Author Topic: KT-88 / 6550s?  (Read 7020 times)

Offline richidoo

  • Out Of My Speaker Cabinet
  • ******
  • Posts: 10639
Re: KT-88 / 6550s?
« Reply #15 on: November 10, 2015, 08:34:09 AM »
  I prefer Sletvana 6550 over the others. better tonality IMO with AR.

Very nice tubes, used in all the big name brands for many years. But it was discontinued recently. Prices popped, but now the normal pipeline has run dry. I would have got them as that was original in the amp I'm retubing.

Some reviews suggest the Gold Lion KT-88 are even better, so I ordered those.
"I don't care much about music. What I like is sounds." - Dizzy Gillespie  (Audiophile or Liar?)

Offline sleepyguy24

  • Obsessively Audiophilic
  • ****
  • Posts: 890
Re: KT-88 / 6550s?
« Reply #16 on: November 10, 2015, 08:52:11 AM »
I think you will be most happy with the Gold Lion KT-88s although I think you should look into the Tung Sol KT120 for your AR. With my Jolida JD502P amp I had a some of the recent re-issue KT88s mentioned.

The JJ blue glass KT-88s to me had boomy bass and a reserved top end.

I also had Penta KT-88 SC solid black plate tubes. They had a very warm tone to them.

The Tung Sol KT88s I found matched what Jim McShane said about them.

Now I just have the Tung Sol KT-150s in the Jolida and am very happy. EL34 sweet midrange and highs with lots of punch in the bass. It is weird to see the tube be almost as tall as the transformers though.

« Last Edit: November 10, 2015, 08:55:55 AM by sleepyguy24 »

Offline rollo

  • Audio Neurotic
  • *****
  • Posts: 4959
  • Rollo Audio - Home demo the only way to know
Re: KT-88 / 6550s?
« Reply #17 on: November 10, 2015, 09:06:41 AM »
  I prefer Sletvana 6550 over the others. better tonality IMO with AR.

Very nice tubes, used in all the big name brands for many years. But it was discontinued recently. Prices popped, but now the normal pipeline has run dry. I would have got them as that was original in the amp I'm retubing.

Some reviews suggest the Gold Lion KT-88 are even better, so I ordered those.


   Cool. Bias adjustment in order I believe.


charles
Free in Home demo.
 contact me  at rollo14@verizon.net
Aqua Formula & La Scala DAC- INNUOS  -VU JADE DAC  - Rethm Speakers - PI Audio Uberbuss - Triode Wire Labs- Kuzma - Furutech - Audio Hungry Qualiton - Fritz Carrera speakers

Offline richidoo

  • Out Of My Speaker Cabinet
  • ******
  • Posts: 10639
Re: KT-88 / 6550s?
« Reply #18 on: November 10, 2015, 09:48:38 AM »
I think you will be most happy with the Gold Lion KT-88s although I think you should look into the Tung Sol KT120 for your AR. With my Jolida JD502P amp I had a some of the recent re-issue KT88s mentioned.

Thanks Dean. I hope so!
Wow, that looks awesome!! That's a lot of tube power!
I asked about KT120, was told they are too heavy to mount horizontally.

   Cool. Bias adjustment in order I believe.

Oh yeah. Zero it out and start from scratch. Wise move even when changing to a new batch of same tubes. The AR instructions make it easy for mk3. Mark 1&2 are tricky.
"I don't care much about music. What I like is sounds." - Dizzy Gillespie  (Audiophile or Liar?)

Offline richidoo

  • Out Of My Speaker Cabinet
  • ******
  • Posts: 10639
Re: KT-88 / 6550s?
« Reply #19 on: November 21, 2015, 08:13:04 PM »
Sol came over and installed the new tubes today. I went with the Gold Lion KT-88s on Jim McShane's recco. He thinks they are the best of the type available now. They feel really solid and good quality. They look beautiful in the amp. A new batch had just come in, so Jim burned in a bunch over a weekend then matched 2 quads for me within 1/4%! He matches then at operating conditions like AR does. With bias zeroed they drew around 10-13mA, right in the middle of the 5-20 range AR wants to see with new tubes. Then after warm up add in most of the bias and let it heat up and settle, then final bias 65mV across .5ohm makes 65mA to each tube (in pairs.) They were rock solid on bias. Just stayed exactly where they were put after 2 hours.  I've never seen tubes that stable before. AR bias pot is nicely padded to make good range of motion and adjustments very easy.

