KT120 vs Shuguang KT88 in my Mark IIIs

I had been running Tung-Sol KT120s in my VTA Mark IIIs since I built them this past December. Chose the KT120s because that's what I used in my previous amp which was the ST120. I wanted to try something different and curiosity got the best of me so I decided on KT88s based on comments by others who felt that the KT88 had a nice midrange and more extended top end.

After reading comments and reviews I decided to seek out the Penta Labs KT88SC only to find out that its no longer available. It was made by Shuguang specifically for Penta Labs. However, the deal between Penta and Shuguang ended for some reason. Fast forward a bit and now Ruby Tubes and also TheTubeStore have picked up the ball and struck deals with Shuguang for that same special construction tube. This particular version has three getters, two side and one top. I ended up with the Ruby KT88V-STR From Doug's Tubes because its the same exact construction as the Penta KT88SC.

I was able to make a direct comparison of the two power tube types by simply unplugging the KT120s and plugging in the KT88s, reset the bias to 0.50mv and listen. I now have about 30-40 hours on the new tubes. The first thing I can say is that, contrary to what I have read, this KT88 goes just as deep in the bass as the KT120. I found the bass to be equally deep and significantly better defined! I guess 'tighter' would be the word? At first, the KT120s sound like they are producing more bass but in actuality their bass is a little muddy and less defined when directly compared to the KT88V-STR. Moving on to the midrange and treble, (which is where I was looking for change) I found the midrange more forward and the treble more extended. Both positives in my system. I like these KT88s. The KT120s are now relegated to back-up duty.

What I plan to do in a couple months is revert back to the KT120s just to make sure that I'm not 'fooling' myself

BTW, I just started rolling some 6CG7s in the nine pin locations using proper adapters. Pretty interesting. Will report on that experience but first need to make sure these new KT88s are fully burned in. That's all for now.

Regards,
Wayne

Hi Wayne!

4 days now into the KT120's, 2 per M125.  Must note that I'm biamping with the treble being driven by a SS amp. Consequently the lower end behavior of the tube is what I'm mainly interested in. The KT120's seem to offer more punch in this regard. But I agree the KT88's I believe offer a slightly sweeter top end.

Wayne,
If you really want to make your socks roll up and down, try PSVanes KT-88 T-II outputs. IMHO a notch above the Shu Guangs and not quite as dark as the Gold Lions and SGs. As with all Chinese electronics, tubes can be a crap-shoot but I've got several hundred hours on mine, no issues, incredible 3D sound and very detailed across the spectrum.
I wish there were a Jim McShane retailing these in the U.S. with the same torture tests he puts his Gold Lions through to ensure their reliability. Returning a bad tube to Changsha or Hong Kong is a fool's errand; shipping costs more than the toob.

I was not very happy with KT120's in my ST120. I replaced them with GL KT88's which in turn got replaced by Shuguang Black Treasure KT88-Z's. I like the KT88-Z's the best. The KT120's got sold and the GL's are serving as backups.

LeGrace,

Good to hear that the KT120s are giving you the improvement in bass performance you were looking for. Which KT88 did they replace? How do they compare on midrange performance?

Dave,

I considered those but the price was a bit overwhelming. Aren't those Psvane tubes made by Shuguang?

eickmewg,

What was it about the KT120s that made you unhappy?

wgallupe,
I felt that the KT120's seemed to lack "presence and body." Exactly what that means is hard to define. Nonetheless, I went back and forth between KT120's and KT88's several times, and I felt the KT88's were more musical each time. Could be my old ears, who knows? I don't consider this a knock on the KT120's; just my preferences.

Bill

wgallupe wrote:LeGrace,

Good to hear that the KT120s are giving you the improvement in bass performance you were looking for. Which KT88 did they replace? How do they compare on midrange performance?

Dave,

I considered those but the price was a bit overwhelming. Aren't those Psvane tubes made by Shuguang?

eickmewg,

What was it about the KT120s that made you unhappy?

