GGG SHEcho Project

[Hozy31]

Since i bought an extra HT8955a when i bought one for the Phonic Taxidermist, i was wondering if this would be a good one for vero and use up my extra chip. Info can be found here http://www.generalguitargadgets.com/wp-content/uploads/ggg_shecho.pdf.

[gul]

That's a great idea! I also bought an extra chip. I looooove that Phonic Taxidermist. I also made the Harmonic Engine. It's just as awesome. I hope that circuitbenders makes more PCB circuits, I would certainly build them.

[BetterOffShred]

Very interesting!!  I was thinking I had one of these chips, but it was the ht8950.. I built the DBA Robot.  Not sure I really like that pedal.. but I digress.  I'd be interested in this delay too. Where did you guys get your 8955A's from?  Cool build link. Thanks
-Brett

[Hozy31]

I agree the Phonic taxidermist is a real beauty as is the Harmonic engine. I'm hoping this one is as good if not better than the taxidermist. I'm tempted to have a go at his drum machine clone if its not to expensive to acquire the parts

Brett, i got my 8955A's from "allpartspipe2008" in Hong Kong on ebay. I trust these guys a lot and have bought numerous bits & bobs from them. Take a while to come but faster than from China.

[MAO]

Hey Hozy31,

This looks like a tough one, I'll give it a shot though.

[MAO]

OK, here goes...

I had to split it into two boards.

I'm hopeful if you lay the caps and transistors down you will be able to fit them both into a 125B. I would place the modulation board 1st, then the main board on top, with a playing card in between. If ticking is a problem, you may need to put a shield between the two boards, which is fairly easy to do. Let me know if needed.

The boards are connected together at points A,B,C and D.

Note, the ICs on the main board are upside down.  I also tried to place the caps so you could lay them down.

Hope you pull this one off!

Layout updated 06/18/2017 (added 1 link)





 

[Hozy31]

Awesome! Thanks so much . I'll give it a go at the weekend if some parts arrive in time.

[BetterOffShred]

So just to be sure here, the 41256 is in fact a RAM chip?     So awesome.   And the SA571 (D)? is a Compandor?   What a neat set of chips.   This thing looks pretty BA.  I need to get a job fast..  So many things to build and play with!
-Brett

[Hozy31]

So, built this last weekend but couldn't get any delay coming through just dry signal. Been over it several times an can't find any issues. MAO can you just run over it again and i'll have another check over the board. I know the chips are good as i subbed them into the phonic taxidermist.

[MAO]

Shoot, I see an issue with the layout. Looks like an easy fix though.

There is a missing link at pin 10 of the 571.

Looking at the main layout, there needs to be a link between column 2, rows 7 & 8.   Connecting pin 10 to the junction of the 36k and 1u+

[Hozy31]

Thanks MAO, that did the trick. Call it verified! I tried a few values between and including 68k and 150k for the delay. If you build this socket and change for taste. It increases or reduces the overall delay and i reckon most will have there own preference.

[MAO]

Excellent!!!

Since it's so similar, I'm drawing up the PT80 from GGG for those who might want a PT2399 version.

[Hozy31]

Great idea.

[MAO]

Here's the Delay board from the PT80 if you'd like to test on your SHEcho.

It should hook up as a direct replacement for the SHEcho modulation board.

Only real difference with the main boards is the PT80 used a 2n5089 and was powered with 12v, so your main board should be good to go as is, just a little less headroom.  

[BetterOffShred]

Any chance you could make a little clip with Max delay time? I guess this project has me really interested because it's got a ton of stuff happening for a 3 knob delay.  I mean I just recently built the Profundis with mod board and it's 6 knobs.. so I'm not sure what the draw to this many chips for 3 knobs is.  I'm guessing it sounds super amazing or something.  I'd love to hear it.  
-Brett

[Hozy31]

So tested the Delay board for the PT80 and its working nicely. It is quite different to the SHEcho but in a nice way. The repeats pot doesn't seem to do much. I was thinking if there is a way that i can put the two delay boards together with the main board and use a switch to toggle between the two.

[MAO]

Nice Hoz!

Let me see if I fat fingered something with the repeats

[Hozy31]

Hey Brett, I'll try and get one up soon. Its got the PT2399 board on at the moment.

[MAO]

I looked it over again, the Repeat appears to follow the schematic.

Does the Repeats work better with the ShEcho delay?

BTW, how does the PT80 compare to a typical PT2399 delay?

[Hozy31]

The repeats works fine with the SHEcho delay. Is there something different maybe with the main board for PT80 which is making it change. I see the PT80 main board vero has some subtle differences.