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Topics - phatt

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31
Tubes and Hybrids / Tecky Q SMPSU
« on: April 08, 2011, 11:12:01 PM »
Hi All,
        A recent posting about the *SC Valve Preamp Kit* got the brain thinking again.

I am trying to establish if this power supply from the silicon chip Valve preamp kit
can run a small pp power stage.

I have built one of these kits and it works great.
The schematic and pictures of the SMPSU can be viewed here;

http://diyaudioprojects.com/Tubes/12AX7_Preamp/

As I'm not up to speed on this technoligy I'm at a loss as to how to establish just how much current can be safely extracted.

My understanding is that it may well be able to deliver a lot more current as these switcher transformers are highly efficient.
one only has to look inside a computer to see that the ferrite tranies are small yet deliver massive current.

The plan is to use 2 6GW8's (ECL86) and one AX7 with the whole thing running from a 17VDC plug pak (wallwart)

So the heater demand @ 12VDC will be around 820mA, which can be supplied via a seperate supply if need be.

The current draw from the wallwart in the unit I built is around 230mA, which of course runs the heater of the AX7 at 12 volts after regulation as well as the HT supply.

So I measured the heater which draws 140mA which tells me the switching circuit is using 90mA to run VHT for 2 triodes.
As triodes only draw a couple of mA then it's a big leap to run two pentodes which need 140mA.

The original artical did hint that the SMPS could run a lot more Valves but gave no estimate of it's actual potential. Darn. :grr

I did find a nixie tube SMode circuit which is tiny and yet can deliver 25mA @ 170VDC. Got me thinking again.

Any help in this regard would be great.
If it's all to scary I can then set my mind at rest as I do have a normal transformer which will give me 320VDC for HT but I'm trying to make this super compact and the SC Valve supply might just be the trick.

I know switching supplies are voodoo to some audio folk but I'd still like to try it out. 
Thanks, Phil.

32
Tubes and Hybrids / AnyWatt Load box
« on: January 31, 2011, 11:04:12 AM »
A member asked about my Reamp system Which I call the *AnyWatt Amp* ;)

Posting pic of the load box.
This is all you really need to know the rest you will likely already have.
Oh an I run it through the The PhAbbTone of course. 0:)

Here's my signal path;

MaxiVerb> PhAbbTone> Tube Amp> Load box> 10band Graphic EQ> 120Watt old factory Power Amp unit.
The second amp should be fairly flat for best results.
(don't run into another hi gain preamp stage of a Guitar Amp as it may well hinder your progess, wink)

The Maxiverb, PhAbbTone and Graphic EQ all have true bypass switching.

My tube Amp is about as basic as it gets, two knobs, Tone Volume.
The preamp is just a Pro Junior copy but the power stage is; Cathode biased, no FB.
The HT is only 260VDC the power tubes are 6GW8's.
So that makes for 3 bottles and a very compact little head.

*Menser* my raw tube amp sound is a little darker and smoother than the brilliant Steve Conner system.


Some thought's.
I see no point in building a 4 by KT88 Monster triple recterfryer amp only to drive a resistor.

Some come at this from the view that the Valve Amp has to make the Mojo and you need Exotic hi teck wizard circuit to faithfully reproduce that one perfect tone.

I don't subcribe to that school of thought because with this setup you can create many different tone shapes giving far more versitility than other systems.

For the money I've outlaid and the many different sounds I can create I doubt you will find a simpler way to do such things.

The simple fact is that all those great guitar tones kids dream about are just distortion with different tone shapes.

The Tube amp in my setup is just a big distortion unit.
As long as you capture the compression effect of the power tubes then the rest is just tone curves and why waste a row of expensive bottles trying to get the right tone shape when all of that can be done with simple cheap SS devices.

In truth my Reamp setup is only marginally better than my All SS setup though the ReAmped Valve Amp does have a more dynamic feel to it.

Don't forget the ground lift or you will drive yourself nuts trying to find the cause of hum with 2 amps connected to the mains. ;)
Cheers, Phil.

33
Schematics and Layouts / Phatt-stuffRevisited
« on: January 20, 2011, 07:16:08 AM »
OK I have been revamping some circuits and finding some small issues so I thought I'd share them with you all.

