Reverb-O-Matic (100 FXs/Reverbs)

DIY STUFF
22

where did you find the juanito Moore PT2399 added cv circuits?. This fx unit turned out awesome.

1 Like
23

dsp fx 100 juanito moore
dsp fx 100 juanito moore3000×2430 914 KB

:wink:

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24

The right side here doesn’t look right:

image

Pins 11, 13, and 16 are opamp − inputs, and 9 is an opamp output. Grounding inputs and outputs is not how you deal with unused opamps, unless you want them to saturate, consume extra power, and possibly get damaged and take out the rest of the chip with them.

The + inputs are internally connected to a VCC/2 rail (pin 2) so seems a better approach would be to connect 9-10, 11-12, 13-14 and 15-16.

EDIT: The 100n in the upper right corner there is also wrong. Decouple to ground, folks, not between the rails.

3 Likes
25

thanks alot really appreciate this send out , synth on brother

1 Like
26

even if the PT2399 is only used as a clock source

27

The opamps are still opamps and will still do opamp things even if you’re not using them :slight_smile:

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28

ok thx, maybe i need to take out of my case to mod it.

just connect it by couple , and keep the GND connection like this ?

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29

No GND, you should connect output to input (which is the inverting input) for each pair of pins. Here’s the block diagram:

image
image1563×1040 91.4 KB

and it’s this pattern you’re after:

image

The non-inverting inputs are connected to VCC/2 already.

But I wouldn’t stress; this might well be an “if it works it works” case, but if the IC gets warmer than expected or burns out this could be the reason.

2 Likes
30

thx @fredrik , I will make the modification :slight_smile:

to be sure, like that

dsp fx 100 juanito moore mod pt2399
dsp fx 100 juanito moore mod pt23991097×891 223 KB

because I also shared this schem on my website with the construction, and if I add this info I prefer to be sure.

and this ?

dsp fx 100 juanito moore 100nf
dsp fx 100 juanito moore 100nf808×574 91.4 KB

1 Like
31

This looks like too much fun not to try!
THANKS! :slight_smile: :raised_hands:

2 Likes
32

Well, I haven’t tested things, so all I know is that the original is wrong :grinning: – but given the block diagram the top two connections (15-16 and 13-14) are obviously correct, the other two already have the output connected to the input via a 4k7 resistor, and internal connections to MOD/DEM, so may be safer to leave them unconnected (not grounded) to protect those circuits. I have some 2399s somewhere but no time to experiment right now.

Your decoupling update is correct.

1 Like
33

thanks, but now I have connected by couple as above this afternoon.Is it less good ? I hope it will be alright, in any case it still works :slight_smile:

34

thanks for your diagram… but could you tell me what pin X1 means, where it should be connected??? Thanks…)

1 Like
35

I should have added one of these onto the end of my synth build. But now I don’t have room for a display and a pot.

36

for the optional part of Juanito Moore with the PT2399, the X1 must be connected to one of the 2 pads of the pcb where there is the crystal timer (which must be cut), but be careful is quite meticulous and it can be irreversible for the pcb if you heat up too much or if you put the 2 pads in contact which are really very close together.
To know which of the 2 plots controls the time, you have to test (nothing dangerous for the circuit if you test the wrong one), but one hour from his video Juanito does it, it can help

2 Likes
37

thank you so much! now it became clear

1 Like