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Author Topic: preamp for LM3886?  (Read 35682 times)

teemuk

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Re: preamp for LM3886?
« Reply #30 on: April 18, 2008, 01:12:18 PM »
Answering whether their output amplitude matches the input sensitivity of your power amp is impossible since we know nothing about your power amp. There is little sense in converting the supply voltage of ROG circuits to 18V: They are designed for supply voltage of 9V and increasing will raise the headroom and skew the bias. In other words, the circuits won't work anymore as they were supposed to. The conversion will have very little effect on gain, which is all that matters. If you want to run FETs at higher voltages just for the sake of it you could try some circuits from Randall amps, they were designed to operate from about 30V rail or something and they definetely sound very good. But anyway, input sensitivity of typical power amps is usually about 1V or less so supply voltage of these circuits definetely has nothing to do with whether the amplitude of the output signal is sufficient to fully drive the power amp. Low output signal amplitude from the preamp shouldn't be a problem unless it's designed to be - and if it's too low you can easily put a transparent gain stage in between the ROG circuits and the power amp. One opamp and two resistors should do it (in minimum) so I don't see what's the problem...

Robin755

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Re: preamp for LM3886?
« Reply #31 on: April 19, 2008, 09:51:58 AM »
I just need around 1V to go to my poweramp, I just wanted to know if these circuits give me this voltage, or do I have to amplify them some more with an opamp,
planning to use 2 TDA2030A's in bridge on a single supply,

 

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