Some CJ News

MylesBAstor

Well-Known Member
Apr 20, 2010
11,236
81
1,725
New York City
Hi Myles...any update? Yes, i know...its only been 24 hours...yeesh...sorry, just very curious. ;)

OK they're installed :) First rxn: they are 2x as heavy as the 6550s and about 1/4 to 1/3 larger. Big puppies!
 

mep

Member Sponsor & WBF Founding Member
Apr 20, 2010
9,481
17
0
OK they're installed :) First rxn: they are 2x as heavy as the 6550s and about 1/4 to 1/3 larger. Big puppies!

Ok, it's been 14 minutes, how do they sound?
 

MylesBAstor

Well-Known Member
Apr 20, 2010
11,236
81
1,725
New York City
Ok, it's been 14 minutes, how do they sound?

I haven't even biased the tubes yet. I don't know about other cj owners, but always turn the bias down all the way when putting new tubes in. Then I wait an hour or so to bias. Plus I took out my Hi Fi Tuning fuses and put the stock fuses in just in case a tube failed. Didn't want it taking out a $50 fuse :)
 

mep

Member Sponsor & WBF Founding Member
Apr 20, 2010
9,481
17
0
It's always a good idea to turn your bias pots down when you first install new tubes so that you don't draw too much plate current and your tubes glow cherry red before they blow. I don't wait an hour before I set initial bias though. I set the initial bias right away, check it in 15 minutes, then recheck again after an hour.
 

LL21

Well-Known Member
Dec 26, 2010
14,411
2,509
1,448
And?...and?...totally kidding. ;) enjoy!
 

jadis

Well-Known Member
Apr 28, 2010
12,347
5,460
2,810
Manila, Philippines
It's always a good idea to turn your bias pots down when you first install new tubes so that you don't draw too much plate current and your tubes glow cherry red before they blow. I don't wait an hour before I set initial bias though. I set the initial bias right away, check it in 15 minutes, then recheck again after an hour.

Same here. I found out the SED KT88s will have a reading of 25mv more than the 6550s which had a bias setting of 65mv. So the next time, I would lower the 6550s bias to 40mv first before I put in the KT88s. I guess the KT120s will have another reading. But yes, I agree with turning the bias pots down to be 'safe'.
 

Coppy

New Member
Feb 5, 2011
13
0
0
Sarasota, FL
I'm running a pair of LP140 monos and have had the KT120s for a couple of weeks now. They are terrific. As to bias, they were about the same as my 700 hour 6550s to start... no excitement. I adjusted them right after warm up and every couple of hours for the first ten or so. They have settled down fine, I'm not seeing more changes. As to sound, at first more base and better, quicker transients but much less debth to the soundstage. That was not good and scared me a bit. After maybe ten hours the debth was back and now it is great with even sweeter midrange. The highs even seem a little more clear. The tube cages no longer fit but I like the look of the amps with the tube wells full so even that's okay. I have heard from one fellow on another forum that his LP70 is worse with the new tubes... but he bought them from a dealer who Cryos the tubes first. I'm convinced that bit of hocus-pocus may have messed up his new tubes. He also maintains that it take no less than 1000 hours for the teflon caps to burn in. That also does not agree with my experience, so I consider the source as my mother used to tell me. Nice fellow who loves c-j though.
 

LL21

Well-Known Member
Dec 26, 2010
14,411
2,509
1,448
Thanks, Coppy. Very good to know. As to the 'other source'...sounds like the KT120 is more powerful and perhaps also a bit more extended/linear while retaining the midrange magic...some people like it 'the old fashioned way' perhaps? i'm guessing the changes you experience might be similar to those experienced by people who go from ART 3 to CJ GAT...Myles?
 

Coppy

New Member
Feb 5, 2011
13
0
0
Sarasota, FL
Here's more on the subject from CJD...


Ed passed this along to me. We have been very much taken with the sound of the new KT120 tubes. Sound quality is even better than our earlier favorite, the "winged C" tubes from Russia. The KT120s are a plug-in replacement for the 6550s on all of our amplifiers. They have higher voltage and dissipation ratings, so should prove extremely reliable (though it is a bit early to be sure of that). The power output of a given amplifier will not change when the KT120s are substituted for 6550s. They are capable of being run for more power, but only if the amplifier is designed for that (higher plate voltages and a different turns ratio on the output transformer). But this means that they are being run very conservatively when simply replacing 6550s.

