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This particular combination is the very worst case. Add a resistor to ground from each wiper.
The resistor's value should be about 10% of the pot's total value. This will do until you find
a better volume pot. It is called "law faking", and actually works pretty well, since linear pots
track much better than log pots. Use 1% resistors if possible.
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Yes it is, except that the input impedance decreases at higher volume settings.
With some tube sources, this could reduce the LF response.
Also, some wiper types can cause added distortion when loaded with a resistor.
These make a nice faked law stereo pot. http://www.ebay.com/itm/Allen-Bradl...506220?hash=item1c6c169f6c:g:pxwAAOSwIgNXo6NR
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Nope, a log pot gives way more clicks at low volumes.
Remember, a linear pot at the center of rotation is only -6dB.
A log pot at the center is about -20dB.
So below halfway in a pot that turns 270 degrees, there is
much more adjustment capability (135 degrees) below -20dB
than for a linear pot (27 degrees) for the same amount of attenuation.
So it's about five times easier to adjust with a log pot at low volumes,
than with a linear pot.
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Thanks. Will definitely give it a go. 3 weeks is no big deal.
Why do you say 10k though, and why "usual"? Like I said, the stock pot in the amp is 50k and I'm only replacing it here - I'm strongly inclined to keep it the same value (as I'm happy with it otherwise) unless there's an explicit reason to reduce it with no potential downsides.
I'll wait for your reply, but I'm tempted to get the 50k (first) either way so I can have a variable-free comparison between the stock pot and an individual-resistor'd stepper for future reference. That way if there's any audible change other than improved balance I'll know why.
RE: Grounding, you mean the metal body is connected to the two signal ground terminals?
No worries. I wouldn't have even known enough to suspect a misunderstanding if I hadn't spent a while reading old posts of yours (and others) on here previously.
Checking back, it seems that the 50k amp input impedance includes the 50k pot, so yes,
using a 50k replacement pot should be fine.
It's best if the pot is mounted on a metal panel that grounds its case. If the panel is not conductive,
then there should be a separate ground connection to its case. This is true for any control that has
a metal housing.
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Ordered it.
Stock mounting panel is metal, all good. Will update later on how it goes. I am slightly concerned about the granularity too but will cross that bridge (with added series resistance) if I come to it.
Thanks again for sharing.
I've been using one of these controls in a secondary system with KEF LS50s for months,
and honestly I have no problem at all with the step size. Extremely efficient speakers
might give a different result, though.
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Yes, I think that one is made in Poland, and is much more expensive.
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24 stepper is expensive if not a cheapo from the Far East.
more than 33steps is very expensive.
Have you looked at the AIKIDO FP from the TubeCAD blog.
https://www.tubecad.com/2006/03/blog0057.htm
The resistor values in the first stage are wrong, but all of them can be changed to give the step values you require.
I set mine up for 2dB steps over the range from -0dB to -70dB
but you could do 1dB steps 0 to -35dB, or 1.5dB steps 0 to -52.5dB
more than 33steps is very expensive.
Have you looked at the AIKIDO FP from the TubeCAD blog.
https://www.tubecad.com/2006/03/blog0057.htm
The resistor values in the first stage are wrong, but all of them can be changed to give the step values you require.
I set mine up for 2dB steps over the range from -0dB to -70dB
but you could do 1dB steps 0 to -35dB, or 1.5dB steps 0 to -52.5dB
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i read the original post with great interest but have to admit that i did not really understand every detail.
what i'm trying to figure out is, wich volume pot would be best to go "in between" a phono pre amp and an lm3886dr amp. i do understand that a pot with a higher value will possibly introduce more noise and that a pot with a lower value will put more load on the source, but what exactly does "load on the source" mean? and how much load is desirable? what happens if the load is too great and how do i measure the load?
loads of questions, i know ....
i should add that i currently use a 50k pot and it seems to do fine .... but i don't have anything to compare it with at the moment.
what i'm trying to figure out is, wich volume pot would be best to go "in between" a phono pre amp and an lm3886dr amp. i do understand that a pot with a higher value will possibly introduce more noise and that a pot with a lower value will put more load on the source, but what exactly does "load on the source" mean? and how much load is desirable? what happens if the load is too great and how do i measure the load?
loads of questions, i know ....
i should add that i currently use a 50k pot and it seems to do fine .... but i don't have anything to compare it with at the moment.