Why does a Fab Flanger have two BBDs?

[Mark Hammer]

I was in a small-own 2nd-hand store yesterday and picked up a cute 60's Japanese gutar for $50, and the guy threw in a Fab Flanger for another $5, which I couldn't resist.  As soon as I got home, I had to take it apart.  Lo and behiold, there are two BL3207s in there, which kind of surprised me.

The thing doesn't flange especially well (which I accept for its normal retail price), but it clearly is NOT intended to do through-zero.  So, the only thing I can think of is that the dual 3207s are placed in series, and overclocked to produce a suitable delay time.  As a double-sided board, it is a somewhat tricky thing to analyse, at least within the 18 hours I've had it.

Anybody know anything about this unit?

[Morocotopo]

Two delay lines in parallel out of phase, sort of like the Boss Dimension C?

[Mark Hammer]

I doubt it.  Remember, these things had a $19 retail pricepoint.

[armdnrdy]

Count em....2 BL3207s

Bizarre

http://www.aronnelson.com/gallery/main.php/v/diyuser/Fab+Flange+Board+1.jpg.html
http://www.aronnelson.com/gallery/main.php/v/diyuser/Fab+Flange+Board+2.jpg.html

The DIL14 on the second board is a 4013 and the DIL16 is a 4053. The other two on that board probably op amps.

If we see a 3102 clock driver on the first board, how can the BBDs be overclocked with that drivers limitations?

[oldschoolanalog]

I don't have a clue about this. But I do know you got a good deal on it just for the parts/enclosure!

[Mark Hammer]

Count em....2 BL3207s

Bizarre

http://www.aronnelson.com/gallery/main.php/v/diyuser/Fab+Flange+Board+1.jpg.html
http://www.aronnelson.com/gallery/main.php/v/diyuser/Fab+Flange+Board+2.jpg.html

The DIL14 on the second board is a 4013 and the DIL16 is a 4053. The other two on that board probably op amps.

If we see a 3102 clock driver on the first board, how can the BBDs be overclocked with that drivers limitations?

The 8-pin DILs on the main switching board are TL072s.
What you don't see is a 4013 and TL072 on the underside of the board with the BBDs.  So, while the simle combination of BL3102 and BL3207 (x2) seems like it could not be overclocked, perhaps the 4013 assists in buffering the BL3102 a bit?  Remember that the limitation of the traditional 3102/3207 pair is not what the 3102 can do with assistance, but what it can do on its own.  It just doesn't provide enough current to overcome the input capacitance of the clock pins on the 3207.

I'm sitting here at home while the workman installs a new garage door, so I'll see what I can decipher about the board from the pin connections on both sides.  I'll note that there is no trimpot for setting bias.  BUt then whaddya want for a $19 MSRP?

[petey twofinger]

i got one in a four pack . it ended up on the steering wheel console cover of my volvo , the dash mount opical theamin w/ echo ran thru it to a 40 watt pa in the grille .

[analogguru]

Maybe one BBD is running on the half of the clock frequency than the other ?

analogguru

[mth5044]

i got one in a four pack . it ended up on the steering wheel console cover of my volvo , the dash mount opical theamin w/ echo ran thru it to a 40 watt pa in the grille .

WHAT?!

[wavley]

i got one in a four pack . it ended up on the steering wheel console cover of my volvo , the dash mount opical theamin w/ echo ran thru it to a 40 watt pa in the grille .

WHAT?!

I know, that statement made me like Mr. Twofinger just a little bit more and I was already pretty fond of his shenanigans.

[Mark Hammer]

Maybe one BBD is running on the half of the clock frequency than the other ?

analogguru

Maybe, though I'm not sure what that would add, in terms of sound quality.

[Mark Hammer]

Well, I looked, but I still can't tell how the two chips are being used.  The combination of through-hole and surface mount components, along with a double-sided board and traces whose path I can't see unless I remove the chips, is making it impossible to do even a partial reverse on this.  I'm sure eventually someone will pop up with some inside information.  I'll wait patiently until then.

[oldschoolanalog]

Have you checked to see if they are clocked the same?

[analogguru]

Well, I looked, but I still can't tell how the two chips are being used.  The combination of through-hole and surface mount components, along with a double-sided board and traces whose path I can't see unless I remove the chips, is making it impossible to do even a partial reverse on this.  I'm sure eventually someone will pop up with some inside information.  I'll wait patiently until then.

Maybe you can do the following while waiting:

1.) Take a multimeter
2.) Turn it on and switch it to diode check (with sound)
3.) Connect one lead to pin 2 of the BL3102
4.) Take the other lead and tip to pin 2 and 6 of each BL3207 (note the result)
5.) Take the other lead and test if you hear a sound when you connect it to pin 3 or 11 of the 4013 (note the result)
6.) Connect one lead to pin 4 of the BL3102
7.) Take the other lead and tip to pin 2 and 6 of each BL3207 (note the result)
8.) Take the other lead and test if you hear a sound when you connect it to pin 3 or 11 of the 4013 (note the result)
9.) Connect the lead to pin 2 of the first BL3207
10.) Take the other lead and test if you hear a sound when you touch pin 1, 2, 12 or 13 of the 4013 (note the result)
11.) connect one lead to pin 6 of the first BL3207
12.) Take the other lead and test if you hear a sound when you touch pin 1, 2, 12 or 13 of the 4013 (note the result)
13.) Repeat the steps 9 - 12 with the second BL 3207

And yes...... maybe you could be so kind and take a picture of the track side ?

analogguru

[Fender3D]

+1 analogguru
just a concern though,
4013 is on another board, I don't think they placed 3207's clock that far....
1 €uro they set it all in parallel multiplex config...

[analogguru]

just a concern though, 4013 is on another board, I don't think they placed 3207's clock that far....
1 €uro they set it all in parallel multiplex config...

You just lost € 1,--:

What you don't see is a 4013 and TL072 on the underside of the board with the BBDs.

And I bet € 1,-- that pin 1 of the 4013 is connected to pin 2 of the second BL3207 (middle chip).

Another chance for € 1,--:
I bet that the inputs (pin 3) of the two BL3207 are in parallel, and that the outputs are mixed together with resistors.

Maybe, though I'm not sure what that would add, in terms of sound quality.

Think of a phaser: It gives a second time delay in an octave distance, therefore making the effect deeper.

analogguru