far from ideal as good *Reliable* circuits.
Yes they work but often the SNR is horrendous because they just hang 1 meg resistors
off every gate like a valve Amp and high gain on high imp = massive noise.

Try reading some of this stuff before you travel down the complex path.
Humans have a habit of insisting that complex problems must have complex answers and
often even the experts can miss a really simple idea.

http://www.amptone.com/truesecretofamptone.htm

A bit dis-jointed in places and rather long winded but it covers a lot of questions
that folks like you ask.

I may not agree with all of it but I'm sure it won't take long to catch on.
anyway I'm just rambling on so time I went.
ps, I only speak 2 languages, English and Oztrayland :P
Phil.
Title: Re: KMG SS Poweramps
Post by: phatt on January 01, 2011, 09:42:37 AM
Hi forgot to mention;
Go to the index at Amptone and trawl through the masses of ideas.
http://www.amptone.com/index.html
Sorry no flash stuff just mainly text,, So You will be there for a long time :-*

Although it focuses on tube amps and attenuation most of it is still just as relivant for an all SS rig.
Phil.
Title: Re: KMG SS Poweramps
Post by: KMG on January 16, 2011, 01:03:13 PM
Quote
Not bad as a concept, but the waveforms he shows are SS type :(, not tube type, so the main object of getting so complex and expensive (just ask for a quotation on his output transformers) is not achieved.Just build a tried and true chip amp, from 5 to 150W; *or* a real tube one; again from 5W to 100W, and experiment with the preamp, stomp boxes, etc.
Good luck.
Several notes about differences between commonly used ss poweramps and tube ones.
Simple chip poweramps usually use very deep negative feedback. This leads to in first to very hard signal clipping & in second to very low PA output impedance.
Maybe first is not so important for modern sound styles which doesn`t use PA overdrive, but for vintage sound it maybe one of the first in creating sound. For example Marshall superlead plexi doesn`t have master volume, so PA begins to overdrive far from preamp overdrive.
Low output PA impedance lead to hard speaker dumping, that doesn`t allow cabinet to "breathe".
Look at frequency response of transformer output fet PA loaded on active load and cabinet (voltage on PA output).
(http://milas.spb.ru/~kmg/files/projects/fetpa/mp/tests/5wafc_r_c.png)
Title: Re: KMG SS Poweramps
Post by: joecool85 on January 16, 2011, 01:13:20 PM
Wow, excellent first post KMG.  Welcome aboard!
Title: Re: KMG SS Poweramps
Post by: KMG on January 20, 2011, 03:25:33 PM
Answer to question:
I was also wondering if KMG would be so nice and post some more info about winding those nice output trafos for his FET power amps...
Number of turns in transformer windings on page "Fet power amplifier with transformer output" (http://milas.spb.ru/~kmg/fetpa_en.html) is given only for reference, because I think that you could not find exactly the same core (cross section & Bmax). So you need to calculate windings for your core parameters. Calculations are exactly the same as for the tube PP transformer. If you have calculator for tube PP transformer you can use it for calculation. Calculations based on primary coil impedance Ra-a (given on my page for each PA), desired lowest frequency (i calculate for 50Hz), core geometry & core material Bmax. Unfortunately i have articles about trnsformer calculations only in Russian.
Title: Re: KMG SS Poweramps
Post by: KMG on February 10, 2011, 05:16:20 AM
If you wish to design your own fet PA, you can use my program to select primary impedance for desired power and supply voltage.
(http://milas.spb.ru/~kmg/files/projects/fetpa/pa.jpg) (http://milas.spb.ru/~kmg/files/projects/fetpa/Pa.exe)

Ra - impedance of half primary winding (1/4 Ra-a)
Vsupply - power supply voltage
Sig Max % - signal amplitude (100% is maximum signal without distortion)
Vsat - fet saturation voltage at peak current
Id0 - idle current
Average Pd - Average drain power (for one side of PP, halfwave)
Average Pl - Average load power (fullwave, but without taking into account efficiency of the transformer)
Average Id - Average drain current (for one side of PP, halfwave)
Peak Pd - Peak drain power (instantaneous)
Peak Id - Peak drain current (instantaneous)
Title: Re: KMG SS Poweramps
Post by: KMG on February 10, 2011, 05:23:55 AM
Scalable down 40W version (Primary coil impedance Ra-a = 200 ohms)
(http://milas.spb.ru/~kmg/files/projects/fetpa/lp/FetPaSwS.jpg) (http://milas.spb.ru/~kmg/files/projects/fetpa/lp/FetPaSw.pdf)
Title: Re: KMG SS Poweramps
Post by: J M Fahey on February 10, 2011, 07:23:26 AM
Hi KMG, thanks for posting your impressive work. :tu:
To be redundant, I also was very impressed about your "day job" too, apparently into mass transportation industrial electronics.
Please tell us something about that.
As of 
Quote
Unfortunately i have articles about trnsformer calculations only in Russian.
feel free to post some links, math is universal and text can be translated through Internet services, although sometimes it can be more garbled and obscure than the original language.  xP
Thanks in advance. :D
Title: Re: KMG SS Poweramps
Post by: KMG on February 10, 2011, 08:06:47 AM
Quote
Please tell us something about that.
Did you see that?
http://www.ssguitar.com/index.php?topic=2020.msg13351#msg13351
Quote
feel free to post some links
Article in Russian from one of the authors of GTLab forum.
http://milas.spb.ru/~kmg/files/literature/%d0%a1%d1%87%d0%b8%d1%82%d0%b0%d0%b5%d0%bc_%d0%b3%d0%b8%d1%82%d0%b0%d1%80%d0%bd%d1%8b%d0%b9_%d0%b2%d1%8b%d1%85%d0%be%d0%b4%d0%bd%d0%be%d0%b9_%d1%82%d1%80%d0%b0%d0%bd%d1%81.pdf
Spreadsheet based calculator form the same author.
http://milas.spb.ru/~kmg/files/distr/PPtrans_1.01.xls
Article in English.
http://milas.spb.ru/~kmg/files/literature/transformers.pdf
Executable PP calculators.
http://milas.spb.ru/~kmg/files/distr/PPCalc/PPCalc.exe
http://milas.spb.ru/~kmg/files/distr/PP-%d1%80%d0%b0%d1%81%d1%87%d0%b5%d1%82.exe

Title: Re: KMG SS Poweramps
Post by: KMG on February 10, 2011, 09:05:34 AM
If you have a problems with the definition of the parameters of the transformer core ("Bm"), you can use the following trick. Not exact, but good enough.
If you use a power transformer as the "donor" for the output transformer, count winding turns while unwinding primary coil. So you will know the ratio of turns per volt for the lower frequency equal to the mains.
Voltage on output winding equals U = sqr(Pout * Rload)
Using turns per volt ratio you can calculate turns in the output coil.
Now start PP calculator, enter parameters (lower frequency = mains frequency of the transformer). Change "Bm" untill you`ll get calculated output coil turns.
Title: Re: KMG SS Poweramps
Post by: J M Fahey on February 11, 2011, 08:12:59 AM
Hi KMG, thanks a lot for your links.
I have no problem with Bm, turns-per-volt, current density, etc., have been designing and winding my own transformers for over 40 years.
Anyway, *every day* I learn something new, and I'm grateful for that.
I'll read them thoroughly.
As a side note, I'm now using Russian EI laminations, the bright greenish ones. Very high quality.
I can routinely push them to 15KGauss with absolutely no overheating problems.
A former University pal visited Russia years ago , as part of an official comission to evaluate and buy Russian railroad equipment; maybe they visited your Company too!!
I'll ask him next time we meet.
Thanks again.
Title: Re: KMG SS Poweramps
Post by: phatt on February 11, 2011, 08:30:11 AM
Hi KMG,
           If I may make a constructive critik point about your wonderful work.

