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Old 4th November 2012, 11:21 PM   #11
Einric is offline Einric  United States
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The datasheet says that the gain setting should be no lower than 10V/V (10 volts per volt?) how does that language translate into db's?
10V/V tells me it is 10 to 1 ratio which is 20db gain correct?

With this logic I would think that 1kΩ & 86.6Ω would give me a gain of 22db.

Last edited by Einric; 4th November 2012 at 11:28 PM.
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Old 5th November 2012, 12:00 AM   #12
AndrewT is offline AndrewT  Scotland
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A CD player typically puts out 2Vac to 2.3Vac.
A 60W into 8ohms Power Amplifier (maximum output ~ 22Vac) with a gain of 20times (+26dB) will clip full output signals, massively.
A 20times power amplifier does not need a gain stage in the preamp.
It needs a buffer after the volume pot, not a gain stage.
A buffer and a 2.2Vac signal will take a 10times (+20dB) gain Power Amplifier right up to the 22Vac clipping level of a 60W into 8ohms Amplifier.

If you have a +19.5dB, or +19.9dB gain stage, then you have bought/built the wrong equipment for your system.
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Old 5th November 2012, 01:01 AM   #13
Einric is offline Einric  United States
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I realized that I have too much gain quite a while ago.
This preamp works great with portable media players that have low output voltage.
This is starting to make me think that I really need a Pass F4.
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Old 5th November 2012, 10:20 AM   #14
AndrewT is offline AndrewT  Scotland
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Then use the gain stage only for those low level inputs that need the extra gain.
Use alternative inputs to the vol pot that have no added gain stage.
All you need after the vol pot is a buffer.
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