I have TAD KT88s in my Reeves and they seem to be fine. They are speced out Shuguang tubes. I think Reeves is shipping with JJs now. http://www.farnell.com/datasheets/2...MIltjrja6U4QIVhoqzCh0XqwUoEAQYASABEgJSCvD_BwE
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Hiwatt bass amps
- Thread starter Big chicken
- Start date
I tried a quad of Shuguang GEKT88s labeled as Ruby KT88V-STR in an amp that likes to go into thermal runaway. GEKT88 have also been marketed as Preferred Series KT88s and Penta KT88SC. These are the supposed super KT88s with a 50W plate rating, rather than the garden variety Shuguang KT88-98.
I bought this tubes with hopes that the higher thermal rating would allow me to eliminate the fan I have to run on the amp for it to hold bias. I found the JJs were more stable. Probably not a surprise as the JJs are noticeably heavier, which suggest they have lot more metal used in their construction.
I also preferred the tone of the JJs more as the seemed a bit brighter and more harmonically complex. I believe the low end response of both tubes was about the same.
The worst thing with the Rubys is the matching was really bad and the tubes drifted significantly for the first two weeks, which suggest the tubes were gasey. This really surprised me as tubes had test results from Ruby and also the vendor I bought them from. I had to open up the amp and rebias it a couple of times. One of the times, the tube that was supposed to run the coldest per the test results was hogging all the current and running at almost 100% dissipation. They seem to be relatively stable now, but they alway go a little hot before the settle in when I use the amp.
I would take either Shuguang GEKT88 or KT88-98 over any of the New Sensor KT88s, but I'll stick with JJ KT88s for now.
I bought the Shuguang EL34Bs for my Matamp because it's really hard on tubes. When it comes time to retube my DR201, I'll probably order some more, or maybe just use the spare Koch labeled sextet of EL34B-STRS I have for my Sadowsky SA200s. Probably put some JJ KT88s in the SA200s when the time comes.
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The only currently manufactured KT88 that has worked for me in my DR201 is the TAD, which I believe is a rebranded (or possibly built to TADs specs) Shuguang. They sound pretty good and I've never gotten any bad ones but they don't last forever and they are a bit fragile for touring in my experience (but so is every other currently manufactured KT88 I've tried).
To be fair I haven't tried everything out there but the ones currently available that I HAVE tried:
JJ: Far too unreliable, always kept drifting and very often one tube in a matched quartet would redplate straight out of the box. Actually I could never get enough time out of them to even decide whether I liked the sound or not.
EHX: Couldn't handle the DR201 at all, started crackling and went bad pretty fast. I didn't like the sound either., very lifeless.
Sovtek KT88: A joke. Is it even a proper KT88???
Rebranded/tested Shuguangs would be my advise. TAD seems to do a great job of matching/testing. Just my personal opinion of course.
It's sad that the Svetlana factory in St.Petersburg ("Winged C") shut down. Their KT88 was the last REALLY good KT88 in my opinion. Sadly their last years of KT88 production suffered from problems with the glass/vacuum and just failed straight out of the box so I wouldn't recommend buying any leftovers online.
To be fair I haven't tried everything out there but the ones currently available that I HAVE tried:
JJ: Far too unreliable, always kept drifting and very often one tube in a matched quartet would redplate straight out of the box. Actually I could never get enough time out of them to even decide whether I liked the sound or not.
EHX: Couldn't handle the DR201 at all, started crackling and went bad pretty fast. I didn't like the sound either., very lifeless.
Sovtek KT88: A joke. Is it even a proper KT88???
Rebranded/tested Shuguangs would be my advise. TAD seems to do a great job of matching/testing. Just my personal opinion of course.
It's sad that the Svetlana factory in St.Petersburg ("Winged C") shut down. Their KT88 was the last REALLY good KT88 in my opinion. Sadly their last years of KT88 production suffered from problems with the glass/vacuum and just failed straight out of the box so I wouldn't recommend buying any leftovers online.
The TAD KT88-STR looks like Shuguang KT88-98 to me. I agree the KT88-98 is a good tube and TAD seems to have a good process for burn in, testing and matching. I think JJs sound a bit better, but that's my subjective opinion.
I have not had your luck with JJs, but I have read others have had similar experience. Whatever tube you buy needs to be burned in and thoroughly tested before matching. I am running JJs in several amps that have similar voltages to Hiwatts including a Reeves 400 which is a Hiwatt DR405 clone, and JJs are more stable and holding up better than any other KT88s I have run. The last quad of JJs I bought from Eurotubes was perfectly matched out of the box and very stable.
I have read the JJ factory puts out bad batches from time to time. This is why the burn in and thorough testing is so important. I have also read that the Chinese can be very tricky and like to sneak bad product into batches with good product...so this relates to Shuguang manufactured tubes as well. The last set of Shuguangs KT88V-STRs I bought were extremely drifty and poorly matched, and they were tested and matched by Ruby and also the vendor I bought them from...maybe I just got a bad set. I should have asked for a refund, but after about 10-12 hours they seemed to settle down.
