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

[cgibsong002]

you can see the mxr type dist(rat)has the clipping diode between the second triode and the out put and it's lead to ground
but the sd1 or ts or zw44 has the clipping diode parrel to the first ic...
so tey the ts or sd board
ds+ give you more hard dist,not harmics

if this is true... this is definitely something i want to look into. i don't need more distortion. i need those extra harmonics and sustain that the ZW gives. can we move the diodes' position in the + to start to change it more over to an sd1? Or why shouldn't i just base the build off the sd1? is it harder to work with and modify?

[Mark Hammer]

Feel free to stick the diodes in either the feedback path or to ground.  In the feedback path, they play a role in altering the gain, once they begin to conduct.  When they go to ground, as shown, the gain is whatever the gain is, and they clip/conduct when the signal reaches a particular amplitude.  Slightly different audio result, but with the original intent being to push a Marshall into breakup, I doubt the difference matters.

ultimately, what I've encouraged you to make is essentially an MXR Microamp, with a couple of tweaks optimized for better amp overdrive tone.  the intent is not to produce an overdrive tone from the pedal alone, of the sort you'd hear feeding a mixing board or clean power amp.

[56335130]

Feel free to stick the diodes in either the feedback path or to ground.  In the feedback path, they play a role in altering the gain, once they begin to conduct.  When they go to ground, as shown, the gain is whatever the gain is, and they clip/conduct when the signal reaches a particular amplitude.  Slightly different audio result, but with the original intent being to push a Marshall into breakup, I doubt the difference matters.

ultimately, what I've encouraged you to make is essentially an MXR Microamp, with a couple of tweaks optimized for better amp overdrive tone.  the intent is not to produce an overdrive tone from the pedal alone, of the sort you'd hear feeding a mixing board or clean power amp.

http://diy-fever.com/misc/flexi-clip/
i just found maybe helpful

[56335130]

you can see the mxr type dist(rat)has the clipping diode between the second triode and the out put and it's lead to ground
but the sd1 or ts or zw44 has the clipping diode parrel to the first ic...
so tey the ts or sd board
ds+ give you more hard dist,not harmics

if this is true... this is definitely something i want to look into. i don't need more distortion. i need those extra harmonics and sustain that the ZW gives. can we move the diodes' position in the + to start to change it more over to an sd1? Or why shouldn't i just base the build off the sd1? is it harder to work with and modify?

i have the  same dream as you.i just think out this yesterday on my bed .I thought it was true.my friend play with his orico rat.it hard and not sweet at all.
i once borrowed a zw44.it's great and "sweet".i dont need it's overdriving stage but the boost.
I just started building a sd1.but when i check the rat's  Schematics after my friendsplaying，i found out they alike except the clipping stage.
maybe we could mod all kind of ic based pedal into those"those extra harmonics and sustain"by only adding the correct diodes or led in the right place even its a one drive stage lpb-1...

there is only two place of clipping diodes and ge si led three kinds of diodes and "2 or three parrel or series " ...those differences
no big work ,right?
have you tried a tube screamer?do they have those" extra harmonics and sustain"?

i'm chinese so poor english forgiving

[cgibsong002]

Yes, the mix of my lack of knowledge and the odd english is confusing me quite a bit  it's mainly just my lack of knowledge though. sounds like you're having the same problems and are trying to do the same thing as me.

if it makes a difference, my amp does not have a tube pre-amp section. power tubes only. so simply loading my pre-amp harder isn't going to cut it or else I probably would've had better results with the lpb-1.

[Mark Hammer]

Eliciting optimal overdrive tone from a tube amp is not simply a matter of hitting the front end hard.  In this matter you are correct.  There is much to be said for the way that gain is distributed throughout a signal path, and the matter in which that gain accumulates harmonic content along the way.

This is not only why simply cranking the front-end gain and turning down the master volume does not always deliver what folks want, and also why tonal shaping of a boosted input is so important.

For example, the Klon Centaur is/was highly prized for the manner in which it could make an amp on the edge break up.  I had many long talks with Klon producer Bill Finnegan, and he was pretty clear that the intent of the pedal was to provide a booster that effectively "preconditioned" the signal to break up the amp in a certain way, not provide an overdrive sound of its own.  The unit blends an internal overdrive signal and a clean signal, then pushes that mix through a treble-control stage that Bill intended to be used primarily for cutting treble.

The Visual Sound True Tone booster also includes a treble cut control to preshape the signal for overdriving purposes.

What I proposed to you was intended to deliver something that had a bit of lower harmonic grit to it, and greater amplitude, but ultimately be something that could be used in tandem with the gain control on your amp's input stage.

[cgibsong002]

I'm going to be honest here, I'm really confused as to what exactly I should do. Lot of information in this thread, and a lot of which is slightly over my head. For further info, my amp has way more distortion than it needs. So I don't necessarily need more gain either. Currently I've got the gain just a touch over where I want it to be, I've got it up a bit high to improve the sustain and harmonics. Ideally, with the use of this pedal, I can lower the gain while simultaneously increasing my sustain and harmonics.

How similar is the sd-1 to the zw-od? if they're practically the same, the sd-1 would be perfect if i could just switch out a cap or two to improve my low end grind.

