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Studiomaster 8 into 4 refresh

hi everyone, i'm new here and i can see a lot of good informations!. maybe some of you could help me doing something.

here's the deal : i recently bought an old studiomaster 8 into 4 that i would like to "refresh" a bit.. my knownledge in electronics is actually poor but growing everyday ;) i don't have the schematics for this console and i can not actually find it, so let's start "a blind".

what i d'like to do is to make the sound more "transparent" or clear (for the summing part). so by looking around, i can read that changing the opamps could be a start. it's equiped with tl072 originaly, and i would like to give it a try with 5532's or 2134.. what do you think about it? would i expect real improvement from this? i also have in mind to follow with changing coupling caps and some resistors that need to (because they went over heated)..

does this step make any sense for someone, or am i trying to play mad scientist?

btw, this board was built in 1981, and as you can see, caps already been changed since (not my job). here are some pictures: the whole master section

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the master bus summing part zoomed
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well, thanks by advance for any return !

mathieu

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mat_432
Reply to
mat_432
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I would stick with fet input amps. Sometimes more bypassing is required with higher frequency amps, else instability. 2134 should have less noise.

Greg

Reply to
gregz

"mat_432"

** Nuts.

** Nope.

The summing stages involve transistors at the inputs to the TL072s - so are very quiet.

The op-amps you mention take much higher DC supply current so would overload the PSU if you changed them all.

Their higher bandwidths could easily lead to HF oscillation problems to.

The scorched resistors seem to be in the headphone amplifier ( cos some dope used a mono plug) and simply need replacing.

.... Phil

Reply to
Phil Allison

Ok, thanks for replys,

so i maybe won't touch te opamp, at least instabillity or oscillation are last thing expected!

this boards has its sound like it is, well but it's still bit noisy, what if i would replace capacitors or transistors with high quality ones?

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mat_432
Reply to
mat_432

"mat_432"

** Studiomaster desks were known to be very quiet.

Very few people have the gear or know how to test a desk for background noise levels.

Turning up all the knobs and listening is the fool's way.

** Waste of time and money.

... Phil

Reply to
Phil Allison

So what happens to the noise, assuming you can meter it somehow, if you either locally squirt freezer spray or warm with hot air, individual op-amps ?

Reply to
N_Cook

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mat_432[/i][/color]

So what happens to the noise, assuming you can meter it somehow, if you either locally squirt freezer spray or warm with hot air, individual op-amps

?

i'm in the cleaning process, so, as each module is separated, i have mounted 2 channels, 2 buses an the master fader (cleaned).

For now, what i can hear is some "white" noise without any gain or fader level, juste the mixer powered on.

by selecting mic source and pushing master fader, i'm getting some hum with nothing plugged in.

my headphone left channel is completly distorded, and changing the scorched resistor had effect..

well, i'm a bit dispponted just now, but i will clean the rest of the channels and give it some more try. just don't know what to do to "fix" things so i'll go step by step... (oh baby)

-- mat_432

Reply to
mat_432

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