I bought a new set of Gold Lion Genalex for my current-production McIntosh MC275. The factory tubes are fine and I wanted to pull and save those (as in, they still work, everything has been perfect with the amp and tubes, not one single issue).
When I powered the new tubes on for the first time, the KT88s made a lot of noise (like the metal heating and expanding...way more than subsequent power cycles) and there was a quick quiet 'pop' from one of the channels about 30 seconds after power on (as I could still hear the metal heating, expanding). I saw a very small blue spark at the base of a tube (specifically the round flat disc at the bottom of the actual insulating spacer...I think that is what it is called).
Everything looks and sounds good.
I got a second (small) pop again today (again, less than a minute after startup) and everything is working fine. I was not watching and not sure what channel or tube it came from.
It 'feels' like there might be some crud burning off vs. it failing but I am not an expert.
Curious if this is normal (or if it goes away, not worry about). Either way, with the holiday weekend and me working from home part of the week, I can put a TON of hours on these. In other words, let them fail if they are going to fail...or see if everything normalizes.
Thanks!
When I powered the new tubes on for the first time, the KT88s made a lot of noise (like the metal heating and expanding...way more than subsequent power cycles) and there was a quick quiet 'pop' from one of the channels about 30 seconds after power on (as I could still hear the metal heating, expanding). I saw a very small blue spark at the base of a tube (specifically the round flat disc at the bottom of the actual insulating spacer...I think that is what it is called).
Everything looks and sounds good.
I got a second (small) pop again today (again, less than a minute after startup) and everything is working fine. I was not watching and not sure what channel or tube it came from.
It 'feels' like there might be some crud burning off vs. it failing but I am not an expert.
Curious if this is normal (or if it goes away, not worry about). Either way, with the holiday weekend and me working from home part of the week, I can put a TON of hours on these. In other words, let them fail if they are going to fail...or see if everything normalizes.
Thanks!
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If they fail will they take anything with them? You don't want your output transformer to suffer in the event.
I don't think a lightning strike could take out these output transformers! But joke aside obviously don't want to push my luck.
Trying to understand what I might be seeing/hearing. Obviously if it got worse I would stop, but if it goes away...no worry?
Trying to understand what I might be seeing/hearing. Obviously if it got worse I would stop, but if it goes away...no worry?
I can strongly recommend Jim McShane for high performance high stress valves. He personally tests and matches all that he sells, and in the single instance I've had of a problematic modern Genalex KT88, he had a replacement on the way next day, no drama. Prices are at least competitive, usually better. And he's a member of diyAudio.
Tube & Information Page
All good fortune,
Chris
Tube & Information Page
All good fortune,
Chris
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I've bough tubes from him before but doesn't really have what my amp needed. Is there something else you see?
What do you mean by high-stress? Other than being power tubes, the MC275 is known for being gentle on tubes and giving people huge hours.
What do you mean by high-stress? Other than being power tubes, the MC275 is known for being gentle on tubes and giving people huge hours.
I see a option for new production 6550WE Sovtek - but that is it. He generally seems to specialize more in NOS stuff.
Not being difficult, I just saw that and nothing else.
Not being difficult, I just saw that and nothing else.
Please forgive me if my post seemed too much an advertisement. I've just had consistently good luck with his biz, and FWIW.
The Mc275's are about as easy on output valves as a competitive commercial manufacturer could be, with under 500VDC B+ and moderate idling currents. But these are still output valves, and they do really make 75 Watts output per channel continuous after 1/3 power warmup, etc. Not as ridiculously abused as an Audio Research or a Manley or something even worse, but still serious duty.
Today, these big boys are made mostly for guitar amplifiers. Some small percentage gets diverted into the whacko audio stream (that's us). Production is done in the BRIC countries where some remnants of production machinery survive. The old guys (and, very largely, gals) who made the originals in the 1950s, 60s, 70s are gone. Original sources of exotic materials are gone. Processes, techniques, details of all kinds are continuously lost and must be reinvented by the even whackier folks starting up new production lines in other places. Goddess bless 'em.