Aside from catastrophic failures (arcing or short-circuits), I find that output tubes often are good for about twice as many hours as the more critical input and driver tubes (as long as not operating with disastrously low impedance loads - no worries with your Wilson speakers), so should be good for around 3000 hours. When the time comes to replace the outputs, I would definitely switch to the KT120s.
 

MylesBAstor

Well-Known Member
Apr 20, 2010
11,236
81
1,725
New York City
Here's more on the subject from CJD...


Ed passed this along to me. We have been very much taken with the sound of the new KT120 tubes. Sound quality is even better than our earlier favorite, the "winged C" tubes from Russia. The KT120s are a plug-in replacement for the 6550s on all of our amplifiers. They have higher voltage and dissipation ratings, so should prove extremely reliable (though it is a bit early to be sure of that). The power output of a given amplifier will not change when the KT120s are substituted for 6550s. They are capable of being run for more power, but only if the amplifier is designed for that (higher plate voltages and a different turns ratio on the output transformer). But this means that they are being run very conservatively when simply replacing 6550s.

Aside from catastrophic failures (arcing or short-circuits), I find that output tubes often are good for about twice as many hours as the more critical input and driver tubes (as long as not operating with disastrously low impedance loads - no worries with your Wilson speakers), so should be good for around 3000 hours. When the time comes to replace the outputs, I would definitely switch to the KT120s.

I'm not sure which input tubes you're referring to? Over the years, cj used a slew of them including 5751s, 6FQ7s, 6922 and 6H30P. That said, can't say that my experience mirrors yours. I find the 6550 output tubes barely last the rated hours while with the exception of the 6H30s, all the other small signal, driver stage tubes worked flawlessly. For some reason, I haven't had good luck with the 6H30Ps in my ART; reportedly, they are super tubes but in my hands, I've had two go within 6 months :) The 6H30s are quite pretty when they go too; they give off a phosphorescent lavender like glow and one hears a lot of static and the tube cycling between colors :(
 

Coppy

New Member
Feb 5, 2011
13
0
0
Sarasota, FL
Myles...

This comment was not my opinion but a response form CJD to my question to them about replacing the eight 6550s in my LP140 monos with KT120s. As a matter of fact though, I just recently replaced the 6922s in my GAT with NOS Mullards from Holland ECC88s or E88CCs. Always get that mixed up. Also a nice little upgrade. Hmm... you could sell the great ART and get the GAT... just two tubes, one chassis and great, maybe better sound.

Bob
 

LL21

Well-Known Member
Dec 26, 2010
14,411
2,509
1,448
Hi Coppy,

Nice pre! I just replaced the stock EH in mine with Amperex US PQ White Label 6922s...absolutely love the music i am hearing. I had NOS Mullards in (ECC88s), and although they were quite sterile for 100 hours, they really relaxed beautifully after that, and i was really enjoying them. I would not have gotten the Amperex had i waited for the 100 hours...but having done so, i will say i prefer them now and bought a back up pair so that i have about 10 years supply (incl the Mullards) and will either keep the preamp that long or sell it with the tubes.

IMHO, i found the Amperexes to add ever so slightly defter a touch in the midrange that allowed delicate upper range piano to 'lilt' just that bit more...perhaps micro dynamic shading is the better term. i found the Amperexs a shade more extended though only in direct comparison. In general i found the sound a hair more effortless...honesetly not sure why. They are also definitely quieter...dead silent in fact (but that is so specific to the individual tube, it could be a nice coincidence.)

AGain, probably would have remained quite happy with Mullards (which i happened to have lying around from when i was tube rolling for Zanden...ended up with Amperex US PQ 7308 so it might just be my taste). They are excellent.

Thought i would share since there aren't too many fellow GAT owners.
 

Coppy

New Member
Feb 5, 2011
13
0
0
Sarasota, FL
Lloyd,

Thanks for the info on the Amperex 6922s. Maybe I'll give them a try. After the ten tubes I've just bought, and knowing the price of the Amperex's , guess I'll probably wait a bit. Poor Myles... he has to buy his pre-amp tubes in lots of eight. Enjoy the music.

