The "Poor Mans" SparkleDrive!

[markm]

Rob Strand's SprinkleDrive layout is now verified in my gallery.
I have to say, I am very impressed with the build in it's "original" state. It is a mild OD with the ability to dial in some sparkley clean signal into the mix......this unit has Loads of potential for mods too!
I may try some Ge diodes in the clipping section just to make it a bit dirtier perhaps but like I said above, I feel it's a worthwhile build in it's own right.
I am rather surprised that, to my knowledge anyway, that this circuit has not gotten more attention. It's worth a try for sure.
BTW, the sound and texture of the overdrive is fairly unique IMO as it's doesn't sound quite like any other OD.
Give it a look and a try!

Here;s the PCB layouy;  http://aronnelson.com/gallery/album76/SprinkleDrive_LAYOUT

....And a perfbuild as well;  http://aronnelson.com/gallery/album77/SprinkleDrive_LAYOUT_perf

Also, if ya have the chance browse around my gallery a bit for some other new stuff and more to be added real soon!!
BTW, thank you Rob for this circuit and some assistance in the previous post about this! 

[John Lyons]

Mark you are a maniac when it comes to these layouts! Everytime i go to your gallery I feel faint for all the circuits I want to try out but can't possibly get around to.

I've had a rough couple days with this Tornado build of marty marts... The layout is compromised somehow... I'll have to gret cracking on a layout for it since it does sound fantastic...just some noise getting in somewhere....

I salute you!

john

[markm]

Thank you for your support John, much appreciated!

[stm]

Markm, are you sure that R10 should go to IC1:pin6?  I backtraced the circuit and believe R10 should go to IC1:pin7 instead, which is the output of the second opamp.

[Mark Hammer]

As you may or may not know, many of the "exciter" type circuits consist essentially of a Sparkle/Sprinkle Drive type circuit, except that the portion being clipped is severely highpass filtered such that you're mixing full-nadwidth clean signal and very often distorted content above maybe 4-6khz.

So, I'm wondering if the circuit could be adapted to be a poorman's exciter by rolling off the mids and lows in the clipped portion of the circuit so that clipping is applied primarily to the top end.  Note that this would likely require a lot more gain for the clipped side since cutting back on mids and lows seriously reduces overall amplitude.

I imagine in this case, the result would be something more like a bite booster than a full-fledged exciter.  Rather than dialing some clean for  "body", one would really be dialing in dirty for some bite to an otherwise generally clean signal.  Because the simple replacement of a DC-blocking cap with a much smaller value would provide a fairly shallow rolloff compared to the 4 and sometimes 6-pole filters one sees in exciters, you'd still get some of the fuzz from the low end leaking through, though not quite so much.

Worth a try I suppose, seeing as how easy and cheap it'd be to do.

[johngreene]

... mixing full-nadwidth clean signal ....

This made me laugh. 

--john

[markm]

Markm, are you sure that R10 should go to IC1:pin6?  I backtraced the circuit and believe R10 should go to IC1:pin7 instead, which is the output of the second opamp.

Yeah, I think you're correct here....
I'll re-route it as soon as I can tonight.
Thanks......

[Mark Hammer]

... mixing full-nadwidth clean signal ....

This made me laugh. 

--john

Oh man, flying fingers failed me again!    But it IS funny.  I was just trying to give it a ballsier sound.

[dachshund]

What's the difference between the Sprinkle drive and Sparkle drive?
(besides three letters....  )

[markm]

Okay fellas,
The updated version is now up in the gallery with R10 corrected.
Thanks stm.....much appreciated. 

Here are the new links;

PCB>>> http://aronnelson.com/gallery/album76/SprinkleDrive_r_LAYOUT?full=1

Perf>>>http://aronnelson.com/gallery/album77/SprinkleDrive_r_LAYOUT_perf?full=1

[Processaurus]

So, I'm wondering if the circuit could be adapted to be a poorman's exciter by rolling off the mids and lows in the clipped portion of the circuit so that clipping is applied primarily to the top end.  Note that this would likely require a lot more gain for the clipped side since cutting back on mids and lows seriously reduces overall amplitude.

A good place for using Ge or schottkey diodes for the clipping, since you wouldn't need big output to get a bit of high end cajones. 

[markm]

... mixing full-nadwidth clean signal ....

This made me laugh. 

