512-stages out of a MN3207?

[Bucksears]

I'm working out a project/PCB for an Ibanez FL99 Classic Flange. Schematic is here http://www.dirk-hendrik.com/temp/ibanez_fl99.pdf

The problem is, it uses an MN3210 (dual-512-stage) BBD. I was going to work around that using two MN3204's; I've actually found several places that have them, but they're not cheap.
I was wondering if there was a way to reduce/buffer the 1024-stage MN3207 (which is much more affordable) in such a way as to only use 512 stages out of it.

I've already got several parts of the circuit worked out in a PCB, but I stopped when I couldn't get my hands on an MN3210.

Anybody got any ideas on how to configure the MN3207 in such a way?

[armdnrdy]

I was wondering if there was a way to reduce/buffer the 1024-stage MN3207 (which is much more affordable) in such a way as to only use 512 stages out of it.
Anybody got any ideas on how to configure the MN3207 in such a way?

It can't be done.

The FL99 uses a dual 512 stage in such a way that the only way to emulate the circuit is to use two single 512 stage BBDs. (but not without a lot of reconfiguring. If you look at the schematic the stages of the BBD are split into two different circuits with a switch to choose between them.

[Bucksears]

What if I just wanted to use the circuit that goes through the (toggle) filter?

[armdnrdy]

It would involve redesigning sections around the BBD.

I would look toward the FL9 which uses a MN3207 and maybe add a few ideas from the FL99. The FL9 service manual is available on the net as well as a Tone Pad project for review.

The FL99 has a footswitch that as I stated switches between the BBD output sections. The Op amps in these two sections are inverted from one another giving an out of phase sound. There might be a way to split the BBD output signal from a single 1024 stage BBD and switch between the op amp outputs for the same effect.

The FL99 has a toggle switch that switches the output through a filter for a different sound. That should be easy enough to implement as well.

[Valentinych]

You can use instead of MN3210 two MN3207.  But increase the frequency of the VCO (MN3102) twice.      
Or one MN3207 just switch the frequency of the VCO twice.  The effect will be the same.

[Mark Hammer]

After looking at the circuit, I would say that you can use an MN3207.  But, apart from the obvious changes that would need to be made with respect to the MN300x type BBD vs the MN32xx series, you would have to forego one of the modes.

The 3010 is used as two 512-stage units in series.  The "intense" footswitch selects between a tap at the midpoint, or taking the signal after the full 1024 stages.  Use of a 3207 has no impact, as near as I can tell, on the feedback path, although obviously the tone will be different for feeding back 1024 stages vs feeding back only half that.

If the sound of the unit in the "full-chip" mode is the sound that motivates you to try and clone it, then you're in luck.  If the sound you like most, and can live without least is the short-mode, then you have a bit of a problem.  You could certainly emulate it with other chips...assuming you could find them, but they are pretty dange scarce these days  For instance, if you could locate an MN3214, it has multiple taps, including one at 621 stages as well as at 1024 stages.  That would be close enough for mimicking the "intense" function.  Personally, I've never seen one in the flesh or even listed for sale anywhere.

[armdnrdy]

Mark is correct.

I missed the output of BBD section "A" being fed back into section "B" via input B pin 5.