modding an LPB-1 into a... ZW OD? Tube screamer?

twabelljr · February 07, 2011, 07:31:59 AM

Q1 in the schematic is a MPSA-14 Darlington NPN. Q2 is for the indicator led. You don't need that for the vero if you are gonna go the 3PDT route for bypass and led control. If you cant get a MPSA-14 try a MPSA-13. Or possibly whatever high gain NPN you have on hand. Just remember the pinout for Q1 on the vero from top to bottom is C-B-E. As for the opamp, the schem. calls for a MC33178P which is described as "high output current, low power, low noise" but the pinout is the same as all the favorite dual opamps. Use sockets for Q1 and the opamp and go from there! You might want to consider leaving the vero a few holes longer on the right end where the tone trim pot will go so you can cut and jump traces as necessary to get the pinout (lugs) oriented correctly.

cgibsong002 · February 08, 2011, 10:40:03 PM

Just out of curiousity.. how does a traditional tube screamer compare tonally to the ZW-44 when used purely as a clean boost (and by clean I mean gain knob on zero, volume at max). Never tried a tube screamer, but figured I'd get an opinion or word of advice before ordering the zw-44 specific parts.

Also, I'm definitely not tearing down this breadboard of the dist + yet. I just realized there is a problem with my amp, so the results might not have been typical. I'm not getting nearly close to full power from my amp. Might be a bad power tube, which would effect my dynamics and possibly harmonic response.

cgibsong002 · February 12, 2011, 12:41:01 PM

edit:nevermind about the resistors

it appears there is no c9 on the vero layout, even though it is listed..

twabelljr · February 12, 2011, 05:48:20 PM

C9 goes across the power rails. From V+ to ground for dc filtering I believe. You can find a spot for it since the 9v and ground strips are right next to each other. Put it on the left side of the board right behind the power and ground wire connections. I compared the schematic to the vero and Renegadrian nailed it. You just need to add a second diode in series to one of the clipping diodes to make it "exact". And don't forget to jump the 2 green vref squares together! If you have some vero and the parts go for it!

cgibsong002 · February 12, 2011, 06:31:55 PM

Quote from: twabelljr on February 12, 2011, 05:48:20 PM
C9 goes across the power rails. From V+ to ground for dc filtering I believe. You can find a spot for it since the 9v and ground strips are right next to each other. Put it on the left side of the board right behind the power and ground wire connections. I compared the schematic to the vero and Renegadrian nailed it. You just need to add a second diode in series to one of the clipping diodes to make it "exact". And don't forget to jump the 2 green vref squares together! If you have some vero and the parts go for it!

i was going to ask about those squares.. thanks for thinking ahead! i just ordered all the parts today. Hopefully everything goes smoothly and I'll update.

cgibsong002 · February 26, 2011, 10:06:11 PM

is the top side of C7 and the bottom of R7 connected to the same strip/hole?

twabelljr · February 26, 2011, 10:28:40 PM

Quoteis the top side of C7 and the bottom of R7 connected to the same strip/hole?

Yes they do. The vref strip.

cgibsong002 · February 26, 2011, 10:34:04 PM

Quote from: twabelljr on February 26, 2011, 10:28:40 PM
Quoteis the top side of C7 and the bottom of R7 connected to the same strip/hole?

Yes they do. The vref strip.

thanks. i wasn't sure if c7 was supposed to be on the strip right above 9v, and he just forgot to fill the hole in. thanks for clearing it up. i've got the board set up.. too late tonight to solder it all up though.

cgibsong002 · February 28, 2011, 11:06:14 AM

Ok. Another completely noob question. How do you guys traditionally go about building a vero layout? I've been soldering the components in so that when i'm looking at the components side of the vero, or non conductive side, i basically have a mirror layout of the circuit. so when i'm looking at the conductive side, if i were able to see through the board, everything would look just as the layout. this has seemed to work fine for me so far. except i just realized that when i go to put in the op amp, its going to be backwards. is there an easier approach here? how do i solder in the op amp without it being backwards?

cgibsong002 · September 24, 2011, 05:35:23 PM

Hey guys... after a very long delay I've finally finished building this. Unfortunately, however, it doesn't sound like the zw-44 as I remember it. I'm very, very close, but not there. When I turn the effect on with my single volume pot at max, I get a slight increase in gain, as I should, and a very slight harmonic increase... not much though and not any noticeable sustain increase. There is no volume increase though, and that's where I suspect the problem lies. On my real zw-44 that I had, when I had the gain at 0 and volume maxed, there was a noticeable volume increase when switched on. I feel like this extra volume is what drove my amp harder and gave me that ridiculous sustain and harmonic character, which my pedal currently lacks. So what is different here? Maybe lower the value of R1? Or how could I increase the op-amps amplification? I'm sure one of you guys will know what to do.. I have a few ideas but I don't want to mess up the circuit.

Just to reiterate what I built, I used this schematic: http://www.aronnelson.com/gallery/main.php/v/Renegadrian/MXR+ZW44+-+Zakk+Wylde.gif.html
Moved the bottom leg of R6 up one to simulate minimum gain, put a trimpot in place of the tone pot, which leaves me with a single volume pot (I'm currently using a 100K instead of 10K)

also the IC is an RC4558P and the trans is a MPSA-14

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modding an LPB-1 into a... ZW OD? Tube screamer?