Echopathetic: the worst, but so simple, analog delay around

Original effect designs complete with schematics, layouts and instructions. Freely contributed by members or found in printed or online publications. Cannot be used for commercial purposes without consent of the respective owners of the copyright.
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allesz
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Post by allesz »

Very proud of this shitty thing... gives around 170 msec of delay (you have to use the "less time" trimmer to set a max time delay without bbd whining) with repeats and even self oscillation :shock: Only problem is it's quite hissy.... put a tonebender in front of it to cure the problem 8) .

Thanks to the people that helped me figuring out how to work with the bbds. marteen from diystompboxes who was the first to make something similar, PRR, Scruffie (now I know wat is a Sallen Key) and Fender3D.

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Post by mictester »

If you want to turn this thing into something really usable (reducing the dreaded hiss) you could add pre-emphasis at the input, and de-emphasis at the output as a first step:

Bypass your 56k input resistor with (say) 5k6 and 33n in series, and then add the same network (33n and 5k6 in series) to ground at the output. This will go some way to mitigating the hiss. It' only four parts - try it. If you haven't got the exact values, try two of the same value of resistor (anything from 4k7 to 10k will work) and two of the same value of capacitor (anything from 22n to 100n will work) - experiment! Note that you will reduce your HF headroom a bit, but this isn't going to be the highest of hi-fi effects anyway!

Further noise reduction will need a compander, but this will increase the complexity of the circuit quite significantly. I'll give thought to a simple (one chip) compander - without resorting to expensive (and rare) 570 or 571 types.
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Post by allesz »

Thank you mic! Just came home from rehearsal (a good one :D ) and having a cigar before sleep, nice advice.
When Scruffie told about Sallen Key, I googled and found some infos. But I did not find about pre and de-emphasis.... did't know it was so simple.
I will try asap, and maybe correct the schem; I noticed I forgot a cap value btw, and maybe I will add another credit :applause:

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Post by allesz »

Hallo, I repost the first schem with some minor errors corrected, and then post a modified schem incorporating some tweaks suggested by mictester.

I put a filter (or de-emphasis 8) ) on the delay output that works good cutting down hiss from the delay line.
Then I put a tiny amount of pre and de-emphasis to the dry and output sgnals; here going too far led to too much high cut, but a gentle one made the dry signal a little better and more natural sounding (I also reduced the gain of the dry guitar here).

I think I will get back working on fuzzes (max three transistors please): that's the real workingman's relax :secret:

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Post by allesz »

Un update just to repost the schematics: I made a mistake in the drawing :oops:
This one should be correct.
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echopatetic.gif
echopatetic II.gif

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Post by Dirk_Hendrik »

Where's the deemphasis?
Sorry. Plain out of planes.

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Post by allesz »

According to mictester's advice it should be the 10k in series with the 1n cap to ground at the output. .. maybe I did not understand it right?
To me it simply cuts some hiss.

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Post by Dirk_Hendrik »

In order to keep the frequency response of the overall circuit correct you need to add an additional output opamp stage where the 10k and 10n are in the opamps feedback loop and the 100k goes to gnd. I other words, a filter with exactly the inverse response of the one you already added. That's the deemphasis

Right now you just have a low pass filter. A poor man's solution. :wink:
Sorry. Plain out of planes.

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Post by allesz »

Well, this is intended to be a poorman's analog echo.
In the workbench section I also tried another schem that souds better.
This one is fascinating for his simplicity: I think it will be almost impossible to have something better with less parts (maybe two bjt?).
I am slowly working on a layout; but I think it will be just a novelty item.

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Post by allesz »

Hallo, yesterday I was quite excited and just posted the soundclip.

Today I am posting the last schematic (super simplified, but it's the one I recorded and, for me, it's quite decent), the perf layout (thank you bancika :hug: ). I found the perf layout quite difficult to do, maybe from the copper trace and components someone will be ablle to make a pcb layout... I can't do it.

The effect is not true bypass, you can see you just need a spst switch to turn it on or off.

The buffer is not perfect, but not bad for my (dirty) taste.

In the recording, as soon as the time delay is increased, you will notice the faint whining of the bbd.... if you have a dark amp it's not too bad; better still id to keep the time not too long and to increase the repeats number, the effect is similar to having longer delays.... in a pathetic way, of course.
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echopatetic III.gif
ECHOPATHETIC.gif

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Post by storyboardist »

Here's a PCB and a little neater perf layout for you. Sounds cool!

Image

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Post by allesz »

A small uppdate: after some tests with my band at rehearsals I remover the "pre enphasis" (the 2,2,n cap in series with the 4,7K resistor at the input).
At full volume the sound was too shrill; now the bypassed sound is just a tiny little bit darker that straight in the amp.

