I've searched this forum (and the web via Google) for an ACTIVE loudness control.
Currently, I use a PGA2310 pre-amp (from Silicon Chip magazine) which I think is very good. It does not have either loudness or tone controls. What I was considering is an active loudness control that is dependent upon the pre-amp volume control, that is, the lower the volume the greater the loudness with it reducing as volume decreases. The level of loudness and the cut-off point able to be set by a control, such as a single pot or rotary encoder.
If this was based on a PGA2310 or similar, all the better.
My question is; does such a thing exist?
Frank
Currently, I use a PGA2310 pre-amp (from Silicon Chip magazine) which I think is very good. It does not have either loudness or tone controls. What I was considering is an active loudness control that is dependent upon the pre-amp volume control, that is, the lower the volume the greater the loudness with it reducing as volume decreases. The level of loudness and the cut-off point able to be set by a control, such as a single pot or rotary encoder.
If this was based on a PGA2310 or similar, all the better.
My question is; does such a thing exist?
Frank
Aiming for the same thing with a MiniDSP....
http://www.diyaudio.com/forums/minidsp/177361-equal-loudness-contour-filter-minidsp-can-done.html
Not sure if it's been done yet....
http://www.diyaudio.com/forums/minidsp/177361-equal-loudness-contour-filter-minidsp-can-done.html
Not sure if it's been done yet....
You might check out the discussion here:
http://www.diyaudio.com/forums/solid-state/154209-reverse-old-loudness-control.html#post1982010
It may be useful for you to read the whole thread. Although it doesn't specifically discuss using DSP methods to implement a loudness control, it does discuss the control laws that the DSP would have to implement.
http://www.diyaudio.com/forums/solid-state/154209-reverse-old-loudness-control.html#post1982010
It may be useful for you to read the whole thread. Although it doesn't specifically discuss using DSP methods to implement a loudness control, it does discuss the control laws that the DSP would have to implement.
ST have a series of IC audio processors with volume, treble, bass and loudness (TDA7303). Unfortunately these are not in the same class as the PGA2310 in terms of THD (0.01% typ). They have source selectors for 3 inputs, and they're easy to control off a PIC or other micro, so they're quite attractive in some respects.
w
w
Ah, I thought that "you" were discussing DSP processing to achieve "loudness control". I see you are actually discussing using something (for example, DSP) to make a "loudness control" circuit, implemented in a PGA2310 or similar, to track a "volume control" implemented in a a PGA2310 or similar. In this case, the thread I referred to is still relevant, as it discusses how to make a "loudness control" track a "volume control". My original suggestion was all-analog, but it required a scarce part (a 6-gang pot). I'm currently looking for suitable "electronic potentiometer" chips so that I can drive 6 such channels/chips from one physical pot.
Here's a dual-pot 8-bit volatile chip from Maxim, MAX5389:- http://datasheets.maxim-ic.com/en/ds/MAX5389.pdf. It has a simple up/down interface. You can get ones that remember their last setting. It's a matter of searching through by category on a suppliers website such as Farnell, RS or Digikey. This is a linear pot, but it can be made into a pseudo-logarithmic one by adding a resistor from the wiper to GND, see:- ESP - A Better Volume Control.
You have to read the datasheets to find out what the distortion, linearity and accuracy are. This make finding the best chip fairly labour-intensive.
w
You have to read the datasheets to find out what the distortion, linearity and accuracy are. This make finding the best chip fairly labour-intensive.
w
Thanks. That chip appears suitable for rotary encoder control. I want to use a "real" pot for control, but it's not hard to build a pulse generator to interface the pot to the chip(s).
For my initial proof of concept, I'm less concerned about chip performance and more about cost and availability at this end of the world. I believe it will work, and the circuit sim appears to confirm this, but there is no substitute for listening tests. I want to see if it actually proves useful in real world music listening.
Hi Don Hills
Have you thought of using 6 tracking optocouplers instead of the “6-gang pot” ?
When time permits, I have to try a simple version with one optocoupler (per channel) as the variable element of an LP shelve filter. This optocoupler will vary with the same “physical pot” used for varying a volume optocoupler.
Regards
George
Have you thought of using 6 tracking optocouplers instead of the “6-gang pot” ?
When time permits, I have to try a simple version with one optocoupler (per channel) as the variable element of an LP shelve filter. This optocoupler will vary with the same “physical pot” used for varying a volume optocoupler.
Regards
George
Now already 5 years passed since last discussion, recently I measured BOSE PC speaker(including amplifier) and found the output frequency response of amplifier is varied by the input level signal. Boosting about 80Hz when input level is low. This would be kind of "active loudness".
An externally hosted image should be here but it was not working when we last tested it.
It probably compensates for the speaker deficiency as much as providing "loudness" compensation. This is very common in today's consumer grade junk.
I'm working on an active loudness control that is continuously variable. It still uses the 4 tap potentiometer that has the loudness tap. A line level signal is modified by a passive Fletcher-Munson network, which is buffered with an op amp. This buffered, level controlled signal is fed to the "fourth tap" of the volume control.
It works! But it still needs work.
My motivation was that loudness controls are almost always terrible and basically useless. I've seen units with continuously variable loudness, which is a big improvement. My goal is to design a circuit that provides variable compensation without changing the volume level. The circuits I've seen (Nakamichi and Yamaha) work well but also change the volume.
I looked for active loudness controls, and none of them I saw used this method. Has anyone done this before?
I'm working on an active loudness control that is continuously variable. It still uses the 4 tap potentiometer that has the loudness tap. A line level signal is modified by a passive Fletcher-Munson network, which is buffered with an op amp. This buffered, level controlled signal is fed to the "fourth tap" of the volume control.
It works! But it still needs work.
My motivation was that loudness controls are almost always terrible and basically useless. I've seen units with continuously variable loudness, which is a big improvement. My goal is to design a circuit that provides variable compensation without changing the volume level. The circuits I've seen (Nakamichi and Yamaha) work well but also change the volume.
I looked for active loudness controls, and none of them I saw used this method. Has anyone done this before?
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