In Reply to: yes, yes... and no. posted by Arbelos on August 16, 2002 at 08:00:12:
I haven't listened to different volume control resistors. My electrical theory supports your observation that 10K sounds better than 100K. Below that, other components within the amp are likely to have greater noise contributions than the volume control.The problem with a bias current of 30-100mA is that it leads to higher power dissipation than can be handled by small-signal transistors designed for good audio performance. One can lower the supply voltage to reduce dissipation, but headroom is also reduced.
The noise effects we're discussing are very small. 100dB S/N ratio is 1 part noise in 100,000 parts signal. A great amount of care is required in circuit design and layout to keep noise below this level. Yes, tube amps have output transformers near power transformers, but at the same time, tube amps are generally not known for low hum and noise.
(Anecdotal evidence: I was once working on my Infinity speaker crossovers and discovered that just placing the soldering gun near the inductors could induce enough current for a loud hum from the woofer. And this was without any amplification!)
Ed
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Follow Ups
- but yes - EdG 08/16/0210:50:04 08/16/02 (16)
- Re: but yes - Arbelos 13:19:04 08/16/02 (15)
- microphonics? - EdG 17:14:05 08/16/02 (12)
- Re: microphonics? - Arbelos 02:49:45 08/17/02 (11)
- Re: microphonics? - Davey 07:13:25 08/17/02 (10)
- Re: microphonics? - Arbelos 12:25:45 08/17/02 (9)
- Re: microphonics? - Davey 20:29:42 08/18/02 (2)
- rheostat - Arbelos 01:56:41 08/19/02 (1)
- Re: rheostat - Davey 07:14:50 08/19/02 (0)
- Passion Ultimate - DaveS 12:08:33 08/18/02 (5)
- Re: Passion Ultimate - Arbelos 17:36:22 08/18/02 (4)
- Re: Passion Ultimate - DaveS 21:58:52 08/18/02 (3)
- Re: ProPassion discontinued - DaveS 14:48:32 08/19/02 (2)
- Re: ProPassion discontinued - Arbelos 03:15:17 08/20/02 (1)
- Re: ProPassion discontinued - DaveS 18:45:11 08/22/02 (0)
- Another interesting series of posts. - DaveS 13:32:24 08/16/02 (1)
- Re: Another interesting series of posts. - Arbelos 16:42:41 08/16/02 (0)