Trying a set of KT-120 in my premier 11-A

[repman]

I just got an email from Ed answering one I sent him regarding the KT-120 tubes and if they are compatible with a Premier 11-A amp.
Ed replied back that it was always drilled into him to only recommend the tubes that came originally with the amp from the factory. He said he was told that he could make an exception with the KT- 120 and he could recommend it as a replacement for the original 6550 power tube however the tube cage would not fit because of the height of the KT-120.
I just ordered a quad of these to try, has anyone here used these in a
11-A ?
I will give my impressions of this amp with this tube after burn in.

[turntable]

Look forward to your impressions

[repman]

Well the KT-120's arrived yesterday , installed, warmed up and biased. I set the cd on repeat and let it play on low levels for about 4 hours as I finished my workday in my home office.

My initial impressions are it has definitely helped the bottom end in fact I had to lower the sub level because it was too much bass. It seems as if the power output has increased as I can hear louder volumes at my normal volume control settings. There is a slight high end glare that I have never heard before with any 6550 or KT-88 tube that I hope will go away as the tubes age in. My overall impressions are very favorable man are these tubes big ( physical size) I am anxious to hear them at 50-100 hours.

[repman]

I took a shot of the KT-120 tung/sol compared to a 6550 Tung/sol

She's a monster!

[jimtranr]

I took a shot of the KT-120 tung/sol compared to a 6550 Tung/sol

She's a monster!

Your photo explains the tube cage fit issue. :yes:

[repman]

Your photo explains the tube cage fit issue. :yes:

Jim, they are huge compared to the 6550's they have been running all day starting to sound sweet.

[joeinid]

:banana::banana::banana:

Cool!

I'm glad you are enjoying the new bottles. :music:

Joe

[MC352]

We need pictures of those big boys glowing!

What is the advantage of using a KT120, more output power?

[repman]

:banana::banana::banana:

Cool!

I'm glad you are enjoying the new bottles. :music:

Joe

Thanks Joe, so far so good :thumbsup:

[repman]

We need pictures of those big boys glowing!

What is the advantage of using a KT120, more output power?

Chuck,yes they are supposed to have more output and much longer
Life. I really like the tung sol 6550's so these were a no brainer for me as they are the only manufacturer making the KT-120's that I know of.

[ronenash]

We need pictures of those big boys glowing!

What is the advantage of using a KT120, more output power?

These tubes can output 150W per pair but only in an amp designed for this. Replacing 6550 in an amp like the Premier 11A you will only gain a bit more power and headroom. Probably around 10-15%. You will gain considerably more tube life as they will not be working very hard.

[Coppy]

As to power, if there's no more energy in (plate current) then there can be no more out. I'm guessing that unless you change the power supply circuit, there's really not much, if any more power out. Depending on the CJ design, maybe they'll give you a bit more.
Unlike most mfgrs., even though it's more expensive, CJ usually over designs the supplies to give plenty of headroom. (ever notice how heavy the equipment is... it ain't them caps) So probably a bit more head room. I need to decide if there is really a sonic benefit significant enough to put up with the strange appearance of the LP140 amps sitting around with the tubes projecting above the top of the chassis. Thanks to everyone here for their experience with the new tubes.
Philippe is doing it right, get the ART amps designed with the KT120s to begin with.:thumbsup:

[Rafale]

As long as could find SED I shall not pass on KT120, expensive and furthermore it is really not attractive, too oversized imo...the problem with SED in the USA is a legal problem concerning the brand and its retailer's network, they are always made to St Petersbourg to my knowledge
The German retailers are furnished and I just come to receive from it...

[Coppy]

Philippe,

Your English is way better than my French (thank you) but I'm confused about your last post. What is the USA problem and are you saying you would not change to the KT120s? Maybe I'm not sure what an SED is. My 6550s are fine with maybe 800 hours on them so no need to replace unless there is an opportunity for really better sound. There are plenty of 6550s available here from CJD and tube retailers when I need them.

Bob

[Rafale]

Philippe,

Your English is way better than my French (thank you) but I'm confused about your last post. What is the USA problem and are you saying you would not change to the KT120s? Maybe I'm not sure what an SED is. My 6550s are fine with maybe 800 hours on them so no need to replace unless there is an opportunity for really better sound. There are plenty of 6550s available here from CJD and tube retailers when I need them.

Bob
Bob, it is complicated, there are problems enter New Sensor (USA) and PM components (UK ) concerning the distribution of the St Petersburg's 6550 Winged C in the USA
SED Tubes - Vacuum Tubes Manufactured in St Petersburg, Russia (http://www.svetlana-tubes.com/#)
PM Components Ltd - World Leaders in Vacuum Tube Supply (http://www.pmcomponents.co.uk/)
Tube-Shop.com - Vacuum Tubes for Hi-Fi, Guitar and Radio amplifiers (http://www.tube-shop.com/store/proddetail.asp?ProductID=695&RelatedID=756&RelatedID2=150)

[Coppy]

Philippe,

Thanks for the links. Looks like The SEDs are currently available in the US only from the UK distributor. I guess that's okay as long as the tube shop is a reliable firm that stands behind their product. Is it your impression that the SEDs are the best brand of 6550s? I note that the tube store also sells Shuggies (Chinese) that I've heard are good. I guess all this explains why CJ didn't want to replace my 6550s when I had it over there for a circuit upgrade last spring.

Also, you would not try the KT120s, is that correct? The amps would surely not be very attractive with those tubes sticking out of them.

