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Old 23rd October 2008, 07:24 AM   #1
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Default loudnes control

most simple anlog integrated amps i ve seen when they have a loudness function the volume pot normally has a center tap ( not exactly center but something like that )

i think that this center tap is there to reduce loudnes while volume is going up .....IE loudnes is no longer active as long as volume level is higher than 40%

i ve seen one amp that have loudness switch but there is no center tap on the pot ....

the amp is no longer in my hands and i really dont know if this amp except loudnes switch could perform also the limitation that after 40% of volume the loudnes is decreased

any ideas or circuits ?????

my target is to apply this circuit to vintage amps that volume pots need to be replaced but center tap versions not easilly available and also costumers like to have both working volume and loudnes ....

thanks sakis
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Old 23rd October 2008, 08:06 AM   #2
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From wikipedia:
Quote:
The "loudness" control on a consumer stereo alters the frequency response curve to correspond roughly with the equal loudness characteristic of the ear.[1] The loudness control is intended to make the recorded music sound more natural when played at a a lower sound pressure level.
It's an equaliser, may be implemented by a chip nowdays.

Some Yamaha amps, like one I own, have a Loudness control, another pot next to the bass and treble, I guess it changes the degree to which the response is altered. It was handy to have that extra tweak in my haphazard systems of old.
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Old 23rd October 2008, 12:44 PM   #3
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Look this schema from:
http://www.belza.cz


regards

Roly
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Old 23rd October 2008, 04:43 PM   #4
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Default AND....

canyou complete the circuit by telling us where the loudnes switch is connected ?????

and/or the effect of loudnes is active 100% or less ????
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Old 23rd October 2008, 07:32 PM   #5
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Default Re: AND....

Quote:
Originally posted by sakis
canyou complete the circuit by telling us where the loudnes switch is connected ?????

and/or the effect of loudnes is active 100% or less ????
Hi Sakis,

see circuit below for defeat switch. This circuit should be made with a linear potentiometer, the resistor R4 makes it into a log taper.

The loudness control in the circuit is active across the whole range of the potentiometer but decreases in effect with increased volume setting.

SONY's passive pre-amps in their Esprit/EHS range used this exact circuit. The amount of bass boost is set by the ratio of R5/R6 and the frequency by C2 & R5.

SONY did not use the HF boost because of their theory that the human ear LF response reduces by SPL but not HF response.

Frequency setting is independent from the pot setting.

Regards

Nico
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Old 24th October 2008, 06:22 AM   #6
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Default thanks Nico

that looks very nice ...i will give a try and let you know ......

its been a while after we talked in private .....i hope you are doing fine .....

i am ok but very busy
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