Skreddy Echo [gut shots]

Lawnchair · Post by **Lawnchair** » 30 Sep 2009, 14:08

Reasonable parts count. Hack it!

lolbou · Post by **lolbou** » 30 Sep 2009, 14:11

The ground wire looks like a dirty ivy plant... Beurk!

WhiteKeyHole · Post by **WhiteKeyHole** » 15 Oct 2009, 23:13

PM@me the schematic, Skreddy.

PM@me.

jimbojetset · Post by **jimbojetset** » 17 Oct 2009, 12:37

Is there a schematic for this pedal anywhere?
cheers.....

Damon Jonesta · Post by **Damon Jonesta** » 31 Oct 2009, 22:23

jimbojetset wrote:Is there a schematic for this pedal anywhere?
cheers.....

sure

bestegw · Post by **bestegw** » 02 Nov 2009, 07:59

OK, let's see what we've got:

* PT2399 all-in-one delay chip
* OPA2604 op-amp (love those!!)
* LFO-LDR combo for modulation of the delay time
* one of the Q's is probably 78L05 voltage regulator (probably Q1, based on the position next to PT2399)
* 3 types of film caps (Greenies, Panasonic, MKT)
* carbon comp resistors (in the audio path???)

My first thought was that it's a modded Rebote delay with a trem-like circuit connected to the delay time.

Build quality looks very good with the pots attached to the print. I also like the method where you can reach the trims from the outside

rocklander · Post by **rocklander** » 02 Nov 2009, 08:09

what's the LED/LDR there for?

[edit] oh, the LFO

[/edit]

soulsonic · Post by **soulsonic** » 02 Nov 2009, 08:45

Look up the scheme for the Yerasov delay to get an idea for how the delay time is controlled. It uses a transistor for the variable resistor element. Marc had mentioned it to me as a cool way to do it, so I'm guessing he's doing something similar here. The LDR is likely controlling a voltage that's affecting that transistor.

bestegw · Post by **bestegw** » 02 Nov 2009, 09:31

So, basically you set the voltage of the base of the transistor, thereby determining the output at the collector-side. Pardon my simplicity, but why wouldn't you just connect the time-pot to lug 6 of the PT2399, like on the rebote or similar pedals? Is this more stable?

BTW, connecting two PT2399's together on the Yerasov looks like a cool idea. The thing sounds very nice and ambient:

Diamond · Post by **Diamond** » 02 Nov 2009, 10:31

That looks pretty tight! Great sounding pedal though.

roseblood11 · Post by **roseblood11** » 02 Nov 2009, 12:22

Would be great to combine this circuit with the NE571 compander, as used in the PT-80.

bestegw · Post by **bestegw** » 04 Nov 2009, 12:58

I've been checking some of the delay schematics out there (Rebote, Echo Base, Yerasov and Magnus Modulus) and considering the possibilities of this delay, it's most similar to the Echo Base. This pedal also uses the delay-time-via-a-transistor method that Soulsonic mentioned.

Could it be that Skreddy has been optimizing the Echo Base to the Skreddy Echo (perhaps even with a name reference???) with carbon comp resistors and film caps in the audio path?

The idea with the compander-expander sounds pretty cool too and would IMHO contribute to an even more analog-sounding delay.

Skreddy, care to share some with us?

All the best!!
Bestegw

sevinisthenumber · Post by **sevinisthenumber** » 10 Mar 2010, 06:04

Can tap tempo be added to this??? I know of other pt2399 based delays that are... Thanks

soggybag · Post by **soggybag** » 10 Mar 2010, 06:31

I built a PT-80 and it sounded pretty good. I'm not sure that is sounded so much better than the Rebote that it was worth building with the extra NE570 and related components.

Skreddy sure loves those carbon comp resistors. For some reason I could not bring myself to use these in a delay.

Jack Deville · Post by **Jack Deville** » 10 Mar 2010, 16:36

Looks like a single transistor phase shift oscillator.
Ref: http://www.electronics-tutorials.ws/osc ... lator.html
Output drives and LED aimed at an LDR in parallel with the "time" resistor.
"Modulation" controls are pretty self explanatory: Speed controls frequency of oscillator, Intensity controls current of LED.

It looks like inductors(?) used in the feedback loop of the PT2399? Neat idea if so.
Effects loop probably interrupts feedback of the echo circuit.
Nice opamp to drive the echo circuit, and mix the echo and dry paths.

Tap tempo on PT2399 is not exactly stable, or easy.
There's a drop in module a guy designed:
http://www.thoughtprocessinc.com/ptap
You will find it in a few "diy"/"boutique" designs. It comes with its own host of instabilities, which if are not immediately apparent, will be discovered shortly after its installation. I'm not knocking the designer of this device. Its in the PT2399, which is a fantastic chip!

There are just easier ways to go about designing a tap tempo delay.

I don't think Marc copied anyone's design. Its a PT2399 based delay. There's only so many ways to use that chip. The magic lies is what you do with it.

culturejam · Post by **culturejam** » 30 Jun 2010, 13:57

More gut shots, courtesy of The GAS Station at TGP.

First two are an older model, last two are from the 2010 version.

///

culturejam · Post by **culturejam** » 08 Feb 2011, 13:38

A few more gut shots from TGP.

I'm really surprised this thing is as expensive as it is and doesn't have a compander.

//

monkeyxx · Post by **monkeyxx** » 12 Jul 2011, 22:21

any new info or circuit trace side pictures of this around? I'm pretty intrigued by this thing. the price isn't that bad, actually

Damon Jonesta · Post by **Damon Jonesta** » 28 Aug 2011, 23:14

Work in progress