Anyone Compared the New 6550/KT88s out there in their Amps?

[Grooves]

Hey Myles,

Why not KT-120's? I thought CJ was using those now instead of 6650's. I'm going to give them a go in my MV60SE at some point.

 

[mep]

I will be listening to some KT-150 tubes soon.

 

[wilson1]

Hi Everyone,

My 6550's on of my ARC VT150SE monoblocks just went out, those were the old Russian ARC supplied tubes if i remembered correctly that was replaced when it went to the ARC recommended service center locally.
What is the current recommendations for 6550/KT88's tube replacements that everyone is happy with?
Do i just replace the 2 pairs of power tubes only?
or replace all 13 of them for each amp ((2 matched pairs) 6550, (2) 6550 regulators, (1) 12AX7 regulator amplifier, (4) 12BH7A driver, (2) 6922 input)?

Thanks!

 

[DaveyF]

Hi Everyone,

My 6550's on of my ARC VT150SE monoblocks just went out, those were the old Russian ARC supplied tubes if i remembered correctly that was replaced when it went to the ARC recommended service center locally.
What is the current recommendations for 6550/KT88's tube replacements that everyone is happy with?
Do i just replace the 2 pairs of power tubes only?
or replace all 13 of them for each amp ((2 matched pairs) 6550, (2) 6550 regulators, (1) 12AX7 regulator amplifier, (4) 12BH7A driver, (2) 6922 input)?

Thanks!

Wilson, I think you might want to reach out to ARC to see if your amp can work with the new KT120’s. These tubes (if they can be safely fitted) would be a major upgrade over the 6550’s.
If not, I would suggest seeing if you can source some Winged C 6550’s...or better still ...if you can find them...and if in budget, some GE 6550’s. Depending on the age of the other tubes (and the budget), it probably pays to replace them all at the same time.

 

[wilson1]

HI Davey,
I have sent an email to ARC.. hopefully i will get an answer soon.
I did inquire about using the KT120/150's a few years ago on my VT150SE, in which the factory said >
"Unfortunately no. Engineering has not approved this use."
I was hoping someone would have tried them on similar ARC models, but not much luck search online.

 

[microstrip]

HI Davey,
I have sent an email to ARC.. hopefully i will get an answer soon.
I did inquire about using the KT120/150's a few years ago on my VT150SE, in which the factory said >
"Unfortunately no. Engineering has not approved this use."
I was hoping someone would have tried them on similar ARC models, but not much luck search online.

Unfortunately the answer is easy - no. Although the KT120 is more powerful than the 6550 it has a spec that precludes its use in most ARC cathode coupled old designs - max grid 1 voltage. It is -300V in the 6550 and only -200V in the KT120.

Audio Research had a modification kit for many of their modern amplifiers, but none was issued for the VT150SE. I have owned it and it was a fantastic amplifier. Looking at what they did in modern amplifiers perhaps it is possible to know what parts should be changed in yours.

 

[DaveyF]

HI Davey,
I have sent an email to ARC.. hopefully i will get an answer soon.
I did inquire about using the KT120/150's a few years ago on my VT150SE, in which the factory said >
"Unfortunately no. Engineering has not approved this use."
I was hoping someone would have tried them on similar ARC models, but not much luck search online.

Wilson, if ARC said the new KT 120/150's are a no no in your amp, that is the answer I would rely upon.

These new tubes are usually incompatible with the older design transformers, as such very few of the older amp designs ( from any manufacturer) are compatible with them.
I just acquired an amp that utilizes the new KT150's, compared to my older amp that uses 6550's, the SQ difference is HUGE....the new tubes are a game changer in the tube amp world,Plain and simple.
If budget allows, I would get rid of the VT150SE and seek out a new model utilizing the KT120/150's.

 

[wilson1]

What amps have you guys upgraded to, microstrip & Davey?

 

[DaveyF]

Jadis JA 30 Mk2 KT 150 version.

 

[microstrip]

(...) If budget allows, I would get rid of the VT150SE and seek out a new model utilizing the KT120/150's.

DaveyF,

Have you experienced the magic of well set up VT150SE system? In some aspects you need at less a REF250 SE to replace the VT150SE.

It is one of the few amplifiers I often say I could have stopped without regret.

 

[microstrip]

What amps have you guys upgraded to, microstrip & Davey?

The conrad johnson premier 350 and later the VTL MB750 and Atmasphere MA-2s, among many others. I needed more power for Soundlabs - first the A4's and later A1's.

Can we know what are the speakers and the preamplfier?

 

[DaveyF]

DaveyF,

Have you experienced the magic of well set up VT150SE system? In some aspects you need at less a REF250 SE to replace the VT150SE.

It is one of the few amplifiers I often say I could have stopped without regret.

Micro, have you experienced an amp utilizing the new KT120's or better still, the KT150's?

