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previous: dave Hi everyone! Anyone have a particu... -- 2/9/2000 9:05 AM

Re: presence

2/9/2000 8:17 PM
moocow	Re: presence The one from the reissue Bassman is pretty good. There is no DC voltage across the presence pot, so it doesn't get scratchy over time. The Marshall presence control has a few volts across it, so the pots get noisy and need to be replaced. Another consideration is how much negative feedback is applied in the circuit. Negative feedback is required to make the presence control work, with more feedback making the control work "better". However, too much negative feedback hurts the basic sound of the amp. I've found that about -4 to -6 dB of negative feedback is enough to have a useable presence control without compromising the sound of the amp (my own opinion, of course).

2/9/2000 8:17 PM

moocow

Re: presence

The one from the reissue Bassman is pretty good. There is no DC voltage across the presence pot, so it doesn't get scratchy over time. The Marshall presence control has a few volts across it, so the pots get noisy and need to be replaced.

Another consideration is how much negative feedback is applied in the circuit. Negative feedback is required to make the presence control work, with more feedback making the control work "better". However, too much negative feedback hurts the basic sound of the amp. I've found that about -4 to -6 dB of negative feedback is enough to have a useable presence control without compromising the sound of the amp (my own opinion, of course).

Replies:

dave Does that mean no NFB, no presence ... -- 2/10/2000 7:31 PM