Volume Control with Loudness and no Taps

[LinuksGuru]

Hi! Anyone have schematic for passive volume control with loudness compensation and 250-500K potentiometer without taps? Tapped pots are very problematic to obtain today unless ordered in quantity 100+ directly from factory.

I found schematic on Steve Bench web site (attached to this post), but I have no idea of its origin. In the books I have there are schematics, but ALL use tapped potentiometers.

Thanks in advance for any suggestion(s).

[LinuksGuru]

Anyone ?

[Don Hills]

Something like this?
Reverse of the old Loudness Control
Also check the latest posts in that thread, starting with this one:
Reverse of the old Loudness Control

... but I haven't seen a way to do it passively. If there was, it would have been done that way from the beginning to avoid the extra cost of tapped pots.

[Steerpike]

I have this one, slightly simpler - I also cannot tell you its origin: (when I saw the useful circuit I just saved it with no record of where it came from)

It should be easy enough - using simulation software - to plot the frequency response curves of both circuits and see which you prefer.

The tapped pot circuits are merely a cheap approximation anyway, so no reason they are inherently better than an arrangement using a standard pot, other than they may give a lower insertion loss.

There are also circuits that use double-gang pots, so for stereo you'd need a four-gang, or two gear-coupled twin-gangs.

[kevinkr]

You can place a parallel RC in series with the cold end of the pot to ground, place a switch across it if you want to be able to defeat it.

Some iteration is required (With 100K pot I might start with 4.7K - 10K and 0.1uF or greater and iterate from there to the optimal values - best done in spice) and this approach works best over a very limited range of the listening levels, and as you would expect boost becomes significantly less as you turn the volume up.

[LinuksGuru]

Seems like passive circuit is not the best solution. May be someone can suggest active one with 12AX7 or6N1P for example (I have them anyway already)?