What is the prefered meathod for controling volume - diyAudio
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Old 29th December 2008, 07:04 AM   #1
peteS is offline peteS  United States
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Default What is the prefered meathod for controling volume

I am having trouble finding 2-channel pots that seem suited for audio

what are your recommendations?
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Old 29th December 2008, 09:43 AM   #2
AndrewT is offline AndrewT  Scotland
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log law 2channel pot. Available from 1k to 1M.
Try somewhere from 10k to 50k.
Add a buffer after the pot to reduce the output impedance and make it suitable to drive the cables feeding the power amplifier.
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Old 29th December 2008, 11:23 AM   #3
peteS is offline peteS  United States
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any brands in particular... the issue is I cant seem to find many made for audio
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Old 29th December 2008, 12:26 PM   #4
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The most "usual" potentiometer out there, that also performed well in a hi-fi shootout, is Alpha's A20K Dual Gang (and the 10k does well too). Its very inexpensive.

There's a good article here about different tricks with volume controls: http://myweb.tiscali.co.uk/nuukspot/...e.html#gcprevc and, you can make your own volume control if you want to.
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Old 29th December 2008, 11:31 PM   #5
peteS is offline peteS  United States
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thankyou
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Old 29th December 2008, 11:54 PM   #6
ccschua is offline ccschua  Malaysia
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can I borrow thread and ask some question about attenuation.

this is my original vol pot. I found the pot too sensitive. Just be switching 10~15 % of volume, I got maximum vol.

Click the image to open in full size.

So Can I change the 250k pot to 50k. If I change, do I need to change the capacitor and 470k Resistor or not?
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Old 30th December 2008, 02:24 AM   #7
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Quote:
Originally posted by ccschua
can I borrow thread and ask some question about attenuation.

this is my original vol pot. I found the pot too sensitive. Just be switching 10~15 % of volume, I got maximum vol.

Click the image to open in full size.

So Can I change the 250k pot to 50k. If I change, do I need to change the capacitor and 470k Resistor or not?
It can't be answered so easily without seeing the rest of the audio circuit. Yes, you can change the pot, but a different pot won't help your "too much gain" situation.

There's a "patch" possible:
You can simply add a voltage divider at the spot where you already have one. Try it like this: pot, cap, 100k series resistor, 470k load. The new 100k series resistor now works with your 470k load to create a voltage divider (fixed volume control). Then, it appears that a 100k pot is compatible if you desire to change the pot.

However, its possible that you could just use the pot you already own along with an extra resistive load, in the neighborhood of 200k to 250k, like this: 250k pot, 225k load, cap, 100k series, 470k load.
There's some more details to potentiometer selectivity, but I can't remember.

Your 3.3uF cap is plenty big, but you can expect it to sound slightly differently whenever you use it differently.

So, yes its possible to "turn down" the input by applying some form of voltage divider (speaker builders call it a "fixed L-pad"); however, the problem is actually too much gain in the amplifier. It would be somewhat better to fix the actual problem.

EDIT: With such high gain, expore some protection via 100pF (or smaller!) ceramic caps positioned as loads upon the RCA jacks. This will slightly hamper digital noises, somewhat compensate cable inductance, and seriously hamper RF interference. Its not the most effective thing for any of those three tasks; but, its not the most expensive either.
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Old 30th December 2008, 02:27 AM   #8
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See the LightSpeed attenuator and the related volume control in the pedal of the Hammond organs. Now, how much fun would it be to have an accelerator pedal on your amplifier?


Oh, I just hate it when I come up with ideas like that. . . because then I simply MUST do them.
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Old 30th December 2008, 04:45 AM   #9
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Wow, mistake! Huge mistake!

Accelerator pedal volume control + 246W amp IS CAT OPERABLE. Mistake!!!!
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Old 30th December 2008, 08:36 AM   #10
ccschua is offline ccschua  Malaysia
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I have put in 50k pot instead of 250k(no other thing I did). So far, I m more than happy as to get the volume I want, I have to turn 40% instead of 15%.
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