Unidrive & Sixteen OD sound samples :-)

[MartyMart]

http://aronnelson.com/userfiles/Unidrive%20clean&breakupamp.mp3
http://aronnelson.com/userfiles/Sixteen%20OD&diodes.mp3

Unidrive has two parts, first at low level, so it's not breaking up the valve
amp (Matamp C7) and second at about 2/3rds volume causing nice breakup !
So the initial "crunch" is the pedal itself ....
I had to do these quick before work, so the Unidrive has some "room boom" around it from the control room speakers .... sorry !!

"Sixteen" is Erik Vanhansens circuit with added diodes, this went through
the JMP-1 so is NOT causing any breakup there, it's all the pedal.
Set to full gain, it has nice "pick" dynamics and will clean up with gtr vol
backed off.
This clip has no "room boom" due to no mic/speakers being involved !!
Both have just a touch of reverb and nothing else.

Gtr -Epiphone Les Paul Classic
Mic -Rode NT2
Fingers -not that great !!


Enjoy,
Marty.

[Eirik]

 The unidrive really sound cool! Did you do any mods to it, or is it built like  in the original schemaic?

[MartyMart]

 The unidrive really sound cool! Did you do any mods to it, or is it built like  in the original schemaic?

I left out the whole "resistor selection" front end, and went in via a 1M
to ground, 1uf poly cap and a 68k resistor to the first stage.
I didn't use the small 2k pot at the end ( which sets minimum level when used with a wah pedal ) and wired up in a wah shell to a 100k wah pot.
That was how the original was used ( not a standard pedal with knobs )
but you could easily use it that way.
I used 2N5089's and an MPSA18 at the end, also changed the 10uf electro's to 1uf poly's.
It makes the thing more "raw and edgy" so some lower gain trannies may calm it down a bit !!
Hope that helps ?

Marty.

[Marcos - Munky]

The Sixteen OD sounds great.

[barret77]

hmmm... adding sixteen to the already inflated to-build list!

[petemoore]

Thanks for the nice clips Marty Mart !
 I see what you typed abou the Unidrive's...drive now, hearing the clip, seems like a nice build for a FuzzJunkie who'se trying to 'taper down' !!!

[MartyMart]

My "to build" list is getting small .... ??   :oops:

M.

[vanhansen]

Thanks, Marty.  All I gotta say is....wow.  Both clips sound great.  That Univalve has a nice mild smoothness to it.  Very nice.  It almost reminds me of a mild Molly Hatchet overdrive.

The Sixteen OD clip made the hairs on my neck stand up.  I never thought it would sound that good with diodes in it.  I was just imaging but hearing it....wow.  Thanks for taking the time to do this.  I would like to host the clip on my site if it's OK with you.  I'm also going to add the diode addition as a mod (and give you credit).  Did you also have 2M gain pot there or was it 1M?

P.S.  just an FYI..vanhansen is just my handle, a nickname given to me by a buddy of mine due to how I play guitar (EVH being my main influence).  My real name is my domain name.  You probably knew that though 'cause my real name is on my schematics.  I hadn't been called Erik Van Hansen in quite a while though.  

[MartyMart]

No problem Erik - sorry for the "mix up" !!
Yes it does sound rather nice eh !!
Can you down load it ? If not PM me your email and I'll send it to you.
Keep in mind that the clip used a "Humbucker" gtr, there's less grind
from a strat/tele so we may need a tad more gain !!
I didn't try the bigger pot yet, its enough for me as I have rather a lot of
"high gainers" around  :wink:
It would be nice to add the "softness" pot from the FAQ, to dial in how
much you want the "diode crunch" present - have a look at it, its a simple
addition.
Just a 50k pot top of the diodes to ground.

Marty.

[vanhansen]

Yup, I can download it.  I'll make note of what was used in the clip.  
You don't have to be sorry for the "mix up".  It's no biggie, just throwin' it out there.
I'll check out that article in the FAQ.  Sounds pretty interesting.
I'm also thinking of adding in Mark Hammer's SSTC or whatever he called his tone control.  Man, it's going from a 2-knobber to 4 just like that.

[MartyMart]

I'll check out that article in the FAQ.  Sounds pretty interesting.
I'm also thinking of adding in Mark Hammer's SSTC or whatever he called his tone control.  Man, it's going from a 2-knobber to 4 just like that.

