kudzurunner
2790 posts
Nov 01, 2011
6:36 AM
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I've got a late 50s Premier Twin-8 amp that was worked on by Skip Simmons a couple of years ago. It's in good working order, but I'm not convinced that it is in optimal working order. Several months ago I had a chance to play through a couple of Premiers that my friend Tom Weston brought to a gig in E. Petersburg and they both sounded stronger (and therefore better). :)
I'd like to invest in a new power tube. The tube I've got right now is a 6L6 GC. It's a GE. I believe it's been in there since I bought the amp, more than 15 years ago. I'm sure Skip would have tested it, but still: I'm willing to invest in a better tube: a NOS, ideally
Before I go any further, here's a page that has a photo of my amp model. The amp in this photo is exactly the same as my amp except for the back; mine has the original, this amp has a more recent back:
http://www.bazaar-world.com/guitar-amp-9529-1950-S-PREMIER-TWIN-8-HARP-GUITAR-TUBE-AMPLIFIER
My amp has serial # 481112
My questions for the amp/tube guys on this forum:
1) Is a 6L6 GC the right tube for this amp? I've come across several forums where 5881's and 7591's are discussed. I'm leery of hot rodding. I simply want to optimize for whatever tube the amp was designed to use.
2) Assuming that the 6L6GC is the optimal tube, what would you suggest as a replacement? I've found several websites where NOS RCA blackplate 6L6GC's can be had, and I gather that they're pretty much the best, with GE's and Sylvania's not too far behind.
All advice is welcome, especially (although not only) from those who have actually owned, used, and/or worked on late 50s Premiers of this sort.
Last Edited by on Nov 01, 2011 6:38 AM
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5F6H
939 posts
Nov 01, 2011
7:35 AM
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7591 and 6L6GC are not interchangeable without rewiring the tube socket and changing cathode resistor value, so if your amp came from Skip with a 6L6, then forget about 7591. Some Premier twin 8 came with a 6V6, but forget about them too.
NOS 5881 were a hi fi, military spec 6L6 with a slightly lower output. Nowadays some tubes are sold as "5881" but have a comparable output & performance to 6L6 types (like the Sovtek 5881WXT). The cost of a NOS 5881 may be prohibitive, though as you are only after one tube, not a matched pair, you might get lucky. However the Twin 8 idles the power tube quite hot...I'd be inclined to avoid NOS 5881 on that basis.
Any 6LGC/WGB/WGC will work in the amp, 7581A too. I'd say the Phillips 6L6WGB is a pretty safe bet & can still be found at a reasonable price
I wouldn't personally use a SED Winged C in that amp, but I wouldn't rule out current production, it's a simple amp so power tube choice can make a fair difference & you can buy several current production tubes for the price of 1 NOS.
The way I would pick the best tubes for the amp (don't forget a tired 12AX7 won't help either) is simply to try every tube I can get my hands on (of the appropriate type) & use the one that sounds best.
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www.myspace.com/markburness
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HawkeyeKane
344 posts
Nov 01, 2011
7:47 AM
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Mark, I'm no expert on tube sockets. Does the 6L6 and the 6V6 have the same contact configuration? If so, would an EL84 in that slot be a good choice for Adam with the help of a VHT or Ruby adapter?
@Adam
Is your twin one of the ones with the downward point in the middle of the grill cloth? I've seen that era Premier both with and without, though I don't know if that's done aftermarket or not.
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Hawkeye Kane
Last Edited by on Nov 01, 2011 9:01 AM
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kudzurunner
2791 posts
Nov 01, 2011
9:22 AM
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@5F: I mean 7581, not 7591. My bad. Yeah, it's always best to try a bunch of tubes, if you've got a situation that lets you do that. I don't, so I was hoping to spend money & mail-order a sure thing.
@Hawkeye: Yes, it has the downpoint. Take a look at the link I provided. That's the kind of amp I've got.
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HawkeyeKane
347 posts
Nov 01, 2011
9:27 AM
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Missed the link. Sorry. Very nice though!
