Sylvania Gold Brand Tubes brochure (and more)

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Sylvania Gold Brand Tubes brochure (and more)

Postby dai h. » Thu Apr 23, 2015 8:53 am

(some interesting bits on the materials and techniques) :

http://www.pearl-hifi.com/06_Lit_Archiv ... _Brand.pdf

plus MORE stuff! :

http://www.pearl-hifi.com/06_Lit_Archiv ... chive.html
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Re: Sylvania Gold Brand Tubes brochure (and more)

Postby David B » Fri Apr 24, 2015 8:53 pm

cool stuff, goes to show how much went into making a great long lasting tube
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Re: Sylvania Gold Brand Tubes brochure (and more)

Postby dai h. » Sat Apr 25, 2015 1:26 pm

yes, I wonder if guitarists will ever get to use such high quality tubes again after all the old stuff is used up. The Russians (I'm guessing) could make high quality tubes, but my impression is that there isn't enough money in tubes for them to bother going through the trouble. (But I've heard sound clips apparently with new tubes that sounded fine to my ear so perhaps things aren't so bad.)
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Re: Sylvania Gold Brand Tubes brochure (and more)

Postby David B » Mon May 25, 2015 5:11 pm

Yeah some of the new manufacture sound nice but AFAIK none equal the longevity of the valves from the golden era.
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Re: Sylvania Gold Brand Tubes brochure (and more)

Postby dai h. » Tue May 26, 2015 6:04 am

I've read that old tube products often treated the tubes as consumables, that could be replaced (and I'm sure were back when you could buy them locally at the drugstore and such places). That is, they might be pushing the ratings to get more performance out of them, and that worked when quality tubes were easy to source and available, but it would seem a bad idea to take that approach today with disappearing old stock and seemingly shorter-lived new production.

Therefore, (especially if using older valuable glass), it's probably a good idea to check that ratings aren't being pushed if you want the most life from them. One possibly big factor in mind is the gradual rise (in United States) of wall voltage over the years. If an old amp meant to run on 110V is receiving 130V (or whatever high AC volts), this could be at the price of tube life (and less reliability). Also, the higher AC voltage could make an amp sound better due to the tendency of the human ear to perceive louder as "better", so if input AC is lowered to compensate, it could take getting used to, or maybe other measures could be taken (turning the output slightly higher if mic'ed, or maybe using more speakers).

From what I understand(read) tubes (obviously) are meant to run hot (materials like copper(alloy?) grid rods and parts like grid cooling fins are designed in to deal with heat), but it's *excessive* heat that is the enemy of reliability (and increasing AC volts would raise temperatures--heater and B+).
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Re: Sylvania Gold Brand Tubes brochure (and more)

Postby David B » Wed May 27, 2015 5:07 pm

Yep not a bad idea with those pricey old valves, I built one of those vintage voltage contraptions on Keens site for my Fender Deluxe & any other amp that's running on the high end or over spec :wink:
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Re: Sylvania Gold Brand Tubes brochure (and more)

Postby dai h. » Wed May 27, 2015 5:34 pm

another possibility (if building) is designing conservatively from the start. I've read of one person (building a monitor use amp using new production EL34s) designing very conservatively (i.e. not pushing things) in order to obtain longer life and higher reliability. Apparently, the approach is something the guy takes as a matter of course. He mentioned being asked to service some solid state PA amp (or suchlike) he custom built years ago (it was still being used). Lots of interesting little things on the said person's site such as not liking to build cathode biased amps (to try to keep heat out of the chassis for greater reliability), setting up the AC so the circuit is barely on to keep a slight voltage on the alu electros (to try to keep them formed for longevity--which is interesting since it goes against the idea of "wasting power from phantom load").

I've wondered if running the B+ separately using a variac would be a good general idea for Marshalls. Seems less taxing (as long as the sound is acceptable) than running really hard and using a power attenuator. Maybe some sort of retrofit kit/mounting thing to plug in a variac and outboard supply for the heaters. Might not be very attractive due to liability issues?
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Re: Sylvania Gold Brand Tubes brochure (and more)

Postby David B » Thu May 28, 2015 11:17 am

I would imagine some/many builders consider the limitations of current tubes & adjust accordingly? but the guy you mentioned seems to have taken things further in designing & building a long lasting amp.

Yep I know a couple of people who use a variac on their Marshall 100 particularity for those amps that like to red plate on V4 & V5, cool idea keeping the heaters in spec unless you only need to lower to the minimum heater voltage, whats that about 5.7 volts.
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Re: Sylvania Gold Brand Tubes brochure (and more)

Postby dai h. » Thu May 28, 2015 5:43 pm

yeah, that's about 10 percent less
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