Gold Lion KT88 vs Tung-Sol 6550 vs Tung-Sol KT120 for use with ST120?

Hello again! I've got a Bob Latino VTA ST-120, currently running Tung-Sol 6550 power tubes. I'm thinking of picking up some other power tubes, just to hear what the difference sounds like. I've heard good things about the Gold Lion KT88 and the Tung-Sol ST120. Any consensus on those two tube varieties for use with the ST120?

I have the same amp and love it. I listen in mostly ultralinear.
I started with TS6550's and got them over KT88's as the description had said they sounded very balanced and musical whereas the KT88 had more low end. As I was new to tubes (hence my name) and didn't know if I lacked bass, I got the 6550's. I liked them. I've tried EH KT88 and wasn't impressed with these. I never had the GL's as they cost almost as much as the KT120's that I've had for a little over a year. They're like the 6550's but gutsier all around. As they run at nowhere near their limit in this amp, they should last a long time too. I got mine from McShane (forum member, no connection). FWIW, they're tall but fit under a dynaco cage with a little bit to spare.

My amps are M-125, so not exactly what you're looking for in a response, but, I've used Gold Lion KT88 and Tung-Sol KT120 tubes.

I loved the KT88's and after about 1500 hours I wanted to try the KT120. After about 30 hours the KT120 tubes were a tiny bit brighter, definitely "easier" sounding, more effortless, more comfortable, just as natural sounding, and run cooler. No steps backward, everything is either equal or better.

GL's have served me well for 7+ years. I run KT-66's. Often thought about getting a quad of 88's but haven't done so yet. Have rolled several driver tubes and really like my 1960's 12AU7 amperex as center and clear top NOS RCA's for the two channels.

I have only run Sov Tec KT-88s and Tung Sol KT-120s. The KT-120s were far superior. I keep meaning to try some GL KT-88s in this amp (running 2 sets of matched quads in my VAC PA160 Mono Blocks) but haven't gotten around to it.

Brap wrote:GL's have served me well for 7+ years. I run KT-66's. Often thought about getting a quad of 88's but haven't done so yet. Have rolled several driver tubes and really like my 1960's 12AU7 amperex as center and clear top NOS RCA's for the two channels.

Are you running KT66's in an ST120?

No, running them in an ST-70

I have not run KT-120's in mine.  For context, I listen to mostly classic rock and hard-bop jazz.  Here's a link to the whole system if you're curious.
I went through numerous tube combinations but found bliss a few years back with the following and have never looked back.  It's impossible to make recommendations as there are far to many factors (speakers, cables, preamp, etc.) - but I have not touched a thing since 2019 when I settled on this combo:

- TAD KT88-STR matched quad power
- Mullard CV4003 driver
- RCA Cleartop 12AU7 phase inverters
- Mullard GZ33 rectifier
- Russian K40-Y PIO coupling caps
- VTA Auto-bias board

great question, great answers, and if anyone has tried KT77s or KT90s, I'd like to hear more about them also !
I don't have much time to do tube rolling, so I depend on the people in this forum and their opinions on all these tubes, thanks

KT90 and KT120 are similar, better than KT88. I would pick KT120 instead since the price is almost the same if I plan to use KT120 in other amps. The KT120 is well balance with Jazz and Classical. Just make sure, the PT has enough current for filament since KT120 is 1.95A

rayton wrote:KT90 and KT120 are similar, better than KT88. I would pick KT120 instead since the price is almost the same if I plan to use KT120 in other amps. The KT120 is well balance with Jazz and Classical. Just make sure, the PT has enough current for filament since KT120 is 1.95A

KT90 ( obsolete ) and KT120 are less linear then KT88. See distance between the curves.

In my ST120 I used Tung-Sol 6550 and thought they sounded great.

In my M-125s I use TS KT120 which also sound great.

I haven’t tried Gold Lions but might for my forthcoming ST70.

peterh wrote:

rayton wrote:KT90 and KT120 are similar, better than KT88. I would pick KT120 instead since the price is almost the same if I plan to use KT120 in other amps. The KT120 is well balance with Jazz and Classical. Just make sure, the PT has enough current for filament since KT120 is 1.95A

KT90 ( obsolete ) and KT120 are less linear then KT88. See distance between the curves.

For rock music, I would go with KT88. Somehow the KT120 doesn't sound good with rock but Jazz and Classical are wonderful, the vocal is very clear and sweet.

rayton wrote:

peterh wrote:

rayton wrote:KT90 and KT120 are similar, better than KT88. I would pick KT120 instead since the price is almost the same if I plan to use KT120 in other amps. The KT120 is well balance with Jazz and Classical. Just make sure, the PT has enough current for filament since KT120 is 1.95A

KT90 ( obsolete ) and KT120 are less linear then KT88. See distance between the curves.

For rock music, I would go with KT88. Somehow the KT120 doesn't sound good with rock but Jazz and Classical are wonderful, the vocal is very clear and sweet.

I agree - I rolled a variety of tubes through my ST-120, finally settled on - TAD KT88-STR matched quad power tubes, Mullard CV4003 driver, RCA Cleartop 12AU7 phase inverters, and a Mullard GZ33 rectifier a few years ago and haven't looked back. For context, the rest of my system can be viewed here: SYSTEM and includes a VTA SP-13 preamp and a VTA PH-16x phono stage.

If you're curious about my music collection, it can be found here: MUSIC

I have identical experience as << ttocs >>, with KT-88 and KT-120, and yes KT-120 sounds better all across top to bottom. Notice, I use the SS weber wz68 rectifier. I have rarely played any rock, but when I had, didn't find anything that I dislike so far. (JBL L-7 towers-with KT-120) and pure silver speaker cables. The human voice rendition is out of this freaking world.
Follow your ears, if you can't hear what others hear, or vice versa, who cares , it is what you hear that counts.

Right now, four matched tubes (Amazon Price), Gold Lion KT88 = $305, Tung-Sol KT-120 = $422......decisions, decision.....

I wish there was some kind of "Tube Library" when we could borrow tubes to try......

GL products are currently hard to get FYI. Have a spare set of 66's on order now for over 6 weeks. Using Tube Depot

I haven't had good luck with GL - I'd probably go 6550s - but it aways seems a flip of the coin.

Bob Latino wrote:

You might also want to check out newer NessTone output tubes. These are reportedly made in China by Shuguang and are modestly priced. I had one customer last year tell me that he had very good luck with their 6550 output tubes. They also make KT88 and EL34 output tubes Link Below.

Quad of Nesstone 6550 output tubes

Bob

Wow a quad for 100 bucks - that is awesome.

as of yesterday NessTone is also out of all tubes, all buy buttons are disabled

Just now they show four sets available and prices have risen to 149.99.

I'll give them a try, so make that three available.

It may be less that that available. Got my quad set in today and one didn't light up, 2 buzzes from the left speaker and then the rectifier arced. Shut it all down. Contacted Nesstone and a matched pair is on its way to me. Good thing I've got a few GZ 34's in my inventory.

i just broke in a new quad of matched Ruby 6550 srt tubes i got as a back up....
Had a new matched quad of new production Mullard KT88's that absolutely killed it!!!
In comparison,  the Ruby's are a great tube and prices are right. Bias has been ROCK steady.
Im running them in my Original ST120 with a NOS 5U4GB.
For the current state of our hobby.....cant touch them for the price IMO.