Sub Sonic Posted June 26, 2015 Posted June 26, 2015 I have a couple of questions for those well versed in electronics - does having a preamplifier with a low output impedance and a power amplifer with relatively high input impedance reduce the effects that different interconnect cables have? - If playing around with different volume potentiometers (for instance in a passive system) how would you select the rating (k ohms)? Is it dependent on the input impedance of the amp or output impedance of the source, or a combination of both? Just trying to get my head around a few things Thanks! SS
Green Wagon Posted June 28, 2015 Posted June 28, 2015 (edited) I have a couple of questions for those well versed in electronics - does having a preamplifier with a low output impedance and a power amplifer with relatively high input impedance reduce the effects that different interconnect cables have? I'd think so. But we all know cables don't make a difference, so it's rather a moot point... <- Joke.No. Really. - If playing around with different volume potentiometers (for instance in a passive system) how would you select the rating (k ohms)? Is it dependent on the input impedance of the amp or output impedance of the source, or a combination of both? Both. The end value will also effect the corner frequency and thus the roll off at both frequency ends. Thats why people come out with 'buffer stages' rather than pure passive. *cough Pass B1 Cough* Just trying to get my head around a few things Thanks! SS Edited June 28, 2015 by Green Wagon
mwhouston Posted June 28, 2015 Posted June 28, 2015 Generally it is good to have a preamp with low impedance and power with high. Generally a pot say coming from a CD play should be high enough resistance to not load the CD player. 50K is probably a good selection.
Sub Sonic Posted June 28, 2015 Author Posted June 28, 2015 (edited) Thanks @@Green Wagon and @@mwhouston for the replies. I'm looking to set up my system with a PC source > Resonessence Herus DAC > passive pre (volume pot) > DIY Pass F5 power amp > speakers. The DAC is essentially a headphone unit but happens to sound particularly good in my system when used as a normal DAC with a loaned Rega Brio. It has an output impedance in the region of 0.2 ohms. The F5 has an input impedance of 100k, so there should be no problems there. What value of pot would be best? I guess a fairly low value unit, perhaps 5k? Cheers! SS Edited June 28, 2015 by Sub Sonic
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