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202.156.2.130
I have just put in 4 Chinese KT88 into my amp and even without refining the bias, at 415V and 35ma it sounded good, nice and airy high, with good dynamics and bass. Teh high seemed to be slighly more then the Russian TS6550, but the 6550 is still more superior in term of the bass. Funny in my EL34 amp, 6550 and KT88 seemed to be much better then those EL34...!
Of the 4 KT88, 3 is un-marked with Made in China on it, suspect it is the cheapest Shuguang, the other one is Valve art KT88. Those are obtained when I bought a Sonic Frontier SF40 5 years ago. So the Shuguang should be at least 8 years old production, while the Valve art may be about 6 years old. The SF bias circuit has a blown power resistor, so one of the KT88 was gone with it or vici-versa...
I hope to learn again what is the feel on the current KT88. From all the posts, It seemed that Shuguang KT88-98, JJ, and EH enjoyed good feedback. I hope to have some insight about those vs the Gold Lion, of course, the ealier production types when the quality was still superb. As I type this, those lowly KT88 seemed to be production quite a nice sound in the class of the re-issue TS6550....Best rgds
William Lee
Follow Ups:
I didn't know you could just replace EL34's with KT88's. Could someone please explain that to me? I thought they were two separate classes of tubes with different pinholes and current/voltage requirements. Am I wrong? Could I just buy some KT88's, bias them and enjoy them?
I'm purchasing a Sound Valves Stereo 70 (basicallly like a Dynaco 70 II). BTW which tubes should I get, the AEG Telefunken EL34's or the Tesla E34L's? My speakers are Carver ALIII+'s in my basement, I listen to mostly dance and progressive rock, however lately I've been discovering smooth jazz.-Taz
My SFS 80 can use either; I'm using it with EL34's now, but have used KT88s in the past. KT88's supposedly give you twice the output wattage, but the amp has plenty of oomph with the EL34s.~Lester
Yes you can in most cases and with a slight rebias.The el34 was originally designed by mullard to replace the EL37 which a glorified 6L6..Many manufacturers wanted a slim profile tube that would look nice nice and give them more room for mechanical layout and making transformer and socket placement much easier.This tube also had to handle a higher plate voltage which they do up to 600vdc i believe.If you look at the circuits that most EL34s and KT88s are in the plate voltage is usually 420 to 500v.They cant handle the current that the KT88s can but when you rebias them to their nominal current rating you get pretty decent power out.Also since most KT88 and EL34 circuits use negative negative bias it makes it pretty straight forward.
As mentioned, it's best to check with the amp manufacturer.However I have done a few mods on amps which included replacing EL34s with KT88s and here are some things to know, some of which reflect my opinions:
1) 6L6s, EL34s, 6550s, KT88s and others are pin compatible.
2) KT88s sound better than EL34s
3) The big things to watch out for when replacing EL34s with KT88s are:
a) KT88s take more filament current than EL34s. Will the filament supply handle the increased load?
b) KT88s REQUIRE higher grid bias voltage than EL34s. If the amp has manual bias adjustments AND a grid bias power supply capable of the required higher KT88 bias voltage (at least -45VDC, -60VDC preferable) substituting should work. However I would never substitute a KT88 for an EL34 in an automatic bias circuit - you'd probably smoke the power supply, output transformers, cathode resistors or all of them.
c) Even if the KT88 swap works, the typical EL34 plate voltage is somewhat insufficient for a KT88. It'll work fine but possibly not reach its full potential.
d) Also the phase splitters in the amp, being designed for EL34 compatibility, may be incapable of sufficient voltage swing to sufficiently drive the KT88 grids.
for 6550's, KT88's, and KT90's, and some will even allow 6L6's, but not many. Check with your amp manufacturer, don't make assumptions on your own. Also, if your amp can use EL34's ask the manufacturer about the bias settings - they will be substantially different for EL34's than the others, from 15 to 20mv would not be unusual.
Dear WilliamYou got to watch that you don't go UL, or put the voltages on the plate too high.
Their main failure is that they go cherry red when you push them.
They do sound very open. The highs are near perfect.
Cheers
Which tube is better the Shuguang KT88 98 or the Art Valve Kt88 Gen reproduction tube. I see ATSI is selling the Art tubes for the same price but will give them the freeze treatment for 40.00 more. In your opinion which is better. I have heard good things abount the Cyro treated tubes and I am axious to try it in my CJ Premier 11a amp. Which is better.