Bob
 

LL21

Well-Known Member
Dec 26, 2010
14,411
2,509
1,448
Hi Bob,

yes...that is a lot! As you know, GAT only has 2. Zanden has 4. And i am Class A SS, so no tubes there. far fewer! In any event, i am sure you have your own excellent sources of NOS tubes. If it helps, try Brent Jessee (Audiotubes.com i think) and tell him i say hi...absolutely great to work with. I have been buying tubes from him for years, and you will likely read many good things about him on the 'net. Enjoy your music as well!

What is the rest of your system, btw?
 

MylesBAstor

Well-Known Member
Apr 20, 2010
11,236
81
1,725
New York City
Myles...

This comment was not my opinion but a response form CJD to my question to them about replacing the eight 6550s in my LP140 monos with KT120s. As a matter of fact though, I just recently replaced the 6922s in my GAT with NOS Mullards from Holland ECC88s or E88CCs. Always get that mixed up. Also a nice little upgrade. Hmm... you could sell the great ART and get the GAT... just two tubes, one chassis and great, maybe better sound.

Bob

Sorry for any confusion. Actually have the GAT :) I had the ART preamp for about 12 years, deciding not to upgrade to the ACT2. It was only when heard the GAT that finally, heartbreakingly, sold my beloved ART III. I was lucky enough to have the opportunity to compare the ART III with the GAT and it was no contest. One item though, that I find essential to get the most out of the GAT is the SRA Isobase. Besides the drop in the noise floor, there's a huge (not hyperbole) increase in the unit's dynamic range.

The ART I was referring to was the amplifier :) The problem I have with tube rolling is that I find it next to impossible to find quiet small signal tubes, esp. for phono stages. I actually have a NOS pair of Tele E188cc/7308s that will eventually try in the GAT. And as a really true NOS tube is getting harder and harder to find, I find myself drawn to finding the best of the new lines of tubes since they will hopefully be available for some time :(

As far the output tubes go, I have recently switched over to the KT120s (yes 16 of them!) and am burning them in.
 
Last edited:

XV-1

Well-Known Member
May 24, 2010
3,591
2,573
1,860
Sydney
Yes Myles

You told me the GAT was quite a bit better than the ART3. Not that I didn't believe you, but like you I was reluctant to let go of the ART.

I have had my GAT for a couple of months now. one set of 6922's went noisy after a couple of hundred hours thou. I think I am over the burn in hump of 400 hours - right Lloyd :D
- it does sound awesome. :cool:
 

Coppy

New Member
Feb 5, 2011
13
0
0
Sarasota, FL
Lloyd,

GAT preamp, TEA 1bc phono pre, Marantz SA7 S1, LP140 monos, Wilson Sasha speakers, Sota table/Kontra B cart, Shunyata power, Symposium vibration, MIT Magnum speaker and ICs. Life is good.


Bob

Hi Bob,

yes...that is a lot! As you know, GAT only has 2. Zanden has 4. And i am Class A SS, so no tubes there. far fewer! In any event, i am sure you have your own excellent sources of NOS tubes. If it helps, try Brent Jessee (Audiotubes.com i think) and tell him i say hi...absolutely great to work with. I have been buying tubes from him for years, and you will likely read many good things about him on the 'net. Enjoy your music as well!
 

Coppy

New Member
Feb 5, 2011
13
0
0
Sarasota, FL
Myles,

Not to long ago I set up some Symposium roller blocks under the GAT not thinking it would make much difference an sat down to read while listening to a little music. To my surprise... a difference! As you know the GAT isolates the tube boards internally so I thought if was a waste of time but not so. Do you think the SRA platform would make a further improvement?

Whatever tubes they sent me in the TEA 1bc seem to be holding up okay... knock on wood... so I'm leaving well enough alone. My best sound is the new RR LP Stravinsky. Amazing.

Also, how are the KT120s doing. Mine are still great.