I feel that some/most of the folk would be detered from building some of your circuits as it's Suface mount Double sided stuff.
Not something that the average hobby type is likely to have access to.  :'(

In my humble opinion, It would be a smash hit build if it where presented as a single sided board layout.
Just a thought. :tu:

BTW, thanks for the maths short cut about OT and I have no doubt it would sound good even if it was not exact.

Besides some of the best sounding Valve Guitar Amps had crap transformers,, i.e. badly matched to output Valves.
Cheers, Phil.
Title: Re: KMG SS Poweramps
Post by: KMG on February 11, 2011, 09:48:32 AM
Quote
I feel that some/most of the folk would be detered from building some of your circuits as it's Suface mount Double sided stuff.
Not something that the average hobby type is likely to have access to.
Double sided assembly, not PCB.
All of my designs use single-sided PCB (no problems to make them DIY).
About SMD, in Russia, it is often easier to find SMD than through hole components. Except maybe the high-voltage electrolytic and film capacitors and some semicinductors that has only one package version.
For example Mouser offers wide range of SMD compoents.
http://www2.mouser.com/Passive-Components/Resistors/Surface-Mount-Resistors/Thick-Film-Resistors/_/N-7h7yz?P=1z0x6frZ1yzvlks
http://www2.mouser.com/Passive-Components/Capacitors/Tantalum-Capacitors/Tantalum-Capacitors-Solid-SMD/_/N-75hr4?P=1yztnms
Otherwise you can take my schematic and make your own layout for components you can buy.
I just wanted to give my version of the tube emulation using semiconductors.
Title: Re: KMG SS Poweramps
Post by: askwho69 on February 14, 2011, 11:37:15 PM
are you related to Einstein? ;D :o  or came from another planet? YOURE GENIUS! your project is super impressive!
Title: Re: KMG SS Poweramps
Post by: Steve Conner on February 15, 2011, 05:11:03 AM
Yes, I agree. No reason to be scared of SMD nowadays. Annoyed maybe, scared no. :)

For these circuits, wouldn't a mains transformer be close enough to use as an OPT? The type with two 120V primaries and a low voltage secondary.

Toroidal ones have pretty low leakage inductance, but they're awfully sensitive to DC imbalance, and saturate more suddenly than EI transformers, which gives harsher distortion. The EI type with chambered bobbins probably have too high leakage inductance.
Title: Re: KMG SS Poweramps
Post by: gbono on February 15, 2011, 02:24:45 PM
I have been "trained" to populate proto SMT PCBs using a pre-heater and a heat gun - the paste is dispensed with an old Madell dispenser and manual "pick & place" with an aquarium vacuum pump. I need a microscope to see what I'm doing  :( Same station does rework
Title: Re: KMG SS Poweramps
Post by: J M Fahey on February 15, 2011, 02:53:10 PM
I have been "trained" to populate proto SMT PCBs using a pre-heater and a heat gun - the paste is dispensed with an old Madell dispenser and manual "pick & place" with an aquarium vacuum pump. I need a microscope to see what I'm doing  :( Same station does rework
I'm impressed !!!!!!!!!!!!  :o :o :o :o :o
Please tell us something about this.
Pictures would sure help; a short film even more so.
Wow!
Title: Re: KMG SS Poweramps
Post by: KMG on April 25, 2011, 06:22:02 AM
How about this sound? ;)
http://milas.spb.ru/~kmg/files/projects/fetpa/micro/reamp/1.mp3
Title: Re: KMG SS Poweramps
Post by: joecool85 on April 25, 2011, 11:04:10 AM
How about this sound? ;)
http://milas.spb.ru/~kmg/files/projects/fetpa/micro/reamp/1.mp3

Sounds great.  Especially love the first 1/3 of the clip - great tone and playing.

**edit**
Are you planning on selling these amps at all?  Or kits to build them?  At least a preamp maybe?
Title: Re: KMG SS Poweramps
Post by: KMG on April 25, 2011, 11:47:48 AM
You will be laughing, but it is the sound of this baby:
http://milas.spb.ru/~kmg/microfetpa_en.html
I simply changed transformer to different one, to match 4x12 cabinet impedance.
Output power is about 70mW, but it really hear with the correct sound of full powered amp head.
It is very suitable for "night playing" when you do not want to disturb sleeping children.
Sample recording path:
E-MU Tracker Pre->Fet JCM800->Micro Fet PA->4x12 Cabinet->Sennheiser E906->E-MU Tracker Pre
Quote
Are you planning on selling these amps at all?  Or kits to build them?  At least a preamp maybe?
Only one item is now planned for production - 5W fet PA
(http://milas.spb.ru/~kmg/files/projects/fetpa/mp/boardS.jpg)
I already received boards & transformers for it.
Title: Re: KMG SS Poweramps
Post by: THChrist on April 25, 2011, 01:42:50 PM
Why not a convertible version? 5w/15w/30w? or something like that? lol
i love the sound you get from those fets!
Title: Re: KMG SS Poweramps
Post by: KMG on April 25, 2011, 03:20:17 PM
The main problem with other PA versions is availability of transformer cores, suitable for sound applications.
5W version uses a standard core, which easy to order.
Title: Re: KMG SS Poweramps
Post by: KMG on May 06, 2011, 08:54:33 AM
Another one sample of fet JCM800 & micro fet PA
http://milas.spb.ru/~kmg/files/projects/fetpa/micro/reamp/12A.WAV
Title: Re: KMG SS Poweramps
Post by: askwho69 on May 11, 2011, 01:20:26 PM
Hi KMG just want to ask what kind of Transformer are you using in Fet PA? i want to make oe for home use amp :D and use my sans amp as preamp :D


thanks


Title: Re: KMG SS Poweramps
Post by: KMG on May 11, 2011, 03:49:20 PM
Which model do you mean?
For some models I use cores of standard transformers from this company
http://www.transled.ru/products/open/
5W - ТПК-15
15W - ТП-30
90W - ТПК-190
40W - old transformer core (don`t know type)
micro PA - TOT60/TOT57
Parameters of these transformers (TOT series) you can find there (unfortunately in russian)
http://milas.spb.ru/~kmg/files/literature/Malogabaritnye_transformatory_i_drosseli.(1985).zip
Title: Re: KMG SS Poweramps
Post by: askwho69 on May 13, 2011, 08:05:20 AM
where can i find transformer for micro PA? the 5watts PA? i really want to make one but i dont really understand how the thing works . .  about amps! :D
Title: Re: KMG SS Poweramps
Post by: KMG on May 13, 2011, 09:57:31 AM
Quote
where can i find transformer for micro PA? the 5watts PA? i really want to make one but i dont really understand how the thing works . .  about amps! :D
For micro PA you can try to use transformer from old transistor radio.
Also maybe this one will match for loading on cabinet.
75mW rating
http://eu.mouser.com/ProductDetail/Xicon/42TL008-RC/?qs=sGAEpiMZZMv0IfuNuy2LUcl0UojJLOKICZc25y8dmyo%3d
200mW rating
http://eu.mouser.com/ProductDetail/Xicon/42TM008-RC/?qs=sGAEpiMZZMv0IfuNuy2LUcl0UojJLOKIC2kkfS0HPnQ%3d