All of the EHX KT88s and 6550s I have received in used amps failed very quickly. The tubes sounded nice in my Reeves 400, but the don't seem to tolerate high voltage. Other New Sensor made KT88 and 6550s also are known for having problems with high voltage. There are related threads on multiple forums across the internet.
I believe Sovtek KT88s have been discontinued. I have a sextet running in a Trace Elliot V6 that have test results indicating they are a matched set. They were in the amp when I bought it. Last time I checked the bias, the tubes were running hot and the matching was not very tight. I dialed the current back into spec and the amp sounds great and makes a lot of power.
After my Sunn 200S got stolen in 1973, I bought a 200-watt Hiwatt head. It was a step up for sure. After a couple of years it got stolen too, and I replaced it with the 100-watt version. I used that for a bunch of years, but really got tired of the weight. I bought the first GK 200RB (feb 1982), and was actually quite happy with it. I've had a LOT of amps since then, and to be truthful I never missed the Hiwatt. between the size/weight and tube upkeep, it just wasn't worth it to me.
I have the Ruby STR in my DR201-like amp and they've been great, got a set of gold lion (new sensor) reissues to try out and they had the same problem you described with the EHX, lots of crackle and noise right off the bat. I spent some time setting the bias on the amp but those tubes didn't seem at all happy so I never even got the point of play testing, just took them out and went back to the Ruby. Bought a backup set of Ruby and put the GL back on the shelf.
I'm with you on JJ as well, they've always been a problem for me. Unless I'm buying rebranded or extended burn in I just don't bother, and even then I only get them if I have no other good option. Seems like no matter where I buy JJ they've been prone to early failures or uneven drift.
Agree on the winged C as well, still have winged C 6550s in my SVT and a set of spares for that amp.
IMHO, buying any output tubes without an extended burn in is risky. Unfortunately the vacuum is not perfect when the tubes are made. The burn in allows the tube getters to clear remaining gases left within the glass envelope. The burn in should be done before matching as the tubes' operating point drifts until the gas is depleted. The burn in also gives marginal tubes the opportunity to self destruct. I am pretty sure both Ruby and TAD do a burn in before testing and matching.
I am at a bit of a loss as to why the Ruby KT88V-STRs I bought were so drifty. They drifted so far apart that they were totally useless, and then drifted back together over about 12 hours. I shuffled the tube order and the best match I could get was: 45mA, 42mA, 42mA, 40mA.
The amp may just be really sensitive to gassy tubes. It has an excessive amount of resistance in the bias supply and grid network. Gassy tubes tend to have a small amount of reverse grid current. The large resistance translates the small reverse current into a significant bias error, which results in increased tube current.
These guys are walking distance from me. I don't know if they do a burn in. KT88 | 6550 | KT90 | KT120 | KT150 Guaranteed Tubes for Sale - VivaTubes.com
New Current Matched Quad (4) Psvane KT88 $97.
Shuguang?
New Current Matched Quad (4) Psvane KT88 $97.
Shuguang?
I guess in the purest sense, neither.
From Wikipedia:
The design is today known as the beam tetrode but historically was also known as a kinkless tetrode, since it is a four-electrode device without the Invalid Link Removed kink in the anode current vs anode voltage characteristic curves of a true tetrode. Some authorities, notably outside the United Kingdom, argue that the beam plates constitute a fifth electrode.
Full article hear: Beam tetrode - Wikipedia
How did the matching go with the Shuguang EL34Bs you put in DR201s? What tubes did you put in the DR405? Results?
I got 2 identical matched sets of Tubestore Sugaug for the 200's. I got 2 identical matched sets of Tubestore Gold Lion for the 400's. All numbers for each pair of amps are the same. I only replaced the tubes in the 200 in the foto so far.
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Here are my 2 DR405 heads. My back dont like um. My shoulders hate um. My feet wish Scotty would beam them to hell. My ears love them.
Jim Carr
Dr. Jim
- Jan 21, 2006
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Those must be very scarce.
Takes me back, and takes my back, LOL!
Jetro Tull at the Boston Tea Party, 1969.
My Marshall Major was 84 lbs. It was a drag even when I was 20. 50 years later?
Oh hell, any not? LOL.
If they weren't so expensive, I'd try to find one. Guess I'll have to content myself with my Prodigy.
Takes me back, and takes my back, LOL!
Jetro Tull at the Boston Tea Party, 1969.
My Marshall Major was 84 lbs. It was a drag even when I was 20. 50 years later?
Oh hell, any not? LOL.
If they weren't so expensive, I'd try to find one. Guess I'll have to content myself with my Prodigy.
If I had one of those Hiwatt amps, and was going to actually gig with it, I would have another box made for it that was shorter and put some serious handles on it. From the pics, it looks like you could save 4 to 5 inches in width.
