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Old 19th April 2005, 10:41 AM   #1
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Default Equalizing input volume

What is the best why the equalize input levels. I have too much gain on the cd and phono amp inputs. The preamp has a 10k balance control in front,then a 100k volume control. I need suggestions.



thanks
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Old 19th April 2005, 11:24 AM   #2
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Do you know the gain of the preamp?
What gain does your power amp have?
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Old 19th April 2005, 01:46 PM   #3
rabbitz is offline rabbitz  Australia
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Try an in line attenuator.... worked for me and here's the link.

http://www.diyaudio.com/forums/showt...614#post547614
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Old 19th April 2005, 04:28 PM   #4
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Quote:
Originally posted by carlosfm
Do you know the gain of the preamp?
What gain does your power amp have?
Bridged lm3886 with 13 voltage gain
preamp has a gain of 2 its the opa2134 with buf634 3k in feedback and 2.k resistor from feedback to ground.

[QUOTE]Originally posted by rabbitz
[B]Try an in line attenuator.... worked for me and here's the link.
Thanks I used that idea a few times
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Old 19th April 2005, 07:03 PM   #5
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Quote:
Originally posted by jaudio
Bridged lm3886 with 13 voltage gain
Change it for 10x gain per chip.

Quote:
Originally posted by jaudio
preamp has a gain of 2 its the opa2134 with buf634 3k in feedback and 2.k resistor from feedback to ground.
That's 2.5x gain.
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Old 19th April 2005, 08:46 PM   #6
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Quote:
Originally posted by carlosfm


Change it for 10x gain per chip.

That's 2.5x gain.
Sorry I meant 2.7k instead of 2k


I really dont want to do that because I will have to change resistors for 20 chips.

I will remove the resistors from feedback and feedback to ground in the opa2134 and buf634 preamp then replace it with wire.
Do you see any problems?
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Old 19th April 2005, 09:31 PM   #7
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Quote:
Originally posted by jaudio
I really dont want to do that because I will have to change resistors for 20 chips.

Anyway, you have a higher than normal gain for a power amp.
It's your choice, but keeping things this way means that you are not going to be able to connect any "standard" preamp to your power amps.

Quote:
Originally posted by jaudio
I will remove the resistors from feedback and feedback to ground in the opa2134 and buf634 preamp then replace it with wire.
Do you see any problems?
Change the 2.7k resistor for 5.6k, that should be enough (~1.5x) , I think you don't need to go unity-gain.
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Old 19th April 2005, 10:27 PM   #8
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Is this a good or bad Idea : 10k pot at the input of each power amp
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Old 19th April 2005, 10:33 PM   #9
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Bad.
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