Bob

[Rafale]

Hi Bob
Yes we consider in Europe that 6550 winged C made to St Petersburg is the best towards the price, there is a lot of attempt of imitation as far as it exists a confusion enters S logo and C logo, the Svetlana name belongs to New Sensor but not C logo, if the tube carries Svetlana he can be also made to Saratov ( Sovtek, EH )
In the end, we can be on that the current choice of the KT120 is only a qualitative choice? I am not on

[Rafale]

another link
Welcome to SED-USA! (http://www.sed-usa.com)
Note that they do not use the word Svetlana

[Joe Appierto]

I just got an email from Ed answering one I sent him regarding the KT-120 tubes and if they are compatible with a Premier 11-A amp.
Ed replied back that it was always drilled into him to only recommend the tubes that came originally with the amp from the factory. He said he was told that he could make an exception with the KT- 120 and he could recommend it as a replacement for the original 6550 power tube however the tube cage would not fit because of the height of the KT-120.
I just ordered a quad of these to try, has anyone here used these in a
11-A ?
I will give my impressions of this amp with this tube after burn in.

Hi,

I'm new to this forum and this is only my second post. I was wondering if you continued to use the KT-120s in your 11A and did you have any problems? I called Ed at conrad-johnson yesterday to ask if it'd be okay to use them but I haven't heard back from him. I've used them in a Pr 140 without any problems but since the 11A is an older model, I wasn't sure if it'd be safe to do so.

Your input is appreciated.

Thanks,
Joe

[chessman]

Joe, welcome aboard! :wave:

[Rafale]

hello Joe and welcome, very pleased to meet you

[Puma Cat]

Hi,

I'm new to this forum and this is only my second post. I was wondering if you continued to use the KT-120s in your 11A and did you have any problems? I called Ed at conrad-johnson yesterday to ask if it'd be okay to use them but I haven't heard back from him. I've used them in a Pr 140 without any problems but since the 11A is an older model, I wasn't sure if it'd be safe to do so.

Your input is appreciated.

Thanks,
Joe

Joe,
Welcome aboard. I've used KT88s in my Pr11A to good success, so I would definitely try the KT-120s...should be fine. They're working great in my LP70S.

[jimtranr]

Welcome, Joe. Good to have you aboard.

[Joe Appierto]

Thank you guys for the warm welcome. I'm going to give the KT-120s a shot and see what happens.

Hopefully, no meltdowns. :)

[joeinid]

Joe, welcome aboard! :wave:

Hi,

Great taste in gear!

Welcome!

Another Joe :)

[repman]

Joe , I have had my 11-A outfitted with the KT-120's since I originally posted this with zero issues - I called Ed at CJ before I installed them and he said that is the only other tube he was authorized to say could be used in an 11-A other than a 6550. I have been very impressed with them and will not be going back to 6550's any time soon.

regards, Larry

[Joe Appierto]

Hi Larry,

It's good to know they've been working well for you. I have them in the 11A warming up now as I increase the bias.

Thanks for the update.

Joe

[repman]

Joe , make sure you give them plenty of time to break in , mine sounded a bit strident at first but really came into full bloom by 50 hrs or so .
I hope you enjoy them as much as I have enjoyed mine.

Larry

[Joe Appierto]

Larry,

This quad that I have in the 11A now for about two hours is half of the set of eight which I ran in my Premier 140 for about three weeks earlier this year. They probably had about 125 hours on them and were decently broken in.

I find, though, that even tubes with hundreds of hours on them need a few days to “settle-in” after they been on the shelf before they sound their best. I have to say that initial impressions in the 11A are quite positive and considering that they’re following some Stromberg-Carlson labeled Tung-Sol 6550 solid gray plates, I think that speaks highly of them. They seem to combine the richness and timbre of a KT-88 with the detail of a 6550. Not exactly to the last degree of either, but a good blending of the two.

I appreciate your sharing your experience with me.

Regards,
Joe

[Puma Cat]

Joe , make sure you give them plenty of time to break in , mine sounded a bit strident at first but really came into full bloom by 50 hrs or so .
I hope you enjoy them as much as I have enjoyed mine.

Larry

+1

Bang on.

Tubes are like kids, they mature in fits and starts. Mine kind of went SNAP! one evening and were there...50 hours is pretty accurate.

[Rafale]

i'm curious.....somebody could post an image of CJ amp with the KT120 ?

[Puma Cat]

I can put one up later this week.

[Rafale]

Merci....Stephen:thumbsup:

[Puma Cat]

Merci....Stephen:thumbsup:

De rien...

[skroudo]

CJ Classic 60 SE

[Rafale]

joli....thanks.... topless transformers, for what motive, less noise ?

[skroudo]

joli....thanks.... topless transformers, for what motive, less noise ?

I like topless things :)

[Rafale]

I like topless things :)

:laughin:

[joeinid]

CJ Classic 60 SE

:drool:

Very nice :thumbsup: I like it.

[repman]

i'm curious.....somebody could post an image of CJ amp with the KT120 ?

Here you go Philippe!! that is some big glass:thumbsup:

[Rafale]

Here you go Philippe!! that is some big glass:thumbsup:

thanks guys.....i like the big bottle :thumbsup:

[Rafale]

Guys how do you like your KT120 ? any downsides vs 6550 ?

[Puma Cat]

Love 'em! No downsides other than I cannot put the tube cages on, but the upsides outweight that by a large margin.

[Rafale]

Stephen....do you decrease the setting on the pre volume control for the same sound level?

[repman]

Guys how do you like your KT120 ? any downsides vs 6550 ?

I am with Stephen I love the sound of these.

They have the punch of the 6550 the liquid midrange of the kt-88 and the bass is tighter and more punchy than either.

I would not go back to a 6550 or a KT-88

Larry

[Coppy]

Stephen....do you decrease the setting on the pre volume control for the same sound level?

Philippe,

I know you asked Stephen but for my LP140s, there's no change in volume. Your question suggests you wonder if there might be increased power output using the KT120s. There is not as the circuits suppling power to them have not changed. They do seem to have more headroom though, for transients and bass notes. They simply seem to do the same job more easily.

Bob

[Rafale]

Philippe,

I know you asked Stephen but for my LP140s, there's no change in volume. Your question suggests you wonder if there might be increased power output using the KT120s. There is not as the circuits suppling power to them have not changed. They do seem to have more headroom though, for transients and bass notes. They simply seem to do the same job more easily.

