Small Clone depth switch

[Somicide]

I've just bought a Small Clone a few weeks ago (honestly, before I'd even played it, I had it open; at work no less, in a mall!) and was wondering, how is it I would go about replacing the depth switch with a pot.  Help'd be appreciated.  Thanks,

PnL,

Jeff

[Mark Hammer]

The depth switch actually does two things at once, more or less like a scaled down version of the 4-way switch on an MXR Phase 100.  Where the P100 provides all 4 combinations of 2 sweep width settings and two resonance/regen settings, the SS only provides two combinations.  One half of the depth switch does the one, and the other half does the other.

You *could* simply use a pair of SPDT switches (all contacts on one side go the identical contacts on a separate switch) and disaggregate the two functions to get all 4 combinations.  Alternatively, the regen half of the switch can be easily turned into a continuously variable control.

You will note that the last phase shift stage goes to the mixer stage, but also goes through a 3k3 and 4k7 resistor, then on to a cap and 270k resistor and back to the input.  The switch normally routes the signal back through the 270k resistor or to ground.  If you unhook that side of the switch, and replace the 270k resistor with a 500k pot, you can vary how much feedback signal makes it back to the start - voila a regen control.

You still only have the two position width control, though, which keeps the modded version from being perfect.

[Fp-www.Tonepad.com]

Mark, you're talking about the small stone!

Check out the small clone pdf, it includes the depth mod... I have performed this mod (with a few twists), and it works. For some reason somebody said that it was a 100k pot, so that's what it's on the pdf, BUT  in fact it should be a 10k pot. (I'll be updating the pdf soon)

http://www.tonepad.com/project.asp?id=8

Fp

[george]

Hey FP and all: I tried the tone pot mod for the heladito - I went back to the switch.

Why?
- I only really needed/could be bothered with 2 settings
- it sounded better with the switch (don't know why ...)

just my $0.02 on what is a great project.

[Mark Hammer]

Mark, you're talking about the small stone!

Erp, you're right! :oops:

Guess that's what happens when you're supposed to be visiting the in-laws and try and sneak in a quick trip to the forum while the wife is standing at the door, saying "Well are you coming?" andyou're muttering "Yeah, in just a sec...(tap. tap, tap)".

[Somicide]

Thanks for the reply, I figured it was possible becuase I was planning on building a SC, but money and impatience got the better of me.  I'll try the pot depth mod, and If I'm not a fan I'll switch back.  thanks for the Small Stone info though, I've got one of those as well!

ON another note, is this thing true bypass?  Instinct says no, but from looking, it does have a 3PDT.  Interesting.

PnL,

Jeff

[Fp-www.Tonepad.com]

George, If you used a 100k pot, I understand. I used a 10k pot and it sounds very good, all the range of the pot is useable. Also, I didn't ground pin1 of the depth pot, instead I coupled it with a 47uF cap (In my effort to keep the DC bias at that spot) (Cap value chosen randomly and without a clue of what another value would do)... I remember there was a difference between using the cap and not. As I said I'll update the pdf one of these days!

Mark, I understand perfectly... I had to add the "chorus" and "phaser" words to the descriptions of those two pedals because of the confusion... Clone a small stone phaser... of course Having all sorts of names to choose from, EH should've thought better

Somicide, Let us know how it turns out. Too bad you didn't build the SC, it's a pretty good project. Ah, and you should also try the vibrato mod.

Fp

[Somicide]

I had started to build it, but when it came to the mn3007 (i think...) or whatever chip was $15, I was at a loss.  Didn't have money at the time.  But vibrato sounds like a good idea!

PnL,

Jeff

[Fp-www.Tonepad.com]

You're right. That MN3007 is expensive...

It should be about time that somebody would've come up with an adaptation for the MN3207 which is a lot less expensive.

Mark, would you help me out with this? I have voltage readings in a schematic somewhere, it shouldn't be terribly hard.

What I don't think I have is an MN3207 to try... Or perhaps in the last samples I got from Small Bear... Hmmm

Fp

[george]

George, If you used a 100k pot, I understand. I used a 10k pot and it sounds very good, all the range of the pot is useable. Also, I didn't ground pin1 of the depth pot, instead I coupled it with a 47uF cap (In my effort to keep the DC bias at that spot) (Cap value chosen randomly and without a clue of what another value would do)... I remember there was a difference between using the cap and not. As I said I'll update the pdf one of these days!

yeah ... I just checked ... I did have a 100K pot in there, I must have got that value from one of the build reports.  I might revisit this mod!

Thanks!

[STOMPmole]

FWIW, I have a 100k pot for the depth mod and I think it sounds fine...it's an audio taper instead of a linear as listed on the Tonepad layout however.

[SirPoonga]

Does anyone have sound clips for a small clone (with mods too?) and the zombie chorus?  I might end up building both to find out myself.

You could add some sort of pot at the 20k resistor (near point D from tonepad schematic) from where the clean and dirty line connect to create a blend, right?  or better yet for more control have a volume pot off pin 1 of IC1a to control clean volume and a pot off (or replace) the 20k resistor?

[H.Manback]

I built a small clone as well, designed my own pcb to get the stereo mod on the same board. When it's completely finished I will post the whole deal on my site.



Sound clips, there are some on the Charlie Lamm page, but IMHO sound clips don't really say everything.

I added a wet/dry mix pot now, but I will have to fine tune it, since now it has unusable noisy settings at both extremes. I used a 50k pot since it adds up reasonably to the 20k and 22k, but as I kind of expected, you can't really go without some limiting resistors. Not sure yet what I am going to make of it, but I'm thinking a 10k and a 12k connected to a 20k pot.

About the MN3007, Dirk_Hendrik pointed out a cheaper variant once, from a company called Belling, smallbear has them too I believe.

Also, I'm going to add some opamp circuit to drive the LED using the output of the oscillator. I still have to determine the pk-pk values of the oscillator, which I won't be able to do until I get to a oscillator.

[Mark Hammer]

Hey, no fair!  You used SIPs!  

Seriously, nice-looking board, and killer ground-plane.

[StephenGiles]

Mark said:

Guess that's what happens when you're supposed to be visiting the in-laws and try and sneak in a quick trip to the forum while the wife is standing at the door, saying "Well are you coming?" andyou're muttering "Yeah, in just a sec...(tap. tap, tap)".

I've been there (frequently) and got the T shirt! It's all a question of priorities really - now I'd better read the thread.
Stephen

[H.Manback]

Hey, no fair!  You used SIPs!  

Seriously, nice-looking board, and killer ground-plane.

Hehe, those SIPs just had to be done, my local electronics shop only carried JRC 4558s in SIP form... The board looks nice but if I were to make another board, I'd seriously change it. This one is double sided, and I did not take into account that the guy who etched it for me did not have the ability to make through hole plated boards. I found out too late that the solder does not flow through those holes (could have seen that one coming), so now it's not nearly as neat as I thought it would be, there are some wire connections on the bottom side to get around the unsolderable parts on the top side.

Also, while the ground plane is very nice and big, I designed the board with too tight tolerances, so the etching was problematic, the etching time has to be just right with this design... not a good thing.

[Mark Hammer]

Well good, then.  Now I don't feel quite so bad. :lol: