Author Topic: KT-88 / 6550s?  (Read 15239 times)

Offline richidoo

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KT-88 / 6550s?
« on: November 09, 2015, 11:14:46 AM »
What's good now?   

I'm deciding between New Sensor reissues Genalex Gold Lion KT-88s and Tung-Sol 6550, for use in ARC VT100.

Anybody familiar with these? Other recommendations?
Thanks

Offline Emil

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Re: KT-88 / 6550s?
« Reply #1 on: November 09, 2015, 11:53:08 AM »

Didn't know you could use a KT88 in an ARC amp
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Offline tmazz

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Re: KT-88 / 6550s?
« Reply #2 on: November 09, 2015, 12:18:35 PM »
I see it all the time. KT-88s and 6550 are pretty much plug in replacements for one an other, from an electrical standpoint anyway. From a sound standpoint the do differ, as do the different brands within each one of them.

Rich, have you checked with ARC to see if those amps will handle KT-120s. From what I hear they are the best of both world and have a higher plate dissipation. However they do draw about 15% more filament current so you need to check and see if the particular vintage VT-100 amp you are re-tubing has a power supply capable of ruining those filaments. Although I have never seen this mentioned I would also be concerned that the output transformers can handle the  the additional wattage that the KT-120s are capable of producing.

If you are interested I am sure one phone call to the ARC techs could clear up whether or not the KT-120s are OK to use in your amp.

Link to the Upscale Audio page on KT-120s:

http://www.upscaleaudio.com/tung-sol-kt120/
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Offline richidoo

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Re: KT-88 / 6550s?
« Reply #3 on: November 09, 2015, 02:30:07 PM »
Thanks guys

Tom, yes I did ask AR about KT-120s, they just said no amid answers to a few other questions. Jim McShane (tube seller) explained that the KT120s are too heavy to be mounted horizontally in VT100, but they are OK in Ref110 because its tubes are vertical.

McShane just emailed back recommending the KT-88 for sonic reasons. But warns no warranty on them when used in tube-finicky AR amps that originally came with 6550s.

I've read that the TS6550 are more bass, thicker sound, while GL KT88 are clearer midrange, refined treble, more forward etc. One guy compained it's not enough bass in his PrimaLuna with small OPT. I'm sure they both have good treble and bass, but maybe one is 'richer' while the other is 'clearer.'

Offline Triode Pete

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Re: KT-88 / 6550s?
« Reply #4 on: November 09, 2015, 02:41:32 PM »
Thanks guys

Tom, yes I did ask AR about KT-120s, they just said no amid answers to a few other questions. Jim McShane (tube seller) explained that the KT120s are too heavy to be mounted horizontally in VT100, but they are OK in Ref110 because its tubes are vertical.

McShane just emailed back recommending the KT-88 for sonic reasons. But warns no warranty on them when used in tube-finicky AR amps that originally came with 6550s.

I've read that the TS6550 are more bass, thicker sound, while GL KT88 are clearer midrange, refined treble, more forward etc. One guy compained it's not enough bass in his PrimaLuna with small OPT. I'm sure they both have good treble and bass, but maybe one is 'richer' while the other is 'clearer.'

FWIW, no power tubes should ever be mounted horizontally! Gravity on the filaments, especially when hot / glowing, is not good. The filaments will sag in-between the plates, causing issues...

Rectifiers tubes are OK mounted horizontally...

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Offline jimbones

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Re: KT-88 / 6550s?
« Reply #5 on: November 09, 2015, 03:10:04 PM »
after hearing about the pyrotechnics some tube power amp owners have experienced i decided to go solid!! :rofl:
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Offline richidoo

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Re: KT-88 / 6550s?
« Reply #6 on: November 09, 2015, 03:43:30 PM »
FWIW, no power tubes should ever be mounted horizontally! Gravity on the filaments, especially when hot / glowing, is not good. The filaments will sag in-between the plates, causing issues...

Rectifiers tubes are OK mounted horizontally...

My $0.02,
Pete

Very interesting! Thanks Pete.  That could be why the following generation AR amps like Ref110 went to vertical and have remained vert in the new 'designer' series too. This amp is circa 2006 iirc.