Bob

you are always welcome Bob :thumbsup:
icing on the cake, they are less expensive.....great stuff

[turntable]

I am with Stephen I love the sound of these.

They have the punch of the 6550 the liquid midrange of the kt-88 and the bass is tighter and more punchy than either.

I would not go back to a 6550 or a KT-88

Larry

That sounds good. I was wondering what they do for the overall bass character and drive.

[Rafale]

Did you notice an emission of heat significantly more important than with 6550?

[repman]

Philippe, they run about the same as a 6550 in my 11a they are much cooler than the gold lion kt-88s which were quite a bit hotter than the 6550 or KT-120

[Joe Appierto]

Guys how do you like your KT120 ? any downsides vs 6550 ?

I had them in for a few days in my 11A and liked the way they sounded, in general. They do seem to have some extra headroom compared to 6550s although they're not really any louder.

I didn't have anything more sophisticated than my hand, but I thought they were running a little warmer than most of the tubes I've had in there. :scratch2:

I know that no one has reportd any issues but since blowing up my Pr 140, I've been a little paranoid about the 11A, so I took them out.

They are good sonding although not my favorites. I still prefer the vintage 6550s and by a small margin, even the Russian "reissue" Tung-Sol 6550s.

Just my 2¢.

[Rafale]

I had them in for a few days in my 11A and liked the way they sounded, in general. They do seem to have some extra headroom compared to 6550s although they're not really any louder.

I didn't have anything more sophisticated than my hand, but I thought they were running a little warmer than most of the tubes I've had in there. :scratch2:

I know that no one has reportd any issues but since blowing up my Pr 140, I've been a little paranoid about the 11A, so I took them out.

They are good sonding although not my favorites. I still prefer the vintage 6550s and by a small margin, even the Russian "reissue" Tung-Sol 6550s.

Just my 2¢.

thanks Joe for your input, bty what happens to your 140 ?

[Joe Appierto]

thanks Joe for your input, bty what happens to your 140 ?

I was trying the Hi-Fi Tuning fuses in the 140 and after they settled in I thought the amp sounded a little more detailed and dynamics were better as well.

Anyway, as you know, conrad-johnson uses the plate fuses as their first line of defense to protect their amps from tube failures. I had put in new set of Ei KT-90s into the 140 that I'd just purchased and one of them took out the left channel Hi Fi Tuning fuse.

I like what they do for the sound of the 140 but at $50 a pop, I stupidly decided to get a higher amperage set of fuses (2 amps instead of the specified 1 amp). Anyway, I had the new 2 amp fuses in and a tube arced. However, instead of popping the fuse, it must've taken out the resistor because after the tube flashed, there was smoke coming out of the socket and then I powered the amp down.

Lesson learned, if you're going to use expensive fuses then be prepared to replace them with correct value substitutes. In the long run it'll be cheaper than trying to be "smart". :yes:

[turntable]

I had them in for a few days in my 11A and liked the way they sounded, in general. They do seem to have some extra headroom compared to 6550s although they're not really any louder.

I didn't have anything more sophisticated than my hand, but I thought they were running a little warmer than most of the tubes I've had in there. :scratch2:

I know that no one has reportd any issues but since blowing up my Pr 140, I've been a little paranoid about the 11A, so I took them out.

They are good sonding although not my favorites. I still prefer the vintage 6550s and by a small margin, even the Russian "reissue" Tung-Sol 6550s.

Just my 2¢.

That is interesting Joe.

I have the reissue Tung Sol 6550's in my prem 8a's currently. Can you elaborate on the differences you hear between the TS 6550 and the TS KT120's?

cheers
Shane

[Puma Cat]

Stephen....do you decrease the setting on the pre volume control for the same sound level?

Hi Philippe mon ami,
No, the power output is the same, so no change in the gain on the pre volume control. The KT-120 have notably more "punch" in their presentation and tighter, deeper bass. Also improved transparency yet a more musical presentation like KT88s. They kind of represent the best of both 6550s and KT88s, but with more of everything.

Stephen.

[Joe Appierto]

That is interesting Joe.

I have the reissue Tung Sol 6550's in my prem 8a's currently. Can you elaborate on the differences you hear between the TS 6550 and the TS KT120's?

cheers
Shane

Hi Shane,

Sure. I find the KT-120s are a little less neutral than the T-S 6550s. Although they are at times more dynamic, I prefer the more well-balanced top to bottom evenness of the T-S reissue 6550s. In terms of sound stage, I find the two of them to be pretty much the same. I think the bass on the KT-120s is a little more pronounced but the 6550s are more articulate in the bass.

Not to put too fine a point on it, the main differences I hear between them are the same differences that I generally hear between good 6550s and KT-88s. Just to give you a perhaps better idea of my personal preferences, although I own vintage Genalex KT-88s, given a choice I'd rather listen to vintage Tung-Sols every time. I like the richness of the KT-88s as change of pace, but it's the neutrality and the clarity (to my ears, of course), that I keep going back to.

Hope this was somewhat more clear. I've never been too good at breaking down my listening impressions into fine gradations like "a thick upper bass/lower midrange" etc.

Regards,

[Puma Cat]

I was trying the Hi-Fi Tuning fuses in the 140 and after they settled in I thought the amp sounded a little more detailed and dynamics were better as well.

Anyway, as you know, conrad-johnson uses the plate fuses as their first line of defense to protect their amps from tube failures. I had put in new set of Ei KT-90s into the 140 that I'd just purchased and one of them took out the left channel Hi Fi Tuning fuse.

I like what they do for the sound of the 140 but at $50 a pop, I stupidly decided to get a higher amperage set of fuses (2 amps instead of the specified 1 amp). Anyway, I had the new 2 amp fuses in and a tube arced. However, instead of popping the fuse, it must've taken out the resistor because after the tube flashed, there was smoke coming out of the socket and then I powered the amp down.