Hi Wayne,
The PSVane / Shu Guang connexion is a tad inscrutable. As I understand it, SG was the original company but a group of their partners and engineers, unhappy with their arrangement with SG, split off to form PSVane. Originally they were just re-branding a lot of SG-made tubes c.f. the KT-88-Z but ostensibly employed better quality controls (i.e. glass consistency, burn-in times) and now apparently have their own factory, also (like SG) based in Changsha in south-central China, Hunan Province. (Being of a mere 5 million population it's barely a wide spot in the road on a Chinese map.) I've visited there several times -- wear a gas mask. There are Pb, Zn and Ag mines nearby whose smelters likely produce some of the esoteric metals used in tube-making). Apparently SG and PSV have kissed and made up so they may be re-branding each others' tubes again. If you skulk around you can find a quad of PSVanes T-II KT-88s for <$300 in the premium brand or significantly less in their "classic" grades, which appear to be the same tube. Both have a distinct grey band around them on the inside of the glass.
Oh, where are the Jim McShanes of yesteryear, to help us sort all this?

wgallupe wrote:LeGrace,

Good to hear that the KT120s are giving you the improvement in bass performance you were looking for. Which KT88 did they replace? How do they compare on midrange performance?

Replaced Genalex Gold Lions. TBH both are fine options. If my system included a pair of 15" subs (come on lottery tickets!) I'd likely revert to the KT88's. IMO they produce closer to an ideal flat response curve. In my current system though this makes the bass feel a bit lean.

For Penta Labs KT-88s check out the "Preferred Series KT88" over at the Tube Store.

Why doesn't somebody here just plonk down $1600 for a quad of those EAT KT-88s and give us a report?

arledgsc wrote:For Penta Labs KT-88s check out the "Preferred Series KT88" over at the Tube Store.  

Yah, They look like a good outfit. Their Preferred Series KT88 is identical to the Ruby KT88V-STR. It boiled down to Doug's Tubes being alot closer and no concerns about import duties.

deepee99 wrote:

Hi Wayne,
The PSVane / Shu Guang connexion is a tad inscrutable. As I understand it, SG was the original company but a group of their partners and engineers, unhappy with their arrangement with SG, split off to form PSVane. Originally they were just re-branding a lot of SG-made tubes c.f. the KT-88-Z but ostensibly employed better quality controls (i.e. glass consistency, burn-in times) and now apparently have their own factory, also (like SG) based in Changsha in south-central China, Hunan Province. (Being of a mere 5 million population it's barely a wide spot in the road on a Chinese map.) I've visited there several times -- wear a gas mask. There are Pb, Zn and Ag mines nearby whose smelters likely produce some of the esoteric metals used in tube-making). Apparently SG and PSV have kissed and made up so they may be re-branding each others' tubes again. If you skulk around you can find a quad of PSVanes T-II KT-88s for <$300 in the premium brand or significantly less in their "classic" grades, which appear to be the same tube. Both have a distinct grey band around them on the inside of the glass.
Oh, where are the Jim McShanes of yesteryear, to help us sort all this?

That Psvane / Shuguang connection sounds familiar. I read something like that. Still very confusing tho. I do wish Jim McShane would carry one or both of these brands. Regarding China, I fully understand what you are saying. Over the years I've been to places like Guangzhou, Jilin, Shanghai, Beijing, Tianjin and a few others I can't remember. Even away from the mines, air quality is awful. However, the local people were always hospitable.

Instead of speculating about various chinese more or less exotic tubes, why don't get a quad
JJ KT88 at eurotubes, they have 6months warranty and the price is just right.
Made in EU where water and air is clean and the beer is fine!

peterh wrote:Instead of speculating about various chinese more or less exotic tubes, why don't get a quad
JJ KT88 at eurotubes, they have 6months warranty and the price is just right.
Made in EU where water and air is clean and the beer is fine!

Peter, how are their signal tubes? That's really where the sound comes from.

deepee99 wrote:

peterh wrote:Instead of speculating about various chinese more or less exotic tubes, why don't get a quad
JJ KT88 at eurotubes, they have 6months warranty and the price is just right.
Made in EU where water and air is clean and the beer is fine!

Peter, how are their signal tubes? That's really where the sound comes from.

