Proper technical help needed with own project (reverse engineer)

[LaceSensor]

Hi

Just wanna throw this out there as a question.
Would someone be prepared to offer me some help?
I am trying to do my first clone from scratch.
Its a Lovetone DoppelGanger Phaser v4.
I have etched and populated the board.
The capacitors are all correct as per the original pedal I have.

The resistors apart from a couple values I am very confident are correct, based on colour codes.
The LFOs work, all the switches do what they should.
However it doesnt really sound like a phaser, moreso a tremolo.
In the vibe mode (which removes the clean signal) it sounds almost right, but the output is almost muted / muffled. When you go to phase mode, the thing gets really loud (louder than bypass) and you lose a lot of the phase /trem whatever sound its trying to make.

I have compared voltages to my real unit, and I cant spot any horrific anomalies.
I have tested it with NSL32 optoisolators, compared to green 5mm high brights and LDRs in the original unit.

I have also tried some 10k/1M LDR and red high bright 5mm (all I have, need to order green). And iits probably similar to the NSL32, if a little worse sounding.

Now, I guess the point of this ramble is to say - what do I do next to get this project off the ground?
I really really do not wanna start desoldering parts from the orignal. Its too valuable to fudge up.

I would appreciate any hints on what people with knowledge of optical phasers might think is wrong. I am going to go back and double check all the values based on photos I took of the original.

I have read up on some other forums some efforts people have made to RE this pedal and it seems there are a lot of correlation in parts values but some anomalies. Im hoping its just a wrong resistor or something.


What do you reckon I should do?!

help me obi wan kenobi's

[LaceSensor]

ok bit of progress made here.

there is a tap from the PCB for direct out.
If I send this to ground, then the unity gain issues are sorted out, and I can hear the phasing much better.
There seems to be a bit of distortion in the sweep.

I have tried some normal diffuse 3mm led with the LDR again and that seems ok.

I will try this configuration with the NSL32 I think.

I reckon it all might come down to getting the right optocouplers.
Anyone with experience know just how sensitive opto phasers are to different ones?

thanks

[madbean]

What I would do at this point, since you have more or less cloned it 100% (to the best of your knowledge) is to start audio probing both and comparing. You should stick to the inputs and outputs of the different circuit blocks and see where your new build has gone south. It is actually the fastest way to debug this monstrosity...no need to remove parts until you know which section(s) are causing the trouble.

I'm looking forward to the results!

[LaceSensor]

What I would do at this point, since you have more or less cloned it 100% (to the best of your knowledge) is to start audio probing both and comparing. You should stick to the inputs and outputs of the different circuit blocks and see where your new build has gone south. It is actually the fastest way to debug this monstrosity...no need to remove parts until you know which section(s) are causing the trouble.

I'm looking forward to the results!

Hi

Thanks for the pointer Brian
Hopefully I can spend some time doing that tommorow.

Ian

[LaceSensor]

Probed the ICs on the audio side, definitely some issues with the Quad opamp.
Im am missing signal on pins 12 and 13
On pin 8, the audio is SUPER loud on my build, compared to the orignal.

Audio in general on the Lovetone, sounds more even volume across pins with signal on.
On mine, some pins are quiet (but signal present).

Hmmm