Lesson learned, if you're going to use expensive fuses then be prepared to replace them with correct value substitutes. In the long run it'll be cheaper than trying to be "smart". :yes:

In my experience, Premier 11As do not get along well with KT-90s, either...I know this for a fact. I would strongly recommend not using them in C-J amps. And I would say that C-J probably knew very well why they specced the fuse to be a 1-amp blow rather than a 2-amp blow.

[Joe Appierto]

In my experience, Premier 11As do not get along well with KT-90s, either...I know this for a fact. I would strongly recommend not using them in C-J amps. And I would say that C-J probably knew very well why they specced the fuse to be a 1-amp blow rather than a 2-amp blow.


For sure. It was really dumb on my part to go for the higher value fuse.

[Puma Cat]

Hi Shane,

Sure. I find the KT-120s are a little less neutral than the T-S 6550s. Although they are at times more dynamic, I prefer the more well-balanced top to bottom evenness of the T-S reissue 6550s. In terms of sound stage, I find the two of them to be pretty much the same. I think the bass on the KT-120s is a little more pronounced but the 6550s are more articulate in the bass.

Not to put too fine a point on it, the main differences I hear between them are the same differences that I generally hear between good 6550s and KT-88s. Just to give you a perhaps better idea of my personal preferences, although I own vintage Genalex KT-88s, given a choice I'd rather listen to vintage Tung-Sols every time. I like the richness of the KT-88s as change of pace, but it's the neutrality and the clarity (to my ears, of course), that I keep going back to.

Hope this was somewhat more clear. I've never been too good at breaking down my listening impressions into fine gradations like "a thick upper bass/lower midrange" etc.

Regards,

I would agree with that, but in C-J amps with Teflon capacitors, I would say that the warmish departure from neutrality the KT-120s bring is pretty slight, and to my ears, welcome, especially with the more neutral presentation the Teflon caps bring. Shane, personally, I think you'd really like the KT-120s in your 8A's, knowing how you prefer ART 3/Premier 16s to ACT2s. I think the KT-120s are a more musical tube, personally, and the 6550s is a colder tube or more neutral in presentation.

[Joe Appierto]

I would agree with that, but in C-J amps with Teflon capacitors, I would say that the warmish departure from neutrality the KT-120s bring is pretty slight, and to my ears, welcome, especially with the more neutral presentation the Teflon caps bring. Shane, personally, I think you'd really like the KT-120s in your 8A's, knowing how you prefer ART 3/Premier 16s to ACT2s. I think the KT-120s are a more musical tube, personally, and the 6550s is a colder tube or more neutral in presentation.

PC brings up a good point regarding the Teflon capacitors which is something both of my amps lack. Given that fact, what I perceive as "richness" could maybe very much be welcome.

Also, I don't know how much this has to do with my impressions of the KT-120, but they are cryo treated and I've read, although I don't know how much stock to put into it, that cryo treated tubes tend to have more pronounced characteristics.

[turntable]

Hi Shane,

Sure. I find the KT-120s are a little less neutral than the T-S 6550s. Although they are at times more dynamic, I prefer the more well-balanced top to bottom evenness of the T-S reissue 6550s. In terms of sound stage, I find the two of them to be pretty much the same. I think the bass on the KT-120s is a little more pronounced but the 6550s are more articulate in the bass.

Not to put too fine a point on it, the main differences I hear between them are the same differences that I generally hear between good 6550s and KT-88s. Just to give you a perhaps better idea of my personal preferences, although I own vintage Genalex KT-88s, given a choice I'd rather listen to vintage Tung-Sols every time. I like the richness of the KT-88s as change of pace, but it's the neutrality and the clarity (to my ears, of course), that I keep going back to.

Hope this was somewhat more clear. I've never been too good at breaking down my listening impressions into fine gradations like "a thick upper bass/lower midrange" etc.

Regards,

Joe, I agree with you summarisation between 6550's and KT88's, at least what I have heard. I prefer the top to bottom coherence of the 6550's over the richness, especially in the bass of the KT88's.

It also sounds that in your system the 6550 upper frequencies are more extended, or am I reading too much in between the lines.

When I had my Mac 2102 tube amps, the difference between 6550 and KT88's was even more pronounced with the 6550 easily being the better sounding tube.the 2102's have a nice rich bass to start with, so the KT88's we too much of a good thing.

I have had full range speakers for quite a few years now, and 6550 tubes with their tighter bass synergises in my system a lot better.

[turntable]

I would agree with that, but in C-J amps with Teflon capacitors, I would say that the warmish departure from neutrality the KT-120s bring is pretty slight, and to my ears, welcome, especially with the more neutral presentation the Teflon caps bring. Shane, personally, I think you'd really like the KT-120s in your 8A's, knowing how you prefer ART 3/Premier 16s to ACT2s. I think the KT-120s are a more musical tube, personally, and the 6550s is a colder tube or more neutral in presentation.

hmmm, not convinced Stephen. perhaps if I had KT88's in when I tried the ACT2 I might have liked it better?

If the bass of the Kt120's is fatter/richer, not for me. especially 18 of the buggers.

Is the upper frequency extension similar?

[Joe Appierto]

It also sounds that in your system the 6550 upper frequencies are more extended, or am I reading too much in between the lines.



Hi Shane,

Actually, no you're not reading in too much. I find the upper range of the KT-120s to be quite good. But (and there's always a but), I find the T-S reissue 6550 to have just a little more to it in the upper treble. And, once you start talking about vintage Tung-Sol, the highs are just plain crystalline. Naturally, I always have to give the caveat of that's in my system, in my room, etc.

No matter how good the tubes I've had in and may have really enjoyed, once I go back to the original T-S 6550s, it always seems to be as if the highs have suddenly opened up. And then within about 20 minutes, I no longer even notice and everything just seems natural.

