Tadek the Compressor - verified

[Freppo]

Here is a very cool compressor for guitar and bass by HEXE Guitar Electronics, an original design based around the TDA7052A amplifier chip.



Demo video by the inventor:


cheers
/ Freppo

[IvIark]

Ha, I'd just added this to my To Do list!  Don't think I'll bother now
Nice one Fredrik

[Neur0]

Thank you very much, Freppo.
I was looking for this one :)

[Neur0]

I have built this, but I am having some problems with 200/300 mV too much on the TDA's gain control input resulting in distortion. This info I found elsewhere.
My question is probably one of a newbie, but how come this VERO differs so much from the schematic?
2 IC's less, different components en lower value caps.
I'm really interested in learning more about actually understanding my hobby :)

Cheers,
Remy

[Freppo]

Hi Remy

I'm sorry to hear you are having problems with your build.
Mine works perfectly with no distortion.
It can go from subtle to really agressive compression.

The vero layout follows the schematic except the DC filtering which was a bit excessive in the original..
There is just one 100uF cap V+ to ground insted of big 220uF caps close to the V+ pin of every IC.
It would have taken alot of space, and a single 100uF should be sufficient.

I also put the polarity protection diode in series insted of parallel.
But other then these changes, the circuit itself is 1:1 with the schematic.

The IC symbols you see in the schematic shows one op amp.
But since these are dual op amps IC's, two schematic symbols is actually one IC.
If you have a look in the schematic, IC1A and IC1B is the same IC. Same for IC2A/IC2B ect

I hope that was helpful :)
cheers
/ Fredrik

[Neur0]

Thank you very much for answering, Fredrik

I didn't look very deeply into the schematics, but I do understand how IC's are "split up" in drawings. The part you omitted is something I don't really understand, but I will use your answer to look over it all and make sense of it that way, making your answer very useful.
When I said "2 IC's" less I was referring to a different project which is my fault for staying up way too late :) . But what I'm really interested in, is if you might have a clue why my TDA is getting 1.250 - 1.300 Volts instead of the +/- 1.00 Volts it is supposed to get? (according to piotr from hexeguitar)

I'm using the Really Cheap Compressor (several actually) but I would like one with more control for some other signals.

Regards,
Remy

[Neur0]

After audioprobing and visual inspection I discovered 2x 4k7 resistors instead of the specified 47k...
I hope this is causing my issue. One of them does have a direct line to the TDA's input gain, so fingers crossed. Anyway I thought I'd post to avoid wasting anybodies time just in case :)
I'll come back when I've had a chance to replace the resistors.

[Freppo]

Sounds like you found the culprit of your problem. :)
Let us know how it goes!

[Neur0]

Well...
It did stabilize and even out the current at about 1.077 volts without any incoming signal. There is however still the distortion when compression is applied. The voltage drops when I open up the input gain potentiometer taking it to 0.984 volts, but of course the shear input will now cause it to overdrive with the humbuckers.
I replaced all the IC's one by one trying to find a faulty one, but to no avail.
I was kinda going by the route given by pz in this thread after somebody reported simular problems. I think that topic is dead though :)