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Hawkeye Kane
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chromaticblues
1040 posts
Nov 01, 2011
9:35 AM
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@ Hawkeye The EL 84 isn't an octal base tube (it has different sockets). Also 6l6's run at higher voltages than is usually safe for a EL84 or a 6v6.
@ Adam I would say a RCA blackplate 6l6GC is the best place to start.
I agree with 5f6h about the phillips being a "good enough tube" if you can't get a RCA. A 1980's Phillips is going to be better than anything being made today.
I bought a bunch of Phillips tubes in the late 80's and had very good luck with them. I sold a bunch of amps that I put those tubes in.
Phillips were the last govt. contracted manufacturer of tubes in the US. So the should be the easiest to find.
When the Govt. shut down the last base (an air base in Turkey) using tube equipment in 1986 they put all there stock of tube equipment up for auction. I still have some early 80's 12ax7's that are very good and consistant from one tube to the next.
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HawkeyeKane
348 posts
Nov 01, 2011
9:48 AM
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@chromaticblues
Right, but what I'm saying is that there are a few different adapters out there that allow you to run an EL84 in an octal based socket. Some have mixed reviews and they vary in price, but take a look...
http://www.musiciansfriend.com/accessories/ruby-a-tone-plug-and-play-tube-adapter/212036000952000
http://www.musiciansfriend.com/accessories/thd-yjsd-yellow-jacket-standard-duet-adapter/210390000000000
http://www.musiciansfriend.com/accessories/vht-special-6-el84-adapter
Like I said before, I'm by no means an expert on tubes and if the voltage is a negating factor, then c'est la vie, although two of the ones above DO regulate voltage. But I've always loved the sound put out by an EL84. Thought it might be an option.
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Hawkeye Kane
Last Edited by on Nov 01, 2011 10:33 AM
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HarpNinja
1833 posts
Nov 01, 2011
12:06 PM
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I order a lot of tubes from KCA NOS tubes. Mike is great to deal with, and, although not a harp player, he can give you tons of info on tubes you might try.
For new tubes, I would stay away from the JJ 6L6 as it might be too harsh for this amp. The Sovtek stuff is really solid. I liked the 5881's in my HG50.
5F6H is right on...rolling tubes will have a dramatic impact on this amp. In the single-power-tube-type amps, you can do a lot of things. I thought a Tung Sol RI set in my VHT would sound great, but it was whimpy compared to a 5881 and a Sovtek 12ax7w. It was like two totally different amps.
I think a lot of harp-amp builders use Groove Tubes, but I am not sold on them. Well, they may sound good live, but other stuff sounds better at home.
I had a full set of blackplate RCA's in a Vibro Champ. It was a fantastic sound for recording. Very warm and creamy.
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Mike
Quicksilver Custom Harmonicas
VHT Special 6 Mods
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chromaticblues
1041 posts
Nov 01, 2011
4:46 PM
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@Hawkeye I understand what your saying, but you can buy SE EL84's on Ebay much easier than single ended 6L6 amps. So it just doesn't make sense to turn a rare amp into an amp that is easy to buy for less money.
I'm aware of tube adapters.
I'm not saying your wrong. I agree SE EL84 amps are great, but an EL84 in this amp would drop the output considerably and that was the original problem.
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strawwoodclaw
277 posts
Nov 03, 2011
6:56 PM
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I owned that exact amp in the photo, I tried different tubes in it inc 40s 6l6ga 6l6G 6l6wgb which is the same as 5881- RCA 6l6GC & GT 6l6GE. I liked the Groove tube 6L6 GE they have a distrotion raitig on them I used a GT 6l6GE raiting 10 which is for later break up & most dynamic I found that helped improve the sound. I also had two Premier 120 amps at differnt times , both looked to be like new but one was 100% original from 54 & the other had been recapped & I thought the origial untouched amp sounded stronger although the person I sold the other to said he changed the rectifier & that made a big improvment.
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