5W PA transformer
Core cross section 20x16 mm
Each half bobbin:
120 turns 0.25 mm (1/4) primary
75 turns 0.5 mm secondary (for 8 Ohm load)
120 turns 0.25 mm (1/4) primary
Title: Re: KMG SS Poweramps
Post by: askwho69 on May 14, 2011, 06:21:42 AM
Wow thank you so much! by the way i found an old monitor and found many things there transformer too. . . but the thing is i dont know how to check the transformers specs . . but thanks anyways!
Title: Re: KMG SS Poweramps
Post by: KMG on May 14, 2011, 06:52:41 AM
Quote
by the way i found an old monitor and found many things there transformer too. . . but the thing is i dont know how to check the transformers specs . . but thanks anyways!
If the transformer has a ferrite core, it is not suitable as the output transformer.
Title: Re: KMG SS Poweramps
Post by: askwho69 on May 15, 2011, 02:15:29 PM
ohhh thanks KMG for the reply ... very informative :tu:
Title: Re: KMG SS Poweramps
Post by: phatt on May 20, 2011, 09:27:04 AM
Yes unlikely to find the right Xformer in SS electronic gear  :'(

Though a thought just crossed my mind,,, hum thinkin,,thinkin headscratch.

You maybe able to source 100volt line transformers as they have been used with success in Valve rigs and it is likely they could be made to work with KMG's concept.

The OT is the tricky part for home builders.

This is what someone with a deep understanding did with an Oven tray, Line transformer and the odd valve.
  http://www.ozvalveamps.org/ava100/ava101minilamington.htm
Might be worth a look?
Phil.
Title: Re: KMG SS Poweramps
Post by: KMG on May 22, 2011, 09:49:43 AM
Quote
You maybe able to source 100volt line transformers as they have been used with success in Valve rigs and it is likely they could be made to work with KMG's concept.
110V transformer with center tap (2x55V) seems to be good for versions with 80V supply.
Just select one with suitable secondary voltage.
Title: Re: KMG SS Poweramps
Post by: phatt on May 24, 2011, 08:52:59 AM
Using mains as OT's?? Yes that makes sense :tu:
But I was actually reffering to *line driver transformers* as used in buildings where very long wires are used to link many speakers.

These unit are probably better suited than mains rated transformers and are intended for audio AC not mains AC.

If anyone is interested I'll try to find more info.
Phil.

Title: Re: KMG SS Poweramps
Post by: J M Fahey on May 24, 2011, 10:20:09 PM
Both types *do* work, with some quirks because of their original intended purpose.
Power transformers work very well in low frequencies (they are designed for 50/60Hz with over 95% efficiency, at full power), they couldn't care less above anything over 400 Hz ; it's a miracle that they have any highs at all.
Cheap line transformers expect to run from 2 to 15W into small speakers embedded in ceilings, etc., meaning their response often starts falling below 200Hz.
Main problem, on both, is getting center-tapped ones.
Well, a 110+110V primary will probably work.
Title: Re: KMG SS Poweramps
Post by: KMG on May 25, 2011, 09:45:39 AM
Quote
Power transformers work very well in low frequencies (they are designed for 50/60Hz with over 95% efficiency, at full power), they couldn't care less above anything over 400 Hz ; it's a miracle that they have any highs at all.
In my FET PAs I used thin ribbon winded cores from power transformers (but with interleaving primary/secondary windings)
5W loss ~3dB@20kHz
(http://www.transled.ru/catalog/76.jpg)
15W loss ~4dB@20kHz
(http://www.transled.ru/catalog/73.jpg)
90W loss ~3dB@20kHz
(http://www.transled.ru/catalog/77.jpg)
Quote
Well, a 110+110V primary will probably work.
In this case you have twice reduced primary coil current limit, due to thinner primary coil wire.
Title: Re: KMG SS Poweramps
Post by: J M Fahey on May 25, 2011, 11:59:55 AM
Of course.
You took special care to rewind and interleave properly.
What I talked about was off the shelf, straight power transformers, used as-is.
Nice cores you got; all I can find is regular EI cores (although I often get the high quality Russian iron ones, the ones with a mottled yellow-greenish surface), the same I found on some Soldano transformers.
Other times I get the dull grey Brazilian ones, which are also quite good.
Title: Re: KMG SS Poweramps
Post by: KMG on July 08, 2011, 09:12:11 AM
Sound comparision - 5W fet PA against 2x6L6 PP, 1хV30 1/3 open cabinet
http://milas.spb.ru/~kmg/files/projects/fetpa/mp/samples/1.wav
http://milas.spb.ru/~kmg/files/projects/fetpa/mp/samples/2.wav
Title: Re: KMG SS Poweramps
Post by: KMG on July 19, 2011, 11:42:25 AM
Samples recorded by my friend DKS from GtLab
Tube preamp UENGO-1 + 5W Fet PA
Midgain
http://milas.spb.ru/~kmg/files/projects/fetpa/mp/samples/JTR_FET_MIDGAIN.mp3 (1,89МB)
Highgain
http://milas.spb.ru/~kmg/files/projects/fetpa/mp/samples/Uengo_Hg8_M.MP3 (1,8МB)
Title: Re: KMG SS Poweramps
Post by: KMG on July 20, 2011, 06:01:15 PM
Quote
But I was actually reffering to *line driver transformers* as used in buildings where very long wires are used to link many speakers.
If anyone is interested I'll try to find more info.
Phil.
Found at least one type
http://www.rcf.it/en_US/products/commercial-audio/attenuators-transformers/td-105
Primary 100V with center tap
Title: Re: KMG SS Poweramps
Post by: phatt on July 20, 2011, 10:46:40 PM
Yep they are the type that will work well.
Tricky for the novice to understand how to convert the taps to something meaningful.

This gives some info on how to wire-up the taps
http://www.ozvalveamps.org/optrans.htm
Phil.
Title: Re: KMG SS Poweramps
Post by: KMG on September 15, 2011, 05:31:58 AM
Results of testing Xicon transformers in micro PA (instead of russian trafos, that hard to find).
Schematic
(http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/sim/micro.jpg)
Voltage frequency response on resisitive load with Presence & Depth action (real device).
(http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/tests/PresDepth.png)
Comparative voltage frequency response on resisitive load & cabinet with Presence & Depth = min.
(http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/tests/Cab_dummy.png)
Sim (LtSpice) project with measured parameters of TM008
http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/sim/
It gives about 100mW of power, really audible at 4x12 cab & suitable for "night" playing.
For line recording I plan to use this kind of load to simulate speaker impedance for adequate interaction of PA with load.
(http://milas.spb.ru/~kmg/files/projects/fetpa/micro/Load.jpg)
And frequency correction after load to simulate cabinet/mic response.

PS Sample:
Fet JCM800->Micro PA->4x12 cabinet
http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/s/8-Southern%20LP.wav
Title: Re: KMG SS Poweramps
Post by: KMG on October 21, 2011, 03:17:43 PM
Additional samples, cab_s - microPA+4x12+mic, cs_s  - microPA+speaker equivalent+cabinet simulator
http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/s/2-Classic%20T_cab_s.mp3
http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/s/2-Classic%20T_cs_s1.mp3
http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/s/4-Criminal%20Def_cab_s.mp3
http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/s/4-Criminal%20Def_cs_s1.mp3
http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/s/6-Kid%20Paul_cab_s.mp3
http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/s/6-Kid%20Paul_cs_s1.mp3
http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/s/8-Southern%20LP_cab_s.mp3
http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/s/8-Southern%20LP_cs_s1.mp3
Frequency response
(http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/tests/Cab_Cs1.png)
Title: Re: KMG SS Poweramps
Post by: joecool85 on October 21, 2011, 03:46:52 PM
KMG, I haven't had a chance to listen to your latest samples, but seriously, is this what you do for a living?  It seems you're working the hell out of this circuit.  Are you planning on selling PCB kits?  Full built amps?  Anything?
Title: Re: KMG SS Poweramps
Post by: KMG on October 22, 2011, 09:10:50 AM
KMG, I haven't had a chance to listen to your latest samples, but seriously, is this what you do for a living?  It seems you're working the hell out of this circuit.  Are you planning on selling PCB kits?  Full built amps?  Anything?
No, it's my hobby to change my thoughts from main work.
Only one item now in production - 5W fet PA kits (assembled & tested board).
(http://milas.spb.ru/~kmg/files/projects/fetpa/mp/boardS.jpg) (http://milas.spb.ru/~kmg/files/projects/fetpa/mp/board.jpg)
In plans home recording box - micro PA+load equivalent+cabsim.
You can use micro PA output on cab for night playing with recording from sim output.
Or you can pass singal to sim input form big amplifier output (in parallel with cabinet) for recording without mic.
Title: Re: KMG SS Poweramps
Post by: KMG on October 22, 2011, 02:42:41 PM
Full micro PA project
(http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/MicroSch_th.jpg) (http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/MicroSch.pdf)
(http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/MicroLut_th.jpg) (http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/MicroLut.pdf) (http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/MicroComp_th.jpg) (http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/MicroComp.pdf)
(http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/MicroSold_th.jpg) (http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/MicroSold.pdf) (http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/MicroSold1_th.jpg) (http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/MicroSold1.pdf)
Title: Re: KMG SS Poweramps
Post by: KMG on October 26, 2011, 07:08:02 AM
Micro PA, load equivalent & speakersim assembled in box.
(http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/box_th.jpg) (http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/box.jpg)
Title: Re: KMG SS Poweramps
Post by: KMG on October 27, 2011, 10:21:08 AM
Full (Micro PA, load equivalent & speakersim) schematic:
http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/sim/micro_eq_sim.pdf
Title: Re: KMG SS Poweramps
Post by: Evil_Food on November 02, 2011, 01:04:13 PM
I don't understand this at all.

In my view the whole point of solid state amps is to save money. The most expensive components in tube amp is usually the output transformer, which usually costs several times the rest of the components. If you just look on sowter's website, the cheapest one is about £100 http://www.sowter.co.uk/acatalog/SOWTER_TRANSFORMERS_PUSH_PULL_OUTPUT_16.html (http://www.sowter.co.uk/acatalog/SOWTER_TRANSFORMERS_PUSH_PULL_OUTPUT_16.html) (guitar OTs are cheaper though).

If we disregard the tone effects of an OT (I haven't read a sophisticated article regarding this subject so far), there are two aspects of a tube power amp - overdrive behaviour and output impedance.

The impedance is so EASY to implement in a SS amp (I bet someone's already posted a link to this http://sound.westhost.com/articles/guitar-amps.htm#s3 (http://sound.westhost.com/articles/guitar-amps.htm#s3)) and is actually widely used.

The other aspect is overdrive behaviour. I've read articles saying that FETs operate like Tubes (which is a stupid statement) and therefore valve circuits can just be copied and components replaced.

What's similair between the two types of devices is that they have very low transconductance and, unlike BJTs, it isn't as strongly dependent on quiescent current (in a BJT gm=Ic/VT and in a MOSFET, for example, above the threshold voltage it is fairly constant).

I tried making a MOSFET gain stage using a BS170 biased with a quiescent current of about 150mA (which is quite high for a preamp). The output waveform (on an oscilloscope, not SPICE) looked pretty much like that of a tube gain stage. But when I played a guitar through it it didn's sound good at all. I decided to look at the spectrum of the output from the gain stage. What I noticed is that there was a strong second harmonic (which everybody goes on and on how desireble and tube-ish it is), but there was also a noticeble 9th harmonic. I tried to find an ideal overdrive value, but there wasn't one. It just doesn't work with single discrete mosfets.

I've wandered off a bit. My main question is - what's the benefit of all this?
Title: Re: KMG SS Poweramps
Post by: phatt on November 03, 2011, 05:25:22 AM


@ Evilfood,
"I've wandered off a bit. My main question is - what's the benefit of all this?"

Answer is IT Works.
I agree that Transformers can be expensive but you can substitute 100 Volt line units which can often be purchased for VERY Low $$.
Phil.
Title: Re: KMG SS Poweramps
Post by: J M Fahey on November 04, 2011, 08:54:39 AM
Dearevilfood.
Generally it is as you say. I agree.
In fact, I HATE the assumption so much believed in a couple famous Forums (won´t give names but everybody knows them) where they foolishly take some classic tube amp, just substitute the tube with some FET, use the same biasing resistor values, power it with 9V and happily "think" it´s the same.
Ugh !!
They even post buzzy horrible sounding clips and find them "the same as the originals"
That kind of "design" is so horrible that they *need* a trimmer on *every* FET to make it work (sort of).

When I first read about these, I must confess my first gut reaction was the same as yours, in fact my first answer to the topic said something similar.
But Mr KMG blew me away, simple as that.
He did his (very extensive) homework, advanced slowly, step by step, and has made everything necessary to capture Tube sound and behavior.
I invite you to read all his posts, from the very beginning ...... then re-read again, a couple times.
Much more important: listen to the MP3's , the REAL proof.
What surprises me even more, is that he generously shares everything here, even PCB designs, he hunts affordable parts for us to build his designs, answers doubts, etc. , when in my opinion he might (and should) be making big $$$$$ with this.
In other high level Technical forums he is much praised by very knowledgeable and experienced guys.
And, as I said before, the proof of the pudding lies in the eating, just listen to the MP3s.
Title: Re: KMG SS Poweramps
Post by: KMG on November 07, 2011, 04:44:55 PM
Preliminary (test) single board version of "recording box" (Micro PA, load equivalent & speakersim).
(http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/full/brdtop_th.jpg) (http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/full/brdtop.jpg)
Title: Re: KMG SS Poweramps
Post by: KMG on November 16, 2011, 11:46:07 AM
Link to full project (microPA, eqivalent, cabsim)
http://milas.spb.ru/~kmg/index_en.html
Micro power amplifier for line recordimg ver. 2
Title: Re: KMG SS Poweramps
Post by: phatt on November 17, 2011, 04:44:28 AM
Plus x 10 on what Mr Fahey stated above.

Beyond doubt this is very clever.

What I Would like to mention is the issue of *Surface mount*
This more than any other problem will slow the progress of the concept.

I'll even stick my neck out here;

The best thing that could happen NOW is have folks build it and report back with Positive findings.
The faster that happens the better chance of success.

So @ KMG,, I hint,

If you want this to take off You need to present it as a Normal single sided board layout.

I have no doubt your ideas are worth building but surface mount is not for the average home builder. xP

Wait till some of you chaps hit 50 years plus and your eyesight starts to let you down and you will see the sense in SANE layouts.

I refuse point blank to work on things I can't even see. :trouble

Not to mention that slowly but surely the experts are starting to realize that the Lead Free Solder stuff is not as good as it first looks.