Regards,

[turntable]

Hi Shane,

Actually, no you're not reading in too much. I find the upper range of the KT-120s to be quite good. But (and there's always a but), I find the T-S reissue 6550 to have just a little more to it in the upper treble. And, once you start talking about vintage Tung-Sol, the highs are just plain crystalline. Naturally, I always have to give the caveat of that's in my system, in my room, etc.

No matter how good the tubes I've had in and may have really enjoyed, once I go back to the original T-S 6550s, it always seems to be as if the highs have suddenly opened up. And then within about 20 minutes, I no longer even notice and everything just seems natural.

Regards,

Joe, where can I get 18 vintage Tung Sol's? I am assuming expensive? :yes: might be way too much $$

[Joe Appierto]

You're joking, right?

In case you're not. There's a seller I've just learned about at your end of the planet - Vietnam - who seems to have a wide selection of Tung-Sol name brand and Tung-Sol OEM (RCA, in fact).

His prices vary from $140/ea for the three hole, test as new; $200/ea for RCA labelled three hole NOS; $225/ea for solid grey plate NOS; $325 for both test as new and others which are supposed to be NOS black plate Tung-Sols. He also has Sylvania 6550s. His web site is www.natubes.com (http://www.natubes.com). I have never done business with this guy so I don't know.

Then there are dealers such as Brendan at Tube World but the stock is more hit and miss and the prices are $300 for single smooth grey plates, for example. They've become much more difficult to source although they continue to pop up. The fact that you need 18 is the really problematic part.

[Puma Cat]

hmmm, not convinced Stephen. perhaps if I had KT88's in when I tried the ACT2 I might have liked it better?

If the bass of the Kt120's is fatter/richer, not for me. especially 18 of the buggers.

Is the upper frequency extension similar?
Hi Shane,
I don't think the bass of the KT120s is fatter/richer. I think in overall quality that KT-120 are very slightly less neutral than 6550s. I find the bass deeper and more pronounced but tigher and more well defined, not fatter and richer.

[turntable]

You're joking, right?

I am joking if they are $200 each. That is the pain I suffer when my amps need 16 power tubes + 2 spares.

I am guessing from your reaction, finding 18 might be nigh impossible:scratch2:

[turntable]

Hi Shane,
I don't think the bass of the KT120s is fatter/richer. I think in overall quality that KT-120 are very slightly less neutral than 6550s. I find the bass deeper and more pronounced but tigher and more well defined, not fatter and richer.

I can see why its easy to get confused as everything sounds slightly different in different systems. :puzzled-2:

But, more information is great!!

[Joe Appierto]

I am joking if they are $200 each. That is the pain I suffer when my amps need 16 power tubes + 2 spares.

I am guessing from your reaction, finding 18 might be nigh impossible:scratch2:

I updated my previous response. Please take a look at it.

Also, here's a link about this dealer on AA you might want to look at:
http://www.audioasylum.com/audio/tubes/messages/24/242687.html

[turntable]

I updated my previous response. Please take a look at it.

Also, here's a link about this dealer on AA you might want to look at:
RCA-labeled TS 6550 - Tubers - Tubes Asylum (http://www.audioasylum.com/audio/tubes/messages/24/242687.html)

thanks Joe, I think a bit steep for me.

[Joe Appierto]

thanks Joe, I think a bit steep for me.

Original Tung-Sol 6550s are an expensive proposition, for sure, no matter which version you get. And although they seem to be long-lived, they'll need to be replaced at some point too which will only be worse in terms of cost if that's the route you take.

Luckily, there seem to be more really good current production 6550/KT-class tubes than at any time since the "golden days". :yes:

[turntable]

Original Tung-Sol 6550s are an expensive proposition, for sure, no matter which version you get. And although they seem to be long-lived, they'll need to be replaced at some point too which will only be worse in terms of cost if that's the route you take.

Luckily, there seem to be more really good current production 6550/KT-class tubes than at any time since the "golden days". :yes:

Very true. I think I will stick with NOS for the small tubes :yes:

I am going to get out my cj Winged C 6550's soon and compare them with the Tung Sol reissues. I have had the Tung Sols in for 7 months ( seems longer) so now is as good a time as any.

From memory I thought the Tung Sols were a bit more detailed in the top end and upper mids, however the wingedC's seem to be more controlled in the bass and seemed to be able to do macrodynamics a little more effortlessly, especially when driven loud.

then again, my memory may not be that accurate :scratch2:

[Joe Appierto]

Very true. I think I will stick with NOS for the small tubes :yes:

I am going to get out my cj Winged C 6550's soon and compare them with the Tung Sol reissues. I have had the Tung Sols in for 7 months ( seems longer) so now is as good a time as any.

From memory I thought the Tung Sols were a bit more detailed in the top end and upper mids, however the wingedC's seem to be more controlled in the bass and seemed to be able to do macrodynamics a little more effortlessly, especially when driven loud.

then again, my memory may not be that accurate :scratch2:

It seems like whenever I go back to the SED =C= 6550s, especially in the Pr 140 which was designed to use them, I'm pleasantly surprised by how good they sound. I've been an apartment dweller for a long time now, so I don't get to play the system as loud as I'd like at times (although my neighbors probably have another take on that statement), but you're assessment of the SED and the T-S reissue is pretty much how they sound to me.

