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Can I bypass this (dirt cheap) delay?

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Can I bypass this (dirt cheap) delay?

Postby Richie Royale » Tue Jan 29, 2019 8:16 pm

I picked up a Belcat Delay (it's listed as analogue, but it's just a digital chip) for a fiver.

My issue with it is that when plugged into a desk with the aux send returning back into it, the repeats cancel themselves out. So I assume there is some weird negative polarity issue in the way the pedal is wired.

Some info on the chip is here:

https://www.electrosmash.com/pt2399-analysis

https://hackaday.com/2018/07/07/the-pt2 ... never-had/

Pictures of the board are here (all SMT crap)

https://www.circuitbenders.co.uk/forum/ ... pic=1591.0

I wouldn't recommend anyone spend much time on looking into this, but if it's a simple fix, any pointers would be great. Otherwise I may just sell it on - I'm only really interested in delays I can abuse with eternal feedback :D
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Re: Can I bypass this (dirt cheap) delay?

Postby Eddy Deegan » Tue Jan 29, 2019 8:52 pm

Richie Royale wrote:I'm only really interested in delays I can abuse with eternal feedback :D

Sorry I can't answer your primary question, but given the 'abuse with eternal feedback' comment you might enjoy this: https://www.youtube.com/watch?v=38DBLGdnlJE :)
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Re: Can I bypass this (dirt cheap) delay?

Postby Richie Royale » Tue Jan 29, 2019 9:22 pm

Eddy Deegan wrote:
Richie Royale wrote:I'm only really interested in delays I can abuse with eternal feedback :D

Sorry I can't answer your primary question, but given the 'abuse with eternal feedback' comment you might enjoy this: https://www.youtube.com/watch?v=38DBLGdnlJE :)

It's like watching 'Get Stuffed' from the 90s. :D
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Re: Can I bypass this (dirt cheap) delay?

Postby Wonks » Tue Jan 29, 2019 10:59 pm

So it's fed from an aux send, and returns to the desk via what input?
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Re: Can I bypass this (dirt cheap) delay?

Postby Wonks » Tue Jan 29, 2019 11:26 pm

Is it the fact that the original signal is being inverted by the delay, and that this is cancelling any signal being sent to it that appears in the mix? I don't think you'll invert it back easily without using say a transformer to isolate the output.

If you've got a DI box and your mixer has a polarity button on the channel inputs, you can feed the Belcat output into the DI, feed than into the mixer as a mic input on a mic channel with the polarity swapped, and then feed that into the main mix without sending anything on an aux from that channel into the Belcat.

Although you might see if the aux return inputs are balanced. If so then you can take a TS jack from the Belcat, connect the T to the R of a TRS jack, connect the S of the TS to the T of the TRS, and leave the cable screen unconnected at the TRS jack. Then feed the TRS jack into an aux return. Should re-invert the signal for you.
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Re: Can I bypass this (dirt cheap) delay?

Postby Richie Royale » Wed Jan 30, 2019 6:35 pm

Hi Wonks.

If I have a signal and then send to the delay on Aux1 returning to the same desk on channel 2, I usually use aux1 send on the return channel to control feedback.

This delay largely cancels out the original signal and then its own repeats when wired this way. I shall have a try with you suggestions.
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Re: Can I bypass this (dirt cheap) delay?

Postby Sam Spoons » Wed Jan 30, 2019 11:14 pm

Post a precise wiring setup, I have a "Dr Tone Analogue Delay" which is definitely digital :headbang: I'll bet the only difference to the Belcat is paint......

But, I can't work out how the delay is cancelling the delay unless you have it reappearing on two different channels at the same time? It the mix sound returning to the original channel and the inverted delay to another? That would leave the 'dry' signal intact but remove the delayed signal.
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Re: Can I bypass this (dirt cheap) delay?

Postby CS70 » Wed Jan 30, 2019 11:57 pm

Richie Royale wrote:I picked up a Belcat Delay (it's listed as analogue, but it's just a digital chip) for a fiver.

Pity it doesn't work on the desk because that delay (digital-simulating-analog and all that) sounds gorgeous when used as a pedal between a guitar and an amp. Actually, I much rather prefer it to my Carbon Copy... if it did still work. Absolutely crappy construction indeed - mine gave up the DC in socket after only a few months of use.
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Re: Can I bypass this (dirt cheap) delay?

Postby Sam Spoons » Thu Jan 31, 2019 12:17 am

I remember, back in the day, we all loved the BBD delay pedals but wished they didn't lose the top end so much with ever tap like a CopyCat! The 'analogue revolution' only happened after digital became easily available. I definitely think valve amps sound better (on average) but the analogue/digital stomp box thing is probably a bit 'horses for courses'. I use both these days, delays and mods are digital, distortions and wah are analogue but, t the end of it is a little 18 watt valve combo :D
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Re: Can I bypass this (dirt cheap) delay?

