Synthbox

[Jerem]

Hi ! I don't find where is C23 on the layout. I think it is between pin 6 ans 7 of the IC1, is that right?. I will use an ICL7660S to replace max1044. I think it should work. For C17, I want to use an 2.2uf film cap, does it ok?

[jdub]

Hi Jerem- Yeah, C23 is the electrolytic coming off of pin 6 of IC1 & connecting (positive side) to R22 (pin 2 of IC3).  Sorry, it's hard to read the labeling.  As for the ICL7660, should work. 

[Zero]

Hi, just wanted to chime in and say that I've been following this thread and can't wait to build it!

I loved the sound samples (from version 1). It's exactly what I'd been looking for.
They sound kinda reminded me of the awesome synth in this classic Tom and Jerry Cartoon (Chuck Jones Era):

Tom and Jerry - "Cannery Rodent"

The synth starts at about 1:00

[Ronan]

I've been playing with this circuit for a while, I found out accidentally that by hooking up the transistor wrongly, I got a different sound, a bit like what liquids sound clip sounds like, and similar to that synth sound in the cartoon. I found I then didn't need the associated cap and diode. How it works now, I have no idea, because it really doesn't look right. I have checked, double-checked, and quad-checked the orientation of the transistor. It worked great 2 weeks ago (on breadboard) and worked great yesterday (still on breadboard). Today I put it through an envelope filter and distortion box, all is well. Schem is here to show the transistor variation, and the circuit I am using it in. I couldn't get "the sound" with the transistor orientated correctly and with the cap and diode. I got "a sound" but not "the sound". Some of the values in the circuit might look unusual but I used what was on hand, for example, the 330uF electro on the 4.5V supply. One can never have too many spare parts laying around...

[liquids]

My "recording rig" is really awful -- an old $5 computer mic into my generic soundcard...but I'll see if I can manage something over the weekend as I imagine more people will be interested once I do.    

Note the date above...

I loved the sound samples (from version 1).

I think the preference for the 'version 1' discrete sound (http://www.aronnelson.com/gallery/main.php/v/liquids/Synthbox+Demo.mp3.html) stems mostly from those samples being recorded:
1) by a cheap omnidirectional computer mic
2) with the mic as far away from the speaker as the $5 computer mic's cord would go, to avoid the digital clipping I kept getting
3) in a small room
4) and eventually edited a 70 second collage of phrases and lines gathered from dozens of minutes of playing once I got the levels clean.

Quite simply, the elusive mojo of V1 is in the recording...in the room it didn't exactly sound midrangy, pure sax-like, fundamental-focused etc...the 'Synthbox 2' has same tone as the first version in my hands, plus or minus active (wonky) filtering and more consistent TRACKING.

I don't know what if any active EQ was used on the second recording anymore (http://www.aronnelson.com/gallery/main.php/v/liquids/Synthbox+2+Demo.mp3.html), but I'd venture to say the major difference is that the 'v2' clips were instead close-miced with an SM57 as stated in the notes for that recording, and hence probably closer to reality...

Somehow V1 has become a discrete component-sensitive mojo-tone because of that sample...

So to those of you who prefer the lo-fi tones better, maybe the better tweak would be buy a lo-fi amp like a sears silvertone to play the synthbox through....

[MAK]

Hi guys! I made SynthBox 2, and faced with the problem. The transistors I used 2N5088. I matched them as indicated. The sound is very dirty and "jumps". What are your ideas?

[liquids]

Hi guys! I made SynthBox 2, and faced with the problem. The transistors I used 2N5088. I matched them as indicated. The sound is very dirty and "jumps". What are your ideas?

Have you heard the sound samples?  Would you call them clean?

It only tracks well if you play cleanly.

[MAK]

No, not like on the sample. My unit sounds very dirty, the sound skips and does not keep a constant tone. The problem arises when the cascade transistors.

[Ronan]

Are you using the neck pickup? Another thing is to set the input level high enough to sustain a note, but not too high that the circuit makes noise when you are not playing. It should be silent when not playing. If it is skipping octave up/octave down, try making the 2 capacitors bigger (or smaller) in the oscillator section, these are the 2 caps connected to the transistor collectors. And only play one note at a time.

[jdub]

Are you using the neck pickup? Another thing is to set the input level high enough to sustain a note, but not too high that the circuit makes noise when you are not playing. It should be silent when not playing. If it is skipping octave up/octave down, try making the 2 capacitors bigger (or smaller) in the oscillator section, these are the 2 caps connected to the transistor collectors. And only play one note at a time.

Well said; +1 to all these.  Can also try rolling back the tone control while using neck pickup. 

[Jerem]

Thank for your precedent answer jdub. Can you confirm me that is R19 wich is under IC4 and R18 on is right?

[liquids]

No, not like on the sample. My unit sounds very dirty, the sound skips and does not keep a constant tone.

The samples sound pretty dirty to me.

[jdub]

@Jeremy- Yep, R19 is under the opamp and R18 is to the right 

[egasimus]

http://www.diystompboxes.com/smfforum/index.php?topic=93508

Here's my layout for Ronan's no-nonsense version. Anyone have some spare time to etch and verify? Cuz I have none...

[jdub]

That there's a good-lookin layout    I'm gonna have to try this one...and the list grows longer...

[Jerem]

I just have finished my synthbox op version. All is ok, the switch selection work good and bass/treeble filter sound good. My only problem come from the gain pot and the attack pot. Nothing working. I believe we have to solder together pin 1 and 2 of these pot?
Thank for your layout jdub, I like the sound of this stompbox !

[Keppy]

I just have finished my synthbox op version. All is ok, the switch selection work good and bass/treeble filter sound good. My only problem come from the gain pot and the attack pot. Nothing working. I believe we have to solder together pin 1 and 2 of these pot?
Thank for your layout jdub, I like the sound of this stompbox !

Nah, just use 2 lugs. Don't worry about joining any together.

If you are looking at the back of the pot (no shaft) with the lugs on the bottom, they go 3-2-1 left to right. Use 1 & 2. It doesn't matter which is which, since they're just variable resistors in this design.

[jdub]

On the layout I did I only showed connections for lugs 1 and 3 of the gain and attack pots, so following that you would have to connect the wiper to one of the outside lugs (I connected 2 & 3).  But Keppy is right, it's probably easier to just use lugs 1 & 2.  I did it that way just as a personal preference to not have hanging lugs.  But either way is perfectly valid. 

Glad the layout is useful to you, but liquids especially deserves the thanks for for this (as well as Isildur100, Gigimarga and all the other cats who helped develop this killer circuit).  And of course the illustrious Joe Davisson for the Shocktave! Hats off to you, dudes! 

[Quackzed]

i havent tried this variation, but indeed the shocktave was one circuit that had great potential! the frist time i got it working i remember the smile on my face. definately a new experience playing through that thing. iirc, shorting one of the flip flop caps to ground gave another tpe of sound... not octave down , but synthy same-octave similar tone... something to try...

[~arph]

On a similar note... check out the colorsound octivider. and there is a thread at FSB with a vero layout..

http://www.mtcom.jp/~schematic/effects/colorsound_octivider_v11.gif

There are some youtube vids too..

Sounds great!