Belcat delay mods

A forum devoted to mod, tips and suggestions for upgrading and rehousing your VERY CHEAP commercial stompbox to near boutique excellence.
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suspiciousminds
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Post by suspiciousminds »

Picked this cheap 350ms belcat delay up for a tenner, just to have a go at modding.
So, i've removed the smd R18 resistor and crudely added a 47k resistor which has increased the delay time nicely.It also seems to have removed the muddy noise that was in the background too.
The downside is that there's a "zipper" type sound now every time you strike a note which i assume is due to the pt2399 chip - could anyone advise how i could remove the noise?
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iq01221
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Is the noise in short times set-up? I guess it's made for short times; so, if you wanna make it longer, you have to change more parts still... :hmmm:
I'm just gessing, ok? Maiybe the pt2399 isn't a good one. :thumbsup

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suspiciousminds
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iq01221 wrote:Is the noise in short times set-up? I guess it's made for short times; so, if you wanna make it longer, you have to change more parts still... :hmmm:
I'm just gessing, ok? Maiybe the pt2399 isn't a good one. :thumbsup
Hi, thanks for the reply - how'd you mean short times set-up?
Next step i thought of was maybe trying to filter it out,poss swap out the caps?

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suspiciousminds wrote:
iq01221 wrote:Is the noise in short times set-up? I guess it's made for short times; so, if you wanna make it longer, you have to change more parts still... :hmmm:
I'm just gessing, ok? Maiybe the pt2399 isn't a good one. :thumbsup
Hi, thanks for the reply - how'd you mean short times set-up?
Next step i thought of was maybe trying to filter it out,poss swap out the caps?
Meaning in times <300ms, as well, as it's made for... :oops:
For get longer times without noises/distortion, you'll need a filter. And it's a big mod( a 571 compandor is a usual example). You'll have to add a new circuit.
Well, I just can't see that kind of filter in the picture. I'm totally guessing, ok? :thumbsup If I'm wrong, please tellme. I'm such a newbee on digitals...
But, there is an extra possibility: the 2399. A friend of mine made a pt80 delay( pt2399 based, with SA/NE571 filter on it), and it get very noisy( just the repetitions) at longer times. He let it like it was a few months, 'till he get some new chips. Than, when he change them, the distortion dissapears. But it's just a possibility...
What I'd do, if the noise isn't a big deal, is just let it noisy :popcorn:
Cheers!!

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Post by suspiciousminds »

Hi iq01221, thanks for the info,
well this afternoon i've added 3 capacitors - 2x10n and 1x330n caps coming off the chip at position 9,10,11,12,13,14 on the underside of the pcb and the zipper noise has gone - there's a very tiny bit of background noise, other than that it sounds pretty good to be honest.
Also turning the feedback knob right up to the max sends it into a weird self-oscillation.
Happy days! :D

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suspiciousminds wrote:Hi iq01221, thanks for the info,
well this afternoon i've added 3 capacitors - 2x10n and 1x330n caps coming off the chip at position 9,10,11,12,13,14 on the underside of the pcb and the zipper noise has gone - there's a very tiny bit of background noise, other than that it sounds pretty good to be honest.
Also turning the feedback knob right up to the max sends it into a weird self-oscillation.
Happy days! :D
How you recognize the value on those smd caps? I hate that uninforming sdm caps :slap:
In case...Congrats in that solution!! :thumbsup
Cheers!

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