PhAbbTone output has been tweaked yet again (even less noise) and The DDC circuit has been revisited.

Have been Trying to use a compressor lately and noticed it was all rather noisey so rather than blame the compressor for everything I thought I should take a long look at my own potential mistakes as well.

So a complete breadboard of the tone circuit and DDC and sure enough I was able to improve the noise floor.

Also I wanted to see if the DDC circuit would sound ok running from 12 volt single supply which it indeed does. It might interest those who wish to make a pedal out of the circuit.
Be aware that the tone stack needs to come before the DDC.
Often most stomp units that have any form of tone control insert it *After the dist* and this may leed to a negitive outcome.
At least it will with my setup as the best effect seems to come from the tone circuit being *In Front*.
Add more soon. Phil.

34
Preamps and Effects / Compressor Mods
« on: December 23, 2010, 09:24:55 AM »
Hi fellow tone tweakers,
 
It seems it's a love/hate thing with Compressors, some like some don't.

My main experiences are with the dreaded CS2. (hated it and sold it,, noisey as hell)
Also still own a Quadraverb GT. (poor me) It's preamp systems where also a horrabillas experience.

My CS2 was a long time ago and I have learnt a lot since those days so I thought I
should at least test some ideas and see what really goes on inside these circuits.
Heck why not,,I've got an LM3080 chip in the junk pile somewhere.

I've always found Compressors more trouble than they are worth but after hearing a neato trick using a CS2 in front of TS9,,,
Wow really did improve sustain and bingo it sounded a lot less like a compressor.
Well you learn something new everyday.
Obviously it got me thinking about Comp circuits again.

Now I'll cut to chase.
Needless to say out came the breadboard and after a few weeks of breadboarding many
ideas I've found a few things you might like to know. None of these tricks will fix the clean sound of these comps but may improve the OD sound if used *IN Front* of Distortion units,, Obviously after Distortion won't work as well.
If you are into a lot of funk rythums then I admit clean comp is a usefull tool
but Still Noise is usually the enemy.

The Pumping action.
After much headscratching it dawned on me that the clamping action is not a matter of speed but *DEPTH*, it's far too much.

I Fixed Pumping action by *Changing diodes to LEDs*.
A switch could be used here for standard (hard) and led (soft) comp.

This raises the comp point and although you loose a bit of clamping it still retains a fair amount of sustain which helps to overcome that dreaded humph mumph you get with most Comp circuits. (Very nice I like)

The switch on the caps changes the recovery time.
2u2= fast, 10uF= slow. Can't make up my mind about that part yet.

**NOISE**,, As said a huge issue. (on all but the rare expensive studio racks
systems)
It seems that everyone just copys the other's ideas with a few changes and throw it on the market. Even Bootweakers don't seem to try hard to solve some of the noise issues found in some classic circuits.
Heck,, maybe I'm alone in my quest to build quiter circuits.  :lmao:

So lower noise was the priority, the *must fix* otherwise it's just going to end up
landfill and I'm wasting my time. ::)

Now being this unit plays around with a lot of gain I can't say I've made it *Noiseless* but I believe I've dramatically improved on the CS2 styled Compressor circuit.

Tokai made one similar to Boss CS2 unit and it apparently had a better S/N so I mixed up some ideas from a whole pile of schematics and then I just kept tweaking things.

So yes I'm very impressed,, With the Sustain full up and Attack slow it works well
with my distortion units.

With the Leds engaged it has already fooled me a couple of times so it would be hard to tell if it colours the sound. Obviously run clean it still retains the classic CS2 comp sound if that is your thing but I'll hazzad a guess and say it will NOT be as noisy and hissy.

Of course if you wind up the level it will still deliver some hiss but I'm assuming you all know not to use the Compressor output as a master volume,  :trouble.
I doubt you would need to turn up the level much as this unit still has heaps of headroom. (A 50k level pot may work just as well here)

So if you wish to get more from your distortion units this may be an improvement.
At the least I've created a working circuit that may give others with better insight some ideas to work with.

When time permits *I will* be building this circuit. The Danger is to keep on tweaking but I doubt I could improve it further without resorting to much more complex circuits.
Have fun with it, Chrissy Cheers from Phil.

