John Curl's Blowtorch preamplifier part II

[Curly Woods]

Originally Posted by Allen Wright

Contrary to some others opinions, I consider cermet pots to sound seriously better than conductive plastic - from personal listening.

Anyone actually also tried cermet critically?

The Vishay cermet is my favorite - it sounds (to me) just like a two resistor attenuator. But it's low end tracking is hopeless.

Regards, Allen

I have never tried them Allen. Any recommendations on a specific unit? I might investigate this.

[mos57]

I not want persuade nobody, but if each experiences is judges only subjective and not objective, then because universally was acceipt that 2A3 is more musical than 6AS7 ?, or that 2A3 mono-plate is better than bi-plate?

Because any makers utilized Dale resistors rather unknow resistors?
I not discover that electrolytic or film caps have proper sound at the end.
If we can spech about its ok, if not no problem, i will go forward to my perceptive sensation.

Francesco.

[fredex]

I use a 100k Black Alps which has some dc flowing through the wiper, I know this is supposed to be bad but it sounds better than with an extra cap and res. Now after a year I am worried that I maybe shortening the life of the pot. Anyone know about this particular pot?

[john curl]

Subjective impressions are often at least as valuable as objective ones. Even with tubes, you can measure differences due to manufacture, even if they have the same tube number. I can prove this.

[mos57]

Originally Posted by john curl

Subjective impressions are often at least as valuable as objective ones. Even with tubes, you can measure differences due to manufacture, even if they have the same tube number. I can prove this.

Thanks, John.

Sometime we can hear differences in sound, but it's more difficult to prove it or at least it is impossible to find differences by electrical measurement.

Not for this reason, people can define this fact as "subjective"

Francesco

[kannan_s]

Originally Posted by john curl

Subjective impressions are often at least as valuable as objective ones. Even with tubes, you can measure differences due to manufacture, even if they have the same tube number. I can prove this.

What type of tests that can reveal - audio attenuator quality ( Assuming Pots are no longer as good as resistor attenuators due to wiper or contact resistance variation issues) ? or whether Precision Bulk foil type resistors perform better as an attenuator than say Metal film resistor with 1% precision?
Kannan

[Curly Woods]

Originally Posted by kannan_s

What type of tests that can reveal - audio attenuator quality ( Assuming Pots are no longer as good as resistor attenuators due to wiper or contact resistance variation issues) ? or whether Precision Bulk foil type resistors perform better as an attenuator than say Metal film resistor with 1% precision?
Kannan

Listening maybe

[Salas]

Originally Posted by Allen Wright

Contrary to some others opinions, I consider cermet pots to sound seriously better than conductive plastic - from personal listening.

Anyone actually also tried cermet critically?

The Vishay cermet is my favorite - it sounds (to me) just like a two resistor attenuator. But it's low end tracking is hopeless.

Regards, Allen

Originally Posted by Curly Woods

I have never tried them Allen. Any recommendations on a specific unit? I might investigate this.

Are we talking about a small white double linear one with short shaft and terrible L/R balance at start of rotation? It would not give any signal on one channel at medium whisper level actually! After kicking off was OK for balance though. I used that little thing back in the early 90s, law faked with Vishay's lowest PPM resistors of the time. I got it from a guy named Russ Andrews from Cumbria UK. Was a TT tweaking guy. I don't seem to can find it easily so to take a pic, I am not sure I still got it even, maybe it finally gave up the ghost, but I found its paper from Russ! If it is the same, yes I remember it as the most transparent pot I ever got in my system back then. The bad functionality broke my nerves in the end. After both channels would kick in (grrr!) then it would climb up fast even with 20:1 law fake. I remember that when I substituted it with Alps blue, and then Bourns blue, I could finally control my volume but they were thick as mud in comparison. Irony, and was costly too.

[1audio]

Cermet may sound quite good at a given setting and may be fine for a trim pot. However as a volume control they can be noisy in operation and wear faster.
I have found that the Vishay metal foil trimmers are the best sounding to me. The Vishay 1280G was the best value of the options. I even figured out how to make it a front panel control- but 20 turns does not make a good volume control.

[mos57]

Originally Posted by 1audio

Cermet may sound quite good at a given setting and may be fine for a trim pot. However as a volume control they can be noisy in operation and wear faster.
I have found that the Vishay metal foil trimmers are the best sounding to me. The Vishay 1280G was the best value of the options. I even figured out how to make it a front panel control- but 20 turns does not make a good volume control.

Have you compared this Vishay Vs. Spectrol and Bourns trimpot, also?