[rthomeint]

I just got new tube set for my 11A from Cyroset. The set consist of a matched quad of KT120s , a matched pair of electro-harmonix 6CG7s and a matched pair of electro-harmonix 5751s. I put the new tubes in yesterday after about two hours of listening the amp blow a fuse in the left channel.I had so spares so I replaced it and continued listening. I thought the sound was a little hard but figured it would soften with time. I let the amp run for five hours yesterday. Today I turned on the system and let it play for six hours before sitting down to listen. When I started to listen I noticed very distorted sound from both channels. I took the 5751s out and put the old ones back the distortion when away but the sound was still hard, then I replaced the 6CG7s with the old ones the sound was still hard but closer to the way was with the 6550s. I then put the 5751 into my MV-52 to take a listen, as soon as I turn the amp on the left channel fuse blow. I replaced it and took the new 5751s out and replaced them with the old ones, turned the amp back and the fuse blew again. That was my last fuse, so I turned the MV52 off and went back to listening to the 11A. The sound is still hard with the KT120s with very annoying sibilances on vocal bordering on a distortion. I can't seem to bias these tubes correctly I then switched back to my 6550s the sound was back to the way it was before. Then I blew a fuse in the right channel. I don't have anymore spares. Now i'm going to put my GAS son of Ampzilla in the system until I can get some more fuses and figure out is the new tubes damaged my 11A. In the twelve year I've owned this amp I never blew a fuse. Does the sound of the KT120's improve over time? Does this hardness go away? Is the hardness from the KT120s themselves or the cryogenic process. I think I my have damages two amps from these tubes. When I get more fuses I will see what happens, if they blow again both amps are taking a trip back to CJ.

[ronenash]

From my experience the KT120 are not hard at all and unless you had the bias settings turned up all the way it should not cause a blown fuse either.
Which fuse did the amp blow? The main power fuse or the tube protections fuse (these are the large white fuses)?
Based on your experience with two CJ amps it seems like the tubes you got don't meet their specs.
Give me some more information and I will try to help.

[rthomeint]

From my experience the KT120 are not hard at all and unless you had the bias settings turned up all the way it should not cause a blown fuse either.
Which fuse did the amp blow? The main power fuse or the tube protections fuse (these are the large white fuses)?
Based on your experience with two CJ amps it seems like the tubes you got don't meet their specs.
Give me some more information and I will try to help.

The tube protection fuse blew (Bussmann BBS-1). I'm not sure if the the hardness is from these tubes having only 15 hours of playing time and will dissipate over time, or is a side effect of the Cyrogenic treatment. The distortion I heard when I first sat down to listen was pretty bad. Swapping the 5751s took care of that but I don't know how many hours tubes were playing after they went bad. I'm thinking the 5751s damaged the amp and I hope not the speakers. I never heard KT120s before I bought these, but I have listened to brand new 6550s in this amp and they never sounded like this. I will try find a local supplier for the fuses tomorrow else I will order some and wait for them to arrive.

[Puma Cat]

rthomeint, I can't speak to what is causing fuses to blow, unless the cryo treatment was causing a failure mode inside the tube, but I have had experience with cryo treatment causing tubes to have a hard sound that can be unpleasant. It depends on a number of things, partly how the tubes were cryo'd and also the tube itself. For tubes that are more on the more mellow and soft side, like Mullards, it can give them detail, crispness and improved bass that can be really nice, but for tubes that are already quite detailed and resolving, I find it can be too much. Too hard sounding And I don't think you want every tube in adevice such as a preamp or amp cryo'd...it takes it too far into a direction you don't want to go....like oversharpening a digital photograph in Photoshop. If you go back and read the thread about which 6922, 6DJ8, 7308, PCC88 tube for C-J preamps, you can read my own recent experiences with mixing some cryo'd and uncryo'd tubes.

FWIW, I am using KT-120s in my LP70S, and none of them have been cryo'd and they sound wonderful, not hard at all.

[Joe Appierto]

I just got new tube set for my 11A from Cyroset. The set consist of a matched quad of KT120s , a matched pair of electro-harmonix 6CG7s and a matched pair of electro-harmonix 5751s. I put the new tubes in yesterday after about two hours of listening the amp blow a fuse in the left channel.I had so spares so I replaced it and continued listening. I thought the sound was a little hard but figured it would soften with time. I let the amp run for five hours yesterday. Today I turned on the system and let it play for six hours before sitting down to listen. When I started to listen I noticed very distorted sound from both channels. I took the 5751s out and put the old ones back the distortion when away but the sound was still hard, then I replaced the 6CG7s with the old ones the sound was still hard but closer to the way was with the 6550s. I then put the 5751 into my MV-52 to take a listen, as soon as I turn the amp on the left channel fuse blow. I replaced it and took the new 5751s out and replaced them with the old ones, turned the amp back and the fuse blew again. That was my last fuse, so I turned the MV52 off and went back to listening to the 11A. The sound is still hard with the KT120s with very annoying sibilances on vocal bordering on a distortion. I can't seem to bias these tubes correctly I then switched back to my 6550s the sound was back to the way it was before. Then I blew a fuse in the right channel. I don't have anymore spares. Now i'm going to put my GAS son of Ampzilla in the system until I can get some more fuses and figure out is the new tubes damaged my 11A. In the twelve year I've owned this amp I never blew a fuse. Does the sound of the KT120's improve over time? Does this hardness go away? Is the hardness from the KT120s themselves or the cryogenic process. I think I my have damages two amps from these tubes. When I get more fuses I will see what happens, if they blow again both amps are taking a trip back to CJ.

Hi rthomeint,

I've used cryoed KT-120 tubes in my Premier 140 and then in my Premier 11A. When they were brand new, I used them in my 140 and after a few minutes the plates on one of the tubes began to glow brightly. I shut the amp down and returned the tube to the vendor who checked it out and couldn't find a problem with it. He sent me back a different tube which I then used without any problems in the 140 for about a month. The cryoed KT-120s didn't sound hard to me at all.

I then used one quad in the 11A again without any issues and without any hardness to the sound. They were in both cases, however, the only cryoed tubes in my system except for a Telefunken PCC88/7DJ8 which I was using as the input tube in the Premier 140 at the same time as the KT-120s. In the 11A, there weren't any other cryoed tubes at all.

My Premier 140 is somewhat prone to blowing fuses but the KT-120s never tripped them.

Hope this helps.