After my daughter's Nutcracker recital this evening I put the amp into the system with AR Ref 1 preamp, and Buffalo2 DAC (all balanced) and my new speakers and immediately noticed the smoothness and liquid sound of the tubes. It was foggy at first, but after an hour it was cleared up a lot. Still not as open as it will be, but it's already so beautiful. Very hard to shut it off and go to bed. I can't believe I have modern AR electronics in my system! They are long term loaners from stereofool, but I am so blessed to hear my music like this. Thanks Steve!   Great to have tubes back in the system again. 10 per side!

Listening to my favorite goodnight last CD of the night record, Leon Fleischer's comeback album, "Two Hands" solo classical piano favorites, played like only he can do. The tubes make it come alive, so magical.
"I don't care much about music. What I like is sounds." - Dizzy Gillespie  (Audiophile or Liar?)

Offline hometheaterdoc

  • Obsessively Audiophilic
  • ****
  • Posts: 655
    • Night & Day Audio
Re: KT-88 / 6550s?
« Reply #20 on: November 21, 2015, 09:00:43 PM »
good to hear you speak so happily about your system, again Rich!!! 

i can practically hear your excitement from that post :)

i got to hear the other pair of your speakers tonight at carl's....  playdate for Luke and Ryan meant playdate for Carl and Shane to listen to his system with the new speakers in the chain...  damn i like his walnut cabinets.. did you get the same finish?

they sounded very  good on live recordings, less so on other stuff.... but Carl was running dac direct into mac amp, giving his tubes a breather in the preamp...  i bet the preamp in the mix would fix it all right up.... i want to listen to some more stuff in his room again...

depending on the tube amp on display, i'll keep these kt88s in mind for a tube roll or retube...

Shane Sangster
Night & Day Audio - AMR, Alpha Design Labs, AURALiC, Audeze, Bakoon, Devialet, ENIGMAcoustics, Exogal, Harbeth, iFi Audio, Lumin Music, M2Tech, PS Audio, Pure Audio, REL Acoustics Ltd, Sennheiser, Tannoy, Unison Research, WyWires & more

Offline richidoo

  • Out Of My Speaker Cabinet
  • ******
  • Posts: 10639
Re: KT-88 / 6550s?
« Reply #21 on: November 22, 2015, 11:26:27 AM »
Hey Shane, yes havin a grand ole time. Cleaned it all up and organized the wires. Ya walnut. Cabs are designed in Italia, built/finished in Mexico iirc? They are very transparent to the amp, so they change like chameleon with different amps. Sol's I15 was super nice, detailed, plenty of power. VT100 more laid back, but only 5 hours on tubes.
"I don't care much about music. What I like is sounds." - Dizzy Gillespie  (Audiophile or Liar?)

Offline rollo

  • Audio Neurotic
  • *****
  • Posts: 4959
  • Rollo Audio - Home demo the only way to know
Re: KT-88 / 6550s?
« Reply #22 on: December 11, 2015, 07:18:09 AM »
  Should all be broken in by now.  Rich is there not a different bias setting using KT-88 in lieu of 6550 ?
   Ya got me thinking on bringing my AR 250DC Servo amp back into the mix. When I owned maggie 3A's a wonderful match. however Maggie wires de- laminated and are now gone gone gone. :(
    Would need [20] 6550 and 12 other small tubes. Costly but worth every penny. All i need is more pennies, oye !
    Actually looking for a quad of Marconi , GE or Tungsol for the power supply and [16] Sletvana. Then there are [2] 12AT7, [2] 7308, [4] 6DJ8, [2] FQ7 and [2] others I cannot remember right now. 32 in total oh my !
   Nice to hear back to tubes all over again.

charles
   
Free in Home demo.
 contact me  at rollo14@verizon.net
Aqua Formula & La Scala DAC- INNUOS  -VU JADE DAC  - Rethm Speakers - PI Audio Uberbuss - Triode Wire Labs- Kuzma - Furutech - Audio Hungry Qualiton - Fritz Carrera speakers

