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Audio Innovations 500 volume pot.

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Hello all.

I am in the process of upgrading/servicing my Audio Innovations 500 amplifier and could do with a bit of advice regarding replacing the volume pot with a stepped attenuator. The stepped attenuator I have is a 50k unit. The balance pot was removed many years ago.
I appreciate that I 'should' be using a 500k attenuator but is it ok to use the 50k unit? Will it be detremental to the performance of the amp and/or sound quality? Can I use 50k effectively by modifying a few other components?
I have attached the relevant schematic showing the Input/Volume/Balance. and power amp. The 500 also has a phono stage so I have attached the schematic.

Thanks.
 

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Thanks for the quick replies. A word of clarification: JonSnell. I intend to leave the balance pot out of the amp. I removed it years ago as it as a potential source of signal degradation and not needed.

I have altered the schematic to show the 50k volume pot and no balance control.

My main concern is whether such a low value stepped attenuator (50k where once there was 500k volume pot followed by the balance pot) will harm the amp and/or have a negative effect on the sound.

I should mention that I have very little knowledge of electronic theory and the effects of impedance mismatching. Reading a schematic and doing a bit of component swapping is within my scope, understanding how a circuit really works is where I come unstuck.

Jacksonsinliss, I also own 2 series 500's. One is totally original, the other I rebuilt with some exotic components as well as a factory fitted Border Patrol power supply. I would be happy to hear your comments and suggestions when you get back to your AI 500 project.
 

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My main concern is whether such a low value stepped attenuator (50k where once there was 500k volume pot followed by the balance pot) will harm the amp and/or have a negative effect on the sound.

No need to be concerned. As I mentioned earlier, 50k will work fine.
You can also remove the 220k resistor at the input. It is unnecessary.

At audio frequencies and line levels, impedance matching is not necessary as long as the output impedance of the signal source is much less than the input impedance of the amplifier.
In practice; Typically the output impedance of the CD-player etc. signal source is, say some tens or hundreds ohms. Input impedance of the amplifier is 50k.
All OK.
 
No need to be concerned. As I mentioned earlier, 50k will work fine.
You can also remove the 220k resistor at the input. It is unnecessary.

At audio frequencies and line levels, impedance matching is not necessary as long as the output impedance of the signal source is much less than the input impedance of the amplifier.
In practice; Typically the output impedance of the CD-player etc. signal source is, say some tens or hundreds ohms. Input impedance of the amplifier is 50k.
All OK.

Thanks very much for that Artosalo . Very helpful & good to have an explaination.
 
I use in my projects input pot. 2 - 20 kohm, HF sound is better in low levels. If second point of pot is close to ground, upper part of pot. 50-100-500 kohm is big resistance for small HF levels.
If Your ALPS is for 20-30 $, it will have noise problem after few months. I"d like to advice You to put pot. 10-20 kohm.
 
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