[Mark Hammer]

At the risk of complicating things further, yes they ARE quite similar, and it may well be possible to turn the one into the other with a few component changes.

Let's use these two schematics as reference:  http://analogguru.an.ohost.de/193/schematics/Mxr_ZakkWylde.gif
and  this one  http://www.indyguitarist.com/schematics1/boss/SD1%20PG2.jpg

First, let's look at the clipping stage.  The only thing that is really different is the presence of the 120pf cap on the ZW and its absence on the SD-1.  Both pedals, I should note, have a TS-derived trimming of bass end via C2/R4 (ZW) and C3/R6 (SD) to even up the amount of distortion produced lower in the spectrum.

The simple RC filter after the clipping stage(R3/C5 and R7/C4 for the ZW and SD) looks the same, but the ZW rolls off lower, given the use of a 47nf cap (884hz vs 339hz for the ZW).  Both add some gain in the tone-control stage that the Tube Screamer does not, by means of the 10k feedback resistor (R5 and R9) instead of the 1k on a TS.  However they both have a 10nf feedback cap (C4 and C6) to produce another bit of lowpass filtering at 1590hz.

Let's look at the tone control.  They both use a 20k pot in the exact same configuration, and a 470R resistor to ground.  The difference is that the ZW uses a .047uf (47nf) cap and the SD-1 uses a .027uf (27nf) cap.

I won't go into detail about what this does to the tone control (Jack Orman does a very nice job of that here: http://www.muzique.com/lab/tstone.htm ), but suffice to say the ZW moves the point of boost and cut in a downward direction.

And, as noted earlier, I think the transistor input stage on the ZW provides some additional gain, but don't know how to calculate it.

So, in summary the ZW and SD are designed to clip the same way, and shape tone the same way, but the ZW seems to have a bit more gain, rolls off more high end, and exerts its control over the tone lower in the spectrum.  The rather extensive treble cut and positioning of the boost/cut control takes the midrange honk away.

So, if in possession of an SD-1 that you can mod, this note tells you what components to change to get the one to very closely approximate the other.

What I proposed also sidesteps a midrange honk, and rolls off the top end for a more vocal-sounding clip.  I'm not claiming it nails the ZW sound, but it is oriented towards the same goals in a simpler circuit.

[cgibsong002]

i'd say that more or less complicated things a bit    but what if i don't want to tone shape? if this pedal was 100% ideal, it would not alter my tone at all, it would enhance it. the zw pedal i had, it was awesome, but i only used it for solos because i did not like how it kind of thinned out my rhythm. ideally i want a pedal that i can leave on all the time. it would leave my tone completely unaltered, but would add the sustain and harmonics so that i can nail those huge pinches in lead work, and then also hit those solos.

[Mark Hammer]

....and believe it or not, the ZW and many others do that by tone-shaping.

If this was a perfect world and all the notes on a guitar were exactly the same amplitude, or if diodes could identify when the amplitude was higher or lower and dynamically adjust how much they clip in response to louder and softer notes, you wouldn't need tone-shaping.

The objective here is to provide something to the amplifier that might constitute a "perfect signal".  What comes straight from the guitar is only perfect if your goal is to sound exactly like the guitar itself.

[Derringer]

When you go to build a pedal, there's two ways you can look at it. You can carry out thought experiments ... which are entertaining and enjoyable, I do these whenever my attention begins to wander while doing some other task that allows my mind to wander, or you can pick a design, build it and then tweak it from there.

Thought experiments only take you so far because ultimately, you have to build the thing and really hear what it sounds like. Because something seems to make huge sense in a thought experiment doesn't mean it will work out in real application.

So that's why I'm of the persuasion to take an idea that seems plausible, breadboard it, and see what it sounds like in real use. Listen for the core tone of the circuit. Does it have the sound that you want in there somewhere? Let your ears tell you if the circuit has potential. Does it need more treble? bass? mids? more/less clipping? too dirty? too compressed? etc etc. And pretty much all of these things can be remedied by tweaking.

So that's why I believe it's in your best interest to breadboard the schematic shown here, plug it in and jam for a while and then report back with what you like and/or don't like about it and then we can figure out what tweaks you can try. That circuit is a very solid, tried and true design. Give it a shot man ... then worry about the little bits.

-Bill

[cgibsong002]

When you go to build a pedal, there's two ways you can look at it. You can carry out thought experiments ... which are entertaining and enjoyable, I do these whenever my attention begins to wander while doing some other task that allows my mind to wander, or you can pick a design, build it and then tweak it from there.

Thought experiments only take you so far because ultimately, you have to build the thing and really hear what it sounds like. Because something seems to make huge sense in a thought experiment doesn't mean it will work out in real application.

So that's why I'm of the persuasion to take an idea that seems plausible, breadboard it, and see what it sounds like in real use. Listen for the core tone of the circuit. Does it have the sound that you want in there somewhere? Let your ears tell you if the circuit has potential. Does it need more treble? bass? mids? more/less clipping? too dirty? too compressed? etc etc. And pretty much all of these things can be remedied by tweaking.

