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Post by Lefty on May 19, 2005 10:02:53 GMT -7
Well, I got my extra quad of EL84's today for my Ghia and I ordered (for sh*ts and giggles) a couple of Tung Sol (Russian RI) 12AX7's. I just had a chance to A/B the TS with the JJ (stock in my Ghia). And the differences I heard where there was less distortion with the TS, less mids, more of a "Fender" type of tone. It sounded deeper a little less Voxy than the JJ. I think this is a useful tube if you don't crank the Ghia for its distortion purposes and use a pedal to push it. But if you use the Ghia and crank it with no pedals stick the with the JJ. I have a couple of Sovtek 12AX7LPS laying about and I'll A/B the TS with them at a later time. But when compared to the JJ they seemed "Lifeless". Just my 2cents, YMMV. As soon as I get my Mini Z I'll have the try the GT12AX7M (Mullard copy) in my Ghia too
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Post by zane on May 19, 2005 10:23:43 GMT -7
I have all nos Rca tubes in mine.I bought it used off ebay,& it had the power tubes,& rectifier allready.It had some "new" preamp tubes. I put the Rca pre amp tubes in ...but ...I never really got "distortion" that every one talks about with mine. It did seem to have a little when I first got it ..but I put the nos tubes in the same day....SO... my question is this, do the newer tubes give a more distorted tone than the nos RCA tube...quess I should dig out my tubes sometime ,& play around with 'em
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Post by kaseri on May 19, 2005 11:09:06 GMT -7
I just placed an order for a new set of tubes for my Ghia. I ended up going with the following.
JJ ECC83s to replace stock ECC83 JJ ECC801 to replace stock 5751 JJ EL84 to replace stock EL84's
I've had very good luck with JJ tubes in the past & I am looking forward to trying these out in my Ghia.
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Post by Lefty on May 19, 2005 12:23:49 GMT -7
I went with the GT EL84S (The S is for Slovakia aka JJ). The only reason I went with the GT's is pretty much for the rating and lack of bias headaches. Even tho with a cathode bias amp you can get too far off the bias mark. Good enough for the Dr. good enough for me!! Plus I had them before with great results.
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Post by kaseri on May 19, 2005 13:06:29 GMT -7
Z told me that as long as I go with a med gain matched set of output tubes I'll be just fine.
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Post by zane on May 19, 2005 13:08:54 GMT -7
I didn't think you had to bias the EL-84 amps. Straight From Dr. Z: Bias Notes
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Post by kaseri on May 19, 2005 13:14:40 GMT -7
Zane... Exactly what I was reading & about to post.
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Post by Lefty on May 19, 2005 15:27:21 GMT -7
Yes and no, but if you get a set of tubes (unmatched or otherwise) that are too far off the mark you could have to do some resistor swapping. But as a general rule, no.
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Post by zane on May 19, 2005 15:54:15 GMT -7
ahhh.I know next to nothing about this stuff
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Post by kaseri on May 19, 2005 18:35:51 GMT -7
What's "too far out" & who makes that designation in regard to tube grades? I'm curious as to how GT grades the tubes they sell & what guidelines they follow to arrive @ the ratings they stamp on the tubes.
Maybe the good Dr. will chime in on this one & enlighten us.
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Post by Lefty on May 19, 2005 21:34:47 GMT -7
"For the last five years I have been shipping new amps with Groove Tubes EL-84-S tubes, and the reliability has been great. The EL-84-S is a Tesla EL-84, and the rating I select is a #6."
They rate them on "hardness" or how early or late they distort, not so much on bias. I figure the bias rate of palte draw should be approx the same so I stuck with the GT-EL84S as they are the same brand I would use anyway.
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Post by perryr on May 19, 2005 22:34:22 GMT -7
Pretty much any good matched pair of EL84's will work fine. The amp is designed around specific rated tubes, and for that sound you need to stay in that range. Going outside the range will cause the tubes to run a little hotter or colder, which may be to ones liking.. matter of taste.. but certainly no problem.
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Post by kaseri on May 20, 2005 3:57:05 GMT -7
"For the last five years I have been shipping new amps with Groove Tubes EL-84-S tubes, and the reliability has been great. The EL-84-S is a Tesla EL-84, and the rating I select is a #6." They rate them on "hardness" or how early or late they distort, not so much on bias. I figure the bias rate of palte draw should be approx the same so I stuck with the GT-EL84S as they are the same brand I would use anyway. Thanks Lefty! You learn something every day. The only thing I really know about tubes is that they sound great!
