Cottage Cheese and Green Russian

[chuckbuick]

First is a Mayo built on my Big Red Bell SMD multi-muff board.  I was gonna use some 2N5133's but the ones I have only measured approx. 100 hfe so I went with good ol' 2N5088's.  The cap tombstoned up against C12 is a cap the Mayo uses that I didn't catch when I designed the board.  I'm not a huge fan of mayonnaise so I opted for cottage cheese.  It's the healthy alternative. :wink:







Second is a Green Russian.  I used the MH Iron Bell "color" control, MHIB treble bleed caps on the Sustain and Volume controls (C18 & C19), Mad Professor Fire Red type transistor clippers (D21 & D22 - BS170 and 2N7002, respectively), and 2N5089 (MMBT5089 in SMD speak) transistors.  Maybe a roided-out Green Russian.  My cold-war isn't over, man. :evil:   I'm not sure how accurate my Russian is on the labels.  It's was the best that Google and I could come up with.

A quick note about the transistor clippers.  The way Mad Professor has these set up they are essentially being used as regular diodes.  I'm not recalling all the details and I don't want to mis-inform.  I can't find the info right now, either.  But it started with one of midwayfair's build docs and took me down a bit of a rabbit-hole on transistor clipping that some you may be interested in reading.  Thanks for posting that, Jon.  If you can chime in with a starting point that would be awesome.  In the meantime I'll see if I can find it again.

[alanp]

Intimidating as usual

[cooder]

... you must have some magic smd parts placement and solder robot in your basement or something fairy dwarf kinda creature that you sold your soul for to do this secrectly....
...you must...

[juansolo]

The Iron Bell (and Spasm Chasm) colour/shape control doesn't work quite as people think. With the B100K pot it messes with the value of both the caps (if you're using the Tone Stack Calculator, you won't be getting what that shows). If you use a C500K however it moves what it effects out of the frequency range we're bothered about. So all the way left will give you the base cap value and all the way right will blend in the parallel cap properly. What you see on the TSC is what you get then.

Bloody impressive as usual though dude! 

[Leevibe]

Perfection

[wgc]

Awesome!  Love the save on c12, I'm not into mayo either.   That wire is killer stuff. Probably worth trying some germs in the cheese.

Nice graphics too!

For some reason, I've never been into this circuit much (probably just need to match it to the right amp), but you cleverly made this is a great platform to play with many of the variants.   

Which one is your fave, Mark?

[pickdropper]

Very nicely executed (as usual).

I like that the Green Russian only uses green wire.  Nice touch.

[midwayfair]

Looks awesome ...

Even if I do have a pet peeve about using Cyrillic letters for the wrong sounds. (That backwards R looking thing is a "Ya" sound.) 

Since you asked me to explain the MOSFETs: A MOSFET as a diode conducts in two directions, a silicon body diode that conducts at ~0.7V like a normal silicon diode when signal goes from the source to the gate-drain connection, and a "special" diode that soft-conducts at ~1.3V and higher (it takes a very long time to hard clip) in the opposite direction. If you put them back to back, the lower forward voltage of the body diode will conduct and the reverse conduction will have very little effect. It's not exactly "no effect" -- Fv drops in parallel -- but it's extremely minor (it's less minor when using Germanium diodes, but that's another show). It is possible to get a slight change in sound compared with, say, a switching diode like the 1n4148 or similar by using only the body diodes, since different types of diodes (inculding MOSFETs) have different turn-on characteristics. They tend to sound very slightly spongier to my ear, but I can only tell when back-to-backing them and that's not exactly scientific. If you have two MOSFETs in parallel and you remove one of them, you'll get an asymmetrical clipping diode from the other one all by itself (see my Mossy Sloth fuzz for multiple examples, including one similar to a BMP stage). If you want only the special diodes all by themselves, you need a diode in series with the MOSFET "diode" to block the body diode's conduction (see the Zendrive). If you want to waste parts, you can do it like the OCD V4 and put a diode in series with one MOSFET, which gives you the equivalent of the single MOSFET because the second will never conduct.

[hylandren]

Man, if your SMD guts were any more pristine, I would accuse you of posting CG created illustrations...

I'm not a huge fan of mayonnaise so I opted for cottage cheese.

Like you, I am not a fan of mayo, (the condiment) and feel the same about cottage cheese. But I really love everything about that Cottage Cheese build!
I also dig the textured color theme, and yes, even the font.
Pardon my ignorance, but who's board is that on the stomp switches?

[jubal81]

Just outstanding. 

[chuckbuick]

Thanks, bro's.  It's always nice to hear kind words from a solid group of DIY guys.

... you must have some magic smd parts placement and solder robot in your basement or something fairy dwarf kinda creature that you sold your soul for to do this secrectly....
...you must...

I would love to have a solder fairy.  That would free up a lot of time.  As far as selling my soul...no comment.

Pardon my ignorance, but who's board is that on the stomp switches?

That's mine.  There are some great 3PDT boards out there but I don't use a lot of the features.  I wanted something 1590A friendly and simple.  If you're interested I'll share it through OSH Park.