 :idea: Maybe I can run the amp on it's side to make the filaments vertical? Is inverted OK? It has forced fan cooling.

Offline StereoNut

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Re: KT-88 / 6550s?
« Reply #7 on: November 09, 2015, 03:45:32 PM »
after hearing about the pyrotechnics some tube power amp owners have experienced i decided to go solid!! :rofl:

Bock-bock-bock!  Chicken, Jim!?!?  Even I have turned to the "glass side".  :rofl:

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Offline Triode Pete

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Re: KT-88 / 6550s?
« Reply #8 on: November 09, 2015, 03:48:25 PM »
FWIW, no power tubes should ever be mounted horizontally! Gravity on the filaments, especially when hot / glowing, is not good. The filaments will sag in-between the plates, causing issues...

Rectifiers tubes are OK mounted horizontally...

My $0.02,
Pete

Very interesting! Thanks Pete.  That could be why the following generation AR amps like Ref110 went to vertical and have remained vert in the new 'designer' series too. This amp is circa 2006 iirc.

 :idea: Maybe I can run the amp on it's side to make the filaments vertical? Is inverted OK? It has forced fan cooling.

Rich,
Inverted is OK as long as the heat dissipates away from the other components... Heat is the enemy of electrical components... I would say normal vertical is best...

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Offline rpf

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Re: KT-88 / 6550s?
« Reply #9 on: November 09, 2015, 04:06:43 PM »

I've read that the TS6550 are more bass, thicker sound, while GL KT88 are clearer midrange, refined treble, more forward etc. One guy compained it's not enough bass in his PrimaLuna with small OPT. I'm sure they both have good treble and bass, but maybe one is 'richer' while the other is 'clearer.'

Yes, the TS 6550 (and TS 6L6STRs, as well as, to a lesser extent, the TS 120s) have a thick, bass heavy sound.

The Genelex KT88s are more balanced while still being full bodied. But I prefer the Penta KT88SC: I found it more balanced still, and more refined, particularly in the highs.

http://www.thetubestore.com/Tubes/KT88-Tube-Types/Preferred-Series-KT88

I have no idea how any of them will sound in an ARC.

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Offline rpf

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Re: KT-88 / 6550s?
« Reply #10 on: November 09, 2015, 04:12:49 PM »
after hearing about the pyrotechnics some tube power amp owners have experienced i decided to go solid!! :rofl:

Rare in a well designed amp if using well tested and burned in tubes. And not really an issue if the tubes are fused, as Rogues (and I think some ARCs and VTLs) are.

I do really want to hear your Modwright "tube state" SS amp though.  :D
« Last Edit: November 09, 2015, 04:21:27 PM by rpf »
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Offline richidoo

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Re: KT-88 / 6550s?
« Reply #11 on: November 09, 2015, 04:41:58 PM »
The Genelex KT88s are more balanced while still being full bodied. But I prefer the Penta KT88SC: I found it more balanced still, and more refined, particularly in the highs.

Thanks Rob, that's very helpful! 

Does tubestore do the screening and matching as required by AR amps? I'll read their website. Thanks

Offline jimbones

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« Reply #12 on: November 09, 2015, 05:23:02 PM »
after hearing about the pyrotechnics some tube power amp owners have experienced i decided to go solid!! :rofl:

Bock-bock-bock!  Chicken, Jim!?!?  Even I have turned to the "glass side".  :rofl:

SN

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Offline rpf

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Re: KT-88 / 6550s?
« Reply #13 on: November 09, 2015, 09:03:54 PM »
The Genelex KT88s are more balanced while still being full bodied. But I prefer the Penta KT88SC: I found it more balanced still, and more refined, particularly in the highs.

Thanks Rob, that's very helpful! 

Does tubestore do the screening and matching as required by AR amps? I'll read their website. Thanks

They claim they match them but I don't know about screening or burning them in. Unlike say Jim McShane or Upscale Audio that definitely do.

However they offer a 3 month warranty on the Genalex and a 6 month warranty on the Penta.
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Offline rollo

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Re: KT-88 / 6550s?
« Reply #14 on: November 10, 2015, 07:48:28 AM »
  I prefer Sletvana 6550 over the others. better tonality IMO with AR.

 
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