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Post by supafuzz on Dec 30, 2007 23:55:16 GMT -7
For those that have retubed their 'Ray, what brands sound the best in the 'Ray? I'm not a big GT fan, but do I really need to match tube hardness for this amp? Is it self-biasing? Anything else I need to know? Thx for any advice.
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Post by Bill on Dec 31, 2007 4:02:28 GMT -7
For those that have retubed their 'Ray, what brands sound the best in the 'Ray? I'm not a big GT fan, but do I really need to match tube hardness for this amp? Is it self-biasing? Anything else I need to know? Thx for any advice. I've been using JJ EL-84's, NOS pre amp (RCA), and Dario Miniwatt EF-86 with good results. I think I have an NOS Westinghouse rec tube.
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Post by benttop (Steve) on Dec 31, 2007 6:51:56 GMT -7
JJ's for power tubes here. I have a NOS Mullard for EF86 and I'm using a Weber Copper Cap for rectifier - seems to work just fine.
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Post by Jones'n for Tone on Jan 6, 2008 19:28:20 GMT -7
I've got Siemens NOS EL84's, a Mullard rectifier tube, and stock preamp tubes in mine. Couldn't be happier! The NOS Siemens change the voice of the amp ever so slightly but they have a wonderfully rich harmonic content.
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Post by bengalb1 on Jan 22, 2008 11:59:24 GMT -7
Was wondering also if the Ray needs to be biased when replacing tubes. Thanks guys...Mike
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Post by craigmccle on Jan 22, 2008 13:04:06 GMT -7
I'm pretty sure that all of the Doc's EL84 Amps are self biasing. Someone correct me if I'm wrong.
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Post by hdahs143 on Jan 22, 2008 17:56:58 GMT -7
You are correct. Just make sure you replace ALL power tubes with a matched set.
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Post by Hohn on Jan 25, 2008 13:23:08 GMT -7
I think "fixed bias" is more accurate than "self biasing". To me "self biasing" implies that the amp makes some kind of adjustment when it doesn't. Instead, the bias is fixed and thus you need to match the tubes to the amp (as best you can) because you can't match the amp to the tubes.
JMO
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Post by amakitalo on Jan 25, 2008 13:41:25 GMT -7
Don't think so. In fixed bias amps one cannot adjust the bias as opposed to say Route 66. Mesa amps would be an example. You actually try to find tubes within certain tolerance of "hotness" if you will for these amps.
Your Stangray is self biasing or autobiasing; The tubes figure out the bias based on operating circumstances. This has to do with high-current resistors and caps and grid voltages, which I don't really understand.
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Post by myles on Jan 25, 2008 14:12:11 GMT -7
I think "fixed bias" is more accurate than "self biasing". To me "self biasing" implies that the amp makes some kind of adjustment when it doesn't. Instead, the bias is fixed and thus you need to match the tubes to the amp (as best you can) because you can't match the amp to the tubes. JMO Not really .... fixed bias amps are grid biased amps. The bias as an example may always stay at -52 volts for a 6L6 tube as an example but on many amps with a bias pot this "fixed voltage" can be changed. Older tweed amps such as a tweed twin and bassman had no bias adjustment for the fixed bias. Same for Hiwatt, Orange, and today Mesa Boogie. If you use tubes within design spec things work great. Cathode biased amps are self biasing but they too expect tubes in a general range. They can run too cold or hot as any other amp. What you want in any cathode biased amp for the most part is a tube that comes as close to design spec of the tube as possible. These are generally called mid range tubes. In the case of GT they are #5-6 rating. There are many great amps from the past (and some current ones too) that do not have adjustable bias pot. These amps worked great because tubes were consistent in the past and the amp designer knew what they were going to get from the tube maker. Unfortunately this is not the case today. Tubes are all over the place. Tubes with low ratings or high ratings are not favored by me personally. To me, these are tubes that are not within design spec. There is something "wrong" with these tubes. Grid spacing may be wrong or there may be other issues. Just because you can adjust the bias to a proper level there is something still basically not right with the tube. Bottom line here is; I prefer tubes that meet design spec. Mesa Boogie as an example, selects tubes for their amps which fall into a narrow range as their amps have a fixed non-adjustable bias. Many people have techs put adjustable bias pots in Mesa amps to use "any tube". My own Mesa amps are stock fixed bias even though it would take me a few minutes to install an adjustable bias pot. I do not need one or want one. I use tubes that fall within spec. And .... that is my thought on the subject writing this as myself ... Myles from GAB who is just a guy trying to help players sound as good as they can sound while shelling out less of their hard earned dollars. That is one reason I list multiple vendors I trust on my own GAB website and if folks do order directly from GT and have some comment in the order that they are from this forum I go through a lot of tubes from GT stock and hand trace them myself for the player. GT normally charges $10 per tube to vacuum trace and spec out but I do this on my own time at no extra charge to folks in here. BUT ...... I am also happy to work with a number of other tube vendors too, and do every day to get the player the right tubes for the best price for their budget.