Since you asked me to explain the MOSFETs: A MOSFET as a diode conducts in two directions, a silicon body diode that conducts at ~0.7V like a normal silicon diode when signal goes from the source to the gate-drain connection, and a "special" diode that soft-conducts at ~1.3V and higher (it takes a very long time to hard clip) in the opposite direction. If you put them back to back, the lower forward voltage of the body diode will conduct and the reverse conduction will have very little effect. It's not exactly "no effect" -- Fv drops in parallel -- but it's extremely minor (it's less minor when using Germanium diodes, but that's another show). It is possible to get a slight change in sound compared with, say, a switching diode like the 1n4148 or similar by using only the body diodes, since different types of diodes (inculding MOSFETs) have different turn-on characteristics. They tend to sound very slightly spongier to my ear, but I can only tell when back-to-backing them and that's not exactly scientific. If you have two MOSFETs in parallel and you remove one of them, you'll get an asymmetrical clipping diode from the other one all by itself (see my Mossy Sloth fuzz for multiple examples, including one similar to a BMP stage). If you want only the special diodes all by themselves, you need a diode in series with the MOSFET "diode" to block the body diode's conduction (see the Zendrive). If you want to waste parts, you can do it like the OCD V4 and put a diode in series with one MOSFET, which gives you the equivalent of the single MOSFET because the second will never conduct.

That's what I was looking for.  BTW, your build docs incredibly detailed.  I dig it, even if I can't always wrap my head around it.
And here's a link taken from the Mossy Sloth doc that has some interesting reading for you clip-curious types:
http://www.diystompboxes.com/smfforum/index.php?topic=90474.0

Which one is your fave, Mark?

I like the Iron Bell a lot and the Mayo is cool, too.  So many variants still to try.

The Iron Bell (and Spasm Chasm) colour/shape control doesn't work quite as people think. With the B100K pot it messes with the value of both the caps (if you're using the Tone Stack Calculator, you won't be getting what that shows). If you use a C500K however it moves what it effects out of the frequency range we're bothered about. So all the way left will give you the base cap value and all the way right will blend in the parallel cap properly. What you see on the TSC is what you get then.

Thanks for the heads up.  I'll have to try that new pot value.

[catfud]

Those are fine builds - you have a knack of making a 1590B look cavernous.

[midwayfair]

The Iron Bell (and Spasm Chasm) colour/shape control doesn't work quite as people think. With the B100K pot it messes with the value of both the caps (if you're using the Tone Stack Calculator, you won't be getting what that shows). If you use a C500K however it moves what it effects out of the frequency range we're bothered about. So all the way left will give you the base cap value and all the way right will blend in the parallel cap properly. What you see on the TSC is what you get then.

I'm not sure what you mean. Are you saying that the schematic showing it as a variable resistor is wrong, or that even at full resistance it's still adding some capacitance from the 33nF? 100K is a LOT of resistance, but of course it does still let through some signal. But at halfway on the 500KC, you're at 4x the value of the stock pot!

[jtn191]

Fantastic builds, as usual!

[juansolo]

The Iron Bell (and Spasm Chasm) colour/shape control doesn't work quite as people think. With the B100K pot it messes with the value of both the caps (if you're using the Tone Stack Calculator, you won't be getting what that shows). If you use a C500K however it moves what it effects out of the frequency range we're bothered about. So all the way left will give you the base cap value and all the way right will blend in the parallel cap properly. What you see on the TSC is what you get then.

I'm not sure what you mean. Are you saying that the schematic showing it as a variable resistor is wrong, or that even at full resistance it's still adding some capacitance from the 33nF? 100K is a LOT of resistance, but of course it does still let through some signal. But at halfway on the 500KC, you're at 4x the value of the stock pot!

I'll have to dig out the conversations we had. But essentially the B100K affects the signal audibly if you drop it into the circuit that previously didn't have one (even at full resistance). So for example, if you had a Violet you wanted to add the mids pot to, simply adding the B100k and parallel cap will significantly alter the sound of the effect when 'stock' (pot all the way anti-clockwise). Going all the other way also isn't right to what the TSC will show you. Now this might have been what the Bell and Chasm was going for. But if you are adding the mids to an existing muff and want to retain that muff's sound, you need to use a bigger value pot. RG explains it better than me http://www.diystompboxes.com/smfforum/index.php?topic=102098.0

We essentially built a little test circuit so that we could measure the capacitance. It was a trial and error job, but at the end of it, using the C500K meant we got out what we expected and could get an approximation of what the resistor based AMZ mids control does (actually better as it doesn't mess with bass and treble like that does). You could probably go smaller to be honest, but C500Ks are easier to get hold of than C250Ks for most people and seems to work well in a muff setting.

Rev log again just worked best with the muff we found to make the control most usable. I wish we could have done the complex maths to work it all out, but it was just a socket and see job in the end. It was only when we started trying different pot values it made any real difference. With the B100K in place we were having to use completely different caps to get the desired effect and then we were struggling to match them up with what we wanted from the TSC. For two days the Ultrastoner teetered on the edge of being scrapped...