Just some thoughts and observations from an old bugga in the  Land down under,,, Phil.
Title: Re: KMG SS Poweramps
Post by: KMG on November 17, 2011, 06:30:26 AM
Quote
If you want this to take off You need to present it as a Normal single sided board layout.
I use components that I can simply obtain.
So rerouting to non smd components will make problem for me - hard to assemble & test, to present fully checked project.
Quote
I have no doubt your ideas are worth building but surface mount is not for the average home builder.
There You can download kicad files for this project (if You use kicad):
http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/full/kicad/
There You can download archive of my kicad libraries (with 3D models):
http://milas.spb.ru/~kmg/share.zip
Overwrite existing kicad files in "share" folder.
Try to change shapes of smd components by yourself & reroute board.
Quote
Wait till some of you chaps hit 50 years plus and your eyesight starts to let you down and you will see the sense in SANE layouts.
Check my date of birth in profile. About a half of month later I will have jubilee. ;)

PS Clock repairing visor can solve problem
(http://www.ronellclock.com/images/1223804177755-1641895394.gif)

Mike.
Title: Re: KMG SS Poweramps
Post by: phatt on November 17, 2011, 06:57:10 AM
Hello KMG,
                Thanks for the reply.

For teck savvy folk sourcing parts is obviously not that hard in this net world we now live in,,
But I'm old school and I DO Not use the Net to do banking or source parts.

This is a spare time hobby and I don't have access to a lot of gear that some might take for granted.

Although I use a computer I have little tecky ability when it comes to the internet and latest Ubertube tricks.
Heck,, I'm one of those lost souls that still uses a Tape deck and a Turntable. :lmao:

As to your Eyes,, Lucky you if you have hit 50 and don't need glasses a magnifying glass and a flood light just to read the Value on a TL072 chip.   For me,,,forget reading cap values on surface mounts.. :loco

I don't even bother trying to work on intricate stuff after the sun goes down.

Anyway thanks Heaps for trying to help us all,,,, You have done a great thing even if blind dudes like me can't read the values on tiny parts

I thank you for your contribution to the cause. :dbtu:

I will look into the *Kicad*

but damn it all ,,, I've got so many things to finish first.
Time time time,,, it just runs away as you get older.

Nuff of my whinging.

Phil.
Title: Re: KMG SS Poweramps
Post by: KMG on November 17, 2011, 07:17:14 AM
Quote
I will look into the *Kicad*
http://kicad.sourceforge.net/wiki/Main_Page
The main advantage of kicad is "free of charge" - you don`t need to pay for it.
But it has most features of "big" CAD.
Also it multiplatform - "Linux, Windows and experimental on Mac OS X."
Title: Re: KMG SS Poweramps
Post by: HENK on November 17, 2011, 10:10:35 AM
phatt:
Tape-deck + Turntable???? :dbtu: :dbtu: :dbtu:

Greets from an another old fart...

KMG: Great work,Man,thanks alot!!!
Title: Re: KMG SS Poweramps
Post by: phatt on November 18, 2011, 06:09:06 AM
phatt:
Tape-deck + Turntable???? :dbtu: :dbtu: :dbtu:

Greets from an another old fart...

KMG: Great work,Man,thanks alot!!!

Arrh,, Good to know there is still a few of us left in this mad world.
When I first heard the term MP3 ,,I thought they said, MP FREE.  :lmao:

Phil.
Title: Re: KMG SS Poweramps
Post by: phatt on November 25, 2011, 04:15:00 AM
Quote
I will look into the *Kicad*
http://kicad.sourceforge.net/wiki/Main_Page
The main advantage of kicad is "free of charge" - you don`t need to pay for it.
But it has most features of "big" CAD.
Also it multiplatform - "Linux, Windows and experimental on Mac OS X."

Thanks KMG.

I have loaded Kicad and it looks impressive. :tu:
I have been able to get some schematics up and saved but still trying to work out how to get from ,, Schematic to board layout. Head scratch?
(I'm used to Eagle which generates a board by one simple cilck,,, this is obviously a different system?)

I'm also waiting to hear if I can get hold of LND150 mosfets.
These units may not be easy to get hold off in Australia? if so it may not be worth the effort.

Meantime I will keep trying to use this new program. :duh xP :loco :grr :'( :-X

I did recently try to use the old Protel,, Easy track stuff after J M Fahey made the suggestion but my Dos ability is scratchy and even using a *Dos Box* Prg it was still extremely hard to find my way around it all.

As I'm sure you can understand this is really just a hobby for me and I don't wish to embark on starting up an Electronics company so I do have to keep it plain and simple.

Thanks for your input and trying to help.

Phil.
Title: Re: KMG SS Poweramps
Post by: KMG on November 25, 2011, 08:10:38 AM
Hi Phil.
Convertation from schematic to board is simple.
1. Annotate whole schematic (reference designators) manually or automatically if need.
2. Export netlist.
3. Start "cvpcb" to assign shapes to components & save result.
4. Read netlist in board editor.
All components will be placed into board.
So you can start to move them to proper places & route traces.
There are good enough PDF help files in different languages:
...\KiCad\doc\help\

I purchased LND150 & trafos for micro PA from mouser:
http://au.mouser.com/ProductDetail/Supertex/LND150N3-G/?qs=sGAEpiMZZMvECErq9cesgJdUgk/FlBvJcYi5pvrBL5Q=
http://au.mouser.com/ProductDetail/Xicon/42TU400-RC/?qs=sGAEpiMZZMv0IfuNuy2LUQ0m87amfyq2VwqQkCtNXxk=
Shipping costs for Australia:
http://au.mouser.com/EstimateShipping/EstimateShipping.aspx

Regards, Michael.
Title: Re: KMG SS Poweramps
Post by: phatt on November 26, 2011, 03:49:28 AM
Thanks Michael,
                      Yep I do *Now* realize the *Net list* is how it converts too the board program.

I Still get errors trying to convert from Schematic. Dang it!!

The CVpcb part shows *Not found parts*

Not to worry,,,I'll just keep on plodding through all the details and reading the help files.
I'm sure that eventually the penny will drop.

I did spend a long time getting to understand how to use Simulators which to the novice can give very misleading results.

Next month I'll D/load the files you worked with and that might help me to come to terms with this wonderful software.

I do have to watch how much I download as my net speed reduces to a crawl if I get carried away.

Hopefully this week I'll find out how much the Mosfets will cost me delivered.

Note; As I'm sure you can appreciate It is easy to D/load a lot of software but few often deliver,, so one has to be careful not to D/load software that is useless.

In some ways I feel that this technology is leaving my tired old brain behind and some time I may have to admit defeat.

I'm really just a guitar player at heart and at times I wish I'd never discovered electronics,,, but at least I've learn't to circumvent a lot of silly useless circuits in the process,,, which has saved me from purchasing useless crap.  $$ money saved at least.
Phil.
Title: Re: KMG SS Poweramps
Post by: J M Fahey on November 26, 2011, 07:57:22 AM
Quote
at times I wish I'd never discovered electronics,

You broke my heart  :'( :'( :-\ :-\ xP xP

I think I  >:( >:( :grr :grr





























Just joking  :lmao:
Title: Re: KMG SS Poweramps
Post by: phatt on November 30, 2011, 05:22:31 AM
Quote
at times I wish I'd never discovered electronics,

You broke my heart  :'( :'( :-\ :-\ xP xP

I think I  >:( >:( :grr :grr

Just joking  :lmao:

Ha Ha very funny.
Not only are you exceedingly gifted in the art of electrical things you are also a talented comedian. ;)

In which I say; May the fleas of a thousand Camels descend upon your Armpits on a very hot sweaty day in Argentina. :P

ps, Jaun ,, you would be proud of me as I have at least got something to happen with *Kicad* software.
I've been able to get a board on the screen with parts and wires. :dbtu:

It's all a bit dodgy and some components are the wrong type but slowly I'm making inroads.

