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Old 3rd September 2010, 10:20 PM   #1
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Default Volume Control with Loudness and no Taps

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).
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Old 5th September 2010, 09:34 AM   #2
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Anyone ?
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Old 5th September 2010, 11:33 AM   #3
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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.

Last edited by Don Hills; 5th September 2010 at 11:35 AM.
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Old 5th September 2010, 01:23 PM   #4
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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.
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Old 5th September 2010, 03:18 PM   #5
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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.
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Last edited by kevinkr; 5th September 2010 at 03:22 PM.
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Old 5th September 2010, 04:28 PM   #6
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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)?
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Old 21st July 2012, 10:09 PM   #7
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Quote:
Originally Posted by Steerpike View Post
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.
Hi Steerpike!
Where is the simulation of this circuit?
At the output of this circuit can be eaten added OA (operational amplifier) IC= NE5532 with gain 2 ... 5dB?
thank you!
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Old 21st July 2012, 10:16 PM   #8
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Quote:
Originally Posted by Steerpike View Post
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.
Hi
Where is the simulation of this circuit?
At the output of this circuit can be eaten added OA (operational amplifier) IC= NE5532 with gain 2 ... 5dB?
thank you!
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Old 26th July 2012, 09:46 PM   #9
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Quote:
Originally Posted by formula 22 View Post
Hi
Where is the simulation of this circuit?
At the output of this circuit can be eaten added OA (operational amplifier) IC= NE5532 with gain 2 ... 5dB?
thank you!
Simulation I have not done, you'd have to do that for yourself using one of the free Spice programs out there.

Certainly an op-amp with any gain you wish can be added to the output.
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