Comparing two tube screamer circuits, what are the differences

[fork]

So I am looking at two different tube screamer circuits, the one on tone pad http://www.tonepad.com/project.asp?id=1

and the srv special found here http://www.aronnelson.com/gallery/main.php/v/ulysses/ulysses_layouts/ulysses_ts_srv_special/

It seams that people say the SRV special version has more gain, and thats not necessarily what I want, but I like that it has a strip board  layout.  I think I would prefer to make something closer to the real TS.  This is also an effort to understand what a few components in the circuit actually do and how they affect the sound.  So I've singled a few out, hopefully someone can explain what they do.

1. The Tonepad schem has a 1M resistor from input to ground and the SRV special has 2.2M.  Similarly the tonepad has a .027uf input cap and the SRV special has 10uf.  What effect do these values have.
2. The Tonepad schem has a 500K drive pot where as the SRV special has 1M pot.  Also the tonepad layout has a 51 pf cap across the first op amp pins 1-2, the SRV this is omitted.
3. The Tonepad layout has a 1uf cap after the second opamp, and the srv special omits this
4. The Tonepad version uses a .1uf cap in the signal path after the level pot  and a 510k resistor to Vb and the SRV special omits this.
5. Finally the Tonepad version uses a resistor after the second transistor in the signal path and the SRV special omits this.

Well I know thats a lot but answers to any of those would help me understand what is going on with these circuits in general.

Thanks in advance for the help.

[Mark Hammer]

So I am looking at two different tube screamer circuits, the one on tone pad http://www.tonepad.com/project.asp?id=1

and the srv special found here http://www.aronnelson.com/gallery/main.php/v/ulysses/ulysses_layouts/ulysses_ts_srv_special/

It seams that people say the SRV special version has more gain, and thats not necessarily what I want, but I like that it has a strip board  layout.  I think I would prefer to make something closer to the real TS.  This is also an effort to understand what a few components in the circuit actually do and how they affect the sound.  So I've singled a few out, hopefully someone can explain what they do.

1. The Tonepad schem has a 1M resistor from input to ground and the SRV special has 2.2M. 
Don't expect any audible difference here.
Similarly the tonepad has a .027uf input cap and the SRV special has 10uf.  What effect do these values have.
A bit more bass input signal with the larger value but not that much.
2. The Tonepad schem has a 500K drive pot where as the SRV special has 1M pot. 
The extra 500meg of pot resistance permits for higher max gain.  All the same low gain settings are obtainable, just with less dialability.
Also the tonepad layout has a 51 pf cap across the first op amp pins 1-2, the SRV this is omitted.
Trust me, you want the 51pf cap....especially with extra gain.  It rolls off more highs as gain is increaed.
3. The Tonepad layout has a 1uf cap after the second opamp, and the srv special omits this
They're bulky, but it's still good practice to block DC IMHO.  Keep it.
4. The Tonepad version uses a .1uf cap in the signal path after the level pot  and a 510k resistor to Vb and the SRV special omits this.
I suppose if you kept the one above, you don't need this one.
5. Finally the Tonepad version uses a resistor after the second transistor in the signal path and the SRV special omits this.
The two resistors on the output (series and ground) are a big part of what distinguishes the TS-9 and TS-808, although I imagine that changes to the output have a sonic impact that is always contingent on what they are plugged into next.  Look at the Technology of TS over GEOFEX and come to your own conclusion.

Well I know thats a lot but answers to any of those would help me understand what is going on with these circuits in general.

Thanks in advance for the help.

[MikeH]

Welcome!  You'll find searching around here that there are countless TS derivatives.  COUNTLESS.  And you'll also find in the layouts gallery a vero layout for a standard TS (I think).

The 1M/2.2M resistors are 'pulldown resistors' to prevent switch pop.  They also effect the input impedence (which is another discussion all together)  Any thing 1M and up will function basically the same.

A lot of people like to work around that 1uf cap because 1uf non polar caps are expensive and they take up a lot of real estate on the board. Generally anything 0.1uf and up is fine here.

[Transmogrifox]

....  COUNTLESS.  ...

I think that's the problem

Do a web search for RG Keen's "Technology of the Tube Screamer" article.  This forum links his geofx page.  The article is very informative and you'll come through the reading knowing a great deal about the TS and what parts make the biggest difference.

[MikeH]

+1 on technology of the tubescreamer.

[aziltz]

+1 on technology of the tubescreamer.

things got controversial last week...  RG does a good job simplifying things to explain them, but some points are off, or missed.

i simulated the circuit and played with gain and tone control settings as well as a few pieces in the tone control circuit.

I posted it all here: http://www.diystompboxes.com/smfforum/index.php?topic=75775.0

[MikeH]

+1 on technology of the tubescreamer.

things got controversial last week...  RG does a good job simplifying things to explain them, but some points are off, or missed.

For the beginner, it's already more than confusing enough 

[aziltz]

+1 on technology of the tubescreamer.

things got controversial last week...  RG does a good job simplifying things to explain them, but some points are off, or missed.

For the beginner, it's already more than confusing enough 

its still good enough for me. 

but if someone wants to know more, my explanation isn't over anyones head.  i just showed what happens when you twiddle each knob.   

[Renegadrian]

If you're after VERO layout for the 808, check THIS ONE - I built it and it just works good.
I think that as the TS is one of the most cloned pedals, you will find several schems/layouts, all with different mods/changes/improvements. As a newbie it is so difficult to understand what each and every single component does, but after some good readings and some pedals built (experience) you will know maybe not everything but enough to build it with a clue and not blindly following the given layout.
Say, the tone control can easily be swapped for a linear 5k. or 10k.
As always, my

[fork]

Damn thanks everyone for all the help this is more than I could off asked for. 

If you're after VERO layout for the 808, check THIS ONE - I built it and it just works good.

I searched and searched and I could not find any other layouts than the one I posted so thanks

As a newbie it is so difficult to understand what each and every single component does, but after some good readings and some pedals built (experience) you will know maybe not everything but enough to build it with a clue and not blindly following the given layout.

Thats exactly what I am going for

Looks like I will be building shortly

[Eb7+9]

It seems that people say the SRV special version has more ...

try googling SRV Special ... the mods primarily revolve around the idea of removing some caps in the signal path ... trivially simplistic analysis of the TS circuit won't reveal its key large-signal behavior