35
Amplifier Discussion / SubWoofer2 GuitarAmp
« on: June 12, 2010, 08:52:01 AM »
Hi folks,
         My old Eagle eyes spotted this on a pile of junk and I could not help myself I had to see what was inside.
Lo and behold,, *An LM3886* complete with a big/reasonable PSU.

So after a few head scratching hours I disconnected all the fancy sub circuitry and I have myself a 50 Watt Powered Speaker.
Just finished adding a small input socket and preamp to the side panel,, works a treat with my other guitar preamps. <3)

I was not expecting much from the little 6 inch *Elcheapo* speaker but to my suprise it reproduces Guitar signal quite well.
Although the speaker is a little low in the SPL department it can still be loud enough to play over a Drummer.

The speaker looks funny from the front but a closer inspection of the rear shows it's just a normal cone with the concave dish added on the front.
So it's not a dedicated *long throw hifi type woofer* which of course would not work for guitar signals at all.

PSU delivers 36-0-36 VDC and drops via Resistor and zener for the 12-0-12 VDC to run the opamps ,,Oh how thoughtful they where. ;D  Everything needed to make a simple cheap but gutsy little compact rig.
I'm stocked chaps.

I think this got dumped because the *Signal sensing circuitry* obviously was switching off but not switching back on when another signal came through.

So if you see one of these grab it,, just for the chip and complete PSU alone.
All the bits needed to make a 50 Watt Amp ,,,how kool.
Cheers Phil.

36
Schematics and Layouts / phatt's Schemo Collection
« on: May 14, 2010, 09:23:54 AM »
The Schematics Stuff I've posted has gone missing but not to worry I'll repost a few here :tu:

The DDC (Dynamic Distortion Control) by itself won't blow your mind but by implimentation of the *PhAbbTone* circuit *in front* of this will reap some classic guitar tones from a bygone era.
(All these clipping circuits distort,,,, but this is very touch responsive.)

The addition of a simple cheap Graphic Equalizer *After* the DDC will deliver more tonal options than most music shops have Amps.
Yes I use these circuits in my setup and I play live gigs (although not to much these days) ;D

So I can vouch for their ability to deliver. :tu:
Phil.

37
Preamps and Effects / PhAbb SS AmpDemo
« on: January 06, 2010, 12:40:25 AM »
Hi everyone,
                 Could not decide where to put this but as there is no actual *PowerAmp* being used to generate the audio then this seems the most logical place.
Well I figured enough talk why not a little demo of my PhAbb SSAmp Setup.

As just about any bit of gear these days (including mine) can produce copious amounts of distortion then why not demo those in between dynamics that are probably harder to reproduce with all SS equipment.

Tube Amps have an area which is on the edge of distortion and this was my aim, to nail/capture that in between *Rattle* that a lot of those famous tube amps where able to do so easily.
The Knophler sound is often a tricky one so I tried it out, see what you think.

First track is done with a bog stock Chinese Strat copy, I like it for this stuff because the Pup's are low winding only 4k DCR.
The second bit is Recorded with my other guitar (real 60's era Strat pup's)

(Maxiverb is a stand alone Spring Rev unit I desiged and built about 10 years ago,, and still going strong.)

Signal path;
Maxiverb > My PhAbbTone box > DDC (My Dynamic Distortion Control)
> A Realistic HiFi GraphicEQ > signal into Line mixer> Into Audigy SCard.
Adding no post efx of any kind.

There is very little difference between the line rec out sound and a real 100Watt power amp driving a guitar speakerbox (To my ears at least) but your speakers will colour the sound to some degree no doubt.

If any interest I will post more short demos and all the setup schematics, might give you some ideas to work on.
Sorry the file is short but only 500kb allowed.

Hope you enjoy, Phil.
Edit 2011
> Reloaded the files and Dloaded back to myself and it seems to be working OK now.<

38
Schematics and Layouts / Passive Tone Circuit
« on: May 24, 2009, 10:18:18 AM »
My effort at tone controls.
Ok "Zappacat and sergscar" have asked for this one so here it is;
The "Tonemender circuit" has been mentioned more than once on these pages and although it works it could be quite easily improved. No disrespect to ROG but I get the impression not much effort goes into "Refining" there ideas. Nearly all these old styled passive tone circuits are quite prone to picking up noise but if you know your way around it they can be greatly improved. At the very least this will give DIYer's some other options to choose from that
I think most will find superior.

