More problems with Russian (Reflektor) KT88s

[GordonW]

Well, just had ANOTHER Reflektor-factory KT88 tube cause an amplifier failure.

VAC Auricle Musicblock amp (monoblock)... client replaced the original (Shuguang-made) KT88s with a new set of Gold Lion KT88s. Amp proceeded to blow the main power fuse. Upon testing (with the original tubes reinstalled- they tested fine), the amp will not bias up correctly on one output tube (acts like the cathode circuit is blown open). Amp's going back to Florida, to get brought back to life...

I talked to Kevin Hayes of VAC about it... he said, in his opinion, that the KT88 tubes from the Reflektor plant (Sovtek, EH, Gold Lion, Tung-Sol, etc.) were actually the least consistent, most problematic tubes he tests, in trials in which he determines what he wants to use in his amps. Surprisingly (at least superficially), he now uses a specially-selected Chinese tube (naturally, he didn't go into all the details- it's sort of a business secret) in the outputs of all his KT88-based amps. Less than a 1% overall failure rate, over the last 2.5 years of usage of these tubes.

It's sort of sad to see what was once the premiere Russian plant fall to this level of low quality. Kevin did mention that in his experience, the Winged-C tubes (coming from the ORIGINAL Svetlana plant- NOT what's called Svetlana now, which is from Reflektor) are usually fine... but, that he likes the sonic character of the Chinese tubes better. But, he was pretty firm in his recommendation to stay away from Reflektor-plant KT88s of any sort...

Regards,
Gordon.

 

[diamondsouled]

Would be interesting to know where he sourced his Ruskie KT88s.

What seems to be of utmost importance with any new manufacture power tubes, Russian,Chinese, or Slavic, is proper real voltage screening.

I've been running Gold Lion reissues in my VAS Citation Sound amps for the past couple years and they've performed very well. Got this quad from the Depot.

Cheers

Lar

 

[Jim McShane]

Well, just had ANOTHER Reflektor-factory KT88 tube cause an amplifier failure.

VAC Auricle Musicblock amp (monoblock)... client replaced the original (Shuguang-made) KT88s with a new set of Gold Lion KT88s. Amp proceeded to blow the main power fuse. Upon testing (with the original tubes reinstalled- they tested fine), the amp will not bias up correctly on one output tube (acts like the cathode circuit is blown open). Amp's going back to Florida, to get brought back to life...

I talked to Kevin Hayes of VAC about it... he said, in his opinion, that the KT88 tubes from the Reflektor plant (Sovtek, EH, Gold Lion, Tung-Sol, etc.) were actually the least consistent, most problematic tubes he tests, in trials in which he determines what he wants to use in his amps. Surprisingly (at least superficially), he now uses a specially-selected Chinese tube (naturally, he didn't go into all the details- it's sort of a business secret) in the outputs of all his KT88-based amps. Less than a 1% overall failure rate, over the last 2.5 years of usage of these tubes.

It's sort of sad to see what was once the premiere Russian plant fall to this level of low quality. Kevin did mention that in his experience, the Winged-C tubes (coming from the ORIGINAL Svetlana plant- NOT what's called Svetlana now, which is from Reflektor) are usually fine... but, that he likes the sonic character of the Chinese tubes better. But, he was pretty firm in his recommendation to stay away from Reflektor-plant KT88s of any sort...

Regards,
Gordon.

I find Kevin's logic hard to follow. If he is using (and has been using for 2.5 years) a Chinese tube, how would he know how the Genalex is doing at this point in time?

FYI, I just sent some KT-88 Genalex to Kara Chaffee at deHavilland. She uses them and hasn't reported any issues back to me at all - FWIW.

Gordon, my KT-88 Genalex reject rate is 1-2% tops, and field failures are well under 1%, maybe 1 tube every 2-3 months.. I sell about 90-100 tubes per month so I see a very good sized sample.

I find the SED/winged C reject rate is climbing. The tubes tend to be EXTREMELY hot biasing, lots of really bad crooked bottles and even some problematic pin soldering. I can't address their KT-88 specifically since I don't carry it (I think it sounds awful), but the EL34s and 6550Cs especially are a bit problematic. Certainly not enough to be a reason not to handle them, but a pain-in-the-a** for sure.

I used to carry the Shuguang KT88-98, but I had to stop because the quality got SO bad - 40% to 50% reject rates. When the tube changed from the triple getter to the dual getter the quality plummeted.