So that's why I believe it's in your best interest to breadboard the schematic shown here, plug it in and jam for a while and then report back with what you like and/or don't like about it and then we can figure out what tweaks you can try. That circuit is a very solid, tried and true design. Give it a shot man ... then worry about the little bits.

-Bill

good advice... will do. Except I might start with the SD-1 instead, not sure. Does anyone know where I can find a vero layout of the SD-1? I could only find regular schematics.

Anyway, it's interesting... I was recently talking with my EE professor about what you were talking about. How the focus in school has become so conceptual that we can't even begin to relate anything to the real world or practical use. That's why I'm getting into pedal building early so I can try to relate what I'm learning to real world applications.

I'll go ahead and order some stuff and just get building, then work from there. I still have a question about the diodes though. Which kind do I want? Is there even a difference in diodes aside from their threshold voltage?

[Mark Hammer]

When you go to build a pedal, there's two ways you can look at it. You can carry out thought experiments ... which are entertaining and enjoyable, I do these whenever my attention begins to wander while doing some other task that allows my mind to wander, or you can pick a design, build it and then tweak it from there.

Thought experiments only take you so far because ultimately, you have to build the thing and really hear what it sounds like. Because something seems to make huge sense in a thought experiment doesn't mean it will work out in real application.

So that's why I'm of the persuasion to take an idea that seems plausible, breadboard it, and see what it sounds like in real use. Listen for the core tone of the circuit. Does it have the sound that you want in there somewhere? Let your ears tell you if the circuit has potential. Does it need more treble? bass? mids? more/less clipping? too dirty? too compressed? etc etc. And pretty much all of these things can be remedied by tweaking.

So that's why I believe it's in your best interest to breadboard the schematic shown here, plug it in and jam for a while and then report back with what you like and/or don't like about it and then we can figure out what tweaks you can try. That circuit is a very solid, tried and true design. Give it a shot man ... then worry about the little bits.

-Bill

Bingo.  And if the suggested circuit is simple enough (whihc this one is) even more reason to try it out.

[cgibsong002]

Bingo.  And if the suggested circuit is simple enough (whihc this one is) even more reason to try it out.

Ordering parts now. I'll update when I get the main layout done.

[Derringer]

don't commit to a layout just yet ... you could be painting yourself into a corner
just prototype what you want on the breadboard first

think about solder later

[Gus]

Something simple, a boost with an simple mid EQ rise and one transistor

http://www.diystompboxes.com/pedals/gusOverdrive.gif

Works best with a turned up amp

[cgibsong002]

don't commit to a layout just yet ... you could be painting yourself into a corner
just prototype what you want on the breadboard first

think about solder later

that's what I meant... my terminology is not so good yet 

[cgibsong002]

Ok, I know it's been awhile, but I finally breadboarded the schematic today (the one markhammer posted). Couple things I'm not too sure about though, mainly the input/output and the power source. For now, do I need the stereo output jack fully wired? I just have it wired as positive and negative. The positive to the middle lug of the 100K pot, and the negative to ground. It's hard to explain the rest, I'll upload a picture and see if you guys can explain to me if I'm doing this wrong. As of now, I get no sound from the circuit. The only thing I hear is the feedback increasing/decreasing when I move the trimpot. I know there's set rules for troubleshooting, but as this is a breadboard which I've never done before, I feel the mistake is simply in how I made the circuit. I'm fairly positive I put the correct values of everything in, so I guess ignore values since you can't see them anyway. Pic uploading...








And right.. I did make a few (kind of) adjustments. In the schematic, Mark didn't specify what D3 was. I used a germanium 1n34a. For C7 he called for .0039-.0068uf. I used a 4700pf. For C5 he called for 47-68pf. I used 56pf I believe. For c4 he called for .1-.22uF. I didn't have those parts on my original list that I bought, so I used .047uF as it was the closest I had. The other diodes I used were 1n914's for D1 and D2

[Mark Hammer]

Looks good, and thanks for following up.  If you have a meter, now would be a good time to use it.

Set the control for stun....er.....a range that lets you measure AC voltages with some accuracy in the under-2v range.

Plug the guitar in and verify that when you strum, there is some AC fluctuation registering at C2, and on each side of R5.

If you're good, apply some power, and measure the DC voltage on pin 7 of the chip and at pin 3 of the chip (without strumming).  If the voltages are good (9v at pin 7 and somewhere in the ballpark of 4.5v at pin 3), then set the meter back to measuring modest AC voltages, and measure the output at pin 6 (with the gain at minimum) while you strum.  There should be a greater AC voltage than you saw at R5.  Now turn the gain up gradually, and you should measure an even greater AC voltage.

If you're not seeing any of this, then I guess there are certainly some very real possibilities that  you've misconnected some things.  Given that the breadboard looks brand new, I doubt whether there would be any instances of something being properly linked up but the connecting wire not making contact with the breadboard.  Still, make sure those connections are secure.

[cgibsong002]

Yeah the breadboard is brand new and I tried going around and double checking each connection was firmly in. Do I have the input and output jack wired in correctly?
As for the measurements, I'll have them up as soon as I can tomorrow. Everything is put away for the night