 

[Barry]

Wonder if everyone is still liking the sound of Shuguang Treasure KT88-Zs? I just popped a new pair into my ARC Ref10 phono PS that I had lying around from when this thread started. I really like the sound of the mids and top end better than either the Sovteks or SEDs Winged "C"s, but they're going to need some time to open up and the bass lacks impact. Both the 6550s variants are a little grainy on top in the phono stage as Marty originally noted. Any other options?

Oh, any observations on reliability? Thanks!

 

[Argonaut]

Barry...Try General Electric 6550A 1970's production for excellent detail and neutrality, Tung Sol Solid grey plate early 1960's or late 1950's Black plate if you are looking for a smooth and tonally rich presentation, NOS 70's Gold Lion KT88's if you can find them and can spare a Kidney, Vintage NOS General Electric KT88's are also pretty good.

Currently running an ARC Ref10 Line.

 

[Enoch Root]

Trying to resurrect an old thread here.

I'm interested in the current thinking on new production KT88 tubes. Price and availability from trustworthy sellers indicate that NOS are not an option for me.

Re-issue Gold Lion are pretty popular on the forums. Many people like the KT120, others say they're dry in the mids.
The Shuggie Treasure sounded interesting earlier in this thread but their availability seems spotty. Have they been surpassed by the Psvane?

Thanks in advance for contributing your opinion.

 

[Ron Resnick]

I chose KT-88s rather than 6550s for my VTL Siegfried IIs.

 

[Mendel]

Trying to resurrect an old thread here.

I'm interested in the current thinking on new production KT88 tubes. Price and availability from trustworthy sellers indicate that NOS are not an option for me.

Re-issue Gold Lion are pretty popular on the forums. Many people like the KT120, others say they're dry in the mids.
The Shuggie Treasure sounded interesting earlier in this thread but their availability seems spotty. Have they been surpassed by the Psvane?

Thanks in advance for contributing your opinion.

I have tried many different KT88/KT90?KT120 in my modified Rogue Audio Stereo 90.
First off, the premium high priced Chinese tubes like the Treasure KT88 and KT120 or the Psvane KT88 grey glass always sound excellent. My problem has been reliability. Without exception, my experience has been that one or more tubes in a quad will become unstable and not hold bias after a relatively short period of time. This is from reliable sellers not Chinese ebay. Very frustrating when $100 tubes fail and your quad becomes useless.
My go to KT88 is the Preferred Series KT88 from the tubestore.com. This is the same tube as the PentaLabs KT88SC. Not quite as nice sounding as the premium Chinese, but very close and better than the Gold Lion reissues in my amp. And very reliable, gone through 2 quads with no failures.
The GL KT88 was not reliable for me (2 tubes lost their vacuums in the box!) but I bought that quad over 5 years ago and quality may have improved. Never thought they sounded that good in my amp (kind of dull). I do love the GL KT66 reissue and now use that often. A more linear and holographic sound than a KT88 in my amp.
I never liked the sound of the Tung Sol KT120 in my Rogue. Very powerful and full sounding, but dry and sterile in the mids and flat sounding overall.
The EI KT90 is big and powerful sounding like the KT120, but no so dry in the mids. An excellent tube!

 

[dminches]

I am glad that someone resurrected this thread. I just bought a Zesto Audio BIA 120 which uses 4 KT88s. They cannot use 6550s. I am currently using Gold Lion reissues and I have no complaints but it sounds like I should try the Preferred Series at some point.

 

[Enoch Root]

Thanks people!

Yeah, it's pretty confusing.
Though I have a history with tube gear, I've been solid state for over 10 years.

I recently bought a new Cary sli-80 w/Mundorf caps, hexfreds, 2 inputs wired w/kimber, Grayhill switch, and WBT's.

Stock tubes were Electro Harmonix and boy did they sound awful. Now that I've got Amperex 7308, RCA 6SN7 and RCA 5U4G tubes, things much better. But the power tubes are a quandary.

I was pretty focused on the Psvane, accepting that there's a good chance of failure, then I noticed the Northern Electric which is apparently the same as Full Music. But the price keeps inching up.

The Preferred tubes are starting to seem like a safe bet.

 

[dminches]

Thanks people!

Yeah, it's pretty confusing.
Though I have a history with tube gear, I've been solid state for over 10 years.

I recently bought a new Cary sli-80 w/Mundorf caps, hexfreds, 2 inputs wired w/kimber, Grayhill switch, and WBT's.

Stock tubes were Electro Harmonix and boy did they sound awful. Now that I've got Amperex 7308, RCA 6SN7 and RCA 5U4G tubes, things much better. But the power tubes are a quandary.

I was pretty focused on the Psvane, accepting that there's a good chance of failure, then I noticed the Northern Electric which is apparently the same as Full Music. But the price keeps inching up.

The Preferred tubes are starting to seem like a safe bet.

I used to own that integrated amp. It sounded great with Vintage Tung Sol 6550s.