I can't confirm this, but I believe that the period when the Russian mafia was trying to force Mike Matthews to sell them the Saratov plant was the period where the quality there was most problematic. That was about 2-3 years ago.

You know, I can sell any KT-88 I want to - I really have no axe to grind. But this all is quite a surprise because I think the KT-88 Genalex is now one of my most reliable tubes.

As Lar said, maybe it's a screening issue. If you want to know more about my screening drop me a note.

 

[LinuxGuru]

Are you sure that VAC schematic/construction itself was not a real culprit? To have real picture, one need relatively large sampling population (e.g. 50 - 100 tubes) running in different devices (5 or 6 at least).

 

[GordonW]

I find Kevin's logic hard to follow. If he is using (and has been using for 2.5 years) a Chinese tube, how would he know how the Genalex is doing at this point in time?

This IS Kevin Hayes here. He's always testing and building new stuff. I don't think that man ever sleeps.

Apparently, he keeps getting sample pieces from various manufacturers, and testing them periodically... from what I know of his shop, he apparently has some pretty sophisticated home-made testing jigs and such he uses.

Regards,
Gordon.

 

[rlr274]

My experience with the Russian Genalex KT88 has been a disappointment as well.I had them in a D79B as well as in a Dyna MK3 pair and both amps had tube failures, causing a good deal of damage in the ARC D79B.The first set came from Jim McShane,the second from Tube Depot,both were well tested before installation by the suppliers as well as myself.In both cases the screen grid shorted to G1 causing the bias circuit damage.I now use GE 6550s in both amps and have had no problems since,the Russian Genalex KT88s did sound as good as promised but not for very long,cheers.

 

[Jim McShane]

Just one last comment...

A few years back (as I have posted before, look in the archives) there was a production run that had too many failures. Since that time the product has gotten steadily better in quality. It's now reached the point of being highly reliable based on my large sample experience - again, as I mentioned previously.

BTW, I love GE 6550As - I had almost 1000 of them come through here - but I had some of them fail in testing too. No tube is immune to failures. If it happens to you personally it's a b*tch!! But it has always happened and it will continue to happen on occasion I'm afraid - on any tube.

Lastly, one thing I have learned - I do not provide ANY tubes for ARC gear other than original equipment. Not Genalex, not Shuguang, not ANYTHING but SED 6550C, and EH or Sovtek front end tubes.

My $0.02 worth anyway...

 

[diamondsouled]

Kevin of Upscale Audio is declining to re-tube some models of ARC amplifiers:

"ATTENTION! We are no longer re-tubing Audio Research VT100 amplifiers. Mk1, Mk2, Mk3... doesn't matter... no exceptions."

Is it that these ARC amps, as well as others, have their power tubes biased too high?

Cheers

Lar

 

[GordonW]

In both cases the screen grid shorted to G1 causing the bias circuit damage.I now use GE 6550s in both amps and have had no problems since,the Russian Genalex KT88s did sound as good as promised but not for very long,cheers.

The VAC amp here hasn't been disassembled yet; however, I'd be willing to bet it was the same failure mode. In this case, from the symptoms, it most likely killed the cathode circuit, and maybe the bias circuit as well...

And, this amp only has around 535v on the plate. I can understand when the tubes fail in ARC and CJ amps (with B+ on the upside of 580v on screen and plate), but only 535? That doesn't seem like much strain...

Regards,
Gordon.

 

[BuzzK]

Gordon,

I've got a few GE6550's tested and certified by none other than Jim McShane.

I'm interested in trading for NOS Mullard EL34s. If you are interested, check your PM - for my phone no.

BuzzK

 

[diamondsouled]

The VAC amp here hasn't been disassembled yet; however, I'd be willing to bet it was the same failure mode. In this case, from the symptoms, it most likely killed the cathode circuit, and maybe the bias circuit as well...

And, this amp only has around 535v on the plate. I can understand when the tubes fail in ARC and CJ amps (with B+ on the upside of 580v on screen and plate), but only 535? That doesn't seem like much strain...

Regards,
Gordon.

It would be nice if New Sensor, JJ, EH, Shuguang, etc. would begin providing more detailed info as to their tubes specs like in the old days. Some graphs, some class A, B, and AB1 ratings, wattage, resistances, capacitance, etc.

Cheers

Lar

 

[Jim McShane]

It would be nice if New Sensor, JJ, EH, Shuguang, etc. would begin providing more detailed info as to their tubes specs like in the old days. Some graphs, some class A, B, and AB1 ratings, wattage, resistances, capacitance, etc.

