BOSS CE-1, CE-2. question about design

[Haze13]

I was looking at the schematic of this old unit, and realized that the "output" (right after BBD) runs from -13 - 0 volts, but the input (before BBD) is running form +/-14 volts so as the LFO. So, the clock, bbd and anti-aliasing filter works from the same voltage,  and input IC with the LFO from the same voltage.
Why not to use same voltage at the output as in the input (before and after BBD)? Will it some how interfere with the clock?

[Haze13]

http://www.tremolo.pl/Efekty/Chorus/Chorus%20Boss%20CE1.gif

link to the schematic.

[Fender3D]

Sorry, I don't quite understand what you mean...
to me, the whole circuit runs @ +-14V but the input gain stage, which runs @ +-13V.

To be more picky...
the LFO also runs slightly less than -14V, for R34/C17's sake of "decoupling"

BTW
here http://www.diystompboxes.com/smfforum/index.php?topic=107353.0 you'll find some arguments about BBD decoupling

[Haze13]

Ups... My mistake. First gain stage runs from the +/- 13 volts and the sallen key that follows runs from +/- 14 volts. Then the signal enters the BBD that runs from -14 volts, (pin 7 -> 0v, pin 11 -> -14v) and Vref for that BBD is 4 volts before 100k resistor. Clock scheme uses the same voltage as the BBD. Pins number 14 and 13 are tied to the ground trough 100k resistors -> pot -> BJT buffer with collector that goes to the ground and the emmiter goes to -14 volts -> Sallen key with the same voltages as a buffer before him...
R37/C17 are for the clock decoupling... LFO is where the Intensity and the Rate controls and it's not decoupled at all...

So, not the entire analog parts of this chorus works from BiPolar power supply and I can't understand why. 

[Fender3D]

Ups... My mistake...

And so did I...
(hmm this thread must be cursed  )
...I meant VCO not LFO...

Well actually, op-amps run bipolar...
MN3002 is a P-channel BBD, according to datasheet, it runs @ -15V Vdd max.
I think Boss (or Roland) simply followed the DS...
Clock and following filters just use negative voltage for easy of design

[PRR]

The LOW level hi-gain input stages get an extra-filtered supply.

After that input gain, all the rest can eat the somewhat-filtered power from the regulator.

[Haze13]

So you think that the second sallen key not using bipolar power supply only because it was easier?

I ask because I have built couple of CE-2's but with different power supply. One of them is boosted with ICL7660/max1044 up to 15 volts after a LM7815, but the other uses Bipolar 15v power supply for Pre-emphasis/De-emphasis and for sallen keys based on Unity Gain IC's. BBD and LFO in both units uses 15v only, and the one that with +/-15 power supply has a problem with a clock. It's bleeds trough the output of the BBD.
I though that I have some problem with etch PCB, but when I connected the BBD+LFO from the other chorus that I have with the same design the problem remained.
I have separate grounds for PSU, Analog part and BBD+LFO connected on the chassis in one point at the jack.
I saw that CE-1 Uses Bipolar PSU but it doesn't have the problem of the clock bleeding.
I don't have a scope, only DVM, google and the second year in engineering in the institute of technology... Does not help actually...
So I decided to post it here, and on other forum because I've read that there is one guy with the same problem (he recorded the sound)
but in the CE-3, with mn3207 inside.

[Fender3D]

So you think that the second sallen key not using bipolar power supply only because it was easier?

I ask because I have built couple of CE-2's but with different power supply. One of them is boosted with ICL7660/max1044 up to 15 volts after a LM7815, but the other uses Bipolar 15v power supply for Pre-emphasis/De-emphasis and for sallen keys based on Unity Gain IC's. BBD and LFO in both units uses 15v only, and the one that with +/-15 power supply has a problem with a clock. It's bleeds trough the output of the BBD.
I though that I have some problem with etch PCB, but when I connected the BBD+LFO from the other chorus that I have with the same design the problem remained.
I have separate grounds for PSU, Analog part and BBD+LFO connected on the chassis in one point at the jack.
I saw that CE-1 Uses Bipolar PSU but it doesn't have the problem of the clock bleeding...

Bleeding has nothing to do with bipolar supply... GND loops, and bad filtering or layout aside...

The sallen key, as well as other op-amp circuits, must be properly biased in order to work correctly...
What's better than BBD's output @ 1/2 -V?

You have it already, then sallen key's supply ought to be -V to GND.

[Haze13]

Thanks for the info. I'll try to make the output single rail...

[Haze13]

Nope...  Didn't work.