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previous: Ricky could someone give me a quick rund... -- 12/31/1999 3:49 AM

Re: rules for a quiet amp

12/31/1999 4:54 AM
Ken Gilbert	Re: rules for a quiet amp a) good filtering of DC power supply rails. This means essentially attempting to elminate all AC whatsoever. b) addressing the AC heaters if so equipped. If AC, they must be as tightly twisted as possible, perhaps even shielded. They must be kept either as far away from other leads as possible, or pushed flat against the chassis. c) good star/heavy buss grounding scheme. In my experience, if you must connect signal ground to the chassis, do it RIGHT AT the input jack sleeve. Ground wires should be as thick as possible. I use 18awg to the buss, which is 12awg copper. d) in the realm of noise, the metal film resistor is far far better than the carbon comp. Use the biggest values of power rating for the resistors as your wallet and chassis space allow. e) good layout is absolutely critical. Keep sensitive stages as far away from large signals/noise as you can. Stages should flow naturally from one to the next, with a minimum of interconnection path. I try to get by with JUST the component leads. Transformer cores should be in different axis of orientation--especially chokes--and well away from everything. f) low resistances everywhere will minimise the thermal noise of the resistances themselves. This includes pots. g) running tubes at high current will produce less shot noise from the electrons hitting the plate. h) DC heaters can be the final step towards deathly silence. Use at least 10,000 microfarads for every amp of heater draw, or perhaps switch to a regulated circuit, or both. That's the big stuff... KG

12/31/1999 4:54 AM

Ken Gilbert

Re: rules for a quiet amp

a) good filtering of DC power supply rails. This means essentially attempting to elminate all AC whatsoever.

b) addressing the AC heaters if so equipped. If AC, they must be as tightly twisted as possible, perhaps even shielded. They must be kept either as far away from other leads as possible, or pushed flat against the chassis.

c) good star/heavy buss grounding scheme. In my experience, if you must connect signal ground to the chassis, do it RIGHT AT the input jack sleeve. Ground wires should be as thick as possible. I use 18awg to the buss, which is 12awg copper.

d) in the realm of noise, the metal film resistor is far far better than the carbon comp. Use the biggest values of power rating for the resistors as your wallet and chassis space allow.

e) good layout is absolutely critical. Keep sensitive stages as far away from large signals/noise as you can. Stages should flow naturally from one to the next, with a minimum of interconnection path. I try to get by with JUST the component leads. Transformer cores should be in different axis of orientation--especially chokes--and well away from everything.

f) low resistances everywhere will minimise the thermal noise of the resistances themselves. This includes pots.

g) running tubes at high current will produce less shot noise from the electrons hitting the plate.

h) DC heaters can be the final step towards deathly silence. Use at least 10,000 microfarads for every amp of heater draw, or perhaps switch to a regulated circuit, or both.

That's the big stuff...

KG

Replies:

Ricky Great! thanks for the excellent inf... -- 12/31/1999 6:18 AM