Offline tmazz

  • Out Of My Speaker Cabinet
  • ******
  • Posts: 7650
  • Just basking in the glow of my tubes.....
Re: KT-88 / 6550s?
« Reply #23 on: December 11, 2015, 10:10:56 AM »
  Should all be broken in by now.  Rich is there not a different bias setting using KT-88 in lieu of 6550 ?
   Ya got me thinking on bringing my AR 250DC Servo amp back into the mix. When I owned maggie 3A's a wonderful match. however Maggie wires de- laminated and are now gone gone gone. :(
    Would need [20] 6550 and 12 other small tubes. Costly but worth every penny. All i need is more pennies, oye !
    Actually looking for a quad of Marconi , GE or Tungsol for the power supply and [16] Sletvana. Then there are [2] 12AT7, [2] 7308, [4] 6DJ8, [2] FQ7 and [2] others I cannot remember right now. 32 in total oh my !
   Nice to hear back to tubes all over again.

charles
   

The Winged C 6550s are out of production, but can still be found at the retail level. But... if you are going to do this, now would be the time, because as that retail sock starts to dry up the prices are going to go nowhere but up.
Remember, it's all about the music........

Nola Boxers
Sunfire True SW Super Jr (2)
Quicksilver Mid Monos
ARC SP-9
VPI HW-19 Mk IV/SDS/SME IV/Sumiko Blue Pt. Special
EE Minmax DAC/Bluesound Node/Denon 2910
TWL Power Cords/MIT Cables

Offline richidoo

  • Out Of My Speaker Cabinet
  • ******
  • Posts: 10639
Re: KT-88 / 6550s?
« Reply #24 on: December 11, 2015, 10:12:16 AM »
Hey Charlie, Yes all broken in and sounding excellent. Gold Lion KT88 are great sounding and great quality tubes. The matching was incredibly accurate so no problems. They biased up steady. After a month they rose about 10% so I need to turn them down a little.  I'm a bit afraid to put my hand in the high voltage chassis, but it's pretty easy to do on mine.

Yes the bias is always different, even replacing the same type tubes from the same brand. You have to turn bias all the way down (usually unintuitively clockwise,) warm up the tubes and bring up the bias slowly to 90%, let it heat up more, then final adjustment. Then recheck after a day, a week and a couple months to note any drift.  New Sensor family tubes are usually very steady bias, ime.

Retubing the 250 sounds like a fun project! NOS power tube prices are very high and they will not be matched as needed by AR. There are no more SED 6550C available, they were called Svetlana when yours  were made, then NewSensor got the rights to 'Svetlana' so the real Svetlana rebranded as SED for American sales, now they are belly up, or at least the 6550s are all done. AR, VTL and others used the SEDs originally. But AR has switched completely to NewSensor for everything. The new production tubes from NewSensor are excellent quality and that's what AR sells for retubing, Sovtek brand. Same mfg as GoldLion, TungSol, Electro Harmonix, etc, American owned company in Russia. Many of your small tubes are probably still OK, test em. Make sure they are marked with Sharpie when you remove them from the amp as older AR amps had small tube bias adjusts. Definitely obtain written bias instructions from AR before bringing it to a local tech. If they try to do it without instructions kablammo. Some of the startup procedures of the older amps were pretty complex.

A quad of sovtek 6550 as you would get ordering direct from AR is $125/quad from McShane. He burns tests and matches with similar quality as AR, probably about half the price. TungSols are supposed to be "more refined" with excellent bass $140/qd, Gold Lions are "the best" for $220/qd. ymmv  For that many tubes in an old amp, I'd do the Sovteks. Probably just as good as SEDs.
http://www.mcshanedesign.net/tubes.htm
Wherever you get them must do thorough burn in and matching, not "factory matched" BS. Upscale is supposedly good at matching. I've bought from tubedepot a few years ago, they weren't as well matched as I would like. AR needs closely matched tubes. McShane is a tech, he understand what different amps need and consequences of mistake. He can offer you advice of what to put in there.

Found the manual online, has bias instructions:
http://www.audioresearch.com/ContentsFiles%5CD250IIServo_Manual_Schem.pdf

"I don't care much about music. What I like is sounds." - Dizzy Gillespie  (Audiophile or Liar?)

