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    Cheap KT-88 for MkIII

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    j beede

    Posts : 317
    Join date : 2011-02-07
    Location : California

    Cheap KT-88 for MkIII

    Post by j beede on Tue Apr 05, 2016 10:53 pm

    I have always run 6550 in my MkIII... with excellent results. There are lots of cheap KT-88s available these days and I was thinking about giving them a try. Anyone have any experience with Electro Harmonix, SOVTEK, JJ, or Valve Art KT-88?

    Bob Latino
    Admin

    Posts : 2378
    Join date : 2008-11-26
    Location : Massachusetts

    Re: Cheap KT-88 for MkIII

    Post by Bob Latino on Wed Apr 06, 2016 8:27 am

    j beede wrote:I have always run 6550 in my MkIII... with excellent results. There are lots of cheap KT-88s available these days and I was thinking about giving them a try. Anyone have any experience with Electro Harmonix, SOVTEK, JJ, or Valve Art KT-88?

    Below are my opinions - SO - they may not coincide with the opinions of others ...

    Sovtek has stopped making KT88's. You may still find some Sovtek KT88's on dealer shelves but they will eventually disappear. They were a great tube for the money. They now just make their 6550 which is a very good and reliable tube and sounds just a tiny bit "smoother" than their KT88 did.

    ElectoHarmonix KT88 .. good tube and an alternate to the Sovtek KT88. These are more expensive than the Sovtek KT88 and IMHO did not really sound any better than the Sovtek KT88.

    JJ - I don't use JJ output tubes. They (IMHO now) have reliability problems and I do not think that the quality control on their KT88, KT77 etc. was as good as the Russian tubes. Maybe 7 or 8 years ago a large batch of JJ tubes came from their plant in the Slovak Republic with undersized tube pins. One time I turned an amp upside down to work on it and two output tubes FELL OUT! They eventually fixed that problem but that issue left a bad taste in my mouth about JJ tubes.

    The Valve Art output tubes are made by Shuguang in China. These are what I would call a "best buy". Very reliable tubes and good sounding. Every now and then one will come in here with the glass a little crooked on the base. I just send it back to the distributor and get a straight one. These have proven to me to be every bit as reliable as a Sovtek or ElectroHarmonix output tube. Chinese tubes have come a long way in the past 10 years.

    Bob

    peterh

    Posts : 643
    Join date : 2012-12-25
    Location : gothenburg, sweden

    Re: Cheap KT-88 for MkIII

    Post by peterh on Wed Apr 06, 2016 8:54 am

    I beg to have another opinion regards to JJ tubes and KT-88 in particular.
    With some hesitation i started redistribution of JJ, as the terms was favorable. But so far
    ( about 1000 tubes later) i have encountered 5 tubes with problems, which i promptly replaced.
    In my vta-70 i use jj 6550 , they have made 1500 hr so far ( i have an hour-meter) , thet sound
    good and i havn't adjusted bias for a year now. ( i do check now & then but when it is 0.55 +. 0.2
    i do not care adjusting).
    I sell mostly to guitar amps, and they do live a hard life ( vibrations, shocks, wrong bias and
    full power ) so any weaknesses should be noticed here.
    I even have a JJ 5ar4 in my vta-70 as the supplied chinese flashed a year ago. I have stocked up
    with "cupper" but have not any reason to switch yet. But the day will come.

    I do not know about US distribution of JJ ( unless eurotubes ).

    This is my opinion and experience , other may differ.
    I have not seen the "pin problem" thus i cannot say anything about it. But as i get my tubes
    from the factory i only get fresh ones.

    bluemeanies

    Posts : 119
    Join date : 2015-02-09
    Age : 66
    Location : Folsom Pa.

    Re: Cheap KT-88 for MkIII

    Post by bluemeanies on Wed Apr 06, 2016 2:35 pm

    I guess I can say since Bob is the expert here that I am lucky since I have the Sovtek KT88's. In my understanding these are a decent power tubes. I myself have never had an issue. Very good imaging. In MY research for outputs tubes I will agree with Bob about the JJ and there reliability. I have read more than once about people's dissatisfaction with the product.
    If interested in the the Sovtek KT88 you might want to try thetubestore.com or Jim McShane.

    PeterCapo

    Posts : 380
    Join date : 2008-12-05

    Re: Cheap KT-88 for MkIII

    Post by PeterCapo on Wed Apr 06, 2016 10:07 pm

    You don't read a lot about this tube, but I have a quad of the Sovtek "Svetlana" 6550 and find them to be pretty good for relatively short $.  

    It's curious that JJ and/or their U.S. dealers do not seem to be making any kind of effort (that I am aware of) to repair the JJ image problem with the audiophile crowd in the U.S.  Maybe we don't account for enough of their sales for them to care, I don't know.

    Had a set of JJ E34L circa 2004 that sounded pretty nice.  More recently had a set of the JJ KT77 that sounded bad enough that I had to consider it some kind of defect - they were more recent production, so the pin diameter thing was not the issue.

    j beede

    Posts : 317
    Join date : 2011-02-07
    Location : California

    Re: Cheap KT-88 for MkIII

    Post by j beede on Wed Apr 06, 2016 11:34 pm

    Thanks for details Bob.

    I think JJ may have overcompensated on the pin diameter issue... I was unable to insert a new JJ KT-88 into the socket of my MkIII. The pins are way larger than the pins on the SOVTEK 6550 that came out of the amp. I was unwilling to apply enough pressure to get them in.

    The Electro Harmonix and SOVTEK both looks like bargains. I think I'll try both.
    ...j

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