It has a nice "tone" stock, so perhaps a tone control could be optional ?
I do prefer 2 knobs to 4, but when its required - no probs !
The "softness" control could be a trimmer rather than an out of box knob
so you can set it to just a "booster" or a "cuncher" to suit !
It kind of works with the "gain" at max all the time, rolling off the gtr vol
may be enough, so I will probably loose that pot ... what do you think?
Then I'd have "diode softness" and "volume" pots .....

Marty.

[vanhansen]

It has a nice "tone" stock, so perhaps a tone control could be optional ?

That's what I was shooting for in the design stages.  I wanted it to sound good without a tone control.  It took some tweaking but once I nailed it, I stopped the tweaking.  Making it optional wouldn't be a bad mod.

I do prefer 2 knobs to 4, but when its required - no probs !

Me too.

The "softness" control could be a trimmer rather than an out of box knob
so you can set it to just a "booster" or a "cuncher" to suit !
It kind of works with the "gain" at max all the time, rolling off the gtr vol
may be enough, so I will probably loose that pot ... what do you think?
Then I'd have "diode softness" and "volume" pots .....

Marty.

Not a bad idea.  Are you talking about taking out the gain pot?  You can do that and replace it with a 1M to 1.5M resistor.  When I tested that out during design, I think I was using a 1.5M there, it was metal film I know that.  I like the idea of the "softness" control.  I personally like the gain pot there to help control how much the second FET stage is driven.  It should work pretty good with the "softness" control to really control the touch and feel of the drive.  We should call it that too.  I've never seen a "softness" control before.  What do you think?

[vanhansen]

Hey Marty,

I re-breadboarded the Sixteen Overdrive today and messed around with the diodes.  I really like it.  I don't have any Ge diodes so I used Si diodes instead.  It's a bit tighter with them, more SD-1ish.  I tried and LED too but didn't care for the sound.  Since I have one NTE458 left, Q1 was a NTE458 and Q2 was MPF102.  Talk about completely different gain levels.  I'm going to swap them around too and see what that does, drive the low gain in to the high gain rather than vice-versa.

Have a great weekend.

[petemoore]

Great new sound samples Marty !!!
 I've caught Unidrive fever now !!
 Q1 was a NTE458 and Q2 was MPF102. Talk about completely different gain levels. I'm going to swap them around too and see what that does, drive the low gain in to the high gain rather than vice-versa.
 I'm interested to hear what you find out !!

[petemoore]

Built it late last night, realized I go in earlier today...
 Nice...it gave me something to ponder doing after work/during work !!
 Hopefully all I have to do is place the transistors and it'll fire up !!

[vanhansen]

I should hopefully have time tomorrow morning to swap the FETs around and see if there's any difference.  It may not make much of a difference at all but worth a shot anyway.

I'll probably have a perf layout for it sometime within a week or two.

[vanhansen]

This morning I swapped the JFETs around Q1=MPF102 and Q2=NTE458.  There was a noticeable difference but not what I expected.  The amount of drive was less in this configuration.  In this scenario, I like it better with the NTE458 in Q1 and MPF102 in Q2.  I don't have any J201's or 2N5457's so I don't know how it will sound.

I've updated the diode schematic on my site.  I swapped the direction of the diodes.  Sounds better this way.

[MartyMart]

Erik, this is wierd, just removed the 1M gain pot and used a 2M2 resistor
and the thing "cleaned up"  !!  ??
Then reduced it in stages to a 10k and I have more overdrive than ever?
Am I going mad, or what ?
Or .... was the pot "driving more" nearer 10k than 1M ... I'm confused
about this circuit now !
RE-biased for a bit more level too ....

Marty.

[Doug_H]

I like the sound of the unidrive a lot, Marty.

I'm going to have to try that one.

Doug

[vanhansen]

Erik, this is wierd, just removed the 1M gain pot and used a 2M2 resistor
and the thing "cleaned up"  !!  ??
Then reduced it in stages to a 10k and I have more overdrive than ever?
Am I going mad, or what ?
Or .... was the pot "driving more" nearer 10k than 1M ... I'm confused
about this circuit now !
RE-biased for a bit more level too ....

Marty.

No, you're seeing normal behavior.  The more resistance you put between the stages, the more it will "clean up", higher resistor = more resistance.  The way the pot works, if I'm wording this right, is with it closer to zero gain, that is where it has it's most resistance.  Less and less resistance comes in as you turn the gain level up.  I haven't measured what the resistance is between the 2nd and 3rd lugs with the gain all the way up but it would be insteresting to know.  I'm almost positive it will be zero between those two points with it turned all the way down.