I'd certainly agree with your goal of setting in a lifetime stock of high stress oxide cathode valves. If nothing else, they'll be valuable in the future. An old Allied Radio catalog here from 1965 has matched pairs of Genalex KT-88s for $12 US. Seemed like a lot of money at the time.
All good fortune,
Chris
The Mc275's are about as easy on output valves as a competitive commercial manufacturer could be, with under 500VDC B+ and moderate idling currents. But these are still output valves, and they do really make 75 Watts output per channel continuous after 1/3 power warmup, etc. Not as ridiculously abused as an Audio Research or a Manley or something even worse, but still serious duty.
Today, these big boys are made mostly for guitar amplifiers. Some small percentage gets diverted into the whacko audio stream (that's us). Production is done in the BRIC countries where some remnants of production machinery survive. The old guys (and, very largely, gals) who made the originals in the 1950s, 60s, 70s are gone. Original sources of exotic materials are gone. Processes, techniques, details of all kinds are continuously lost and must be reinvented by the even whackier folks starting up new production lines in other places. Goddess bless 'em.
I'd certainly agree with your goal of setting in a lifetime stock of high stress oxide cathode valves. If nothing else, they'll be valuable in the future. An old Allied Radio catalog here from 1965 has matched pairs of Genalex KT-88s for $12 US. Seemed like a lot of money at the time.
All good fortune,
Chris
No! I did not think it was an advertisement. I thought you were suggesting I shop with them even if they didn't have the tubes I needed. I have bought a bunch of odds and ends from him and it was a very good experience.
My hope in purchasing the Gold Lions was I would be getting something that would theoretically be better than the cheapest ones out there - but I know these are fragile devices that need to survive shipping so even if they were good at the factory, or retailer, they might have been compromised in transit.
Thanks again, appreciate everyone's help and comments.
My hope in purchasing the Gold Lions was I would be getting something that would theoretically be better than the cheapest ones out there - but I know these are fragile devices that need to survive shipping so even if they were good at the factory, or retailer, they might have been compromised in transit.
Thanks again, appreciate everyone's help and comments.
Update! Parts ConneXion was VERY good. I asked for a new set of power tubes, and they immediately sent them with the return on the others to be worked out later (and they said they will provide the shipping label, which is a very nice touch, not trying to get me to pay return shipping). So A+++ service there!
Popped in the new ones and everything seems fine!
On the old set, one or both of the left channel tubes seemed to warm up for multiple minutes (hundreds of ticks and clicks, like thermal expansion...in addition to the blue spark and pops), with the new ones in, they just came up to temperature with maybe one or two little clicks. I feel a lot better. I had no frame of reference if new KT88s should warm up like that...and it is clear they should NOT.
Thanks again for the help!
Popped in the new ones and everything seems fine!
On the old set, one or both of the left channel tubes seemed to warm up for multiple minutes (hundreds of ticks and clicks, like thermal expansion...in addition to the blue spark and pops), with the new ones in, they just came up to temperature with maybe one or two little clicks. I feel a lot better. I had no frame of reference if new KT88s should warm up like that...and it is clear they should NOT.
Thanks again for the help!
I had a 1975 TungSol/Dyna 6550 (same basic guts) that creaked like an old Volkswagen on start-up and shut-down. Particularly in a class-A amp on dummy-load testing. (Class A really does run cooler at FULL power.)
That tube had run 35 years, some of them hard, at the time I pulled it out for more testing, and I could not find any flaw compared to one of the last SovTek 6550s and one of the last Kentucky/G.E. 6550s (both NOS).
That tube had run 35 years, some of them hard, at the time I pulled it out for more testing, and I could not find any flaw compared to one of the last SovTek 6550s and one of the last Kentucky/G.E. 6550s (both NOS).
All three of those really deserved their excellent reputations. Audio Research built a business on those MPD Kentucky GE's for years. When the military dumped their warehoused ones, everybody was in Fat City for quite a while. ARC and VTL ran them at 600 VDC . These days, we'd just say Yikes!
All good fortune,
Chris
All good fortune,
Chris
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