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Messages - kikey

#1
Schematics and Layouts / Re: CMOS Power Amplifier
February 01, 2010, 04:45:10 PM
Hi rowdy_riemer, thanks a lot for the info.

I attach the 'my version' of the CMOS configuration as an attachment to this post.
Please note that this is a principal schematic!
Transistors, OPs are not optimal and dc-servo is missing etc.
Do you see any problems with this way of handling the bias current?
How much bias will I need?
#2
Schematics and Layouts / Re: CMOS Power Amplifier
February 01, 2010, 10:53:03 AM
Thanks for posting the clips again !

I think the sound is very promising. :)
What gain/damping factor did you use?

What do you think about the sound you get with this amp compared with the sound you get from your preamp using other amps?

I like the simplistic approch of your amp, it reminds me of the "Zen amplifiers" (Single-Stage Single-Ended Class A HiFi amp):



Best Regards,
#3
Quote from: rowdy_riemer on January 27, 2010, 03:30:29 PM
Awesome!!! :) Let me know how it turns out.

Thanks rowdy !  ;)
Do you have any sound clips available from your experiments?

My idea is lower the quiescent current and use temperature compensation.
This would make it possible increase the supply voltage.
Since there will be very little nfb I will need a dc-servo.

There is, of course, no active current control and its not true 'current drive'.
But thats the charm with it, I think that makes it more simplistic and 'tube like'. :)

How many times have you heard "ss-amps are super-clean and clips ugly"?
I think this is one way to change that and thats why I find this idea so interesting.
#4
Thanks for the replies and the link  :)
Nice to see that we have open minded people on this forum.

Here is another current drive link:
http://www.lenardaudio.com/education/13_guitar_amps_3.html

I find current drive an interesting approch for a guitar amp.
Some Peavey and Vox designs are clearly inspired by current drive.
Many tube amps (without nfb) are basically current drive.
I suppose many classic speaker models are designed for high output impedance(?)

I find rowdy_riemer's 'CMOS amp' an interesting and simplistic approch for current drive.
http://www.ssguitar.com/index.php?topic=1177.0
I am working on an amp inspired of rowdy's amp.  ;)

Have you seen other current drive projects on this forum?

Best Regards


#5
Interesting new book:

http://www.diyaudio.com/forums/vendors-bazaar/157787-secret-tube-amplifiers-revealed-much-more.html

www.current-drive.info

I know that high output impedance can be a good thing when it comes to creating a good guitar sound, but this book seem to take the discussion to higher level  :D

What do you think?




#6
Preamps and Effects / Re: Another guitar tone control
January 07, 2010, 09:50:35 AM
Hi

Here is my latest sim.
I hope I got it right this time  ::)
I am sure it can be tweaked some more.
It got some similarities with the resonse of your PhAbbTone.

Phatt, I do not think this circuit is better or worse than other tone controls.
I am no expert but I think it got some nice details.
Its just a circuit idea. ;)

The nice thing about trying out these circuits is the knowledge you get about what is needed to create the sound you want. To me it seems much harder to create a good sound with a ss-amp than with a tube amp. But on the other hand you can really fine-tune your design in an easy way. 8)
Many people like their boutique (ss)stompboxes but tend to prefer their tube amps for poweramp.
I suppose tube amps got its own characteristics when it comes to damping-factors, distortion and power supply sagging...
When simulating these charcteristics I think this post was interesting:
http://www.ssguitar.com/index.php?topic=1177.0
Unfortunately the sound clips are gone :'(

There are MANY ways to go when it comes to creating a good guitar sound and the sound some people like is terrible to others, its about taste. :loco

#7
Amplifier Discussion / Re: HH IC100S
January 06, 2010, 04:23:17 PM
Quote from: J M Fahey on January 06, 2010, 11:51:20 AM
You mean the hidden/potted Valve Simulator module?
I'll check, I had it somewhere, but basically they overdrive a FET, to mimic a Tube, and they equalize it a little, not NASA technology here.