HiWatt tone does not get much mention (probably because it looks a little tricky) even though it was the best of all the famous tone stacks. In fairness it's no better than the classic Fender in regard to the Amount of bass and treble but the midrange cut leaves fender types for dead.
I doubt many will read all this but I have built a lot of these old circuits both Valve and SState so I'm fairly confident in stating how well they actually DO or Do Not perform.
If you are just hell bent on replicating a specific tone circuit then It should become obvious that you can use most of the old tone stacks in place of mine if you so wish.
For those that wish to replicate the EXact HiWatt circuit be aware that the bass pot was a *TRUE LOG* 500k unit and you may have trouble sourcing those nowadays.  What is often sold today has a psudo log curve and will be very disappointing in use.

I've tweaked the components for what I think is the best mid freq Q point and max cut, it's around 400hZ.
Play around with the values if you so wish but what you gain at some place you may loose out elsewhere. Like all the other tree type tone circuits the controls are very much interactive. There is No Gain/Boost with passive tone stacks so the game plan is all about making the biggest difference between frequencies. A deep notch cut is what you want as shallow scoops tend to sound unconvincing or bland.
Side note;
My Alesis Micro EQ cannot deliver the 30/35Db difference at 400hZ when compared to the passive HiWatt even though the Alesis is an Active parametric device,,, and yes I A/B tested this many times.

This schematic is version 2, which is better than the original circuit that I've already posted on this board. I've built 8 of these units for mostly working musicians and over time it became apparent that the noise/hiss
was an issue with some Hi gain Amps. This is all good because it forces me to work harder and find better ways to implement the circuit.
Very low noise opamps might help in extreme situations, I've used both TL072 and LM883 and you can hardly pick the difference by ear.

Be aware that altering or deleting R5(10k) will just increase the noise in quite a dramatic fashion but not the gain.
I discovered from some in-depth reading that this is how to do it and keeps the noise down. The 10k/10k voltage divider network (R5 and R6) seems to deliver the best results. Some here may have even better ideas so feel free to comment.
Also make VR4 100k lin or log if you need more power to drive your amp but don't go mad here as the noise will climb fast. The intention here was to just use this to balance the bypassed sound level and is not intended as a high gain section,, there are plenty of those around so use them for gain.

A good understanding of wiring up high impedance circuits helps as well. For those that may not fully understand,, Everything above R1 R2 R3 R4 in the tone stack is going to be prone to picking up unwanted crap,,
so just use metal film R's for the whole circuit and be done with it.

What! No active input? :duh
One of the not so obvious subtleties of famous valve driven tone stages was the simple fact that the output of the tone stage had a natural roll off in the high freq response.
With an active opamp buffer stage front-end this may not happen so by using the tone passively you are likely getting closer to the original Valve Tone effect. The passive tone stack input imp is plenty high enough for the magnetic PU's used in electric guitars.
Feel free to use a buffer in front but don't expect it to be vastly
improved.
When players first hear this box there is often a comment about the presence/brightness,, so again attaining more hi freq will likely render it more SState sounding which is the very thing your probably trying to avoid. so your call.
And for those that think it can't work passively you need to go way way back as this was how it was done in some early equipment.

How to use;
The treble dominates the tone in old standard fenders and I wanted to avoid that as much as I could. So if you want the treble to sparkle with this one,, just turn down the mid as it is now the dominant control.
I've deliberately tilted the output slightly to the treble freq but without loosing to much bass.
If you want more bass make R1 smaller, try 56k. Lower values will likely upset the mid cut ability.
Now I've bored you long enough so here's The schematic and some pictures that might give you some ideas of how to build it. I use the old printer selector boxes, you can pick them up for next to nothing as they are of no use anymore.
I do this cause someone may as well benifit from all my frustrations of trying to get a decent sound.
After 20 plus years of fiddlin with circuits,,, on rare occasions you have a win and I think this is one time I did pull something off that actually worked.
Have fun with it, Phil.

*Edit*  Just a note, Scroll down for the up to date SCHEMATIC. Cheers, Phil.

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