A great thank to storyboardist who is a perf and pcb layout artist;
only remember that is layout if for true bypass wiring (he says this in his wonderful layouts blog, but not here)

I am not a fan of true bypass delays because I really like the bypassed dry signal to be the same as the dry signal when the delay is on.... it always bugs me when turning on the delay changes the dry sound; but you can try it both way: it's a very simple mod on storyboardists layout.

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Post by deltafred »

The idea is that you apply pre-emphasis at the input (which boosts the high frequencies) then apply de-emphesis at the output which brings the high frequencies back to what they should be and more importantly cuts the hiss as well.

You had pre-emphasis but not de-emphasis so no wonder it was too shrill.

It's what was done with records (vinyl and shellac) to cut the hiss generated by the needle. Pre-emphasis was applied when cutting the master disc and de-emphasis was applied in the reproduction. Look up RIAA equalisation if interested.
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Post by allesz »

I received a request by a forum member to help him modify storiboardist's layout of the echopathetic for non true bypass.

I can't (or don't know how to) send him pictures by pm... and via email too.

This is a modified storyboardist's layout... so, dear story, if you don't like it, tell me and I will remove it. To turn on and off the delay connect A and B on the layout with a switch.

Also I spotted an error in my perf layout, so I repost it corrected.
Attachments
ECHOPATHETIC.gif
EchoPatheticmod.gif

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Post by aishabag23 »

allesz wrote:Very proud of this shitty thing... gives around 170 msec of delay (you have to use the "less time" trimmer to set a max time delay without bbd whining) with repeats and even self oscillation :shock: Only problem is it's quite hissy.... put a tonebender in front of it to cure the problem 8) .

Thanks to the people that helped me figuring out how to work with the bbds. marteen from diystompboxes who was the first to make something similar, PRR, Scruffie (now I know wat is a Sallen Key) and Fender3D.

If you box it you're crazy.
I love, love, love this effect. I have used it on many recordings. However, it has the worst switch pop of any effect I have ever built, so I wouldn't be able to use it live without putting it through a line selector of some kind. I tried the usual AMZ LED Popping fixes, I'm fairly certain it's not related to the LED. Has anyone else built and boxed this one? I'm grateful for any advice.
Loe Sounds

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Post by allesz »

Happy you like it mate, thank you for giving it a go.
I am slowly working on a refined version.

Do you use the true bypass layout, or the original not true bypass? The not true bypass version pops a little for the first couple of stomps; I had no probs for the true bypass version, but I use a split limiting resistor for the led.

I plan to go true bypass only btw, modding a little the first buffer: feedback resistor is 120k, guitar input resistor is 100k (so you have just a tiny little bit of gain and you can get rid of pre emphasis, and some hiss), delay input resistor is 120k too.

Then I woul increase the value of the cap in the feedback loop of the second op amp to 4,7 n, to cut some hiss.

The perfect "time" capacitor is 200nF (two 100s in parallel) in order to avoid wining at max time.

Sometimes some switch pops more than others, sometimes some leds pops more than others, sometimes splitting the limiting resistor is good (1/2 on ground and 1/2 to V+). Some designs are just too poor, and some designers just suck... it may be the case :oops:

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Post by zoof »

allesz wrote:Happy you like it mate, thank you for giving it a go.
I am slowly working on a refined version.

Do you use the true bypass layout, or the original not true bypass? The not true bypass version pops a little for the first couple of stomps; I had no probs for the true bypass version, but I use a split limiting resistor for the led.

I plan to go true bypass only btw, modding a little the first buffer: feedback resistor is 120k, guitar input resistor is 100k (so you have just a tiny little bit of gain and you can get rid of pre emphasis, and some hiss), delay input resistor is 120k too.

Then I woul increase the value of the cap in the feedback loop of the second op amp to 4,7 n, to cut some hiss.

The perfect "time" capacitor is 200nF (two 100s in parallel) in order to avoid wining at max time.

Sometimes some switch pops more than others, sometimes some leds pops more than others, sometimes splitting the limiting resistor is good (1/2 on ground and 1/2 to V+). Some designs are just too poor, and some designers just suck... it may be the case :oops:
I also love this thing. The time capacitor, is that the 220nf ? I would really like to get rid of some wining noise :)a

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Post by allesz »

Hallo, the time cap is the 330pF. Try 200pF (two 100s in parallel), or 220 or, if you find the value, 180 pF.
It should cut down the wining but the repeats will be shorter but still useable as sjmple slap back echo.

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Post by zoof »

Thanks! Will try!
And thanks for sharing, love the sound of this delay!

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