"loudness" circuit

[nyazzip]

too often i am forced to listen to my music/radio at extremely low levels, to avoid disturbing others late at night....but, i get almost no bass whatsoever at these levels, usually. just wondering how a "loudness" function works, lots of SS equipment used to have it a decade ago and farther.....
as you cannot really increase bass if the caps are already full range, i am guessing the focus on reducing upper midrange.
i'd like to give something like that a shot with my rh-84, for starters

[kheper]

The good, newer ones have an algorithm which boosts bass frequencies and slightly boosts treble frequencies at low volume, but progressively cuts the boosts as the volume is raised.

The old, cheap loudness circuits from the 60s and 70s boosted bass frequencies only, and did not progressively cut them when the volume was raised. The result was sonic muddiness or blown speakers when the volume was cranked up.

Late at night, connect your amp to a computer soundcard, and use mplayer (or that panel in windows with sliders) to boost the bass and treble frequencies.

I tried an equalizer to boost frequencies:

mplayer -> sound card -> equalizer -> amp

But, never do this, as it is something like a noise making, frequency amplifier with an impedance mismatch.

http://www.extron.com/company/article.a ... control_ts

[nyazzip]

The old, cheap loudness circuits from the 60s and 70s boosted bass frequencies only, and did not progressively cut them when the volume was raised. The result was sonic muddiness or blown speakers when the volume was cranked up.

...i'd be willing to try the old, cheap version! i wonder if the loudness functions also used compression....

[Shannon Parks]

Sandwiched in this GSG thread I have some tips:
http://www.diytube.com/phpBB2/viewtopic ... t=loudness

You can still get the Radio Shack pot with the loudness tap and ALP knockoffs on eBay have them. I think it's worth checking out.

Shannon

[kheper]

One that flattens out the boost at higher volumes:
http://www.tablix.org/~avian/blog/archi ... ass_boost/

http://www.audioasylum.com/cgi/vt.mpl?f ... y&m=187892

http://www.diytube.com/phpBB2/viewtopic ... a292a9922d

[nyazzip]

cool, i think i might try it. could this be done as an external box outside the amp? like a guitar "pedal"? built in to a "passive pre" box? i don't see why not.
i know it will take some fiddling though, because i am very particular about "boomy", and thats what a lot of loudness switches seemed to do. i have better speakers nowadays though, so maybe it won't be as big a problem

[kheper]

Why not just buy a pre-amp with a good loudness circuit? You can find used, Adcom pre-amps and pre-amp tuners for about ~$100 on ebay.