How do I reduce the overall gain in my preamp ?


AUDIO RESEARCH
MODEL: LS2B
SN.61352029
STEREO LINE AMPLIFIER

Many thanks,
Regards,
albert.
azcd204
Thanks guys for your wonderful help!
I hope some of your tips will work for me.
Anyway, thanks again.
albert.

I have LS-2 that had gain reduced by dealer. There is a
jumper on the board that is replaced with a resistor. Gain
is reduced by 12 db I believe. Do not know where in circuit
they do this, contact dealer or ARC.
Marakanetz, you can do it as you state with a less sensitive amp OR speakers. Going from 95db sensitive speakers to say 92db speakers will give your system less overall gain/volume.

KF
Hi Albert
Dweller's suggestion is definitely the best of the above. If you aren't able to follow the mod instructions for lack of technical know-how, a local repair shop should do this for you fairly inexpensively. Retain the mod instructions for future reversal in case you decide to sell it later on.
Or insert a quality passive attenuator into the tape loop, as an aside on Newbee's suggestion.
KF, I believe you meant poweramp and not speakers.

If poweramp is sencitive and source component(s) with high output why not going for passive preamp and sell the line-stage?
I would not try to modify your preamp.

I would look at getting a different preamp or look at getting a source that outputs less. Or look at getting speakers that are less sensative.

Just my 2c.

KF
I owned an ARC LS-1 and also had to tame this monster!
Call Lenard (at the ARC factory) and tell him your problem.
He sent me a diagram of the solder traces (bottom of circuit board) and told me where to sever a trace to reduce overall gain (it worked, of course).
I put a passive line stage in my tape loop - for casual listening i have remote control also. works fine. When i'm feeling picky about sound i simply flip the switch turning off the tape loop. If you can accept some minimal signal loss (there will always be some) you can put a passive preamp of high quality between your amp and preamp but you must deal with the cable between the passive and the amp carefully to minimize the loss. I've done this with some success - not as funky as it sounds, but you'll get booted out of the audiophile corp if you tell anyone you did it!
This is tedious unless you really know what you are doing. I would not attempt if you are not familiar with electronics. The circuit is "tuned" for all the parameters involved - you change one, you change everything. Just turn down the volume or get a different preamp IMO.
If it is adjustable than you can reduce it.

You can also reduce the gain with varing anode DC feed with potentiometer or in SS case where there are few possibilities of implementing the amplification stages but in any case you should use the output DC feed. In the most common example with emitter-coupled stage you should apply the variable DC voltage to Kollector.

In both of the above cases the large variations of the gain are not acceptable since your offset is set to be for a particular gain i.e. you should vary the offset as well accordingly to the DC applied to the output electrode. That's why the variable gain is usually implemented stepped with for example 3...4 settings where you vary the output DC feed along with the offset.