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Post by Phil (aka Phil) on Jan 26, 2008 18:16:06 GMT -7
Cathode biased amps are self biasing but they too expect tubes in a general range. They can run too cold or hot as any other amp. What you want in any cathode biased amp for the most part is a tube that comes as close to design spec of the tube as possible. These are generally called mid range tubes. In the case of GT they are #5-6 rating. This is something that I've wanted to clarify for those not as technically knowledgeable for a long time. A lot of people get the impression that cathode bias amps are *totally* self biasing; that you can put any old tube in there and it will be optimally biased. Nothing could be further from the truth. As Myles said, putting a tube that is not a 5,6, or 7 rating on GT's scale (or the equivalent) into a Dr. Z cathode biased amp is probably asking for the tube to fall outside of its proper bias range. The cathode resistor (or resistors, in the case of split load biasing) is chosen to give the proper bias for a mid range tube.
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Post by jdspelledzz on Feb 6, 2008 12:21:54 GMT -7
I think "fixed bias" is more accurate than "self biasing". To me "self biasing" implies that the amp makes some kind of adjustment when it doesn't. Instead, the bias is fixed and thus you need to match the tubes to the amp (as best you can) because you can't match the amp to the tubes. JMO Not really .... fixed bias amps are grid biased amps. The bias as an example may always stay at -52 volts for a 6L6 tube as an example but on many amps with a bias pot this "fixed voltage" can be changed. Older tweed amps such as a tweed twin and bassman had no bias adjustment for the fixed bias. Same for Hiwatt, Orange, and today Mesa Boogie. If you use tubes within design spec things work great. Cathode biased amps are self biasing but they too expect tubes in a general range. They can run too cold or hot as any other amp. What you want in any cathode biased amp for the most part is a tube that comes as close to design spec of the tube as possible. These are generally called mid range tubes. In the case of GT they are #5-6 rating. There are many great amps from the past (and some current ones too) that do not have adjustable bias pot. These amps worked great because tubes were consistent in the past and the amp designer knew what they were going to get from the tube maker. Unfortunately this is not the case today. Tubes are all over the place. Tubes with low ratings or high ratings are not favored by me personally. To me, these are tubes that are not within design spec. There is something "wrong" with these tubes. Grid spacing may be wrong or there may be other issues. Just because you can adjust the bias to a proper level there is something still basically not right with the tube. Bottom line here is; I prefer tubes that meet design spec. Mesa Boogie as an example, selects tubes for their amps which fall into a narrow range as their amps have a fixed non-adjustable bias. Many people have techs put adjustable bias pots in Mesa amps to use "any tube". My own Mesa amps are stock fixed bias even though it would take me a few minutes to install an adjustable bias pot. I do not need one or want one. I use tubes that fall within spec. And .... that is my thought on the subject writing this as myself ... Myles from GAB who is just a guy trying to help players sound as good as they can sound while shelling out less of their hard earned dollars. That is one reason I list multiple vendors I trust on my own GAB website and if folks do order directly from GT and have some comment in the order that they are from this forum I go through a lot of tubes from GT stock and hand trace them myself for the player. GT normally charges $10 per tube to vacuum trace and spec out but I do this on my own time at no extra charge to folks in here. BUT ...... I am also happy to work with a number of other tube vendors too, and do every day to get the player the right tubes for the best price for their budget. "Rack 'em!!" Exalted!! I learn somthing every time.
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Post by Hohn on Feb 7, 2008 21:02:48 GMT -7
I'll take the credit for playing the ignoramus to allow Myles to educate us all:D
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