HEXE Tadek - TDA7052A based guitar/bass compressor

pz · Post by pz » 16 Jun 2012, 10:59

Check the DC voltages at the indicated points:

sparki · Post by **sparki** » 16 Jun 2012, 12:09

pz wrote:Check the DC voltages at the indicated points:

new bat: 9,65V

T1 - 9,65
T2 - 4,84
T3 - 4,84
T4 - 1,11
T5 - 1,06
T6 - 1,06

pz · Post by pz » 16 Jun 2012, 12:38

The in and out stages are ok. The problem is at T6 and T4. These points are directly connected:

And you have a 100mV difference there. Check if there is a connection between T4 and T6. A highres picture of the bottom side would definitely help.
A correct value at T4 = T5 = T6 without any incoming signal should be at about 1V. The 100mV more is quite a lot for the sensitive gain control input on the TDA chip. This is most likely the source of your distortion.
Does the gain reduction led flash when you hit the string?

sparki · Post by **sparki** » 16 Jun 2012, 12:58

I checked again, same voltage is on T4, T5 and T6. (my crappy battery droped the voltage from when i checked the one and other ic)
here's my board bottom.
had to make 2 pics couse of the pots.
and yes, the led light up as i hit the strings.

sparki · Post by **sparki** » 16 Jun 2012, 13:52

here's the whole thing in action.
https://img62.imageshack.us/img62/6974/zvf.mp4

pz · Post by pz » 16 Jun 2012, 14:06

What are the DC voltages at the outputs of the TDA chip? (Pin 5 &

Should be at about half of the supply.

sparki · Post by **sparki** » 16 Jun 2012, 16:28

Bat: 9,5V
tda: pin 8=8,8V and pin 5=0,7V

pz · Post by pz » 16 Jun 2012, 16:48

Ok, last step, check the voltage at the + input (pin 2) of the TDA chip. The 1uF pad, which goes into the +in look suspicious on the 1st pic (possible short to the nearest +9V track, probably it's only the perspective). If you have something like Vsupply or 0V, look for possible shorts. If the PCB and soldering are fine, the chip is fried, replace it.

sparki · Post by **sparki** » 16 Jun 2012, 17:02

ok, pin2 on tda is 1.1V, the 1uF witch leads from the poty is 4,7V and after the 1uF is 1.1V witch goes to pin2.
it's the angle of the picture, the contact is clean. (no shorts)
funny i replaced the chip today already xD i'l see if i can get another one.

roseblood11 · Post by **roseblood11** » 05 Jul 2013, 08:16

mictester wrote:I breadboarded this, and it's excellent. There are a few mods you can easily do (like "jangle" mode, and a decay time control)

Explanation please!

roseblood11 · Post by **roseblood11** » 15 Dec 2013, 23:18

- mictester, you never answered...

- does somebody have a pcb for this project for me?
(I'm too lazy to draw a vero layout...)

smurfberry · Post by **smurfberry** » 01 Jan 2014, 23:29

If someone wants to swap a (as in one) tda7052a for something real trivial like a few transistors or an op amp let me know through pm

roseblood11 · Post by **roseblood11** » 01 Jan 2014, 23:46

they are easily available on eBay...

johnk · Post by **johnk** » 30 Aug 2014, 04:44

I just finished building one of these today and I think that it's a very nice sounding comp (I play bass BTW).
thanks for posting the pdf files pz!

pz · Post by pz » 30 Aug 2014, 08:44

Great build johnk!
I have updated the PCB design a few days ago and got the pcbs fabbed:

There is a small change in drill layout (ON/OFF led). All the new design files are here:
https://github.com/hexeguitar/Tadek-Compressor

Neur0 · Post by **Neur0** » 09 Sep 2014, 11:22

Thank you pz!
Looks really great and is def a must build for me, using Freppo's Vero.
mictester: I would be interested to know how one would go about making the mods you mentioned.