I'm back on 1176.. audiotest here..

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tamtamstudio

Well-known member
Joined
Jun 4, 2004
Messages
118
Location
Italy
Hi guys, i'm back from holidays.
:sad:
Today i'd worked again on my 2 1176 that i leaved on the desk in the last months.
I made the last correction on the board, i had an hum, and now disappear.
OK, i had some pics of the panel. here[http://homepage.mac.com/tamtamstudio/PhotoAlbum11.html]

after that, i made some audio tests, in this folder you will find 5 files: no comp, 1:4, 1:8, 1:12 and 1:20
Please can you hear these? for me seems to much saturated, is it normal?
[http://homepage.mac.com/tamtamstud... What do you think guys? Let me know. :thumb:
 
Yeah, sounds like you've got some distortion there. It almost sounds like driving tape too hard or something. Weird...sorry but I have no idea why you might be having those problems.
 
:cry: SIC!
now you know why i'm sad.. why the same prob on both devices, if it's something wrong (blobs or else) it's too strange for 2 units..
mumble mumble..
If you've got any suggest..
 
OK, checked:
Resistor and caps i had checked 3 times since now.

Transistor type are:
BC107 (no A or B or C) nothing else is written on it.
BC 560
BF245A
BD 135 and BD 136 (with changed pins)

TL071CP
no NE5532 (i used trafo input)



:shock:
 
Ok i solved the prob on 1:20 ratio (left channel with different level) was Q14 that touched Q15, i changed FET (Q1) on 1 unit with no result.
I had substituted 6.8 uF (was tantalium) with 10uF electrolitics, now is a little better (less saturation), but is only a very small difference. can be something else?
The sound is very good before starting compression, but is degrading (saturation) when these units start to compress..
:cry:
For something can be good, (ex. Guitars,etc.) but is not useful with the most of sources..voice or else.
also the voltages on transistors seems to be correct..
 
Yes , the attack and release are working, but if i turn clockwise, the compression will be more aggressive and also the saturation.
Moving the dist trim i not feel any changes (i don't have got a distortion tester)
i tried also to move the bias in a higher position, the saturation will fall down but i've got less compression; if i put up input signal, also the saturation will come again.
:cry:
 
ok, guys.
now i replaced all my BC107 with BC107B.
The result is: NO AUDIO AT ALL.. only some statics clip..
uauu, i had destroyed something?
:evil:
 
ok, but i don't know if they are philips or else is not written on it.
I've got a multimeter with hFE tester, all give me 0 (?) except one that gave me 71 (?)..
What's mean..burned?
 
Ok, all the problems seems comes from Q2, Q3 and Q4.
i tried to change from BC107 with BC107B and the units play very much better, more clean.
After I changed also a couple of broken BC 107B.
What do you think, i have to choose the right transistors or change with other else?
 
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