No M Fahey, I mean the "sustain" circuit that is built into the IC100s.
(I think you mean the Valve simulator module that was built into the "vs. musician"-model.)
I dont know if it is hidden/potted module or not.
I have never played on an IC100 but I suppose that it is this "sustain" circuit that creates the distortion of this classic amp.
According to some sources the IC100s was the best sounding amp of all the HH models. <3)


Regards.
#8
Preamps and Effects / Re: Another guitar tone control
January 06, 2010, 04:11:44 PM
Quote from: J M Fahey on January 06, 2010, 12:54:59 PM
1)The treble/bass labels are inverted: top one is Bass, bottom one is Treble.
2) C2 (10n) should be a resistor, 10k to 22K . A capacitor there (as drawn) will kill or severely hamper the action of treble control.
3) The mid control implementation is unusual, but it should work as cut-only; with a couple extra components it would be boost/cut, but anyway, if you like it as-is, good.
4) Without simulation , I'm too old for that, I can still see that the mid notch can be around -20dB, as posted. (200 ohms/4k7)

Thank you for your comments!
I was a little too fast when posting this schematic  :)
1 + 2) Yes, that Baxandall network was strange to start with and even worse since I made some errors in the schematic. xP
That circuit comes originally from this document:http://www.techniguitare.com/projets/ChaosPreamp/Preamp-Schems-V1.1-En.pdf Page 4.
I find that document ambitious and interesting. Especially the pre/post filtering.
3 + 4) I think this mid control is nice since it got constant Q (bandwidth) and allows for a narrow bandwidth cut.
I agree with Phatt that this type of narrow bandwidth cut sounds great.
A narrow band boost is not as nice...

I am working on an updated schematic.
#9
Preamps and Effects / Re: Another guitar tone control
January 06, 2010, 08:52:39 AM
The mid control functions ok to me.
You can also change the values of C and R.
See plot below.

The bass-treble is a standard circuit.
I found this one at this site: www.techniguitare.com
Use another bass-treble circuit if you like.
I admit, I have not simulated this one.
#10
Preamps and Effects / Another guitar tone control
January 05, 2010, 08:52:05 PM
Here is a circuit I have found interesting.

It is simply an enhanced version of the classic FMV tone stack but without its weaknesses.

First a standard baxandall bass/treble circuit then a mid control allowing only a mid cut to get "scooped" tone.
The advantages are:
- The pot settings do not depend of each other.
- No signal loss.
- Bass/treble boost and cut can be set.
- A constant Q mid scoop.

The circuit can easily be tweaked to simulate any FMV tone stack.
Q (the bandwidth) can be adjusted with R and the frequency with C.


#11
Amplifier Discussion / Re: HH IC100S
January 05, 2010, 08:20:59 PM
Hi

I am interested in the sustain circuit in the HH IC100S.
Anyone here know where to find a schematic ??  ???

Thanks,
#12
Preamps and Effects / Re: cabinet simulator
December 08, 2009, 06:08:45 AM
Maybe this link will give input for people trying to simulate classic amps:
http://www.harmony-central.com/Guitar/guitar-amp-evolution.html
#13
Preamps and Effects / Re: cabinet simulator
December 07, 2009, 04:25:57 PM
Hi Phil

Thanks for sharing your ideas and thoughts!
I agree 100%, EQs are the key to a better sound.  :tu:

The setup I am working on will look something like this:

EQ > DIST > EQ > OD > + > poweramp
                      v
                      + > cab sim > headphone amp/line out


I am very interested in your PhAbbTone-circuit.
It looks like a tweeked tone stack.
I am going to try it in my simulator.
Is the steep notch produced with the mid-control at min ?

I am very interested in your ideas about Fender/British/ModernHigain/Metal sound.
I have not seen these characteristics sorted out anywhere on the net.
It would be nice to have it all in a table on a webpage  :)
Your ideas seem correct, the notch should be able to give the clear and open fender sound.
For achieving the British sound I think it is a good idea to limit the bass response to minimize intermodulation effects.
This can be compensated for in the post EQ.

Regards
/Bjorn
#14
Preamps and Effects / Re: cabinet simulator
December 05, 2009, 04:45:54 PM
Quote from: phatt on December 04, 2009, 11:08:55 PM
One curve in one place *May not work* you often need multiple stages of EQ and you have to know where to insert them.

I've built 4 of the JTM simulator and sold them mainly to folks in recording situations.
JTM circuit Live they can be a pain to work with you need to insert them *After* distortion effects.

Yes, you are right, you need several LP-filters to achieve good results.
I have tested the circuit below with very good results when using headphones.
I think for example the Vox amPlug suffers from a bad cabinet simulator.
phatt, in what situations do you get problems with these circuits?


#15
Preamps and Effects / cabinet simulator
November 27, 2009, 07:45:10 AM
Hi

I have been testing a few cabinet simulators inspired by:

http://www.herby.kielce.pl/~piter/hexenew2/ie.php?c=cabsims_e&l=diy_e
http://home3.netcarrier.com/~lxh2/

I would also like to add a simulated high impedance output from the driving amp.
I suppose this could be done by adding a notch filter to simulated the impedance curve of the speaker.

Have you guys any experience with these circuits?