The loudness function is most often tied into the volume control via a separate tap.
There are drawbacks to this scheme though as it cannot take into account the amplifier or speaker's sensitivity. If you familiarize yourself with the operation of loudness circuitry you might find a workaround.
Try googling for - loudness control circuit - or something similar.
There are drawbacks to this scheme though as it cannot take into account the amplifier or speaker's sensitivity. If you familiarize yourself with the operation of loudness circuitry you might find a workaround.
Try googling for - loudness control circuit - or something similar.
Probabaly the most useful contibution in this field is to be found in an old copy of "The Journal of the Audio Engineering Society" (JAES). It is a four page article that describes a "loudness control" built around an inverting op-amp with seven passive components and a linear potentiometer. The authors tackle the problems in this area by having both a fixed and a variable breakpoint to the time constants in the bass region and come up with a circuit that follows the Fletcher-Munson contours to within 3db over a 40db range. The full reference is; "Practical Loudness: An active circuit design approach." Arthur L. Newcomb and Richard N. Young. JAES Jan/Feb 1976 Volume 24, No.1. It is easy to miss the article as it wasn't large enough to go in as a feature and you will find it hidden away in the section called "Project Notes/Engineering Briefs". Many of the bigger City/Uni libraries hold large sets of the JAES but if you can't reach one of these The Societie's reprint service is very efficient. Unfortunately I haven't got their their contact details. They're in New York I believe. Another member may be able to post the details. Jonathan Bright.
Loudness
This variable loudness is not a traditional loudness since the Loudness effect does not vary with volume setting control.
The pre-amp circuit includes a gain 5.7 without the loudness. When the switch is in OFF position, the pre-amp still give low sub-audio frequency a pre-emphasis allowing the phase shift at 10 Hz to be lower than 0.5 deg, thus the 10 Hz square wave is almost perfect.
I am very pleased with the result. If anyone has tried something similar or would like to comment...
This variable loudness is not a traditional loudness since the Loudness effect does not vary with volume setting control.
The pre-amp circuit includes a gain 5.7 without the loudness. When the switch is in OFF position, the pre-amp still give low sub-audio frequency a pre-emphasis allowing the phase shift at 10 Hz to be lower than 0.5 deg, thus the 10 Hz square wave is almost perfect.
I am very pleased with the result. If anyone has tried something similar or would like to comment...
Attachments
, but do not know the value of the components of a schematics?There are other threads which may be useful:
http://www.diyaudio.com/forums/solid-state/154209-reverse-old-loudness-control.html
http://www.diyaudio.com/forums/tubes-valves/173029-volume-control-loudness-no-taps.html
http://www.diyaudio.com/forums/analog-line-level/182258-active-loudness-control.html
http://www.diyaudio.com/forums/solid-state/154209-reverse-old-loudness-control.html
http://www.diyaudio.com/forums/tubes-valves/173029-volume-control-loudness-no-taps.html
http://www.diyaudio.com/forums/analog-line-level/182258-active-loudness-control.html
if you want something w/o adding any active circuit in series in your existing system, use the circuit in post #7 where the loudness is included in your actual pre-amp (in the feedback path of your pre-amp, provided that is is a non-inverting one). You simply have to modify your pre-amp but ensure to put the potentiometer close to the pre-amo circuit to prevent capturing too much noise, thus locate the pre-amp circuit close to your pre-amp front panel where the pot is located...
Hi
Is can be seen the measured Frequency response characteristics of this circuit (post 7). How much is raised (in dB?) frequency of 50Hz frequency and how to about 16kHz?
thank you!
Hi
there is no hi frequency compensation b/c I have never experienced the need to have one.
See this link for the freq response: http://www.diyaudio.com/forums/solid-state/77599-loudness-experiences-3.html#post3105849
Fab
Oh , it's very easy
Just substitute the actual tweeters with ones having more sensibility ( and SPL !!!! ) ;maybe the crossover has to be redone ; putting an L-pad you can
vary from normal to +10 dB , and maybe a compression driver is required !
For the bass region , no problem again : multiple subs ; those can be driven
by just a mono amp ; 3 or 4 would already give a 10 dB boost at 50 Hz
Just substitute the actual tweeters with ones having more sensibility ( and SPL !!!! ) ;maybe the crossover has to be redone ; putting an L-pad you can
vary from normal to +10 dB , and maybe a compression driver is required !
For the bass region , no problem again : multiple subs ; those can be driven
by just a mono amp ; 3 or 4 would already give a 10 dB boost at 50 Hz
Hi picowallspeaker!Oh , it's very easy
Just substitute the actual tweeters with ones having more sensibility ( and SPL !!!! ) ;maybe the crossover has to be redone ; putting an L-pad you can
vary from normal to +10 dB , and maybe a compression driver is required !
For the bass region , no problem again : multiple subs ; those can be driven
by just a mono amp ; 3 or 4 would already give a 10 dB boost at 50 Hz
I need electronic circuit for loudness in the pre-amp with the above characteristics.
thank you!
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