Lightspeed Attenuator a new passive preamp

[georgehifi]

Just reverse the two positive ldr feed wires from the pot.

Cheers George

[wushuliu]

I have a slight balance issue with imaging leaning little to the left side. Which trimmer do I adjust, left or right?

[jonclancy]

Originally Posted by MoltenLava

I have a quick newbie question. On the 100k volume control dual potentiometer, what is the purpose of shorting pin 2 and 3 on one gang and pin 1 and 2 on the other gang? Can we just use the pin 2 on both gang, and leave pin 3 and pin 1 alone?

It's a voltage divider. So, as you turn the pot, the voltage to one set of LDRs (say, the Series pair) increases at the same time the voltage to the other set of LDRs (Shunt pair) decreases.

[AndrewT]

Originally Posted by wushuliu

I have a slight balance issue with imaging leaning little to the left side. Which trimmer do I adjust, left or right?

try matching the "lean" by leaning in the opposite direction.

Seriously,
read the adjustment procedure for your purchased version. In it, it should tell you how to balance the image at the most used volume setting.
If it doesn't say how, then you bought from someone who does not give adequate support to their customers.

BTW,
there could be gain errors in the source or in the pre-amp or in the amplifiers or in the sensitivity of the speakers.
Maybe you should actually check the overall gain & sensitivity of the supply chain rather than assume it is correctable in the volume control.

[wushuliu]

Originally Posted by AndrewT

try matching the "lean" by leaning in the opposite direction.

Seriously,
read the adjustment procedure for your purchased version. In it, it should tell you how to balance the image at the most used volume setting.
If it doesn't say how, then you bought from someone who does not give adequate support to their customers.

BTW,
there could be gain errors in the source or in the pre-amp or in the amplifiers or in the sensitivity of the speakers.
Maybe you should actually check the overall gain & sensitivity of the supply chain rather than assume it is correctable in the volume control.

er, thanks andrew.

[joemana]

Will there be a signal degredation if you mount the volume pot to the (instead of to the PCB) front panel add about a foot and half long wire for board connection and mount the board at the back of the case?

Thanks,

Joe

[udailey]

Wushuliu
Dont know if you bought from me or not. If its from me then you can use either the 200R pot or the 5k pot to adjust balance. If its the Oliver board then ... man I gotta go back and look.. I forget if the trimmers are on series or shunt supply.. okay its on series. On the channel that is loud you want to let less current in, on the channel thats not loud enough you want more current so you trim accordingly. I guess that doesnt help because it depends which direction you turn the pots so just listen as you turn and the image will adjust to center.

[udailey]

Joe
There is no connection between signal and the volume pot. Mount it anywhere. Try keeping the entire circuit away from transformers as they seem to inject a bit of hummmm.
Uriah

[jonclancy]

Easiest way to adjust channel balance at your preferred listening level is with a sine and dual channel scope. A doddle if you can get access to that equipment...

[troystg]

A mono recording and sitting in your sweet spot and you can dial in the center in no time with only your ears if you don't have equipment.