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Post by jordanbunte on Oct 29, 2008 19:35:37 GMT -7
To be honest, I'm just now learning the in's and out's of tubes. I just got a Z28 and in a book that I have (Dave Hunter's Amp book) it says that the Z28 was designed around a currently produced Electro-Harmonix 6V6. On Dr. Z's website it says that all of them come new with Groove Tube 6V6's.
What did I miss? When did they switch from EH to GT? Is there something wrong with the EH tubes now?
Also, Dave's book mentions that NOS / ANOS tubes are the best to pick up if you can find them; however, I'm finding two problems with that: 1. they are getting very expensive and 2. most all of them are "out of stock" where I'm looking (KCA, Tube Depot, etc.).
While I'd like to have the "best" tubes available....I'm perfectly fine with decent new production tubes that are more affordable. Does anyone have any suggestions for me (brands, where to get them, etc.)??
Also, if you know anything regarding the biasing I'd love to hear it. I know the amp is a fixed bias, but what does that mean other than getting a matched pair of tubes? I read something on Groove Tubes website that says if you keep the "number" (not sure which one) the same that you don't have to have the amp rebiased.
Any other thoughts or comments are welcome. Thanks!
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Post by jordanbunte on Oct 31, 2008 19:54:46 GMT -7
bumpty bump
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Post by zdogma on Nov 1, 2008 13:58:44 GMT -7
Okay, I'll have to think back to my Z28 days for this.
The doc designed the amp around the 6V6 EH tube, but used the groove tube version (6V6R) for the first few years. About a year or two ago he switched to the 6V6S (jj/slovakian) I used the 6V6S tubes in my Z28 and loved them, much preferred them to the 6V6R's. I think I biased them at 28 mA per tube, but don't quote me on that. The 6V6S tubes have a bit more headroom and sounded a bit brighter/clearer to my ear. I also used NOS tubes (blackplate RCA 6V6 and Sylvania 6V6) and didn't notice a huge difference.
If you're going to spend money on NOS tubes for this amp, I'd get a NOS GZ34 rectifier (for reliability, mainly) and a NOS EF86 (for tone and reliability)
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Post by jordanbunte on Nov 2, 2008 9:16:15 GMT -7
Okay, I'll have to think back to my Z28 days for this. The doc designed the amp around the 6V6 EH tube, but used the groove tube version (6V6R) for the first few years. About a year or two ago he switched to the 6V6S (jj/slovakian) I used the 6V6S tubes in my Z28 and loved them, much preferred them to the 6V6R's. I think I biased them at 28 mA per tube, but don't quote me on that. The 6V6S tubes have a bit more headroom and sounded a bit brighter/clearer to my ear. I also used NOS tubes (blackplate RCA 6V6 and Sylvania 6V6) and didn't notice a huge difference. If you're going to spend money on NOS tubes for this amp, I'd get a NOS GZ34 rectifier (for reliability, mainly) and a NOS EF86 (for tone and reliability) Thanks for the info. Mine has 6v6-r groove tubes in it. I'm still confused as to why he switched.....the "tubes" section on his website says that they come with 6v6-r's still. I dunno. I wish the Doc would set me straight. =D
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Post by nitehawk55 on Nov 2, 2008 19:47:24 GMT -7
Okay, I'll have to think back to my Z28 days for this. The doc designed the amp around the 6V6 EH tube, but used the groove tube version (6V6R) for the first few years. About a year or two ago he switched to the 6V6S (jj/slovakian) I used the 6V6S tubes in my Z28 and loved them, much preferred them to the 6V6R's. I think I biased them at 28 mA per tube, but don't quote me on that. The 6V6S tubes have a bit more headroom and sounded a bit brighter/clearer to my ear. I also used NOS tubes (blackplate RCA 6V6 and Sylvania 6V6) and didn't notice a huge difference. If you're going to spend money on NOS tubes for this amp, I'd get a NOS GZ34 rectifier (for reliability, mainly) and a NOS EF86 (for tone and reliability) Thanks for the info. Mine has 6v6-r groove tubes in it. I'm still confused as to why he switched.....the "tubes" section on his website says that they come with 6v6-r's still. I dunno. I wish the Doc would set me straight. =D Shoot him an email , he doesn't read all the threads here . The new Tung-Sol's are worth a look too BTW and if you really want to go nuts get some Bendix 5992's which sub for the 6V6GT . These were designed for use in the ICBM's and other heavy duty military stuff in the 50's . Said to be as good as the RCA black plates
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Post by Phil (aka Phil) on Nov 3, 2008 13:31:07 GMT -7
