Mad professor deep blue delay issue (updated)

[bbsen]

Hi all, just built this delay pedal, the problem I first encountered was that I only get one repeat, the mix and delay are working, at least I can tell the differences easily.

I  followed the repeat pot lug 3 and pass 22n , 5.1k then to the 10ks... back to the IC... I re-soldered what I suspected to be cold joints, I managed to get the repeated sounds....

a new problem arised, when I turn the repeat and delay pots to near max levels, the sound started off normally, gradually it gets more and more overlaping, messy and noisy.... eventually turned into infinite and continuous high-pitched sound.....@@

at this point, I have no idea how to do further diagnostic.

Assitance is very much appreciated.

cheers！

[ξεναγος νεκροπολης]

that's exactly how it supposed to work. maxing repeats introduces self oscillation. and the longer the repeat time(delay pot maxed) the more distortion comes in. the pt2399 delays are famous for that!

[bbsen]

Thanks for your reply, really appreciated!

I didn't know that how it supposed to work, still a bit confused as it ddoesn't seem to be a delay effect, it's more like unbearable continuous high pitched noise..... it disappeared as soon as I turn the pots down, though, so it's ok.  

One last question if you don't mind.

I am building the tail version using a on on dpdt switch, http://tagboardeffects.blogspot.hk/2012/02/mad-professor-deep-blue-delay.html

when the switch down the effect as well as the led light are on, but when I switch to the other side, I have no more delay effect at all....

in the layout page, it said:

With this version the usual stomp switch wiring isn't used, and instead the input and output wires go directly to the sockets.  The stomp here will cut the signal going into the PT2399 and so when bypassed the output of the PT2399 will continue until the repeats are complete and IC1 will then act as a buffered bypass.

I am sorry for my poor english comprehension skill, is my built behaving normally?

sorry for asking so many questions, cheers.

[induction]

bbsen wrote

still a bit confused as it ddoesn't seem to be a delay effect, it's more like unbearable continuous high pitched noise..... it disappeared as soon as I turn the pots down, though, so it's ok.  

The delay chip only makes one repeat. To get more repeats, you feed the repeated signal back into the chip (by turning up the Repeats pot) and it makes a repeat of the repeat. Each time it repeats, the signal quality degrades, like making a photocopy of a photocopy of a photocopy. Eventually it's just noise.

The longer the delay, the more the signal degrades with each repeat, so signal turns to noise with fewer repeats. It sounds like your build is working fine, but if you don't like the oscillation, you can do a small mod to get rid of it.

 I am building the tail version using a on on dpdt switch, http://tagboardeffects.blogspot.hk/2012/02/mad-professor-deep-blue-delay.html

when the switch down the effect as well as the led light are on, but when I switch to the other side, I have no more delay effect at all....

...

is my built behaving normally?

From your description it's behaving normally. The main difference between a delay with tails and a delay with true bypass shows up when you switch it off while there's signal. With tails, the repeats from anything you played before you switched it off will continue to repeat and decay naturally, but anything you play after you switch it off will not generate repeats. With true bypass, all the repeats stop abruptly as soon as you switch it off.

Hope this helps.

[bbsen]

It's really helpful, thank you very much!