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Post by myles on May 20, 2005 10:02:07 GMT -7
I just placed an order for a new set of tubes for my Ghia. I ended up going with the following. JJ ECC83s to replace stock ECC83 JJ ECC801 to replace stock 5751 JJ EL84 to replace stock EL84's I've had very good luck with JJ tubes in the past & I am looking forward to trying these out in my Ghia. The JJ ECC83S is the stock tube the Doc uses ... it is just more closely selected in the case of the stock tube. The ECC801 is a 12AT7. The AT7 throws out about 10mA vs 1.0 for a 5751. The 5751 has a transconductance of about 1200 vs 5000+ for an AT7. The AT7 may sound much more harsh due to its different rise time too. The 5751 was originally also intended to be a phase inverter and the two sides are generally quite well balanced. I have seen very few AT7's or ECC801's that have this trait. The JJ EL84 is, once again, the stock output tube the Doc uses except he uses the GT-EL84S in a #5 or #6 rating. These ratings are chosen dynamically and not on static test gear. This assures that the tubes will be balanced when they are running ... not merely at idle. I can set the idle on my 1998 VW Jetta at 750rpm and set it the same on a BMW M5. At idle the cars are the same but when running it is a much different story. You may want to check your fretboard in every used position and at full guitar volume and the amp at 9:00 on the volume and about 2:00 on the tone, see how long each note holds from old set to new set. When you find dead spots it is not your guitar. Your output section is now unbalanced from most odds. If you found an improvement when you went to the new tubes it could be as simple as your old output set was due for replacement. If you are local and bring the tubes to me I will be happy to spec all of your tubes as you may not be comparing apples to apples.
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Post by kaseri on May 20, 2005 10:05:52 GMT -7
Myles... I wish I were close to you but I'm not. Oh well...
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Post by myles on May 20, 2005 12:47:23 GMT -7
Myles... I wish I were close to you but I'm not. Oh well... Well .... for folks that are close ..... I am always happy to check out your Z amp for free. If I find something I do not like such as a tube somewhere, I usually replace that for free too as I cannot stand having a Z amp leave my place that does not sound it's best.
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Post by kaseri on May 20, 2005 12:59:33 GMT -7
Myles...
Am I able to specify the grade of tube I want when ordering from GT? In other words, if I want a #6 graded El84 can I specify that I want a #6 or do I have to choose the 4-7 option via the online store?
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Post by myles on May 20, 2005 15:08:44 GMT -7
Myles... Am I able to specify the grade of tube I want when ordering from GT? In other words, if I want a #6 graded El84 can I specify that I want a #6 or do I have to choose the 4-7 option via the online store? Just select the 4-7 option but in the comments section just say something such as "#6 ONLY please". If you put a comment in there too about being off this Z forum I will pick a few sets and trace them on the 570 and pick what I like the best. If this is for a Ghia I have some specific things I look for. Also, are you using the 5751 phase inverter? If using a 12BH7 I do things a bit differently.
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Post by Lefty on May 20, 2005 15:29:39 GMT -7
Check out Musicians Friend, they have 'em. 40.00 for a quad, and you can choose the rating.
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Post by kaseri on May 22, 2005 19:47:45 GMT -7
Myles...
I've decided to go with exactly what the good Dr uses for tubes in the Ghia. So I want to buy a replacement set of tubes. Does GT sell 5751 tubes?
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Post by myles on May 23, 2005 8:57:02 GMT -7
Myles... I've decided to go with exactly what the good Dr uses for tubes in the Ghia. So I want to buy a replacement set of tubes. Does GT sell 5751 tubes? GT does not currently carry a 5751. I get mine and those for my clients from Mike at KCA .... www.kcanostubes.com
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Post by kaseri on May 23, 2005 9:10:46 GMT -7
Myles...
Which 5751 do you recommend ?
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Post by myles on May 23, 2005 9:25:30 GMT -7
Myles... Which 5751 do you recommend ? Hard call. I love the RCA Command Series and GE five star the most but the Raytheon, RCA's and Sylvania's are also really terrific. By the way, they will last 10-20 times longer than the currently made 5751s that don't really trace as a 5751. You can find these at www.kcanostubes.com - just ask for Mike over there. Great fellow.
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Post by kaseri on May 23, 2005 9:29:01 GMT -7
If I wanted to stay as close as possible to my Ghias "factory" sound which one would you recommend?
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Post by myles on May 23, 2005 9:39:03 GMT -7
If I wanted to stay as close as possible to my Ghias "factory" sound which one would you recommend? JAN Philips 5751 I believe this is what the Doc tries to use most often but you may want to check with him.
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Post by kaseri on May 23, 2005 9:44:40 GMT -7
Balanced or unbalanced? Sorry.. I'm slightly "lost" when it comes to tubes.
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Post by myles on May 23, 2005 10:07:12 GMT -7
Balanced or unbalanced? Sorry.. I'm slightly "lost" when it comes to tubes. In the phase inverter, balanced for sure.
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Post by kaseri on May 23, 2005 10:42:42 GMT -7
So is the factory location of the 5751 tube the "phase inverter"?
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Post by myles on May 23, 2005 12:39:02 GMT -7
So is the factory location of the 5751 tube the "phase inverter"? Yes
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Post by kaseri on May 23, 2005 12:57:09 GMT -7
Myles...
Let me see if I have this correct...
The Ghia has 5 tubes in it.
1 ECC83s which is the preamp tube 1 5751 which is the phase inverter tube 2 EL84 which are the power tubes 1 5Y3 which is the rectifier
Is that right ? Does the 5751 tube have any effect on the tone of the amp?
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