digital delay line

[cardinalflyer]

Here's a couple of pics of a digital delay line I designed & built not long after being out of college.
Uses sample & hold to capture line-in  for Analog Devices AD574 single channel ADC with and store it in 32K x 12 SRAM (8 8Kx8 chips 1/2 of one bank not wired up).
Then selectable time delay on 3 channels of AD7541 DACs to re-create audio back out. Each channel had one selectable time delay (from 1 to 1024, mSec?. Not sure what 1 = for time delay, will have to play some) and own analog volume level and analog feedback/regeneration level. Sounded really good. Will have to get it running again.  Need to find my schematics!
Was a little slow selecting times, had to select the channel with the push button and then hold to toggle switch while it cycled up/down (2-way toggle) to the time you wanted.  And never wired up a footswitch to select it on/off, more of a set it & forget it kind of thing.
All hand wirewrapped, not bad for a first big-time audio project after some little diode/op-ap fuzzbox pedals.
Will have to get it fire up again now that I'm starting to make some 'noise' again with my teenage son.

http://www.crossroadsfencing.com/img/Digital%20Delay,%20inside.jpg
http://www.crossroadsfencing.com/img/Digital%20Delay,%20outside.jpg
(watch the caps in there, are needed)
Robert

[cardinalflyer]

Dang, it still works! Sounds about like expected with a guitar and regular headphones plugged in - kinda weird in mono, and likely the output driver overloaded some as its not very loud, so a little distorted with the guitar and the 4 box volumes everything turned all the way up to hear it very much).
3 channels. Feedback/regeneration starts getting to be too much if turned up more than about halfway with all three channels on. Really need some kind of math behind the settings vs trial & error to get a nice sound. Gonna try it tomorrow with my Blackheart 5W amp and Eminence Wizard speaker in a home built cabinet (been playing with different "ports" on the back (its a 1x12 cabinet, about 1/3 of the back is open, plenty of treble if needed, seeing if I can use WinISD Pro and find a calculated setting for more bass as an option).
Maybe plug a mic into this mixer and get some sound samples to post.

Robert

[cardinalflyer]

Oh yeah - and it is 1 second delay too. Settings under ~100 sound kind of, I don't know, metallic?

[scratch]

I'd be interested in seeing that schematic ... no stranger to wire wrapping ... see the OT Picture thread for the Freq. Counter I posted.

I was going to take an existing 8-bit 'echo' project I had found on the net and 'upgrade' it to 16-bit and longer delays by extending the SRAM.

[scratch]

finally found the original 'echo' project, it's no longer at the original url I found it at ...

a copy of it is here http://members.fortunecity.com/webee/projects/digital_echo/index.shtml

the circuits dates from 1994, so many of the parts are impossible (obsolete) to find. I had hoped to modify it using more modern parts, all in good time I guess ...

[Taylor]

That's pretty nuts. While I commend your achievement, I'm glad for the sake of my own laziness that a 1-second digital delay can now be done with one chip. Amazing how far things have come in 20(?) or so years.

[peterv999]

That's pretty nuts. While I commend your achievement, I'm glad for the sake of my own laziness that a 1-second digital delay can now be done with one chip. Amazing how far things have come in 20(?) or so years.

I do also very much recognize Cardinalflyer's achievement and would like to add to his approach the usage of a audio codex as in many delay structures today (phoneline delays etc..Device: VBAP TCM320AC38 as an example). Myself I'feel very,very blessed by having found a perfect solution in a FV-1 product by Spin Semiconductors that would deliver up to 1000mS of delay and fullfills my vintage echo requirement 100%.

-Peter

[Taylor]

You can even do 2000ms on the fv-1 at 16k sampling rate.

[peterv999]

You can even do 2000ms on the fv-1 at 16k sampling rate.

Taylor, this Fv-1 is a killer if you need delays!! The actual cost versus other solutions is just great so it's very affordable and of great value. I'm wondering if there are more people here working with this unit as a delay/echo device?

Regards

-Peter

[Ice-9]

Great project there, I built a delay rack about 20 years ago which used the same AD-DA chips Zn428 etc, it was quite similar and i think it was a project in "Practical electronics" wish i still had it now.

You can even do 2000ms on the fv-1 at 16k sampling rate.

Taylor, this Fv-1 is a killer if you need delays!! The actual cost versus other solutions is just great so it's very affordable and of great value. I'm wondering if there are more people here working with this unit as a delay/echo device?

Regards

-Peter

Yeah I've been working with the FV-1 chip , but have not yet gone into the programing  of it yet.  I did etch a PCB and made a test unit which i need to get back to soon. It's a great chip. There is a thread with pictures, sound clips   and schematics etc on this site.