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Old 27th August 2002, 12:08 AM   #1
JoeBob is offline JoeBob  Canada
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Default Bad Pot?

I mean my potentiometer...

I built a gainclone for my dads friend, and well, one channel sounds great. But the other channel won't go nearly as loud. So I sent in a 1k sine wave and probed it from my CD player with a scope, it was fine, then with the amp still off I probed the wave coming out of the pots on full volume, and one was about half as loud as the other (my dads friend wanted a pot per channel, so that's what I did, although not my preference). I don't understand because when I probe the pot for resistance it has a value of 0 Ohms when turned to "full volume" between the input and the audio circuit, so I don't see how it could be attenuated such a large amount. So is it most likely the pot? Or should I look even more closely at my circuit for problems (I've already checked it over in case there were any obvious mistakes, but it wasn't so)?
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Old 27th August 2002, 12:35 AM   #2
Duo is offline Duo  Canada
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Hmmm, this is a toughie!

I don't suppose you'd be willing to show your diag would you?

I've had that sort of problem, and it usually takes someone else to take a peek at it.

Check your resistors (if any) to make sure you didn't see a faded color as another. Check all your wiring and soldering and see that the load from the amps or a bad cable isn't causing the drop.
Otherwise, I can't think of much else...
Did you check to see if the output from the CD player was being loaded by something near or before the pot??? Perhaps something is wrong that's not attenuating the output to the amp but overloading the output from the cd player.

I hope this helps, but if you are willing to post a diagram, I'll happily check it over for you!

Glad to help
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Old 27th August 2002, 12:43 AM   #3
JoeBob is offline JoeBob  Canada
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I slap together a diagram if need be. But I just noticed something curious, if I use the headphone output of my cd player they're both the same intensity, but with excessive noise on the suspect pot. I'll probe some more right before the pot to see, but this seems really strange, because this happens when the amp is turned off as well, one less then the other, except with the headphone plug where they're both the same but one with huge amounts of noise...
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Old 27th August 2002, 12:44 AM   #4
fcel is offline fcel  United States
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Default OT: always wanted to ask this question

Speaking of decimal, why do people use comma instead of dot? Example ... 56.2K instead of 56,2K. A lot of people are doing that ... use comma. Any particular reason other than typo error?
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Old 27th August 2002, 12:50 AM   #5
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Commas are used when seperating hundreds in large numbers, for example 56k is equal 56,000. But it is improper to use a comma where a decimal is necessary for example, you should say,
if applicable, 56.2K, not 56,2k (improper). By the way, my point in saying they forgot the decimal is that it never usually goes over
5.6k so that's the punchline.

However, this is completely irrelevant to the current topic so I shall no longer elaborate upon it in this thread. If you wish to extrapolate upon this philosophy, we can start a new thread, ye?
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Old 27th August 2002, 12:51 AM   #6
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Default Re: OT: always wanted to ask this question

Quote:
Originally posted by fcel
Speaking of decimal, why do people use comma instead of dot? Example ... 56.2K instead of 56,2K. A lot of people are doing that ... use comma. Any particular reason other than typo error?
I thought you knew, but coma comes with the metric system.

JoeBob, why don't you swap the pots and see what happens.
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Old 27th August 2002, 12:52 AM   #7
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Peter Daniel: That's a good suggestion, it'll at least eliminate the pots from the checklist.
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Old 27th August 2002, 01:18 AM   #8
JoeBob is offline JoeBob  Canada
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Well Peter, I really wonder why I didn't think of that ... That's in fact an ingenious idea. Although I just probed the pot again and noticed that it isn't even logarythmic like the other, it goes up down and then up again at the end, it's very strange.

But again, I guess I just wasn't thinking, I'll try swapping the pots, sometimes you just need a second opinion on what to do...
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Old 27th August 2002, 03:35 AM   #9
fcel is offline fcel  United States
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JoeBob,
I guess you have isolated the problem.
When I saw DUO's "signature", I can't resist posting that inquiry about using comma instead of dot.
Now just one question for Peter and then I won't take up any more space on this thread about my silly inquiry.

Peter,
quote ... "I thought you knew, but coma comes with the metric system".

You're pulling my leg, right?
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Old 27th August 2002, 03:46 AM   #10
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Not really. When I was going to school in Europe, we always used coma, not dot.
Sometimes, I still have a hard time remembering which one to use.
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