[rthomeint]

I blew another fuse that this mourning in the 11A, so I went out and bought seven new fuses. I replaced both fuses in the 11A with new and turned on the system and let it play with the old tubes for 1.5 hours. The fuses held so the I replaced the 6550s with the KT120s and kept the old input tubes then I listen for two hours. They definitely sound better than yesterday. the sound improved as I was listen and the sibilances I heard are mostly gone. Hopefully the problems are solved with this amp. I will not put the cyro'd input tubes back in the amp. Now I have to see if my MV52 is damaged. Thanks for all the input.

Rob

[ronenash]

If the tube protection fuse is blowing you have a bad tube. Its actually an output transformer protection fuse that is intended to protect the output transformer when a tube goes bad. It might be marginal in your case but I would not continue to use these tubes in the Pr11A. You seem to have a problem with the input tube as well with the high levels of distortion. I would just return the whole lot if I were you.

[Puma Cat]

Good advice.

Fortunately, with all the tube rolling I've done, I've never blown a fuse.

[ronenash]

One other thing to note is that the fuse is there to protect your amp in extreme situations. If it blows buying a bunch of fuses and replacing them every time one blows is a very bad idea!
At one point you will cause major damage to your amp.

[rthomeint]

I plan on returning the 5751s and the 6CG7s. I think 5751s are bad to begin with and the 6CG7s just sound bad. The KT120s are sounding better and they played for 2 hours with no problems. I will give these tubes a couple of days of listening to see if any problems develop. I think I'm going to send the 11A back for the C1 capacitor upgrade soon any way I've been waiting on a payment from one of my customers to pay for this. I asked Lew Johnson at CES about buying LP66s or Classic 60SE vs. upgrading the 11A, he said upgrade the 11A and use the difference to upgrade my preamp. He also told me he has an 11A in second system that he will have upgraded.

[Puma Cat]

I plan on returning the 5751s and the 6CG7s. I think 5751s are bad to begin with and the 6CG7s just sound bad. The KT120s are sounding better and they played for 2 hours with no problems. I will give these tubes a couple of days of listening to see if any problems develop. I think I'm going to send the 11A back for the C1 capacitor upgrade soon any way I've been waiting on a payment from one of my customers to pay for this. I asked Lew Johnson at CES about buying LP66s or Classic 60SE vs. upgrading the 11A, he said upgrade the 11A and use the difference to upgrade my preamp. He also told me he has an 11A in second system that he will have upgraded.

Lew's right...upgrade the 11A. The guy knows what he's talking about.

When I had my 11A, I used NOS GE-JAN 5751s and Mazda 6CG7s that the seller had purchased from Kevin Deal at Upscale Audio. IIRC, these were fairly inexpensive and readily available. I would order some from Kevin and call it a day. I never cryo'd these and they sounded fantastic. As I mentioned before, I've had mixed success with cryo treating tubes. It works magic on some and can make others too hard-sounding. I used the Gold Lion KT88s as the output tubes because I preferred their mids to the stock 6550s, but the stock 6550s were more transparent and had tighter, better defined bass. Both were excellent overall. By the way, my 11A is in the hands of my good buddy Paolo, who is enjoying it very much every day. The 11A is really a great amplifer, and it was in production as one of C-J's top amps for almost 10 years. I'm sure with the cap upgrade, it will be fantastic. I think with some KT-120s will make it a very, very nice amplifier.

[rthomeint]

Lew's right...upgrade the 11A. The guy knows what he's talking about.

When I had my 11A, I used NOS GE-JAN 5751s and Mazda 6CG7s that the seller had purchased from Kevin Deal at Upscale Audio. IIRC, these were fairly inexpensive and readily available. I would order some from Kevin and call it a day. I never cryo'd these and they sounded fantastic. As I mentioned before, I've had mixed success with cryo treating tubes. It works magic on some and can make others too hard-sounding. I used the Gold Lion KT88s as the output tubes because I preferred their mids to the stock 6550s, but the stock 6550s were more transparent and had tighter, better defined bass. Both were excellent overall. By the way, my 11A is in the hands of my good buddy Paolo, who is enjoying it very much every day. The 11A is really a great amplifer, and it was in production as one of C-J's top amps for almost 10 years. I'm sure with the cap upgrade, it will be fantastic. I think with some KT-120s will make it a very, very nice amplifier.

I just not looking forward to being without it for three weeks and then the long break in period after it comes back.

[Bugs762]

I just got an email from Ed answering one I sent him regarding the KT-120 tubes and if they are compatible with a Premier 11-A amp.
Ed replied back that it was always drilled into him to only recommend the tubes that came originally with the amp from the factory. He said he was told that he could make an exception with the KT- 120 and he could recommend it as a replacement for the original 6550 power tube however the tube cage would not fit because of the height of the KT-120.
I just ordered a quad of these to try, has anyone here used these in a
11-A ?
I will give my impressions of this amp with this tube after burn in.

I didn't see this answered in the rest of the thread. With the LEDs, how do you know where to bias the KT-120s? Is it the same as the 6550s? I'm thinking about using KT-120s in my MV-60SE

Thanks
Bugs

[Joe Appierto]

I didn't see this answered in the rest of the thread. With the LEDs, how do you know where to bias the KT-120s? Is it the same as the 6550s? I'm thinking about using KT-120s in my MV-60SE

Thanks
Bugs

You would bias them as you'd any other output tube: turning them down once they turn red until the LEDs just go out.

The usual procedure as I understand it, is to let them warm up for 5 minutes at lowest bias setting and then turn them up until the lights come on and then to back off enough so they just go out. Then after 30 minutes to again turn up the bias until they light and then back it off one final time.

I follow a different procedure in which I gradually turn the bias up in 3 or 4 increments until finally after 30 minutes, I have the LEDs red, then I back it off. I'm not recommending this procedure but it seems to work for me.

[Bugs762]

You would bias them as you'd any other output tube: turning them down once they turn red until the LEDs just go out.

