Originally posted by pdf64
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Master volume and treble loss
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Originally posted by vintagekiki View Post
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Originally posted by Boy Howdy View PostAs we all know volume controls are very touchy down low on the dial. For a clean sound I'm running at about .5 (that's one-half of one) and it's a bit of a pain to get it just right. So I generally just set roughly where I want it and then use the master volume to control the actual volume.
I have a Ken Fisher type PPI master on the amp. mod101_ppimv_master_volume_mod.pdf (tubesandmore.com) The problem is that when I turn down the master, I lose treble. So then I have to do this dance of balancing the two volume controls to get the best sound, which defeats the whole purpose of using the master in the first place.
Can I install bypass caps on the master to recover the lost treble?
Yeah, I always put a bright cap on the volume control, can't live without it. This time I actually installed a 470K resistor in series with the cap to get it just right. That worked out really well. I get what I want there, as long as I don't turn down the master too low.
The dual 100K is just what the recipe called for. I didn't give a second, or even a first, thought. . . . Gulp.
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Originally posted by vintagekiki View Post
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Originally posted by vintagekiki View Post
And cross-phase MVs cause bass loss at low settings.Last edited by Helmholtz; 12-12-2020, 10:57 PM.
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Yes you could.
But the actual place where treble is lost in the amp is the vol pot and the input capacitance of V1b at low vol settings.
Have you tried a bright cap of 47p to 150p across the vol pot?
Also I wonder why you use a dual 100k master pot. That low value loads down the PI output. I would use a dual 470k pot instead and try 100p to 330p bright caps if necessary. But as the MV is within the NFB loop, the bright effect will be small.
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Err it would be helpful to provide the specifics of the amp you’re asking about
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Master volume and treble loss
As we all know volume controls are very touchy down low on the dial. For a clean sound I'm running at about .5 (that's one-half of one) and it's a bit of a pain to get it just right. So I generally just set roughly where I want it and then use the master volume to control the actual volume.
I have a Ken Fisher type PPI master on the amp. mod101_ppimv_master_volume_mod.pdf (tubesandmore.com) The problem is that when I turn down the master, I lose treble. So then I have to do this dance of balancing the two volume controls to get the best sound, which defeats the whole purpose of using the master in the first place.
Can I install bypass caps on the master to recover the lost treble?
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