Phil.
Title: Re: KMG SS Poweramps
Post by: J M Fahey on November 30, 2011, 08:23:25 AM
Well, I think *both* of us will soon be proud of each other.
Thank to KMG´s kind suggestions, plus your own problems with old DOS Easy Trax, Auto Trax , etc. , I´ve also decided I must upgrade.
Lately I do not seem to see that many horse drawn carts on the street, finding instead strange smoking horseless carriages, with drivers strapped inside, so I guess the World must be changing after all :lmao:
For my own silkscreened or thermal transfered PCB production, fine, but I realize that if I send somebody a design they won´t be able to even open it, let alone any kind of printing.
And forget having any commercial PCB made. (well, *maybe in Australia) 8|
I hated EAGLE, plus the tiny board they allow in the Free version is useless for me.
*Any* discrete power amp PCB is *at least* 8x10cm; *any* guitar preamp is at least 6 pots long (18 cm), even more if I include PCB nounted jacks, some switches, even a couple LEDs, so I was on the lookout for a modern, free PCB pack.
Remember our friend going crazy to cut his Laney PCB down to fit in a Rack enclosure (19" wide).
KICAD seems to be it.
I´m *starting* to learn it (it ain´t easy to teach new tricks to the old dog) and so far I like it.
It would be good to standardize on it, at least here in SSGuitar, so we can all exchange schematics and PCBs at will.
I mean: all those Robotics and PIC or STAMP forums are happy with EAGLE, but for them the PCB size allowed is more than enough.
Not so on the Guitar World.
Title: Re: KMG SS Poweramps
Post by: phatt on December 02, 2011, 10:40:19 AM
@ KMG,

Well it looks like the LND150 mosfet is going to cost way more than I planned, so hardly worth all the effort.  :'(  As much as I'd love to build some of Your work with all SS it really is not worth my effort, as it's only a hobby for me and I can't justify the extra expense.

I already have a good Hybrid setup which only uses one AX7 to get the big voltage swing and the rest is all done via SS.  So for now it's bottom draw of the hard drive. :'( :'(

My local electronics store is still looking to source these components but I don't like my chances.

I only wanted to do it Because I have a big soft spot for SS guitar gear and it would be a buzz to have the whole Amp running SS.

Truth is that learning to understand Transistors and opamps gave me the grounding I needed to take on building Valve rigs.

But I'd like to say thankyou as the Kicad software may well prove very useful as it will give me the ability to implement a few larger builds that have sat in the bottom draw, (too hard to hand draw with ink pen)

I'm still reading the help files but other projects are still not finished and meantime, it's summer and the grass grows at insane speed in this part of the world.


@ JM Fahey,
           I have no doubt that even an old dog like you will make faster progress than myself.  :)
I'm hoping to get the local print shop to lazer print my PCB. At 35 cents a copy it may work out cheaper than purchasing my own lazer printer. (those ink cartridges are not cheap)
I really don't wish to embark on all that photo etching if it can be done with the lazer ink and iron on trick.

I only need a few boards so Lazer print is very appealing for my small needs.

Phil.
Title: Re: KMG SS Poweramps
Post by: polo16mi on December 03, 2011, 05:13:20 PM
For those old dogs that bark in spanish,  and are looking for new tricks, here Kicad tutorial
http://www.aclibre.org/archives/KiCad-es.pdf (http://www.aclibre.org/archives/KiCad-es.pdf)
Title: Re: KMG SS Poweramps
Post by: J M Fahey on December 03, 2011, 05:41:42 PM
Thanks, in the name of all Spanish speaking members. :tu:
Title: Re: KMG SS Poweramps
Post by: KMG on January 25, 2012, 06:53:42 AM
Additional sample (mix) of micro PA (250mW) on cabinet
http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/s/AR.mp3
Guitar - LP
Preamp - UENGO-1 (http://kdyworks.com/index.php?option=com_content&view=article&id=68&Itemid=63)
Cabinet - 1x12 CELESTION G12M
Title: Re: KMG SS Poweramps
Post by: KMG on February 21, 2012, 09:42:18 AM
In progress design of final version of micro PA + speaker simulator +  mini mixer +  headphone amp
Title: Re: KMG SS Poweramps
Post by: joecool85 on February 22, 2012, 09:52:14 AM
I'm still of the mindset that you need to get these things into production and start selling them  :dbtu:
Title: Re: KMG SS Poweramps
Post by: KMG on April 03, 2012, 04:10:18 PM
Got front & rear panels for micro PA+ speaker simulator +  mini mixer +  headphone amp
(http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/full/Panels_th.jpg) (http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/full/Panels.jpg)
& 5W FET PA
(http://milas.spb.ru/~kmg/files/projects/fetpa/mp/Panels_th.jpg) (http://milas.spb.ru/~kmg/files/projects/fetpa/mp/Panels.jpg)
Waiting for the chassis will be made for both devices.
Title: Re: KMG SS Poweramps
Post by: joecool85 on April 04, 2012, 08:57:03 AM
Those look great, how'd you make them?
Title: Re: KMG SS Poweramps
Post by: J M Fahey on April 04, 2012, 02:45:39 PM
Very good !!
Is it Laser engraved?
Title: Re: KMG SS Poweramps
Post by: KMG on April 04, 2012, 03:23:39 PM
Painted anodized aluminum.
This technology is more durable than silk-screening.
I ordered these panels at this company:
http://translate.google.com/translate?hl=en&sl=ru&tl=en&u=http%3A%2F%2Fm-graf.ru%2F
Big panels 9.7"x2" costs about $5 each, small 7"x2" about $3 each.
Panels are 1mm thick &  has adhesive at reverse side.
This is cheaper than laser engraving in quantities more than one.
I think you can find same companies in each country.
http://www.mpofcinci.com/anodized-aluminum-panels.html
http://www.macnameplate.com/
http://www.alumaphoto-plateco.com/products/nameplates-and-control-panels.html
....
Title: Re: KMG SS Poweramps
Post by: joecool85 on April 05, 2012, 10:07:19 AM
That's pretty cool!
Title: Re: KMG SS Poweramps
Post by: J M Fahey on April 05, 2012, 01:41:41 PM
OK, thanks.
Title: Re: KMG SS Poweramps
Post by: KMG on April 10, 2012, 09:15:04 AM
deLuther: Quick test (webcam mic) of KMG microamp prototype (250 mW)

http://www.youtube.com/watch?v=by2tYl6iqRo

Charvel Model 6 Orange Crackle (2xJackson J200+Caparison CMB3 as boost, SD Blackout AHB-1),
Chris Custom Screamer, ENGL Tubetoner e430,
KMG microamp 250 mW (prototype) into Randall RG75 cabinet
Webcam mic
Tubetoner Heavy Lead channel with TS on entire video
Title: Re: KMG SS Poweramps
Post by: polo16mi on April 10, 2012, 12:55:06 PM
http://www.youtube.com/watch?v=by2tYl6iqRo

wow...nice sound!
Title: Re: KMG SS Poweramps
Post by: KMG on April 10, 2012, 03:26:17 PM
http://www.youtube.com/watch?v=dm67Lv4KGBI
Quick test, Randal RG75 vs KMG microamp as poweramp
Charvel Model 6, ENGL Tubetoner e430, Chris Custom Screamer
Recorded with Shure SM58 (without cap) into Digilab SPM-100, slight EQ processing
KMG 250 mW prototype
Title: Re: KMG SS Poweramps
Post by: KMG on April 13, 2012, 04:57:17 AM
Randall RG75 and KMG microamp in mix