The usual procedure as I understand it, is to let them warm up for 5 minutes at lowest bias setting and then turn them up until the lights come on and then to back off enough so they just go out. Then after 30 minutes to again turn up the bias until they light and then back it off one final time.

I follow a different procedure in which I gradually turn the bias up in 3 or 4 increments until finally after 30 minutes, I have the LEDs red, then I back it off. I'm not recommending this procedure but it seems to work for me.

Hi Joe, thanks for the info. What was more on my mind, and maybe I have this wrong, but I thought different tube types had different bias points. The way I understand it is that LEDs are set to come on and go off at the bias point for the 6550. I'm assuming that the LEDs are set for a bias voltage that the 6550 wants to see and not the right bias point and not for any other type of tube unless they happen to be the same or very close to the 6550 bias point? For all I know the KT-120s may have a completely differnt bias point than the 6550 which would make the LEDs useless for using them to set the bias?

Thanks,
Doug

[ronenash]

Hi Joe, thanks for the info. What was more on my mind, and maybe I have this wrong, but I thought different tube types had different bias points. The way I understand it is that LEDs are set to come on and go off at the bias point for the 6550. I'm assuming that the LEDs are set for a bias voltage that the 6550 wants to see and not the right bias point and not for any other type of tube unless they happen to be the same or very close to the 6550 bias point? For all I know the KT-120s may have a completely differnt bias point than the 6550 which would make the LEDs useless for using them to set the bias?

Thanks,
Doug

There is no need to change the bias point in CJ amps when moving to the KT120. At least this is the situation with their current models. Its best to check with CJ customer service. In any case all CJ power amps have a small potentiometer to change the bias point inside the amp. Your dealer can probably make adjustments for you if needed.

[Bugs762]

There is no need to change the bias point in CJ amps when moving to the KT120. At least this is the situation with their current models. Its best to check with CJ customer service. In any case all CJ power amps have a small potentiometer to change the bias point inside the amp. Your dealer can probably make adjustments for you if needed.

Good information thanks.
Doug

[Bugs762]

Okay, now I'm rethinking what I know (which is a little bit) and what I don't know (which is a lot). I was thinking the bias point was a function of the tube, meaning that when you set the bias you where the tube wants to operate. But what I tink I'm hearing is that the bias point is a function of the amp, meaning when you set the bias you are setting the amp to run where it want to operate.... So, the amp will have the same bias point regardless of which tube is being used? However, all tubes may not function at the amp's bias point. I'm I close here?

Does anyone know if the MV 60SE was voiced for the GE 6550A or the Winged C 6550C? I've read the Stereophile article and the different poosts on this forum and I really want to try the KT-120s, but I don't want to damage the amp either. I haven't received an answer back from CJ when I emailed them and asked.

Many many thanks,
Doug

[ronenash]

Regarding your first point, both are true. The bias point is to bring the tube to its linear operating conditions. A 6550/KT88/KT120 operate in their linear range when the tube dissipation is above 24w and below its maximum dissipation value (35w for the 6550, 42w for the KT88 and 60w! for the KT120). Operating the tube at its maximum dissipation will provide more Class A power but will shorten tube life.
The tube power dissipation is a multiplication of the B+ voltage and the bias current through the tube. CJ Operate their power amplifiers at a B+ voltage of 525v and a typical bias current of 60mA. 525*0.06 = ~31W.
The bias current has nothing to do with amplifier power. In order to achieve more power from the same number of output tubes you need to increase the B+ voltage. with two output tubes you will get 100w at a B+ voltage of ~580v, this will be above the safe operating range of most 6550s and you will need a KT88 to achieve that much power from a pair of output tubes. The KT120 can go even higher and achieve 150w from a pair of tubes. The operating point that CJ uses with the KT120 is very conservative and ensures the tubes will last for a long time.

As for the MV60SE, it was designed with the 6550C as the GE 6550A were no longer available in mass at the time. I think the last amplifiers that were supplied with GE 6550A were the Premier 11A,12,8. With that said the MV60SE will work with KT120 as well.

Hope this clarifies things for you.

[Bugs762]

Regarding your first point, both are true. The bias point is to bring the tube to its linear operating conditions. A 6550/KT88/KT120 operate in their linear range when the tube dissipation is above 24w and below its maximum dissipation value (35w for the 6550, 42w for the KT88 and 60w! for the KT120). Operating the tube at its maximum dissipation will provide more Class A power but will shorten tube life.
The tube power dissipation is a multiplication of the B+ voltage and the bias current through the tube. CJ Operate their power amplifiers at a B+ voltage of 525v and a typical bias current of 60mA. 525*0.06 = ~31W.
The bias current has nothing to do with amplifier power. In order to achieve more power from the same number of output tubes you need to increase the B+ voltage. with two output tubes you will get 100w at a B+ voltage of ~580v, this will be above the safe operating range of most 6550s and you will need a KT88 to achieve that much power from a pair of output tubes. The KT120 can go even higher and achieve 150w from a pair of tubes. The operating point that CJ uses with the KT120 is very conservative and ensures the tubes will last for a long time.

As for the MV60SE, it was designed with the 6550C as the GE 6550A were no longer available in mass at the time. I think the last amplifiers that were supplied with GE 6550A were the Premier 11A,12,8. With that said the MV60SE will work with KT120 as well.

Hope this clarifies things for you.

ronenash -

Thank you for taking the time to explain amp/tube biasing to me. Still a little over my head, but I get the general idea.

Best,
Doug

[ronenash]

ronenash -

Thank you for taking the time to explain amp/tube biasing to me. Still a little over my head, but I get the general idea.

Best,
Doug

All you basically need to know is that KT120 are safe in your Pr11A and that you do not need to change anything except setting the bias with using the LEDs once you replace output tubes.

Enjoy and let us know how you like the KT120s in your 11A if you get to replace them.