--john

Oh man, flying fingers failed me again!    But it IS funny.  I was just trying to give it a ballsier sound.

That is hilarious!

[MartyMart]

Nice work Mark - hope this doesn't get "lost" in a sea of bloody DS-1 quetions  !!!! 

MM

[WGTP]

What is the unit of measurement for a Nadwidth?  Inches?   I think Mark has presented the new measurement for the overall ballsiness of a distortion pedal.  Maybe use a scale of 1-10. 

[MartyMart]

What is the unit of measurement for a Nadwidth?  Inches?   I think Mark has presented the new measurement for the overall ballsiness of a distortion pedal.  Maybe use a scale of 1-10. 

1-14 IF your name is John Holmes  !!!!!!!! 

[Mark Hammer]

I think the thread is already poised to step beyond the perimeter of what our web-filters at work will tolerate , so I will simply say the unit of measurement is officially "the jeremy", with 100 millijeremies = 1 centijeremy, etc.

On a more practical note, I've lost track of the schematic for the Sprinkle Drive, so a link would be appreciated.  I'd rather not be declaring with a wave of the hand that something is easy to do when maybe it isn't.

[johngreene]

What is the unit of measurement for a Nadwidth?  Inches?   I think Mark has presented the new measurement for the overall ballsiness of a distortion pedal.  Maybe use a scale of 1-10. 

All due respect, I think it should be measured in "Hammers". From "ball peen" to "10 pound sledge". 

--john

[markm]

Here's the schem from Rob S.



Rob,
If you disapprove of this being posted here I will remove it ASAP.
Thank you.

[gaussmarkov]

mark,

nice work bringing the sprinkle drive to the forum!  the schem floating around for the voodoo labs original has profound errors on it anyway.

by the way, i dont' think that you will be able to remove rob's schem above, because you linked to rob's site and we cannot change our posts after a short period.  next time you might load the schematic into photobucket.com or similar and reference that.  then you can always change the graphic later.

all the best, gm

[Mark Hammer]

Okay.  Thanks for that.

Let's say a person wanted to convert the unit to a poorman's exciter.  The following mods would need to be done:

• The bandwidth (or "nadwidth" ) of U1b would need to be changed.  Easy to do by reducing the value of C3.  Currently, it provides a TS-like low-end rolloff around 720hz.  Dropping the value to .01uf or .015uf would achieve the sort of rolloff required that would only tend to provide harmonic content sans fundamental in that channel.  It may seem kind of high (.01uf = 7.2khz) but again remember its only a 6db/oct rolloff so there will still be plenty of content under 7.2khz for a couple of octaves below.  Also note that C2 (33pf) produces a rolloff above around 9.5khz so maybe drop that to 27pf.
• The tone control on the dirty channel is essentially that of a Proco Rat.  When it's wide open, the high-end rolloff is well above anything you can hear.  When rolled back fully, though, it bleeds content above around 480hz to ground.  The user's choice to either leave it wide open or adapt it for a different range.
• C9 (1uf) also presents another opportunity to roll off the lows and mids.  You can experiment with values, but my guess is that you start with .047uf and work downwards from there.Same general strategy applies to C8 and C4.  You want them each to take away a bit of mids and lows so as to leave only mid and upper harmonics.
• Finally, as has been noted, maximum crispness would come from having more gain in U1b and a lower clipping threshold. With that in mind, you can either up the value of R7 (to somewhere between 47k or 220k), swap one or both of the 1N4148 diodes for Ge type, or both.
• RV4, the blend control, makes some assumptions about relative levels from each channel, essentially that they would be roughly equal.  If the intent is to blend in some harmonic content to an otherwise clean signal, then you don't really want it to be able to pan hard to each of the two signals.  Rather, you want to be able to blend in one with a fixed level of the other.  In that respect, maybe consider having the clean signal go through a 1k-2k2 fixed resistor (just after C7) to the mixing node where RV3 takes its feed from.  At present, the wiper of RV4 is that mixing node.  In the arrangement I'm suggesting, RV4 turns into a variable resistor, and the mixing node now becomes the point where the added fixed resistor and one of the RV4 lugs are joined.

Let me state for the record that this not going to suddenly blossom into an Aphex.  Rather, if you have a PCB layout for this circuit, you can easily use it to provide a different sort of effect simply by changing a few component values, adding one resistor, and rerouting one between-pots connecting wire