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Old 10th March 2003, 08:28 PM   #1
Raymond is offline Raymond  United Kingdom
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Default Superfluous Volume pots on power/ amp

Hello to all,
Could someone please offer me advice on removing a couple of pots and v.u. meters off my power amp as I never use the pots to control the output volume, I want to remove and bypass these.....will it create any problems? I will simply disconnect the V.U. meters. I'm hoping that the removal of the potentiometers would improve the sound a little by allowing a cleaner signal path. Thanks.
Regards,
Raymond.

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Old 11th March 2003, 02:15 PM   #2
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Hi Raymond,
I assume that you normally use the amp with the volume pots set to 100% ( fully on)?

If so then the only real issue is the value of the pot, typically 47K or so.
you can replace the pots with good resistors of the same value, connected to the outer 2 connections of the volume pots, with the centre (wiper) connection of the pot connected to the 'hot' side of the new resistor.
you'll know if you've got it on the right side, if it's not you will get no output

with decent resistors you should get improved channel matching over a dual-track pot , and probably better noise performance due to the lack of mechanical contacts in the signal path, but you won't automatically get lower 'resistor noise' , 'cos you are really replacing one tapped resistor with one fixed one, so the only noise reduction here would be 'impulse' or 'shot' noise , the 'thermal' noise will stay much the same.


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ray ( another one! )
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Old 11th March 2003, 02:31 PM   #3
Raymond is offline Raymond  United Kingdom
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Quote:
Originally posted by TheFettler
Hi Raymond,
I assume that you normally use the amp with the volume pots set to 100% ( fully on)?

If so then the only real issue is the value of the pot, typically 47K or so.
you can replace the pots with good resistors of the same value, connected to the outer 2 connections of the volume pots, with the centre (wiper) connection of the pot connected to the 'hot' side of the new resistor.
you'll know if you've got it on the right side, if it's not you will get no output

with decent resistors you should get improved channel matching over a dual-track pot , and probably better noise performance due to the lack of mechanical contacts in the signal path, but you won't automatically get lower 'resistor noise' , 'cos you are really replacing one tapped resistor with one fixed one, so the only noise reduction here would be 'impulse' or 'shot' noise , the 'thermal' noise will stay much the same.


HTH

ray ( another one! )
Hello Ray,
Thanks for your response, Yes your correct concerning the pots being in the fully on position, i'll put it into practice over the weekend. Just one point I would like to ask and that is, what is the wattage of the resistor?
Regards,
Ray the other one.
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Old 11th March 2003, 08:43 PM   #4
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Default The input pot...

If you are using only high level sinal sources...why not conect the cd directely to the power amp and the input pot does the volume regulation...

Less is more!

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Old 11th March 2003, 09:25 PM   #5
Raymond is offline Raymond  United Kingdom
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Default Re: The input pot...

Quote:
Originally posted by Tube_Dude
If you are using only high level sinal sources...why not conect the cd directely to the power amp and the input pot does the volume regulation...

Less is more!

Regards

Hi Jorge, I play vinyl, but thanks anyway.
Regards,
Raymond.
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Old 12th March 2003, 11:30 AM   #6
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what is the wattage of the resistor?


for a signal resistor in this position it's not going to need to dissipate any power at all really, I would suggest a pair of good 1% 0.6W metal films ( one for each channel ) , or better still the smallest wattage non-inductive wirewounds if you absolutely must have the lowest noise.....

but really anything would do , even mini 0.125W films or 0805 series surface mounts if you like, so choose something which fits best I guess. just try to make sure that they're reasonably matched or you will have balance problems.

ray
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Old 12th March 2003, 12:14 PM   #7
Raymond is offline Raymond  United Kingdom
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Quote:
Originally posted by TheFettler
what is the wattage of the resistor?


for a signal resistor in this position it's not going to need to dissipate any power at all really, I would suggest a pair of good 1% 0.6W metal films ( one for each channel ) , or better still the smallest wattage non-inductive wirewounds if you absolutely must have the lowest noise.....

but really anything would do , even mini 0.125W films or 0805 series surface mounts if you like, so choose something which fits best I guess. just try to make sure that they're reasonably matched or you will have balance problems.

ray
Thanks for your help Ray, Excellent.
Regards,
The other ray.
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