Bob

Sorry for any confusion. Actually have the GAT :) I had the ART preamp for about 12 years, deciding not to upgrade to the ACT2. It was only when heard the GAT that finally, heartbreakingly, sold my beloved ART III. I was lucky enough to have the opportunity to compare the ART III with the GAT and it was no contest. One item though, that I find essential to get the most out of the GAT is the SRA Isobase. Besides the drop in the noise floor, there's a huge (not hyperbole) increase in the unit's dynamic range.

The ART I was referring to was the amplifier :) The problem I have with tube rolling is that I find it next to impossible to find quiet small signal tubes, esp. for phono stages. I actually have a NOS pair of Tele E188cc/7308s that will eventually try in the GAT. And as a really true NOS tube is getting harder and harder to find, I find myself drawn to finding the best of the new lines of tubes since they will hopefully be available for some time :(

As far the output tubes go, I have recently switched over to the KT120s (yes 16 of them!) and am burning them in.
 

MylesBAstor

Well-Known Member
Apr 20, 2010
11,236
81
1,725
New York City
Myles,

Not to long ago I set up some Symposium roller blocks under the GAT not thinking it would make much difference an sat down to read while listening to a little music. To my surprise... a difference! As you know the GAT isolates the tube boards internally so I thought if was a waste of time but not so. Do you think the SRA platform would make a further improvement?

Whatever tubes they sent me in the TEA 1bc seem to be holding up okay... knock on wood... so I'm leaving well enough alone. My best sound is the new RR LP Stravinsky. Amazing.

Also, how are the KT120s doing. Mine are still great.

Bob

One advantage of the SRA base is that it's tailored to individual component weight as well as weight distribution. I haven't heard the latest RB but while I liked them, I did think the earlier ones were a little lean in the midrange. That said, perhaps Peter's bases might also work :)

OTOH, one issue that I have with the TEA phono is that the older Ei ECC83s that cj used to supply (like with the Premier 15) are far better sounding than the current redone Tungsols. Maybe the Eis were a touch softer (kinda how I find Mullards) but far more musical and more instrumental body. But the only way to get them is on ebay nowadays. The quality, as well as lifespan of the Eis, was however, extremely variable--not to mention their predisposition to developing or coming with microphonics in one or both triods. Couple that with the necessity of the two tubes in the "critical" positions in the circuit being dead quiet (a problem find in so many tubes nowadays; it seems with all the improvements in the circuit design, we are now becoming aware of the importance even more for quiet tubes, esp. for phono sections). So far the only tubes that I've tried that meet that requirement are the cj supplied Tungsol reissues or the EAT issues. Which was frustrating because I like the box plate Mullards :( So one is really left to playing with the third, less critical tube position to get most out of the TEA :)
 

LL21

Well-Known Member
Dec 26, 2010
14,411
2,509
1,448
Yes Myles

You told me the GAT was quite a bit better than the ART3. Not that I didn't believe you, but like you I was reluctant to let go of the ART.

I have had my GAT for a couple of months now. one set of 6922's went noisy after a couple of hundred hours thou. I think I am over the burn in hump of 400 hours - right Lloyd :D
- it does sound awesome. :cool:

Hi Turntable...great to see you on the forum. Yes, my EH tubes went super-noisy at 850 hours and i took them out and CJ is sending a replacement pair. Meanwhile, yes, after 500 hours all the bass comes back and i honestly could not tell you if there were any changes after that, or i am just enjoying the system more by the day.

Enjoy!
 

About us

  • What’s Best Forum is THE forum for high end audio, product reviews, advice and sharing experiences on the best of everything else. This is THE place where audiophiles and audio companies discuss vintage, contemporary and new audio products, music servers, music streamers, computer audio, digital-to-analog converters, turntables, phono stages, cartridges, reel-to-reel tape machines, speakers, headphones and tube and solid-state amplification. Founded in 2010 What’s Best Forum invites intelligent and courteous people of all interests and backgrounds to describe and discuss the best of everything. From beginners to life-long hobbyists to industry professionals, we enjoy learning about new things and meeting new people, and participating in spirited debates.

Quick Navigation

User Menu

Steve Williams
Site Founder | Site Owner | Administrator
Ron Resnick
Site Co-Owner | Administrator
Julian (The Fixer)
Website Build | Marketing Managersing