Volume attenuation on test bench setup..

[No Pk]

I've occasionally purchase cheap amps/receivers at garage sales etc
and do some quick, simple fixes (clean controls, dial string repair
etc) before passing them off to friends/family for their use..

Problem is, I recently moved into a basement suite and don't want to
start blasting the landlord with loud volume..

I know I've seen a setup where there was a pot installed in a box with
a small speaker, and the amp could be driven with its vol control set
quite high, while the pot on the small speaker box kept the volume at
a reasonable level.

Can someone give me an idea what resistance and wattage of pot (or a
different setup entirely?) I should be looking at to do what I need?

Thanks a million..

Brent

 

[TimPerry]

I've occasionally purchase cheap amps/receivers at garage sales etc
and do some quick, simple fixes (clean controls, dial string repair
etc) before passing them off to friends/family for their use..

Problem is, I recently moved into a basement suite and don't want to
start blasting the landlord with loud volume..

I know I've seen a setup where there was a pot installed in a box with
a small speaker, and the amp could be driven with its vol control set
quite high, while the pot on the small speaker box kept the volume at
a reasonable level.

Can someone give me an idea what resistance and wattage of pot (or a
different setup entirely?) I should be looking at to do what I need?

Thanks a million..

Brent

sometimes called a "power soak" this is a series of resistors wired in such
a way as to present a constant impedance to the amplifier (8 or 4 ohms or
whatever is desired) while attenuating the power to a speaker.
level is controlled by a rotary switch which selects different resistor
value combinations.

wirewound continuously variable "L pads" are available, however in my
experience they tend to get hot and melt when employed for the duty you
intend... even the 100 watt versions.

hers a java L pad calculator http://www.lalena.com/audio/calculator/lpad/
of course you will have to round off to nearest standard values unless you
are heavey into winding you own.

the purests and the audiophools will say you have to use non-inductive
resistors. thats fine if you can find them in the values and power ratings
you need; if not the wirewounds do fine for general servicing.

 

[t.hoehler]

I've occasionally purchase cheap amps/receivers at garage sales etc
and do some quick, simple fixes (clean controls, dial string repair
etc) before passing them off to friends/family for their use..

Problem is, I recently moved into a basement suite and don't want to
start blasting the landlord with loud volume..

I know I've seen a setup where there was a pot installed in a box with
a small speaker, and the amp could be driven with its vol control set
quite high, while the pot on the small speaker box kept the volume at
a reasonable level.

Can someone give me an idea what resistance and wattage of pot (or a
different setup entirely?) I should be looking at to do what I need?

Thanks a million..

Brent

Years ago, I found some 10 ohm, 100 watt Dale resistors at a hamfest, got a
couple of them for my stereo service bench. Got a couple of auto rear seat
speaker fader controls from the junk box, put them in series with two small
box speakers. Now the dale resistors soak up the power, and you tap off the
amount of audio you want using the fader controls. I would guess the faders
are about 50 ohms. Works great, 10 ohms is perfect for all amps I work on. I
don't mess with the high power car audio amp 4 and 2 ohm stuff, so my setup
is fine for me.

Really saves on the old ears, lets you listen to the amps running wide open
without deafening yourself (and pissing off the family/neighbors.) Do
yourself a favor and protect your hearing. You will thank yourself down the
road. Your hearing is also much more acute at lower sound pressure levels.
Regards,
Tom