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I'd be more concerned about the amp shutting down.
GL KT88's are fine tubes.
Yes, I have a voltmeter and biased the tubes using that. The amp also has an EZ bias feature where you don't need a meter. I've used both and decided the meter was a little more accurate.
I haven't had the same problem with the EL34 tubes only when I tried the Golden Lion Kt88's. Are Kt88's and 6550's always interchangeable? The amp goes into a standby mode after playing it for an hour or so with the GL's. If I check the bias, it's usually lower than originally set for those tubes.
Your amp will be fine with both KT88's or 6550's. However (and your mileage may vary), that Gold Lion KT88 is the most unreliable version of that tube I have ever used. You probably have at least one bad one in the group and possibly more.
as both McIntosh and VTL use Gold Lion KT-88s in production. It doesn't make sense they would choose unreliable tubes.
There is, however, a difference between buying tubes from any random source and purchasing those that has been thoroughly tested and matched in advance. Many are rejected by manufacturers in their supply chain.
I bought the Golden Lion's from an on-line source I found on Ebay I think. Vacuum Tubes Value. They claim to thoroughly test their tubes. Does that mean they actually do? IDK. As I said, I used those tubes in an old Rogue Model 88 before for not very long. So, they didn't have a lot of use on them.
I would choose.
Let me ask this though. If you are buying a tube or tubes with a good rep such as the Genalex GL KT88's and they are supposedly tested, what difference does it make who you buy them from?
What is a more 'reputable' source selling the same tubes going to do that another not-so-known or reputable dealer isn't?
If you are buying a tube or tubes with a good rep such as the Genalex GL KT88's and they are supposedly tested, what difference does it make who you buy them from?
*Tested* how? For how long? Under static or conditions using live voltages?
I see. What dealers in tubes do you recommend that test their tubes so stringently?
I mean the ones you know for sure and not just say they do.
As previously mentioned, I prefer those who burn them in for an extended period using live voltages. Manufacturers like Audio Research and VTL do.
Dealers Jim McShane and Keven Deal likewise do the same.
Thanks E-Stat. I have some NOS Mullard 12Ax7 I bought from Upscale Audio years ago but really didn't pay any attention to how they were tested or burned in. I would rather pay more $ for a thoroughly tested tube that may result in more longevity.
Good question. I see if I can find out.
This is what it says on the web site:
We sell factory matched tubes, matched on proprietary factory test equipment. Test results are typically labeled on each tube box. Insist on factory matched tubes, not tubes matched on generic testing equipment.
Just so you know - the "factory" matching is really not very good.
I believe I bought a quad set of EH KT88's from you in the not so distant past. One went bad and I have another set I got from somewhere else and one of those went bad. So I have two sets of three EH KT88's. So, I now have 6 EH Kt88's and 3 EH 6550's not to mention the quad set of Genalex GL KT88's that my amp doesn't seem to care for unless one or more of those is bad which I have no way of knowing.
Now I need to buy another quad set? I'm running out of storage space.
Dude, you gotta stop buying tubes of ebay.
One quad set came from rogue audio. One from Jim McShane and the golden lions came from the guy that advertises on ebay.
I wonder how many GL kt88's the reputable dealers have to throw out due to bad measurements?
The GL KT-88s are my most reliable power tube - I reject well under 1% of them. However, the factory matching is terrible, just so you know...
Check out my FAQ for some helpful info:
Jim, I was reading the post you wrote about 'Tube Problems That May Not Be Tube Problems'.
The section about making sure the bias is adjusted well below the current value for that tube when replacing them with newer tubes got my attention. I replaced a set of EL34's with the Genalex GL KT88's. There's a switch on the back of the amp that you must move from the EL34 position to the 6550 position. Alas, I failed to do this when I first installed the Golden Lion Kt88's and biased them. I realized what I did and moved the switch to the correct position and rebiased the tubes but maybe the damage was already done? They are not noisy but do cause my amp to go into the standby mode after an hour or two of playing at loud but not ear splitting levels. It doesn't do this with the EL34's or the mix of Elecro Harmonix Kt88's I now have currently installed. So, I'm not sure the amp is at fault. Is it possible that I damaged one or more of the Golden Lion Kt88's? In what way would they be damaged to cause the amp to go into standby when they play noiselessly?
They are getting a lot of power out of two 6550s. They must be driving them pretty hard. My Prima Luna makes less than half that power with the same tube compliments.
A note of tubes: Places like Upscale Audio spec the tubes they purchase at higher values than what the factory accepts as a good tube. Then they burn-in and match to eliminate any lessor product. They send the rejected tubes back to the factory and they are sold to somebody else.
Correction: They spec their tubes tighter than the factory but the factory does not allow returns of working tubes.
Yeah, I heard/read similar things about the Golden Lions. They were fine in my old Rogue but coincidentally the Rogue Model 88 died with the GL KT88's in it.
As I said before, I have 3 EH6550's and 6 EH KT88's but have no way of checking the specs or matching them.
Would it hurt to randomly try 4 of the Electo Harmonix KT88's in there to see how it reacts? Of course, I will bias them.
I had 2 quads that ran for years in my Rogue M180's.
replaced them with another 2 quads just because they were running long the in tooth.
Also ran that set for years, although not as much as first set.
Not one issue.
The last set was purchased in 2010, so maybe new prod has issues?
Not ware of any amp that can't take both KT88's and 6550's.
Jolida lists both for this amp, as you mentioned.
So.. you may have bad KT88 as well.
Or something in the amp that is killing tubes? Fun, no?
If you can bias each tube individually, you can just get a single 6550.
Unless this is a used up set, then I'd just get a new set and leave this trio for backups.
The bets tube advice I have received here has been: clean the pins and sockets. Amazing how many issues this can fix. Just passed this on by my ex-bro-in-law a month ago when one of his guitar tubes was making a racket.
Not sure it will help, but can't hurt.
I think I will try a set of the EH KT88's in the Jolida and see if it behaves like it did with the Golden Lions.
I'm good about cleaning pins and sockets and I don't use any contact enhancers on my tubes.
No. Nothing obvious.
Do you have access to a tube tester? Has your tube vendor tested these tubes out?
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