Offline rollo

  • Audio Neurotic
  • *****
  • Posts: 4959
  • Rollo Audio - Home demo the only way to know
Re: KT-88 / 6550s?
« Reply #25 on: December 12, 2015, 06:20:14 AM »
  Thanks richidoo. I have the manual and orig. box. I blew the 1 Ohm biasing resistor and it needsreplacing. Yeah hit the wrong TP POP. Easy enough to do. Getting NOS resistor from AR.
   Biasing is real easy, the hard part is this sucker weighs 150 Lbs. Tough to move for me.
    The reason not being used with Pipedreams is that the tubes were noisy and the Pipes very sensitive and tube hiss was annoying.
     Then came along my SET amps. Consonance Cyber 211. A great match until a 211 failed and took out trannie and more. Had the amps totally rebuilt with better everything. V-caps, Tantalum resistors Custom trannie. O all cool again and then my beloved RCA 211 tubes failed. The last set I had now $1800 a pair if one can find them. United as well almost $2000. Went back to GE to 211 and sound was different and not to my liking.
     Then I heard the Arion hybrid in my system. Game over they are fine with my speakers and two tubes.
     Went back to SET since I thought that was my Eden. However the SET could not match the Arion. So now I'm thinking [ dangerous] that the Ole AR250 will change that.
     Heck I'll put back the Snell's which are a match made in heaven with AR amps.
     Heck I could sell the AR250 for good money I see them at $3500. Man if I had Maggie's again one would have to rip the AR out of my dead cold hands.


charles
    Ba
Free in Home demo.
 contact me  at rollo14@verizon.net
Aqua Formula & La Scala DAC- INNUOS  -VU JADE DAC  - Rethm Speakers - PI Audio Uberbuss - Triode Wire Labs- Kuzma - Furutech - Audio Hungry Qualiton - Fritz Carrera speakers

Offline richidoo

  • Out Of My Speaker Cabinet
  • ******
  • Posts: 10639
Re: KT-88 / 6550s?
« Reply #26 on: December 12, 2015, 06:34:26 AM »
OK, good luck with your decision!
"I don't care much about music. What I like is sounds." - Dizzy Gillespie  (Audiophile or Liar?)

Offline richidoo

  • Out Of My Speaker Cabinet
  • ******
  • Posts: 10639
Re: KT-88 / 6550s?
« Reply #27 on: December 13, 2015, 09:56:56 AM »
The tubes only rose 2-3%, not 10%. Damn common core math.  :duh
"I don't care much about music. What I like is sounds." - Dizzy Gillespie  (Audiophile or Liar?)

Offline rollo

  • Audio Neurotic
  • *****
  • Posts: 4959
  • Rollo Audio - Home demo the only way to know
Re: KT-88 / 6550s?
« Reply #28 on: December 17, 2015, 10:05:10 AM »
Still a major investment for the DR250 still contemplating.

charles
Free in Home demo.
 contact me  at rollo14@verizon.net
Aqua Formula & La Scala DAC- INNUOS  -VU JADE DAC  - Rethm Speakers - PI Audio Uberbuss - Triode Wire Labs- Kuzma - Furutech - Audio Hungry Qualiton - Fritz Carrera speakers

Offline steve

  • Obsessively Audiophilic
  • ****
  • Posts: 433
    • Reference components
Re: KT-88 / 6550s?
« Reply #29 on: October 12, 2016, 08:04:00 PM »
  Should all be broken in by now.  Rich is there not a different bias setting using KT-88 in lieu of 6550 ?
   Ya got me thinking on bringing my AR 250DC Servo amp back into the mix. When I owned maggie 3A's a wonderful match. however Maggie wires de- laminated and are now gone gone gone. :(
    Would need [20] 6550 and 12 other small tubes. Costly but worth every penny. All i need is more pennies, oye !
    Actually looking for a quad of Marconi , GE or Tungsol for the power supply and [16] Sletvana. Then there are [2] 12AT7, [2] 7308, [4] 6DJ8, [2] FQ7 and [2] others I cannot remember right now. 32 in total oh my !
   Nice to hear back to tubes all over again.

charles
   

The Winged C 6550s are out of production, but can still be found at the retail level. But... if you are going to do this, now would be the time, because as that retail sock starts to dry up the prices are going to go nowhere but up.

I have 7 Winged C Kt88s, and would love to have 8 to complete a double quad. Does anyone have an extra they would be willing to sell?

Cheers
Steve
Pre/Amp/ICs are the only components that can be tested for accuracy/naturalness.

Steve Sammet (retired)

SAS Audio Labs Test Phono Stage
SAS Audio 11A Preamplifier
SAS Audio 25 W Triode Amp
Test Speakers 20-20khz
SAS Audio ICs
12 parallel 18 gauge wires