Cheers

Lar

I can assure everyone that 535 volts is no problem. It sounds to me like a plain old defective tube. I wish it NEVER happened, but it sometimes does.

I SUSPECT (I have no proof) the screen windings sag when hot and touch another internal element.

There are some new curves/specs for the Saratov built tubes around, but not many. I agree Lar, I'd like to have them too. The ones I've seen were done by j c morrison, the "tech director" for New Sensor (and former audio writer in Sound Practices and other mags.

 

[Steve O]

It would be nice if New Sensor, JJ, EH, Shuguang, etc. would begin providing more detailed info as to their tubes specs like in the old days. Some graphs, some class A, B, and AB1 ratings, wattage, resistances, capacitance, etc.

Cheers

Lar

Technically, they have provided the requested info by designating their device a "KT88" or whatever. If their offerings aren't up to the capabilities of the chosen namesake then they should designate them as something else. I know I'm being a bit idealistic but AFAIC the old time designator shouldn't be used if the device doesn't meet the old time specs. Any other usage of the designator is misleading at best and just plain fraudulent at worst.

In the current situation, I'd like to believe we're dealing with the exception. If it isn't, it wouldn't be the first time ratings have been inflated (probably not since the early 60s could an EL34 reliably handle 800V on the anode but the books spec'ed that as the max value well into the 80s) and it probably won't be the last.

 

[BmWr75]

Damn!! I just ordered a matched quad of these reissue Gold Lion KT88s for PrimaLuna Dialogue Two integrated with the adaptive autobias circuit. Tubes purchased from the same company that sells PrimaLuna equipment in the U.S. Should I be worried about installing them?

 

[diamondsouled]

Technically, they have provided the requested info by designating their device a "KT88" or whatever. If their offerings aren't up to the capabilities of the chosen namesake then they should designate them as something else. I know I'm being a bit idealistic but AFAIC the old time designator shouldn't be used if the device doesn't meet the old time specs. Any other usage of the designator is misleading at best and just plain fraudulent at worst.

In the current situation, I'd like to believe we're dealing with the exception. If it isn't, it wouldn't be the first time ratings have been inflated (probably not since the early 60s could an EL34 reliably handle 800V on the anode but the books spec'ed that as the max value well into the 80s) and it probably won't be the last.

Agree there Steve.

Perhaps they should be selling them as KT88 type tubes. Mmmmmm.

More openness on their part would go a long way on reassuring buyers that they are getting tubes which can be used in the very same applications as the original KT88 tube could be.

Same with 6550s etc. of course.

Someone should pick up one of the new computer based tube testers and do some graphing and spec testing. The results would be very interesting.

Cheers

Lar

 

[Jim McShane]

Damn!! I just ordered a matched quad of these reissue Gold Lion KT88s for PrimaLuna Dialogue Two integrated with the adaptive autobias circuit. Tubes purchased from the same company that sells PrimaLuna equipment in the U.S. Should I be worried about installing them?

No! Not anymore than you would worry about any tube. They are fine tubes, and the vendor you describe does a good job with them.

Don't let reports of occasional failures bother you. They sound GREAT and reliability is as good as almost anything out there. There are THOUSANDS of them working away just fine, day after day.

Enjoy them. :thmbsp::thmbsp::thmbsp::thmbsp:

 

[BmWr75]

Thanks Jim. They just arrived today, looking forward to installing and giving them a listen.

 

[stoutblock]

Thanks Jim. They just arrived today, looking forward to installing and giving them a listen.

Let us know what you think. I have 8 of these on my short list.

 

[Bill H]

I also will be looking into the GL KT-88's for my Citation II (with Jim's kit's of course), and possibly my Audio Research VT-50. Are these tubes no good for the VT-50 as well??

 

[Jim McShane]

I also will be looking into the GL KT-88's for my Citation II (with Jim's kit's of course), and possibly my Audio Research VT-50. Are these tubes no good for the VT-50 as well??

Hi Bill!

For the Cit II - a big time thumbs up. That's my tube of choice, and I have hundreds out there doing really well. Just a handful have acted up, and they sound GREAT!

For the ARC - well, I won't put anything in an ARC other than what they put in them - which means SED/winged C 6550Cs. It's not just me - there's a bunch of tube guys who are restricting what they'll sell for ARC.