Hi guys, if you can hold a soldering iron and solder and have a small amount of electronic knowledge you can make a Lightspeed Attenuator yourself.
Yes I also do a production ready made Lightspeed Attenuator over 800 units world wide now, which was released at the same time as I put up the diy version.
What is a very simple idea I started back in the 1960's, can't be improved on, no matter what the Lightspeed clones are trying to say to make a quick buck.
So lets get started.
To explain a little the 5 photo attachments.
1st: Is the basic led/ldr and how it works in the Lightspeed Attenuator, it mimics a 10kohm series shunt logarithmic potentiometer.
2nd: Is the Lightspeed Attenuator stereo version, complete circuit diagram, note how the signal goes through nothing but one soldered resistor, no sound robbing light contact of a metal wiper on a resistive track in a volume control (potentiometers) in the signal path.
3rd: Is the same but a dual mono, good for room or system imbalances, (for some reason owners of both say the dual mono has the edge sound wise) I believe it's the fact you can precisely centre the image regardless of recording or environment influences.
4th: Is the buffer Nelson Pass designed a few years back for the Lightspeed Attenuator (later to be known as the B1 Buffer) for it to be able to drive low input impedance amps of less than 33kohm.
5th: Is the $5 led tester you can get on Ebay. With this you can quad match your own set of NSL32SR2S(sorted) Silonex led/ldr's you'll need get about 15 pieces to get 2 sets of quad matched led/ldr's for two x stereo Lightspeed Attenuators. So go halves with a buddy and you can have one each.
Match the LDR resistances using a DMM, powering the LED from 1mA to 20mA, give them time as they need a few minutes to warm up.
PS: You can skimp on the cheaper NSL32SR2 but you have to buy almost twice the amount, as their low resistance is not as low and constant, they cannot get to quietest minimum volume level as the NSL32SR2S (sorted) can.
Cheers George