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Old 31st May 2004, 07:41 PM   #1
pjmont is offline pjmont  Italy
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Default threshold SL10 - DC output

Hello, i have a Threshold SL-10 preamp and a threshold TA300 poweramp, now i have a problem with the preamp :

Only in the left channel i have found one DC of 0,12V, this cause a problem with the poweramp (only the power amp without the pre is ok), and so my left woofer have a strange and unusual movement, even if sound the same one.
What's it? a any broken transistors?

Thank you
Pierluigi (Italy)
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Old 31st May 2004, 11:24 PM   #2
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I am posting the schematic of the high level stage, which
(hopefully) shows a direct coupled output whose DC offset is
adjusted by an op amp. The op amp could be bad, or the
capacitor could be leaking, or some other component could
be failed sufficiently that the op amp can't make the correction.
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Old 31st May 2004, 11:48 PM   #3
pjmont is offline pjmont  Italy
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Ok many thanks Nelson.
Bye
Pierluigi
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Old 21st February 2012, 03:20 AM   #4
tfender is offline tfender  Thailand
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Quote:
Originally Posted by Nelson Pass View Post
I am posting the schematic of the high level stage, which
(hopefully) shows a direct coupled output whose DC offset is
adjusted by an op amp. The op amp could be bad, or the
capacitor could be leaking, or some other component could
be failed sufficiently that the op amp can't make the correction.
Hello
I take an interest that try out , Pre SL-10 , this , I want to know position value aforementioned , and the circuit , Supply , Click the image to open in full size.[/IMG]

Thanks
Click the image to open in full size.
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Old 21st February 2012, 03:43 AM   #5
Zen Mod is offline Zen Mod  Serbia
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search

it's there
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Old 27th February 2012, 07:44 PM   #6
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i really love the sound and look of this preamp , the only thing is the hi level stage gain , too much gain for nowadays sources and amp . is there a solution to reduce the gain of this stage without affecting too much the sound ?

i have already put a 30k resistor in series with the volume pot but it is the max i could had before affecting the sound..

any idea ?
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Old 27th February 2012, 08:09 PM   #7
Zen Mod is offline Zen Mod  Serbia
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didn't I already told you (somewhere ) - just cut that 18K2 in half , for 6db gain reduction

gain is roughly 18K2/750
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Old 27th February 2012, 08:24 PM   #8
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hey zen guy sorry it was not me , can you explain how to cut ? i have the scissor ready
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Old 27th February 2012, 08:26 PM   #9
Zen Mod is offline Zen Mod  Serbia
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either solder another one 18K2 across existing one , or desolder existing one and solder 9K1 instead

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Old 27th February 2012, 08:31 PM   #10
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you are a killer.. thks
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