Any knowledgable BBD-based effects guys out there? I need help bad.

[guitylerham]

* Modulation LFOs are very interesting subcircuits here. LFO "base" speed is set mainly by C16/R42 values** and is adjusted by voltage at E1 point, network around C17 sets time, shape and range of the "glide" (fluent speed-up and slow-down of the LFO speed).

F($# a duck! I just noticed the schematic calls for 0.082uf (82nf) caps for C16/C30 and the capacitors on my board read "822J." According to a capacitor conversion page I use, this equals 8.2nf!!!! Nooo. I need to order some new capacitors.

Well, there's one problem. In circuits like this, the bigger the capacitance, the lower the frequency. You need to double the original cap value to get the speed to halve. So the cap ought to be 3nF (about) for your purposes.

RG, are you positive? I'm only questioning it because apparently people have made it work with the 750pf caps across the clocks:

For doubling the clock you need to half the 1n5.

The clock-frequency limitation doesnt óccur in the 4046, it is determined by the BBD.... So - I plugged them in and doubled the clocking speed by adding another 1n5 capacitor in series with each the existing 1n5 capacitors - I could have used 750p capacitors I know, but i did not have any that value.
How does it sound - very nice - possibly a little clearer and slightly quieter than the TDA1022 chips and definitely a keeper

Does any of this help? Man, I've got some big problems but I am narrowing it down thanks you to you guys! Yesssss.

[Thomeeque]

... it seems to me that the pulsing from the clocks and whatnot is set waaaay too fast. I've read and reread the project thread that I pulled all this from and they mention halving the clock speed to accommodate using the MN3007 instead of MN3004. So instead of the 1N5 clocking capacitor on each 4046 (between pins 6/7), I used a 750pf. Is there another component that yields an effect on pulsing speed to this effect? ...

Well, there's one problem. In circuits like this, the bigger the capacitance, the lower the frequency. You need to double the original cap value to get the speed to halve. So the cap ought to be 3nF (about) for your purposes.

But he does not need to slower clock - he really needs to double it to get same delays as with original MN3004 (MN3007 is twice longer BBD). Plus he complains about modulation speed ("The problem is that the "slow" setting seems to have very fast vibrato"), clock has nothing to do with it.

I am not getting any signal from the emitters of Q5/Q6. Only the faintest audio from the bases of those two. Shouldn't I be hearing a signal?

Probably not. Those transistors are being driven as variable resistors to shunt some signal to ground, changing the gain of the mixer a bit. Finding only a very small audio signal is probably correct.

Emitters of Q5/Q6 lead amp. modulated treble wet signal via C15 to the negative input of output mixing opamp.



T.

[Thomeeque]

* Modulation LFOs are very interesting subcircuits here. LFO "base" speed is set mainly by C16/R42 values** and is adjusted by voltage at E1 point, network around C17 sets time, shape and range of the "glide" (fluent speed-up and slow-down of the LFO speed).

F($# a duck! I just noticed the schematic calls for 0.082uf (82nf) caps for C16/C30 and the capacitors on my board read "822J." According to a capacitor conversion page I use, this equals 8.2nf!!!! Nooo. I need to order some new capacitors.

And here we go That's it, your vibrato is ten times faster than it should be, it must sound awful. Add 82nF there and you should be OK.

If you don't want to wait for new order try some close values meanwhile (you may have few 100nF's around).

Good luck, T.

[guitylerham]

It sounds terrible indeed! I just ordered new parts. I will wait for them to come. I'm too excited now. I'll let you guys know ASAP!!! 

[guitylerham]

Wouldn't you know after replacing those two capacitors with 100nf's on the LFO generator... it works perfectly!!!!

You guys did it! Much thanks to you all. I will continue to make some slight modifications to clean up the sound but it's up and running. It sounds pretty good too.  Wow, what a relief to have it working correctly. I will still replace the 100nf with the 82nf's when they come tho.

Now that all my circuits are completed, I can start the process of wiring them into the enclosure and working out what kinks the power supply/xformers might cause. Oy. Anyway, thank you RG, Thomeeque, and PRR. 

[Thomeeque]

 I'm glad you had all those troubles actually I like tricks used in this circuit, which I would not know about otherwise Good luck with the boxing, T.

[R.G.]

Hey, great! Congratulations!

But he does not need to slower clock - he really needs to double it to get same delays as with original MN3004 (MN3007 is twice longer BBD). Plus he complains about modulation speed ("The problem is that the "slow" setting seems to have very fast vibrato"), clock has nothing to do with it.

DOH!! (smack! goes my forehead) 
Do what I would have said if I'd thought about it the right way, not what I actually said!