Uses a PT2399, as one might expect, but provides inputs for voltage control of a variety of parameters.  So, for instance, you could arrange to have echo level fade in and out with and LFO, or use an LFO to modulate the delay time.  Think of it as a "baby" Blacet Time Machine using modern available chips.

Here's the schem:  http://www.musicfromouterspace.com/analogsynth_new/ECHOFXXX/pdf/ECHOFEX_Schematic.pdf

Cool schematic - there is more info including sound samples here -

http://www.musicfromouterspace.com/index.php?CATPARTNO=&PROJARG=ECHOFXXX%2FECHOFXXX.php&MAINTAB=SYNTHDIY&SONGID=NONE&VPW=2015&VPH=1216

Andrew.

very interesting stuff! thanks

How can he get away with so little filtering? 

QuoteHow can he get away with so little filtering?

(yet) Another cool link from the Elliot Sound webpages, a good info on designing with the PT2399 (including limits for minimal filtering)

http://sound.westhost.com/project26a.htm

Andrew.

Thanks Mark, looks very interesting!

Quote from: knutolai on January 17, 2014, 05:50:00 PM
How can he get away with so little filtering? 

Probably because it's designed to go in a synth, where you'll generally have a bunch of filters at your disposal to put before or after it, so I guess he figured he'd try and get the most most out of the PT2399 and leave any extra filtering to the user. It certainly doesn't sound particularly noisy on the more "normal" soundclips.

External filtering wont help much if the feedback loop feeds HF noise generated by the internal clock. I mean, with the lack of proper filtering, as you are wobbling the Delay time around noise from hetrodyning or aliasation could occur through the feedback loop? I feel I have way more to learn about this chip and the workings of its ADC and DAC even though I've probably scavenged every online resource regarding the chip

Nice circuit, but that schematic's a nightmare. Couldn't it have a *little* bit more space so that it could lay out nicely and make the signal path a bit more obvious?

I love the MFOS stuff, and that's really my only criticism.

T.

Couldn't agree more.

People can often forget how important a well laid-out, and easy-to-follow, schematic can be to making more sense of a circuit, and often to recognizing its inherent virtues.

I printed the schematic out for commuter-bus reading, and ended up having to go over the various inputs and outputs with a highlighter, just so I could figure out how the thing is supposed to work.

I'm seeing what can be done in Photoshop!

Okay....so who's going to redraw the more stomp box friendly version? 

Quote from: armdnrdy on January 18, 2014, 12:40:16 PM
Okay....so who's going to redraw the more stomp box friendly version? 

Mmmmmmm not so easy, perhaps Paint is kinder!

https://www.dropbox.com/s/se6ijf7zqa8an2i/ECHOFEX_Schematic.jpg

Converted to a jpg with canvas size doubled - that's a start for somebody.

https://www.dropbox.com/s/obd4cr1e36dork7/ECHOFEX_Schematic2.jpg

Moves bits and pieces not going anywhere to outside - now a little clearer perhaps?

I tried to draw a more viewer-friendly version of the schematic with Paint.

http://imageshack.com/a/img802/7858/8m43.jpg

The CV circuits, and their explanation on MFOS site, are so interesting. It could help for designing CV inputs for any PT2399 delay (Echobase, Rebote...) and tremolo projects, phaser projects, etc. 

Excellent, many thanks

Can't see it at work, but thanks from me too, just the same.

You are welcome. 

Okay, I can see it now...and I was right to thank you.