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Got busy for a couple days. Can't wait til this holiday crap is over. Thanks, Holmz, for sharing your knowledge! Unfortunately, most of what you're talking about is a tad over my head. Consequently, often times the price I pay for not being very smart is learning things the hard way. So unless you foresee major flaw or impending doom with my schematic, I'm going to go ahead with it.

I guess I should ask more simply; do you see the increased resistance of the signal at the amps after passing through doubled-up pots as being a serious issue? How detrimental are we talking?
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I am not sure "smart" is the right word.
If you had HS electronics, then that would be handy. If not, then you have some significant work ahead of you.
It is pretty much HS level, but it will be like taking that course without the teacher to help... if you do not have the background in it.


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I am using 50k audio taper pots. I picked up 5 of them from mouser. Quick specs on this page:

Maybe you can make a picture of how you are planning on wiring those in?
I suspect it would be attractive to just put it "in line", but I think you need it shunting between the single ended wire and the ground.
And probably you want a resister in there as well...
Maybe 2 of them, with one in line and maybe 1k, and then a 100 ohm before the pot... that would likely work best with the 10k pots.

If you are using the 50k ones (in line) then you would want maybe a 5k resistor between the signal and ground.

Whatever you do, just do it on a bench first.

Maybe use a 1.5V battery and a 600 ohm resister... then you should get between 0.15V and ~1.5V if you have a 20dB max attentuation.
 

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Discussion Starter #23
Outer braided shielding will be grounded at the source end and left floating on the amp end of every cable. Signal and ground will be wired according to pot datasheet.
 

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You're probably going to want to tie 1 and 3 together with a 5k resistor...
(Maybe a 2.4k, 6.3k, 8k...)
Try it and see.
 

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What will that accomplish?
Review post #21...

Basically the pot being inline will do next to nothing as the preamp's output impedance goes to zero and/or also as the amp's input impedance goes to infinity.

This is the reasoning for the suggestion to test it on the bench.
(The 1.5V battery works for that.)

Upon closer inspection I think you want 1 and 2 tied together with the resistor... (not 1 and 3).
 

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Discussion Starter #29
I guess I'm just not following. What preamp do you keep referring to? Sorry, I don't know the jargon like you do.
 

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Discussion Starter #32
I think I have some 5k's laying around. I'm going to test on my home AV amp. I'll listen for noise with and without a resistor. If there is no noise without, then obviously not needed, correct?
 

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Why doesn't anyone else use resistors on their volume controllers?
What makes you think that they do not use resistors?
I would bet most of those volume controllers also use OP-Amp's... ;)


I think I have some 5k's laying around. I'm going to test on my home AV amp. I'll listen for noise with and without a resistor. If there is no noise without, then obviously not needed, correct?
It has nothing to do with noise.

I believe it was in post #28 where I said it would do nothing to adjust volume without a resistor in there somewhere...
 

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Discussion Starter #35
I linked the above video at the relevant time in the video.

So, you're saying to add a resistor after a resistor (the pot itself)? I'm just not grasping the concept here.
 

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Discussion Starter #37
Along with articles and other forum build threads I won't muck up this thread with posting, there is never any mention of a shunt resistor in any of the sources I have read or watched. Can you tell me what it is it will accomplish? I can usually do pretty well with the how, given I have a why.

 

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Discussion Starter #39
Well at the ~6 minute mark he talks about the why.
He also m nations an LM825 which I believe is an OP-amp.
And his wiring is shown different than your sketch showed.

All ^these^ point to doing it on the bench first.
And not catching that is where my lack of knowledge bites me in the ass. So from what I understand, he says to choose a resistance value of that of half the input impedance of the amp. I looked at a few amps and their manuals just to get specs, but the input impedance does not seem to be a commonly published data point. I say I looked at a few different amps as the amp that I will be using (SALT-8) to power the subwoofer hasn't been released yet and there are no impedance values for the other two amps I am using for my system.

You mentioned earlier amps run 10-100k and that makes sense in that it allows for compatibility with many different sources/source impedances. So when I test, am I just looking for the efficacy of the volume adjustment, i.e. the pot's ability to attenuate from zero too max volume?

I really appreciate your help in this. I don't at all expect to be spoon fed, so, that you're still hanging in there is pretty cool to me. Thanks!
 

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Well it looks like that pot is intended to be wired as in the video, so I think you may not need to extra resistor.

The reason to bench test is:
1) to make sure it is working and in the reasonable range.
(50k ohm is probably good, but if it was not, then you could try a 24k-ohm... for instance)

2) crosstalk and other noises are not a problem.
 
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