Mad Professor - Deep Blue Delay  [traced]

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The Rotagilla
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Post by The Rotagilla »

pz wrote:HK723, a viariation of pt2399, according to datasheet offers delay time up to 700ms.
I may be wrong and please correct me if I am...after looking at the data sheets for both IC's quickly, the HK723 looks like a pin for pin drop in for the PT2399. The basic echo app notes look very similar.

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Post by soggybag »

That HK723 chip sounds like a pin for pin replacement for the PT2399. Where can you get some to experiment with?

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The Rotagilla
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Post by The Rotagilla »

soggybag wrote:That HK723 chip sounds like a pin for pin replacement for the PT2399. Where can you get some to experiment with?
Looking right now. :D

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Post by The Rotagilla »

Checked the usual suspects, no dice. I emailed the manufacturer.

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Post by BJF »

Hi,
Actually PT2399 has a low noise up until about 400mS after that there's a limit reached but depending on how you set the controls noise can anyway be accaptable and less than some of the tape echoes I have.

The circuitboard in DBD is three sided and the schematic as posted has a few flaws but it is impressive just the same that somebody took the time to trace thus far

Have fun
BJ
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neilnil
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Post by neilnil »

Hey guys, sorry for coming back late.
I built one from the schematic I posted and there was no problem.
I tried to find out my flaws but I couldn't so far and don't want to bother any more.
And nice to see you, BJ! I really enjoy your pedals.

Jun

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Post by lohstah »

did you use the tonepad layout and change components and a few traces or did you make a layout yourself ?
in either case, could you post the changed layout or the one you used ?

cheers,
lohstah

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neilnil
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Post by neilnil »

I used my modified tonepad layout which you can find on page 3.
With that layout, you'll have some off-board components and a few jumpers.
I'd like to update it to dbd spec but diy layout creator gets too slow to handle this so I'm afraid I can't do this soon.

Jun

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The Rotagilla
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Post by The Rotagilla »

bajaman wrote:I have built rebote delays and modded them extensively - a NE570 or NE571 makes quite a difference in my humble opinion - more later on - got to feed the dogs and go for my daily walk now :lol: :cry: :wink:
That must have been the longest walk ever!

I'm curious to read your findings on PT2399 based delays. Do tell!

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Post by bajaman »

That must have been the longest walk ever!
Yep - just got home five minutes ago :lol: - sorry, I will dig up my notes
cheers
bajaman

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BJF
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Post by BJF »

Hi,

Ah well, engaging an NE570 would roughly cut noise from delay by 20dB, feedbacknetwork needs to be nested into the companding Hm, well background noise is quite low as is but side effects from oscillator triggering can be somewhat lowered.


If powersupply falls below limits there will be just first whining then just white noise..........just an interesting note and that can be good to know for anyone experimenting with this chip

Sound is restored with correct voltage

Have fun
BJ

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The Rotagilla
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Post by The Rotagilla »

pz wrote:HK723, a viariation of pt2399, according to datasheet offers delay time up to 700ms.
Well after several emails, attempts to conquer the language barrier and some money I finally received my HK723 samples. Despite the claims of 700ms of delay time, I'm pretty certain the HK723 is a rebranded PT2399. Extending delay times beyond 400ms yielded digital hash and just about the same loss of sound quality as the PT2399. I may continue to play with the components around the IC but in the immortal words of the NYPD..

"Nothing to see here. Let's go, move along."

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Post by audioguy »

neilnil wrote:I used my modified tonepad layout which you can find on page 3.
With that layout, you'll have some off-board components and a few jumpers.
I'd like to update it to dbd spec but diy layout creator gets too slow to handle this so I'm afraid I can't do this soon.

Jun
I dont suppose you could type up a little guide to do the conversion? I'm interested in hearing a $350 rebote!

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Post by estragon »

The Rotagilla wrote:Well after several emails, attempts to conquer the language barrier and some money I finally received my HK723 samples. Despite the claims of 700ms of delay time, I'm pretty certain the HK723 is a rebranded PT2399. Extending delay times beyond 400ms yielded digital hash and just about the same loss of sound quality as the PT2399. I may continue to play with the components around the IC...
Hi Rotagilla,

I checked both datasheets and it seems quite plausible that they are indeed the same device.

Something that has intrigued me are the two 100nF capacitors on pins 7 and 8 to ground. Since this is a delta modulation A/D and D/A, I guess that slow clocks (intended for longer delay times) would need some adjustment to avoid saturation in the integrating capacitors. One thing to try this is to increase said capacitors to 220nF (or maybe just 150nF) and see if it helps somehow.

In a similar line of thought, the two 82nF or 100nF capacitors across pins 9-10 and 11-12 (if memory serves me well) could be increased also.

Hope it helps.

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The Rotagilla
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Post by The Rotagilla »

estragon wrote:
The Rotagilla wrote:Well after several emails, attempts to conquer the language barrier and some money I finally received my HK723 samples. Despite the claims of 700ms of delay time, I'm pretty certain the HK723 is a rebranded PT2399. Extending delay times beyond 400ms yielded digital hash and just about the same loss of sound quality as the PT2399. I may continue to play with the components around the IC...
Hi Rotagilla,

I checked both datasheets and it seems quite plausible that they are indeed the same device.

Something that has intrigued me are the two 100nF capacitors on pins 7 and 8 to ground. Since this is a delta modulation A/D and D/A, I guess that slow clocks (intended for longer delay times) would need some adjustment to avoid saturation in the integrating capacitors. One thing to try this is to increase said capacitors to 220nF (or maybe just 150nF) and see if it helps somehow.

In a similar line of thought, the two 82nF or 100nF capacitors across pins 9-10 and 11-12 (if memory serves me well) could be increased also.

Hope it helps.
As soon as time allows I'll give that a shot. Thanks for the input.

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Post by estragon »

The Rotagilla wrote: As soon as time allows I'll give that a shot. Thanks for the input.
Cool! Look forward to hear how it goes.

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Post by Camphausen »

Is there a modified Rebote layout out jet for the DBD?

I tried it myself...but i'm not really sure if I replaced/added the correct parts :scratch:

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Post by modman »

Camphausen wrote:Is there a modified Rebote layout out jet for the DBD?

I tried it myself...but i'm not really sure if I replaced/added the correct parts :scratch:
Man, you really dug up the oldie of the month. I had completely missed this one. Didn't know this one was traced. There are layouts at GGG et al. check the thread from the beginning. There are a number of links there.
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Post by playon »

I had one of these pedals, and honestly, if you don't need longer delays, my Arion SAD-1 sounded better for regular slap-back kind of stuff.

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Post by moltenmetalburn »

has anyone verified the filtering of this one?

it really is wonderful sounding but there is no way im paying #350 for a rebote, id like to modify mine.
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