6L6GC vs 6L6WGB

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6L6GC vs 6L6WGB

Postby mijmog » Thu Jun 15, 2017 2:12 am

I've just picked up a really clean '73 non master volume silverface Pro Reverb for a great price, I'm really happy with it, after going through most of the silverface era amps, I feel this combination of speaker size and quantity, valve rectifier, output tube type, general overall physics and wattage are the perfect balance for me.

The extra bonus with the amp was that the previous owner had done some mods that I was going to carry out anyway, and that sealed the deal for me. He has fitted a larger OT and more efficient Celestion Type A speakers, plus the amp has been blackfaced. I love the bigger wattage and larger transformer in the Bassman, but I miss the reverb and the fact that they are a little too loud, and I love Super Reverbs but don't like the 10" speakers and the extra height of the cab. I like Bandmasters and Pros but don't like the weedy OT, so fitting a Bassman OT was always on the cards.

The other thing that has been done to this amp is that its been fitted with some Jan Phillips short bottle 6LG6WGB output tubes. I was wondering if anyone could enlighten me on what the advantage of these tubes in an amp such as this are. I've done some digging on the internet and but I can't seem to find any solid information, other than a lower plate voltage, I've read contradicting statements such as they allow earlier onset of output distortion, and other people saying increased headroom.

So, amp experts, help!

> Bearing in mind the other mods to this amp, and what the previous owner was trying to do, have they been fitted to increase headroom?

> If I was to change back to 6L6GC would I need to rebias or adjust anything?

Thanks!
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Re: 6L6GC vs 6L6WGB

Postby jthomas » Thu Jun 15, 2017 3:34 am

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Re: 6L6GC vs 6L6WGB

Postby MechaBulletBill » Thu Jun 15, 2017 4:37 am

Great amp find, I'd love to get my hands on one of those. pre-MV, of course ;)
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Re: 6L6GC vs 6L6WGB

Postby kosmonautmayhem » Thu Jun 15, 2017 6:40 am

jthomas wrote:https://www.kcanostubes.com/content/nos ... ips-6l6wgb



This is pretty much what I know about these. I have a pair of blue labeled JAN 6L6WGB in my Custom Vibrolux and they sound excellent! I don't know how much they 'tame' the amp per se. Maybe a little (amp is still super loud). If anything I'd say they might add some nice compression because of the lower headroom.
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Re: 6L6GC vs 6L6WGB

Postby ziess » Thu Jun 15, 2017 10:08 pm

Those have exactly the same plate structure as late '70s/'80s Sylvania/Phillips 6L6GCs (such as the STR 387 you used to get in Fenders of the time), but have a slightly shorter glass enclosure (which is actually about the same size as most 6L6GCs, it's just that the '80s Sylvanias were taller). I've seen nothing to suggest these have any lower output than 6L6GCs, unlike a more traditional 6L6WGB, which knocks off a few watts. I think if you want to drop output you should look for a 'proper' 6L6WGB, such as the original Tung Sol or the highly regarded Canadian GE version; these have he benefit of being near indestructible in my experience, though I wouldn't run them much above 460VDC on the plates. The Phillips 6L6WGBs in question are, however, the last affordable old school 6L6-type, and as such are rugged, long lasting tubes that are a much sounder purchase than new stock tubes.

In short; rugged, long lasting tubes, but they're not really a 6L6WGB and you won't cut that much (if any) output against 6L6GCs.

Tommy.
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Re: 6L6GC vs 6L6WGB

Postby ziess » Thu Jun 15, 2017 10:10 pm

Also, if you're replacing output tubes then you need to rebias in a fixed-bias amp.

Tommy.
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Re: 6L6GC vs 6L6WGB

Postby mijmog » Mon Jun 19, 2017 3:34 am

MechaBulletBill wrote:Great amp find, I'd love to get my hands on one of those. pre-MV, of course


I've been after a non MV for years, it was a no brainer when it turned up.

I got it from Billy's List on Facebook, so thanks Bill for pointing me in that direction! That blonde Bandmaster went up in price for some reason, it got way out of reach...

Turned out "Billy" bought my old '75 Strat years ago, its a small world (especially oop north). I want to get it back.

I tried the amp with a '66 ES335, which was very upsetting.

jthomas wrote:https://www.kcanostubes.com/content/nos ... ips-6l6wgb

ziess wrote:In short; rugged, long lasting tubes, but they're not really a 6L6WGB and you won't cut that much (if any) output against 6L6GCs.


Thanks for all the help and advice. I might leave them in there, mainly as I won't be able to get the amp to someone who knows what they are doing to rebias for 6L6GCs.

Need to learn how to work on them myself.
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Re: 6L6GC vs 6L6WGB

Postby ziess » Mon Jun 19, 2017 8:16 am

Ever pass though York? I'm moving there, would be happy to teach you how to rebias.
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Re: 6L6GC vs 6L6WGB

Postby mijmog » Tue Jun 27, 2017 10:55 pm

ziess wrote:Ever pass though York? I'm moving there, would be happy to teach you how to rebias.


I'm not far away at all, I'd gladly take you up on that offer. Thank you. I need to learn, there's no amp techs anywhere near me anymore.
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