http://www.youtube.com/watch?v=LM8Q6nj6vxI

ENGL Tubetoner E430, Chris Custom Screamer
Charvel Model 6 (EMG 85 and SD AHB-1), Caparison TAT
Title: Re: KMG SS Poweramps
Post by: KMG on May 24, 2012, 12:43:28 PM
Another one microamp test.
Charvel Model 6 Orange Crackle with EMG 85 and Jackson J50BC
Chris Custom Screamer, ENGL Tube Toner e430 into KMG FET microamp (250 mW)
Randall RG75 used as Cab only
Test includes recording with Shure SM58 without cap, PA line output parallel to cab with impulse and cabsim out of microamp
http://www.youtube.com/watch?v=FDiursxnwOw
Title: Re: KMG SS Poweramps
Post by: KMG on June 13, 2012, 05:12:52 AM
Assembling process.
(http://milas.spb.ru/~kmg/files/projects/fetpa/mp/box2_th.jpg) (http://milas.spb.ru/~kmg/files/projects/fetpa/mp/box2.jpg)
(http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/full/box2_th.jpg) (http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/full/box2.jpg)
Title: Re: KMG SS Poweramps
Post by: J M Fahey on June 13, 2012, 06:21:22 AM
IMPRESSIVE stuff.
I guess you should quit your "other job" and get into producing these beauties full time.  :dbtu:
Not kidding.
Title: Re: KMG SS Poweramps
Post by: KMG on June 14, 2012, 11:34:13 AM
Assembled 5 W PA
(http://milas.spb.ru/~kmg/files/projects/fetpa/mp/box3_th.jpg) (http://milas.spb.ru/~kmg/files/projects/fetpa/mp/box3.jpg)
(http://milas.spb.ru/~kmg/files/projects/fetpa/mp/box4_th.jpg) (http://milas.spb.ru/~kmg/files/projects/fetpa/mp/box4.jpg)
(http://milas.spb.ru/~kmg/files/projects/fetpa/mp/box6_th.jpg) (http://milas.spb.ru/~kmg/files/projects/fetpa/mp/box6.jpg)
Title: Re: KMG SS Poweramps
Post by: joecool85 on June 14, 2012, 03:54:51 PM
WOW!

I'm with Juan, you need to start selling these, that's impressive!!  :tu:

Honestly, I'm not kidding, I'd buy one as I'm sure many others would as well.  Please let me know if you do decide to start selling these as I know of a few places around here that would probably be interested to sell these locally.
Title: Re: KMG SS Poweramps
Post by: KMG on June 17, 2012, 07:13:26 AM
Assembled micro PA:
(http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/full/box3_th.jpg) (http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/full/box3.jpg)
(http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/full/box4_th.jpg) (http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/full/box4.jpg)
(http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/full/box6_th.jpg) (http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/full/box6.jpg)
Title: Re: KMG SS Poweramps
Post by: bassetrox on June 20, 2012, 08:56:26 AM
Hi KMG, once again, great work,

and thanks for sharing so liberally.

I've been trying to simulate your 5W PA design to help me better understand it, but I can't get more than a couple of millivolts clean signal. Any idea what I'm doing wrong? I haven't got much experience simulating fets with tx.
Title: Re: KMG SS Poweramps
Post by: KMG on June 20, 2012, 10:28:42 AM
bassetrox, you can use LTspice simulation files from there
http://milas.spb.ru/~kmg/files/projects/fetpa/mp/sim/
Title: Re: KMG SS Poweramps
Post by: bassetrox on June 27, 2012, 05:02:25 AM
Thanks a lot KMG,
comparing your to mine, I cant see what I was doing wrong :s No worries anyway.

Have you tried any dual rail designs with complimentary pairs of lateral FETs into a tx?


bassetrox, you can use LTspice simulation files from there
http://milas.spb.ru/~kmg/files/projects/fetpa/mp/sim/
Title: Re: KMG SS Poweramps
Post by: KMG on June 27, 2012, 06:56:33 AM
Quote
Have you tried any dual rail designs with complimentary pairs of lateral FETs into a tx?
I tried this prototype, but it has zero temperature drift & I finished experiments with it.
http://milas.spb.ru/~kmg/files/projects/fetpa/nt/FetPaNt.pdf
Also you can try to read this article
http://translate.google.com/translate?hl=en&sl=auto&tl=en&u=http%3A%2F%2Fgtlab.net%2Fgtlab4%2Farchives%2F30
Title: Re: KMG SS Poweramps
Post by: KMG on July 06, 2012, 03:15:01 PM
Comparision records (made by my friend) of 6V6 PP PA & 5W fet PA:
http://milas.spb.ru/~kmg/files/projects/fetpa/mp/samples/ModS%20-%206V6PP%20vs%20KMG%20FET%205W.rar
They recorded using MOD_S custom amplifier using its own PA & 5W fet PA connected to "Send" jack.
Frequency response of both PA was equalised using Presence & Depth controls.
(http://milas.spb.ru/~kmg/files/projects/fetpa/mp/samples/6_V6_vs_FET_5_W.png)
Recordings are unnamed (numbered) so you can try to estimate "who is who".
Title: Re: KMG SS Poweramps
Post by: KMG on September 11, 2012, 11:57:04 AM
40W transformer output PA Module.

Partially SMD version.
(http://milas.spb.ru/~kmg/files/projects/fetpa/lp/nv/pa1_th.jpg) (http://milas.spb.ru/~kmg/files/projects/fetpa/lp/nv/pa1.jpg)
(http://milas.spb.ru/~kmg/files/projects/fetpa/lp/nv/pa3_th.jpg) (http://milas.spb.ru/~kmg/files/projects/fetpa/lp/nv/pa3.jpg)
(http://milas.spb.ru/~kmg/files/projects/fetpa/lp/nv/pa2_th.jpg) (http://milas.spb.ru/~kmg/files/projects/fetpa/lp/nv/pa2.jpg)

All through hole version.
(http://milas.spb.ru/~kmg/files/projects/fetpa/lp/nv/pa1-1_th.jpg) (http://milas.spb.ru/~kmg/files/projects/fetpa/lp/nv/pa1-1.jpg)
(http://milas.spb.ru/~kmg/files/projects/fetpa/lp/nv/pa1-3_th.jpg) (http://milas.spb.ru/~kmg/files/projects/fetpa/lp/nv/pa1-3.jpg)
(http://milas.spb.ru/~kmg/files/projects/fetpa/lp/nv/pa1-2_th.jpg) (http://milas.spb.ru/~kmg/files/projects/fetpa/lp/nv/pa1-2.jpg)
Information about both versions  there (http://milas.spb.ru/~kmg/files/projects/fetpa/lp/nv/).
Title: Re: KMG SS Poweramps
Post by: J M Fahey on September 11, 2012, 12:35:00 PM
Wow!! In-cre-di-ble !!!
Congratulations !!!!
It's way too generous of you sharing such advanced work with us   :tu:

PS: as a side note: your actual physical construction is *so* good, that I thought those were not pictures but some CAD design, go figure  :cheesy:
Title: Re: KMG SS Poweramps
Post by: KMG on September 11, 2012, 02:09:30 PM
PS: as a side note: your actual physical construction is *so* good, that I thought those were not pictures but some CAD design, go figure  :cheesy:
You're right, it's rendering from SolidWorks (http://www.solidworks.com/).
Title: Re: KMG SS Poweramps
Post by: J M Fahey on September 11, 2012, 04:45:19 PM
Ouch !!!  :o
You are considered such a good builder, that I thought *in this case* they were "real".
Go figure !!!  8|
Title: Re: KMG SS Poweramps
Post by: KMG on September 24, 2012, 08:29:55 AM
Mini head project - LND150 based JCM800 preamp + 5W PA.
(http://milas.spb.ru/~kmg/files/projects/jcm800mv/fet/lnd150/head/Head1_th.jpg) (http://milas.spb.ru/~kmg/files/projects/jcm800mv/fet/lnd150/head/Head1.jpg)
(http://milas.spb.ru/~kmg/files/projects/jcm800mv/fet/lnd150/head/Head2_th.jpg) (http://milas.spb.ru/~kmg/files/projects/jcm800mv/fet/lnd150/head/Head2.jpg)
(http://milas.spb.ru/~kmg/files/projects/jcm800mv/fet/lnd150/head/Head3_th.jpg) (http://milas.spb.ru/~kmg/files/projects/jcm800mv/fet/lnd150/head/Head3.jpg)
Title: Re: KMG SS Poweramps
Post by: J M Fahey on September 24, 2012, 01:13:39 PM
*Very* cool, congratulations !!! :dbtu: :dbtu:
Title: Re: KMG SS Poweramps
Post by: KMG on October 26, 2012, 07:15:33 AM
I got ordered PCB's for
Micro fet PA with speaker simulator
(http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/full/MicroBoards_th.jpg) (http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/full/MicroBoards.jpg)
& mini mixer for it
(http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/full/MixerBoards_th.jpg) (http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/full/MixerBoards.jpg)
Title: Re: KMG SS Poweramps
Post by: THChrist on October 30, 2012, 11:41:53 PM
Are you planning on selling these?

I got ordered PCB's for
Micro fet PA with speaker simulator
(http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/full/MicroBoards_th.jpg) (http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/full/MicroBoards.jpg)
& mini mixer for it
(http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/full/MixerBoards_th.jpg) (http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/full/MixerBoards.jpg)
Title: Re: KMG SS Poweramps
Post by: joecool85 on November 01, 2012, 02:05:25 PM
Are you planning on selling these?

I'm also curious. 
Title: Re: KMG SS Poweramps
Post by: THChrist on November 01, 2012, 02:16:24 PM
I have a question [raises hand]
how can you make(using LND150's) a shared-cathode stage like a superbass?
Title: Re: KMG SS Poweramps
Post by: KMG on November 04, 2012, 01:28:17 PM
Quote
Are you planning on selling these?
Only as part of complete devices.
(http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/full/box3_th.jpg) (http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/full/box3.jpg)
(http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/full/box4_th.jpg) (http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/full/box4.jpg)
(http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/full/box6_th.jpg) (http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/full/box6.jpg)
Quote
how can you make(using LND150's) a shared-cathode stage like a superbass?
I don't see problems. Only careful selection of the values in source network (& maybe biasing of this network).
Title: Re: KMG SS Poweramps
Post by: THChrist on November 05, 2012, 10:09:15 PM
Quote
Are you planning on selling these?
Only as part of complete devices.
(http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/full/box3_th.jpg) (http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/full/box3.jpg)
(http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/full/box4_th.jpg) (http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/full/box4.jpg)
(http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/full/box6_th.jpg) (http://milas.spb.ru/~kmg/files/projects/fetpa/micro/xicon/full/box6.jpg)
Quote
how can you make(using LND150's) a shared-cathode stage like a superbass?
I don't see problems. Only careful selection of the values in source network (& maybe biasing of this network).

but in what point i can do the "shared cathode" thing? between the diode and Rk?
Title: Re: KMG SS Poweramps
Post by: joecool85 on November 06, 2012, 12:37:26 PM
Quote
Are you planning on selling these?
Only as part of complete devices.

Let us know when you start selling them, I'll be sure to add some links on the site and on my personal blog.  Plus I might buy one...
Title: Re: KMG SS Poweramps
Post by: KMG on November 06, 2012, 02:13:13 PM
Quote
but in what point i can do the "shared cathode" thing? between the diode and Rk?
Something like this
Title: Re: KMG SS Poweramps
Post by: THChrist on November 06, 2012, 06:37:14 PM
Ok, i got it. thank you! (BTW, would you send your amps to Peru?)

Quote
but in what point i can do the "shared cathode" thing? between the diode and Rk?
Something like this
Title: Re: KMG SS Poweramps
Post by: THChrist on November 06, 2012, 07:34:09 PM
BTW, will you make some of these?
Title: Re: KMG SS Poweramps
Post by: KMG on May 31, 2013, 09:29:03 AM
Some time ago I found very interesting MOSFETS IXTP01N100D.
http://ixapps.ixys.com/DataSheet/DS98809C%28IXTP-U-Y01N100D%29.pdf
1kV of the drain voltage, 25W power dissipation. That allows to use them with standard transformers for tube amplifiers.
I already received ten of them from arrow electronics.
Now I'm waiting for the ordered transformer http://www.classictone.net/40-18045.pdf to start testing.

Title: Re: KMG SS Poweramps
Post by: THChrist on July 25, 2013, 07:40:45 AM
Hey! Any news about those transistors?
Title: Re: KMG SS Poweramps
Post by: greenm01 on October 10, 2013, 09:49:13 PM
Now I'm waiting for the ordered transformer http://www.classictone.net/40-18045.pdf to start testing.

Hi Mike,

Would these be suitable transformers for your 5W FET amp?

http://www.classictone.net/40-18030.html (http://www.classictone.net/40-18030.html)
or
http://www.classictone.net/40-18031.html (http://www.classictone.net/40-18031.html)

/MAG
Title: Re: KMG SS Poweramps
Post by: KMG on October 11, 2013, 12:38:25 PM
Quote
Hey! Any news about those transistors?
Not yet, I'm very busy now by official job.
Quote
Hi Mike,

Would these be suitable transformers for your 5W FET amp?

http://www.classictone.net/40-18030.html
or
http://www.classictone.net/40-18031.html
I don't tried SE transformer FET PA.
Title: Re: KMG SS Poweramps
Post by: file1 on November 22, 2017, 03:41:20 PM
Dear All,

I want to build 90W PA version , but I have a huge problem with output transformer. Plase could somebody provide me some more information about it? Link on internet where it could be bought also can be usefull. Does it someone tried to build it with EI core and could provide parameters for 90W version?  Which type of tpk-190, exactly could be used for rewinding ? Thank you in advance, Igor
Title: Re: KMG SS Poweramps
Post by: Katoda on November 23, 2017, 03:39:29 AM
I think there is no way around winding the transformer for yourself. I built the 40 W version of it, and it is quite big with the windings and all. Just be careful to get a big enough core. All of the data is on the KMG site, I believe.
Title: Re: KMG SS Poweramps
Post by: file1 on November 23, 2017, 03:33:07 PM
Thank you, but on kmg site info about output 90w transformer is very poor. I have some workshops who can wind it but for them, info from kmg site , simple is not enough. As I said i would like to try EI core because C core is hard to find in my country and C core is quite expensive (beside quality) 
Title: Re: KMG SS Poweramps
Post by: Katoda on November 26, 2017, 05:12:23 AM
Well, you might as well search the internet for an EI core that can handle 100 watts, and then just use the winding ratios from KMG site. Should be close enough.