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Hi,
I am hoping somebody will help me with a very basic question. I bought a pair of Shallco attenuators a while back and am just going to install them in a passive control unit.All the wiring diagrams I have seen showing attenuators show the following three connections:
One going in to unit from positive source
One exiting attenuator to postive at destination
One exiting attenuator to ground coming from source and going to destination.
My question is, my Shallco attenuator only has two connection points that I have seen. One for in and one for out. How should I wire this between 2 sets of RCA?Sorry if this question is lame, but I honestly would appreciate any help with this one.
Thanks in advance for input.....
Follow Ups:
My Shallco attenuator switches in 2 resistors per step. I'll assume the 2 connections you mention are the 2 "posts" I'll reference below.1. Connect one post to common(gnd) on both RCAs.
2. Connect the other post to signal input from 1 RCA. Which post is which depends on how the resistors were installed. Full counter clockwise position should pass no signal.
3. The center points on ALL resistor pairs must be tied together. I used a continuous piece of magnet wire. Connect this to the RCA signal output.
Hello CM7,Thanks very much for your response. My attenuators only have one set of resistors positioned in a circle perpendicular to the front and back plate and gear mechanism. The shaft turns the contacts between the resistors and the resistors are stationary.
There are just two gold plated posts that connect to the resistors. I don't see a way to connect the resistors to each other and don't think in my case that I should.
I think I will try to connect the source positive to the input to the resistors. I know this is supposed to be a voltage divider and so the resistor should probably take voltage to ground - so I think the output after the resistor should go to ground.
I am uncertain how (what) to connect to the positive RCA at the destination?
What do you think?
Thanks very much for your help!
Lou D'A
Lou,I am not sure but it sounds like you have a "fixed series - stepped shunt" attenuator. If so, you will need an additional resistor for the fixed series element to form a resistor divider. The value of the series resistor depends on the existing resistors in your attenuator. I would start with 1K but anything from 1K -10K should work for now. Let's call your Posts A and B.
1. Connect RCA input to one side of of the new series resistor.
2. Connect the other side of series resistor to POST A AND RCA output.
3. Connect BOTH RCA commons(gnd) to POST B.As you rotate and switch in smaller resistors the signal will be attenuated more. The fully counter clockwise end should be 0 ohms (short) and fully clockwise end open (no shunt resistor).
If you measure all the resistors in your unit and know how many dB per step it is supposed to be, we could calculate the correct series resistor value.
Best Regards,
cm7
Hi Cm7,Thanks again for helping me figure out my problem! It has been a couple of years since I bought the attenuators and given it any thought.
I was really confused myself when I got inside my existing control unit which has potentiometers.
I feel kind of lame, but thank you so much for taking the time to help me.
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