Forget the KT90! The Shuguang triple-getter KT88-98 outclasses the KT90s in both my ARC amp and my modified Dyna MKIIIs. The treble has an airy, detailed quality, the mids are much warmer, and there is an almost 3D soundstage, nearly like REAL GEC/M-O Valve KT88! The KT90s had better bass, but I don't consider bass top priority. The KT88-98 is fantastic @ $90/quad. This tube is also marketed as Valve Art KT100. Even better is the octal base Shuguang EL156! Using an outboard Lambda regulated DC bench supply rated for 525 VDC at up to 800 ma, I fired up a quad of EL156 Shuguangs (reportedly made by liuzhou factory for Shuguang; starting in mid 1970s even Telefunken and Siemens labeled/boxed 10 pin base EL156 were made by Liuzhou)to great results. The plate dissipation tops 50 watts, so I cranked the bias to 90 ma at 525 volts; WOW! Everything Ilike about EL34 sound with superslam KT88 tones! $120/quad from SuperTNT. They are HOT!
hi Anon,Great news if there is EL156! What is the filament current? if they are around less then 2 A, then we could easily use them in the EL34/KT88 amp. I guess I will try the KT88-98 since I have not heard any thing bad about them so far!
Tks and Best rgds
William Lee
Filament current is identical to KT88. The EL156 is the most exciting tube in production. The original Telefunken plate dies, grid winders, and bottle formers were retained by Liuzhou who made them for Telefunken from 1970-`1981. It is made in small batches much like Tianjin tubes. The main drawback I saw with old Telefunken EL156 was the ten pin base; with an octal base, no problem! This tube REALLY bridges the gap between EL34 and 6550, and is ideal for SE designs as well as use in pure class A. If your xformer can handle it, a plate current of 100 ma (plate plus screen) per EL156 at 450VDC is NO problem, and a pair is capable of in excess of 125 watts in push pull. I have not tried them in triode, but they are a sweet, sweet tube. Perhaps someday China will be recognized as a top rank tube manufacturing country.
I just saw at his site he has about 200 pcs that he is testing. I sure hope most are good.PRM
To clarify, I actually have 150 in my possession right now, 50 are still enroute. The ones I have are about 1/2 of each types, I and II.
I'm burning in as we speak, but it takes a good bit of time for that. I'll know more about the dud count, etc. by later this week.I've got my fingers crossed!!
If you can get older production EI KT90s, they are FINE. Sadly, what's coming out of EI's factory these days has MAJOR QC troubles, across types. So, without an IRONCLAD guaranty, steer clear of EI, at least for now.Jim McShane likes the EH KT88 as a reasonably close runner up to properly made EI KT90s. IMO, that's a GOOD recommendation.
Eli D.
hi Eli,This is still the same that Manley helped to design? Some how I dont like the look, not as sexy as the KT88... :)
tks and best rgds
William Lee
Personally I like the slender shape of the KT90 more than the tubby shape of the KT88. But to each his own, right? ;-) For me the sonics and the looks of the KT90 are a great combo.
No, being a straight sided tube it isn't as cute as the coke bottles. But the sound is magnificent.Yes, David Manley had a role in their development, in fact in my files is the reply he wrote me back in early 1991 after I'd asked him about potential KT-90 use in the Citation II amp. David also hooked me up with Bill Perkins of PEARL who sent me a quad of type II during the first embargo on Yugo products back in the mid 90s (when KT-90s were impossible to come by!). BTW, Bill Perkins apparently had a hand in the changes made to the tube to take it from the type I to the type II.
Hey, Mullard EL34s are straight sided too! :-)
Tks Jim,I know you do go thru your tubes carefully, and that is a big assurance when those tubes are important to the amp. I went to your web site so many times and like some of the item, except that there is no check out feature etc. I hope to suggest if you could add some click click to check out or at least a link to your email handy.
tks and best rgds
William Lee
...in 'Vacuum Tube Valley' issue 19.
hi Jeffrey,It seemed that every one prefer KT 90 to KT88... The KT90 I saw was those produced in the mid 90s, that Manley helped to designed. It really look ugly! I don't mind VTL amp, but could not like the look of the KT90....
Best rgds
William Lee
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