4x3*05 BBD Delay?

[thomasha]

Hi guys,
this is kind of late, but I just saw the DOD rubberneck for the first time, and OMG! 1.5s with 4xV3205s!

I saw some guts on another forum and all bias trimmers are missing.
Makes me question how did they bias it or powered the V3205s.
They are intended to be used at 5V, but work up to 8V.
Any higher and they produce no output no matter what (I tested it in my first bbd build).

What do you think? Is it really usable at higher delay times or does it get dark and distorted?
Was wondering if with some changes something like this would be possible using the dirty bag board, with some extra parts. Would be a nice thing to try, considering the price of the v3205s.

[rockola]

Hi guys,
this is kind of late, but I just saw the DOD rubberneck for the first time, and OMG! 1.5s with 4xV3205s!

I saw some guts on another forum and all bias trimmers are missing.
Makes me question how did they bias it or powered the V3205s.
They are intended to be used at 5V, but work up to 8V.
Any higher and they produce no output no matter what (I tested it in my first bbd build).

What do you think? Is it really usable at higher delay times or does it get dark and distorted?
Was wondering if with some changes something like this would be possible using the dirty bag board, with some extra parts. Would be a nice thing to try, considering the price of the v3205s.

I have one, in fact the gut shots you saw may be mine. It's a nice piece of gear EXCEPT for the flimsy wire harness between the boards which I course broke when taking it apart for some pics. No biggie, easy enough to fix when I get the time. Anyway, if you want better pics of some detail, just ask as mine is still in pieces.

Sent from my Redmi Note 7 using Tapatalk

[thomasha]

Thanks, that would be helpful!
if you could take close pictures around the BBDs and the larger IC on the right (guess it's the compander), it would help to understand how they structured the gain stages.

Unfortunately they used SMD parts, which makes identifying the caps values impossible. I think the gain structure will already give an idea of how they manage to avoid distortion at least.

[danfrank]

I can't speak about the Rubberneck but I do have a DMM TT1100 and it's super noisy when the delays are long. Frankly, I think it kind of sux, sound wise. I really don't think it's because it has 4 X 3005 ICs. I think it's more because of bad design of the pedal. It has some really nice features but overall the sound is kind of flat and uninspiring...
To design a better version (or at least a good sounding one) I think a redesign of the low pass filters would be a good place to start. Also, at least one (maybe more) op amp(s) in-between BBD chips for gain recovery, like the original DMM or MB Total Recall has...  1.5 seconds is pushing it though for 4 3X05 ICs. Maybe use 6 BBDs?

[thomasha]

In the pictures I saw just 4. They may be exagerating a little bit, otherwise it would mean 375 ms of each BBD. If I could get 1.2s from 4 chips would be nice. I knew about the DMM with 4 chips, but also had heard that it's not ideal for longer delays. I thought the rubberneck could sound better.
Unfortunately all the videos I can find are with the time pot in the middle. 

[rockola]

if you could take close pictures around the BBDs and the larger IC on the right (guess it's the compander), it would help to understand how they structured the gain stages.

[thomasha]

Thank you!