Catalinbread - CB30  [traced]

General documentation, gut shot, schematic links, ongoing circuit tracing, deep thoughts ... all about boutique stompboxes.
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atreidesheir
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Post by atreidesheir »

MIke,
Any plans to feature this on your youtube channel. Your demos are enjoyable. You are one of my wife's favorite blokes now. :thumbsup
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ShortScaleMike
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Post by ShortScaleMike »

haha.. very kind of you (and her) to say so.

Unfortunately I'm mad busy at the moment, building pedals is taking up a fair amount of my spare time away from my day job, so demoing and building pedals for me personally has to take a backseat (or else my girlfriend really will be understandably pissed off with me).

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Post by atreidesheir »

Worth the wait.
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Post by roseblood11 »

Has someone built this in the meantime? Can the schematic be regarded as verified?

I plan to make a vero layout with integrated voltage doubler in the next few days...

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Post by roseblood11 »

I made a new vero layout, inspired by Mikes version.
THIS IS COMPLETELY UNVERIFIED!!!

Changes:
- voltage doubler included. Use ICL7660S (max 12V) or MAX1044 (max 9V)
- correct leg spacing for (most of) the caps (film caps for the 100nF and 220nF)
- 100µF cap for power filtering before the voltage doubler

I still don´t see a reason, why a 22µF electrolytic and a 680nF film cap are used in the original pedal?!? Both are quite expensive (a Nichicon Muse and a Panasonic), but I guess the filtering could be better with a) higher values and b) a ceramic cap in parallel with the electrolytic.

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Post by ShortScaleMike »

Very cool.

I guess I am inclined to go for reduced size layouts irrespective of cap spacing - I know this is annoying to some people.

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Post by kbibs »

Thanks for all the work on this so far! Just curious if there was any updates? If I remember right, there appears to be some posts that were lost in the down time.

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Post by roseblood11 »

I haven't built this yet, as there are some things that look rather strange to me:

-the 2n2 from signal to gnd at the input (C1 in my layout).
-the 10n, 22n, 330p and 470k left to Q1 and Q2 (C3, C4, C5 anr R4 in my layout)

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Post by bajaman »

I built one and it doesn't work very well - I am very suspicious of the value of that capacitor off the gate of the top jfet (10n) :hmmm: :scratch:
and 390 ohm source resistors?? and 22n ?? very small :scratch:
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Post by roseblood11 »

mmolteratx wrote:Here's the 220n cap from Source to Gate of Q4 (marked Q3 on the silkscreen)
Maybe this indicates some kind of confusion...
I never understood, why the parts numbers from the silk screen aren't used in the schematic. Only the transistors have parts numbers and they differ from the numbers on the board.

Next (little) problem: There seem to be two styroflex caps, but we have to guess which they are...

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Post by kbibs »

I breadboarded this and agree with everybodies questions. The 10n cap drops the gain too much on the 1st mu-amp and the 2n2 cuts the treble and adds too much capacitance to the input. The 22n does appear to be too small on the feedback of the first mu-amp but the 330pf, not sure how, but adds back some low end. If you pull the 330p cap it just kills all the low end. I put a 470p cap in place of the 10n and a 330p cap in place of the 2n2 input cap and it sounds pretty good. It has some midrange honk like a vox and some high end but I'm not sure it really sounds like an AC30.

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Post by ShortScaleMike »

If someone gives me a corrected schematic, I'll update the vero

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Post by kbibs »

I'm not sure the schematic is wrong except for some of the cap values and those I can't see from the pictures.

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Post by kbibs »

mmolteratx,
I just went through the schematic vs. the pictures and I think you got it right, nice job! I was wondering, if you still had the pedal could you open it up and note the cap values on one of the pictures? The resistor values look correct its just some of the cap values on the schematic seem odd. Also I believe the source to gnd cap on the 2nd mu amp is bigger than 2.2uf (at least thats what it appears).

I just heard some new sound clips on the catalinbread site and this thing sounds really good.

Thanks!

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Post by kbibs »

I have a question fr anyone that has one of these. With the gain turned down all the way, where about on the volume knob do you get unity volume? ... with my breadboard build and a few different cap values I'm about at max volume before unity. Is this about right?

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Post by roseblood11 »

bump

@mmolteratx:

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Post by soggybag »

Looks like BSIAB 2 with a James/Blaxandall tone stack.

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Post by roseblood11 »

The drive pot and the last transistor stage are different as well.

I still doubt that the marked parts are correct. The cap from input to ground is most likely 220pF.
But there are too many things unclear. I think we need better pictures or a look at a different pedal.

@mmolteratx:
- Could you please recheck the parts values (at least those of the marked parts) and maybe post the codes on the caps?
- Are the connections around the 330pF cap really correct?
- Is the cap from output to gnd really 10nF?
Attachments
cb30.gif

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kbibs
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Post by kbibs »

The drive pot with the 470p input and 100pf bypass is identical to the AC30 preamp. The tone stack is as well. The last transistor stage is a high impedance buffer and the 10nf with the 4.7k resistor form a LPF at 3.4khz which might be a little low. So all that makes sense.

From the pictures it looks like it to me that the schematic is drawn correctly, but some better pictures might expose an error. The input cap to ground looks like a film/foil type which I can't find a manufacturer that makes them smaller than 1nf, so it really might be a 2n2. If I buffer the input to my breadboard the 2n2 doesn't load it down as much. The value of the cap from the gate of Q2 to V+ looks wrong, sounds wrong too. The cap looks smaller than the 2n2 input cap and I'm not sure what type it is. All I know is if I put a 10nf in it just drops the gain way too much. I think somewhere in the 470pf to 100pf is more like it. The source cap on Q3 looks bigger than the other 2.2uf caps and looks the same size as the power supply cap of 22uf. This increases the gain some.

Some cap codes or values would be helpful in deciphering this. Hopefully mmolteratx doesn't mind taking it apart again!

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Post by mmolteratx »

roseblood11 wrote:bump

@mmolteratx:

:lol:

Sorry guys. I've been busy with school. Still am actually but I'm burned out for the moment so I'll take the CB30 apart in a couple minutes and grab some more pics/values.

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