Dealing with low input impedance of cheap amps

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#22
notakosan said:
Thank you for understanding my point. I was worried it would have been too incoherent.

I did some analysis, and found that the effective impedance is always lower than the volume pot resistance. So if a 1k pot is used, the effective impedance is always 1k or lower. As you said some sources may drive it and some may not.
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Thankfully most of us use not the maximum position of volume potentiometers so matters may have less impact 😉

DUG said:
Agreed, and this is where some have experienced "noise" issues at higher pot settings.
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Maybe we can learn from this that 9 kOhm is no issue when driving it with an active output stage (as common). When doing it passive probably next value is more optimal when using a volume control directly in front? Just saying... A 10 kOhm potentiometer and 15 kOhm from the TPA3116/8 seems a good combination certainly when a meanwhile necessary input RC filter is used with let's say 1 kOhm series resistor and 220 pF capacitor?!

Now I am confused... when is it active and when is it passive? 😀
 
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#24
Never noticed or experienced that with plain good industrial metal film resistors and at such signal levels. Nearly all good ready made amplifiers have an RC filter so with series resistor. Class AB amplifiers are full of resistors 🙂

I recall you using digital volume control, now that has often way more impact than good old analog volume control with just 1 series resistor. So...I think you blamed something that wasn't the cause of the disturbance. It may very well be that the chosen path of convenience is not the way to maximum result.
 
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#31
Hi, in nearly all my devices and tests the DAC/source needs to be at maximum level to perform best. I would never compromise quality for convenience.

2 Years ago I visited a guy that had very expensive tube amps and speakers. He was a Chinese businessman and demonstrated several systems. I was not very impressed and mentioned that. It turned out he used Spotify Connect with 128 kbit MP3 marvel...never had even bothered to use FLAC 16/44.1 let alone 24/96. Said he thought it to take too much time. Spent all his free time to buy new stuff though...
 
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#35
@notakosan: Self inductance of resistors in the kOhm region and above is neglible in audio applications. Period!
But if you insert a resistor into the output of some pre-amp driving a screened cable of several meters length - then you get a low-pass filter that may cut treble in an audible manner.
 
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