can a 250K vol.pot be used in place of a 470K one?

[trane]

as above in the (first series) Audio Innovations S500 w/o sound degradation, I wonder? or is it a solution to solder a pair of 220K e.g. Caddock MK-132 resistors to a 250K pot to mimic the 470K for the rest of the circuit? if so, is it better to put the resistors in front or behind the pot? many thanks for your help

[Reid Malenfant]

Hi Attila, i don't see why not after a bit of thought about it Whatever circuitry will be connected to the wiper (for variable output) so i can't see it upsetting anything as the resistance to ground would vary on the 470K pot from 0 ohms to 470 kohms. These things generally tend to be near the input though & there is often some kind of resistor capacitor filter/s to prevent the amp having to amplify ultrasonics (& often infrasonics) & if this is the case it/they will be altered. You might need to alter certain components to bring this back to standard Chances are you'd reduce the high frequency bandwidth & increase the low frequency roll off, so you'd need to change one or two capacitors to compensate.

To mimic the 470K pot you'd need to have a 220K resistor in series with the potentiometer, no matter which way you connect it you'll either not be able to take the volume full or not be able to turn it down below half the volume level.

I'd suggest that attempting to mimic it goes out the window as a consequence

[trane]

Mark, thanks for your views on the matter, pretty logical. BUT what can I do with an amp that was built with a 470K volume pot - which is not available in it's original sound quality equivalent (Noble), only ALPS produce it in their lesser-sonics-quality Blue Velvet line, I wonder? The other source may be TKD, but it's pretty high-street price, hence my try... See?

[Reid Malenfant]

Have you considered fitting a decent 470K stepped attenuator? While you may not have the precise control of a pot the channels will be better matched & the sound quality will be superior to any potentiometer

[Rare Bird]

He might not get a step Att in that amp it's quite slim.

What about a 1M Linear pot with 470k resistor wired between the pots Out & 0v, (same for both channels) Linear pots are more accurate at tracking, what your doing is immitating a Log pot using the resistor to modify the curve, the 470K resistor will still give you your original pot value.. The 1M would be trial as i see no top notch pots higher than this.. The resistor quality will of course have a marked effect on SQ. Just a thought chaps.

[trane]

He might not get a step Att in that amp it's quite slim.

What about a 1M Linear pot with 470k resistor wired between the pots Out & 0v, (same for both channels) Linear pots are more accurate at tracking, what your doing is immitating a Log pot using the resistor to modify the curve, the 470K resistor will still give you your original pot value.. The 1M would be trial as i see no top notch pots higher than this.. The resistor quality will of course have a marked effect on SQ. Just a thought chaps.

you may be right, Andre, but IMHO it's the same solution as what i started with - only back-wise however, i am not an electronics specialist, hence my (perhaps) silly questions

[trane]

Have you considered fitting a decent 470K stepped attenuator? While you may not have the precise control of a pot the channels will be better matched & the sound quality will be superior to any potentiometer

never, Mark, but am still not tempted. they add a switching noise when actually doing so, and i can not judge the exact steps that i would need, only could do after some experimenting, which i won't feel like doing. also, if a really good quality switch (e.g. ELMA) is used together w/ only good(not great)-sounding resistors (e.g. Takman) i am also at high-street prices

[Dr Bunsen Honeydew]

as above in the (first series) Audio Innovations S500 w/o sound degradation, I wonder? or is it a solution to solder a pair of 220K e.g. Caddock MK-132 resistors to a 250K pot to mimic the 470K for the rest of the circuit? if so, is it better to put the resistors in front or behind the pot? many thanks for your help

Just put the 250k in and don't worry about it, I doubt you will hear any difference, and it certainly wont harm anything.

So just do it and report back.

[Rare Bird]

you may be right, Andre, but IMHO it's the same solution as what i started with - only back-wise however, i am not an electronics specialist, hence my (perhaps) silly questions

Yes but the LFR pot is a more accurate pot, should have better control at low level too