To be honest, I'm just now learning the in's and out's of tubes. I just got a Z28 and in a book that I have (Dave Hunter's Amp book) it says that the Z28 was designed around a currently produced Electro-Harmonix 6V6. On Dr. Z's website it says that all of them come new with Groove Tube 6V6's. What did I miss? When did they switch from EH to GT? Is there something wrong with the EH tubes now? Also, Dave's book mentions that NOS / ANOS tubes are the best to pick up if you can find them; however, I'm finding two problems with that: 1. they are getting very expensive and 2. most all of them are "out of stock" where I'm looking (KCA, Tube Depot, etc.). While I'd like to have the "best" tubes available....I'm perfectly fine with decent new production tubes that are more affordable. Does anyone have any suggestions for me (brands, where to get them, etc.)?? Also, if you know anything regarding the biasing I'd love to hear it. I know the amp is a fixed bias, but what does that mean other than getting a matched pair of tubes? I read something on Groove Tubes website that says if you keep the "number" (not sure which one) the same that you don't have to have the amp rebiased. Any other thoughts or comments are welcome. Thanks! jordan, The reason you're confused is that the EH 6V6 *is* the same thing as the GT 6V6R. Same tube. They're just sold by two different vendors. GT takes the same tubes from the Russian factory that EH does but GT tests and grades the tubes into their numbered 1-10 rating system. I'm sure the Doc was using the GT branded tubes vs. the EH branded ones due to availability/price from a given vendor at that particular time. I know he's also used the JJ, which is a very robust tube, more like a 6L6 in some ways. It's a good tube but if you're looking for the classic "6V6" sound it may not be what you're after; they're more midrangy and don't have quite the "sparkle" of real 6V6's. The glass sure is nice though-it's like real crystal. The price/lack of availability of the NOS and ANOS is what frustrated the owners of amps like Deluxe Reverbs for years until some decent new production alternatives like the EH/GT became available. My personal belief is that there still isn't a new 6v6 that's as well built or as good sounding as the NOS ones. Having said that, the Doc takes great pains to tweak his amps to sound as good as possible with new production tubes. My own RCA Blackplate 6V6's, for example, are not in my Z28, they're on my shelf ;D Biasing is a long and technical subject, but to simplify it, a set of tubes will draw a certain amount of current. Once you set a fixed bias type amp (like the Z28, Route 66, EZG-50, etc.) for proper operation with that set of tubes, you're done. Blindly plugging in a new set of tubes that aren't tested and rated to be similar could result in problems with underbiasing or overbiasing, it's a crap shoot. GT isn't the only vendor that can test and rate tubes. I buy a lot of JJ tubes from Eurotubes.com, and they have an *excellent* testing and rating system as well. If you buy a set of what they rate a "28" on their meter, for example, as long as you're using another "28" set you won't have to rebias. If you just order a set and don't specify a rating, they might send you a 12, or a 32, or 24. Each tube in the set will be the same rating, but you'd have to rebias the amp. As far as which tubes are "best", that's a subjective thing. Is "better" louder, more midrangy, clearer, smoother, harder? It depends on your guitar, speakers, where you set the amp controls, the room you're playing in, and most importantly what sound you're looking for. That may sound silly, but I've worked with a lot of guys in the past that didn't yet know what sound they were after. Some sounds sounded good to them, but they did not have the experience to articulate why. What it usually takes is a starting point; where you can say "I've got a ____ guitar and a Z28 through _____ speakers and I need more _____ and less _____ ". Then you can tweak tube manufacturer/bias levels etc. to get you closer to the sound you're after. Myles Rose is the best there is on planet Earth at this art. Hope this helped.
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Post by jordanbunte on Nov 3, 2008 20:30:29 GMT -7
Thanks so much for the response Phil. It clears a TON of stuff up for me. =D
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Post by Deleted on Nov 3, 2008 22:10:30 GMT -7
Warning! If you don't know what you are doing let an amp tech bias your amp. It could be deadly. That said, there is lots on the web about tube amps and biasing. I have found this to be helpful. www.duncanamps.com/technical/lvbias.htmlThere is more to biasing than just looking at the readings on a volt meter though. Some amp owners use a bias tool which will make the job a lot safer. taweber.powweb.com/biasrite/br_page.htm
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