Postby Wonks » Thu Jan 31, 2019 11:26 am

BBDs aren't inherently dull. If you had a fixed delay time with enough BBD chips to clock them at a high speed for that delay time, then you would have a near pristine delay. But because the timing is variable and they tried to get the longest delay possible from a single chip, the anti-aliassing pre-filter has to be set really low, knocking all the treble and a lot of the mids off.
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Re: Can I bypass this (dirt cheap) delay?

Postby Sam Spoons » Thu Jan 31, 2019 11:50 am

Presumably they simulate that effect in these cheap 'pseudo analogue' digital pedals to some extent. FWIW my Dr Tone 'Analogue' Delay lives on my electric pedal board and, to my increasingly dodgy, ears sounds great.
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Re: Can I bypass this (dirt cheap) delay?

Postby Richie Royale » Thu Jan 31, 2019 7:58 pm

Sam Spoons wrote:I remember, back in the day, we all loved the BBD delay pedals but wished they didn't lose the top end so much with ever tap like a CopyCat! The 'analogue revolution' only happened after digital became easily available. I definitely think valve amps sound better (on average) but the analogue/digital stomp box thing is probably a bit 'horses for courses'. I use both these days, delays and mods are digital, distortions and wah are analogue but, t the end of it is a little 18 watt valve combo :D

I own a mixture of delays through random purchases over the years - tape, analogue and digital. I like them all and they all offer something each of the others don't.
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Re: Can I bypass this (dirt cheap) delay?

Postby Wonks » Thu Jan 31, 2019 8:03 pm

Richie Royale wrote:I own a mixture of delays through random purchases over the years - tape, analogue and digital. I like them all and they all offer something each of the others don't.
don't... don't... don't... don't... don't...
don't... dn't... dn't... n't... n't... n... n...
don't... dnn... dnn... dn... dn... d... d...
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Re: Can I bypass this (dirt cheap) delay?

Postby Hugh Robjohns » Fri Feb 01, 2019 12:22 pm

Wonks wrote:BBDs aren't inherently dull. If you had a fixed delay time with enough BBD chips to clock them at a high speed for that delay time, then you would have a near pristine delay.

Quite so!

BBDs operate as an analogue sampling system, so the audio bandwidth is directly related to the sampling frequency, while the delay time is related to the number of stages in the BBD chain. So if you want a long delay with a wide bandwidth you need a lot of BBD chips running very fast... and that means a high cost which isn't likely to make it an attractive purchase. So most of the commercial BBD-based delay effect pedals had quite a restricted audio bandwidth and sounded duller even than a knackered tape loop system!

The advent of real digital delays overcame that cost/bandwidth/delay time conundrum and virtually killed off the BBD solution overnight.

Today, the 'dull' BBDs are often sought after specifically for their own low-fi sound...

H
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Re: Can I bypass this (dirt cheap) delay?

Postby nathanscribe » Fri Feb 01, 2019 12:37 pm

Is this not just a signal polarity issue?
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Re: Can I bypass this (dirt cheap) delay?

Postby Sam Spoons » Fri Feb 01, 2019 1:00 pm

Hugh Robjohns wrote:
Wonks wrote:BBDs aren't inherently dull. If you had a fixed delay time with enough BBD chips to clock them at a high speed for that delay time, then you would have a near pristine delay.

Quite so!

BBDs operate as an analogue sampling system, so the audio bandwidth is directly related to the sampling frequency, while the delay time is related to the number of stages in the BBD chain. So if you want a long delay with a wide bandwidth you need a lot of BBD chips running very fast... and that means a high cost which isn't likely to make it an attract purchase.

The advent of real digital delays overcame that cost/bandwidth/delay time conundrum and virtually killed off the BBD solution overnight.

Today, the 'dull' BBDs are often sought after specifically for their own low-fi sound...

H

Yeah, I have a TC Flashback which has various models including old school delays and tape echo. I tend to use a clean digital delay model myself but I get using some BBD models for authenticity.
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Re: Can I bypass this (dirt cheap) delay?

Postby Richie Royale » Fri Feb 01, 2019 2:27 pm

Wonks wrote:
Richie Royale wrote:I own a mixture of delays through random purchases over the years - tape, analogue and digital. I like them all and they all offer something each of the others don't.
don't... don't... don't... don't... don't...
don't... dn't... dn't... n't... n't... n... n...
don't... dnn... dnn... dn... dn... d... d...

Ha ha.
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Re: Can I bypass this (dirt cheap) delay?

Postby Richie Royale » Fri Feb 01, 2019 2:29 pm

nathanscribe wrote:Is this not just a signal polarity issue?

That is my presumption. The board is all SMT which makes trying to re-wire anything more tricky.

I am going to try out Wonks phase inverter idea when I can.
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