I have no complains from my customers, personally i have 3 12AU7/ECC82 in my vta70
I know eurotubes stacks them too.

I have been pleased with both the JJ 12AU7 and 12AX7 equivalents. Very inexpensive and also very quiet as drivers.

peterh wrote:Instead of speculating about various chinese more or less exotic tubes, why don't get a quad
JJ KT88 at eurotubes, they have 6months warranty and the price is just right.
Made in EU where water and air is clean and the beer is fine!

Hi Peter,

I never gave JJ KT88s a thought. They don't get much attention on the various forums. I guess 'speculation' would apply to JJ KT88 more than the Shuguangs as they are less known. My only experience with JJ was with their 6DJ8 in my SP12 phono pre where NOS Amperex 6922 sounded a lot better so the JJs are stored away somewhere.

The Shuguang made KT88s I mentioned above also come with 6 month warranties.

So, as mentioned in post no. 1, What I plan to do in a couple months is revert back to the KT120s just to make sure that I'm not 'fooling' myself

Well, I did and I have to say I may like the KT120 better after all. There is a certain smoothness in the midrange and highs that I characterize them to be a bit more laid back compared to the KT88s. I suppose what I should say is that neither is better than the other. Just a little different. The KT120 being smooth and laid back but still presenting plenty of detail while the KT88s are comparatively more forward with even more detail. At first I really liked the detail but eventually found it very slightly fatiguing over the long term.  

Here's what I have settled on for now  

Power tubes: Tungsol KT120, driver tubes: NOS Tungsol 6CG7 triple black plates (using 6cg7 to 12au7 pin adapters), Rectifier tube: NOS Mullard GZ37 including the diode mod.

This combo provides the best balance of bass impact, mid/high smoothness and detail.

wgallupe wrote:So, as mentioned in post no. 1, What I plan to do in a couple months is revert back to the KT120s just to make sure that I'm not 'fooling' myself

Well, I did and I have to say I may like the KT120 better after all. There is a certain smoothness in the midrange and highs that I characterize them to be a bit more laid back compared to the KT88s. I suppose what I should say is that neither is better than the other. Just a little different. The KT120 being smooth and laid back but still presenting plenty of detail while the KT88s are comparatively more forward with even more detail. At first I really liked the detail but eventually found it very slightly fatiguing over the long term.  

Here's what I have settled on for now  

Power tubes: Tungsol KT120, driver tubes: NOS Tungsol 6CG7 triple black plates (using 6cg7 to 12au7 pin adapters), Rectifier tube: NOS Mullard GZ37 including the diode mod.

This combo provides the best balance of bass impact, mid/high smoothness and detail.

Soon after I had my ST-120 broken in with the supplied Sovtek KT-88's I sprung for a full set of TungSol tubes including the KT-120's. For some reason I also switched to a Webber SS rectifier that I think may have been a red plated TungSol rectifier, and I was quite happy with the KT-120's. To me they added a more open dimensionality to the soundstage. The I heard that Gold Lions were supposed to be even better. Though they sound good I think I prefer the KT-120's more. Unfortunately one red plated and that's when I switched to the Genelex tubes. I'm thinking another quad of KT-120's are what I need but I think maybe I can get away with one to complete the set I have.

I've had really bad luck with Shuguang KT-88 types. I've tried two sets (years apart) of their high end Natural Sound series KT-88T only to have catastrophic failures that burned the cathode resistors in my ST-120. Psvane, which I think are manufactured by Shuguang, have been very good though as far as ruggedness. And having tried a lot of KT-88s I eventually settled on KT-120s. I like their punchy bottom and smooth highs.

I do love the Shuguang CV-181Z and T plus the 12AU7Ts. They have been very reliable and still in service.

Any love for the TAD KT88STR?



Currently my backup set - the KT120's are still doing their thing nicely with a couple thousand hours on em.

** I'd think a lot of the difference people hear might be EQ and room treatments/interactions. I "voiced" my system using the KT120's, which might have a lot to do with why I prefer their sound to either the TAD's or Psvane's.

PS - I get bored, I may swap the TAD's back in for a while. Not many miles, and I hear rumors they DO take a while to break in properly.