Distortion+ Recovery

[anti-idiot]

Hi. last day i saw this schematic, bout using the second opAmp in the 4558 as a recovey stage,  and started to think 'bout use the same thing in Distortion+. How can i do that? may i use the same values of the unmarked caps and resistors? or should i tweak 'em, like this schemo:


'Salida del D+' stands for 'From D+ Output' and 'Salida' stands for 'output'.

i took the 'output pot' from the D+ out, added a marshall tonestack (unlabeled), and added a modded recovery stage. now, i wanna know if the values are correct or if i should change something.

Thanx

Edited: oh crap, i forgot bout the100k resistor into the input of the second half of the op-amp.

[Jered]

  How does it sound? No better way to know if the values are right, and no better way to learn.
  Jered

[Mark Hammer]

First, smart.

Second, I couldn't tell you whether the values for the tone stack are "right" but I think you may want more gain from the second stage.  You have it set for a gain of around 6 (can you actually *get* 50k resistors?  I'm assuming you mean 47k.)  Keep in mind that if you use germanium diodes for the clipping, you would probably want a gain of at least 3-4 in the recovery stage because of the very low output level from the Ge clipping diodes.  However, the tonestack itself causes a certain amount of passive signal loss, which may necessitate more stage 2 gain to compensate.  Not a *lot* more gain, but maybe 68k may be more appropriate than 47k/50k.  That should enable you to get decent output levels when set for only a bit of distortion.

Since you don't need whatever hiss is produced by all that cumulative gain (first stage times second stage), a 220pf-330pf cap in parallel with the 2nd stage feedback resistor might be a smart idea.  You don't need or want any of that bandwidth above 7-8khz anyways.

[anti-idiot]

well, the values for the tonestack are the marshall standard, waht d'ya mean with 'right'? -sorry, i'm not familiar w/this language, i'm the peruvian guy, rememeber me?-.
for the 50k, my bad. i'll use the 68k.
for the bias resistor (which i forgot), what value should i use? the first stage (this sounds like ozzfest) is 1M, i thought bout using 100k, what d'ya think?
'bout the caps (C1 & C2) are they ok?

thanx for all mark.

[Mark Hammer]

Every EQ section is a compromise that *might* change the frequency content that is important for you with your pickups, speakers, and style, but might not be right for you either.  That's all I meant by "right".  If what you picked works well for you, good.  But don't feel obligated to use it or prohibitted from changing the basic circuit in any way.

You can use whatever feedback resistor you want.  I suggested 68k because I think most players will want to be able to get a loud output without necessarily having to turn the gain way up.  Adding some gain to the second stage will let you do that.

The bias resistor will depend on what op-amp you use, to some extent.  I think 470k to 1M will be fine, though.

[anti-idiot]

thanx for all man, i'll use it like u said. any other recommendation? i'll use a 1458 dual op-amp. the first stage will be the Distortion +, then the tonestack, and then the second stage buffer.