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Underwhelmed by these new KT77's, break-in needed?

jmitchnh

jmitchnh

Active Member
I recently decided to try a little tube rolling in my Cayin A-50T. It came with JJ EL34's which I thought sounded really nice, but wanted to try something different. After much online research, I settled on a quad of Cryoset matched Gold Lion KT77's given their numerous positive reviews.

I installed all four, set them at the factory bias, .325 mv and let them sit for about 30 mins and re-checked. Powered up the system and gave a listen. Unfortunately I did not experience the distinct improvement in sound others have. Actually my system sounded worse. Very bright sounding, no low end and very high listener fatigue, to the point I couldn't listen to them anymore.

This seems so opposite of what most users of this tube experienced. Now I'm wondering if there's something I'm doing wrong? Bias is holding steady. I know these tubes had a 24 Hr. burn-in from the dealer, am I expecting too much too soon? Before I give up on these and put the JJ's back in, just curious if anyone else has had this same experience?
 
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In some amp designs the GL KT66 and 77 can bring out too much of a good thing. In my situation I found as I moved up to the KT88 it finally all came together.

What driver tubes do you have? Because rolling them also has a tremendous effect on the "tone" of the output tubes. I don't know the actual design but if you are still using the EH12AX7 and EH12AU7 I've found those to be VERY hard sounding. I'd switch those to GL B759 and TungSol 12AU7 respectively.

Is it hard to listen too in both triode and ultralinear settings?

Also if you like the EL34 sound you may want to try the EH6CA7.

Sorry but this IS part of tube rolling. Sometimes you win and sometimes you have tube being stored in the closet until you die. We all got-em.
 
I like the JJ kt77's in My st70. It did take a little time for them to break in. I used a set of 88's, but wound up putting the 77's back in. You may find you just like el34's better. :dunno:
 
I did a little more reading on the A-50. Try rolling the 12AX and 12AU tubes. Again use the tubes recommended
 
First, thanks for all the feedback! As a tube newbie, it's great to hear from those who have experience and background.
Second, I looked and found that this amp has 2 Tungsol JTL-12AU7's and 2 Svetlana 12Ax7's.
Third, after some more listening today I still find it a bit bright but I believe I'm also hearing greater detail and clarity (a good thing) esp in the vocals. I'll try and put some more hours on it during the week and see if I hear any difference.
I really love the availability of changing the sound of an amp by simply changing tubes. Understanding you may make things better or worse, but tube amps def have an amazing sound quality all their own!
 
I had exactly the same experience as you.
Clear bright sound but thin and sterile. However I did not wait for the tube to break-in.

I then tried 6CA7EH from Electro-Harmonic and this one rocked ever since.
 
Brice said:
I did not wait for the tube to break-in.

I then tried 6CA7EH from Electro-Harmonic and this one rocked ever since.
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I would agree. If you don't like the tube this much breaking in isn't going to change the character that much. If you like the EL34 then the EH6CA7 is an excellent choice. I really love the way the GL KT88s sound in my amp. But again it's all dependent on the amps design. However one day I may try a set of the EH 6CA7s on my VTA ST-70.

I was always a sucker for a good EL34. Enjoy
 
They need more time to break in. This is a common mistake with people. They don't give enough break-in time. I made the mistake of doing that with a phono cartridge once.....
 
Your KT77 tubes need a lot more hours before they reach their full potential. I was initially disappointed with mine, mainly because they seemed too thin and lean in the bass. However, I decided to leave them in for a while just because I hated to waste the money I had spent on them. And surprise, surprise! After a couple weeks of daily use they blossomed and became my favorite output tubes. A well broken-in set of reissue GL KT77 tubes is rich, warm, very dynamic and very detailed. Since I wasn't bothering to keep track of the hours, I can't estimate how many hours are required, but maybe 50-75. I have never experienced such a change in sound with output tubes going from new to fully broken in.
 
Salectric said:
Your KT77 tubes need a lot more hours before they reach their full potential. I was initially disappointed with mine, mainly because they seemed too thin and lean in the bass. However, I decided to leave them in for a while just because I hated to waste the money I had spent on them. And surprise, surprise! After a couple weeks of daily use they blossomed and became my favorite output tubes. A well broken-in set of reissue GL KT77 tubes is rich, warm, very dynamic and very detailed. Since I wasn't bothering to keep track of the hours, I can't estimate how many hours are required, but maybe 50-75. I have never experienced such a change in sound with output tubes going from new to fully broken in.
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Have a set on the way. Hope I get same results. KT77 GL on modified st70
 
I formerly used the EL34's in my Musical Paradise SEP, they sounded pretty good but not much bass, fairly typical I think and a little down up top. Nice mids. I tried 6L6 and found them too lean in the middle. Then an 6L6 derivative, the 7581A and liked it better. Nice bass and top and not as lean, but still not an EL34 in the middle. Then I tried JJ KT77's. I don't know about break in but they are the best of the lot. Nice bass, better top than the EL34, maybe not quite as the 7581A, and the mids are close to the EL34, so that's what I roll with.
 
fredgarvin said:
I formerly used the EL34's in my Musical Paradise SEP, they sounded pretty good but not much bass, fairly typical I think and a little down up top. Nice mids. I tried 6L6 and found them too lean in the middle. Then an 6L6 derivative, the 7581A and liked it better. Nice bass and top and not as lean, but still not an EL34 in the middle. Then I tried JJ KT77's. I don't know about break in but they are the best of the lot. Nice bass, better top than the EL34, maybe not quite as the 7581A, and the mids are close to the EL34, so that's what I roll with.
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I tried various tubes in my ST70 and found the JJ KT77's to be a great value for the money. The 77's are my favorite so far. I keep hearing if you like the JJ's you will love the Gold Lyons. The 77's just have a well balanced sound to my ears.
 
Lavane said:
I tried various tubes in my ST70 and found the JJ KT77's to be a great value for the money. The 77's are my favorite so far. I keep hearing if you like the JJ's you will love the Gold Lyons. The 77's just have a well balanced sound to my ears.
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One of these days I'll jump up to the Gold Lions.
 
I love my GL KT77's, but I had a somewhat similar experience. I found that the GL's had too much separation. It's like I wasn't hearing a song, but more of a collection of instruments and vocals. It was really jarring. I think my problem was never hearing that level of separation before. My brain was trying to chase down each instrument or sound, because they were ALL suddenly prominent and important. I sold the first set of 77's after about a week. I just figured whatever was going on wasn't for me. Some months down the road, after continuing to read glowing, (no pun intended), reviews of the GL's, I figured I pretty much had to give them another shot. I was told by an Upscale Audio rep that they could take up to 100 hours to break in. This time I waited, and played, and waited, and played. I couldn't say when or how either the sound of the 77's, or my perception of them, changed. But I came to love that sound. Eventually one died, after only 4 months. But there are duds in every line of tubes. I ordered a replacement that measured close and rolled the 6CA7's the amp came with stock back in.

I was...really disappointed in the sound. It was like a muddy mess compared to the Lions. That was a loooooong week for me.
 
I recently bought a pair of Manley Snapper monoblocks that came with 8 Gold Lions KT-77 installed a few months prior. They sounded very good but a tad bright. Edgy. I've got sensitive ears. Don't like hyper high definition clinical sound. Nope. Amps are practically new, caps good...Next I tried Mullards (Russian EL34), smoother but a bit slack in the bass. Next, EH 6CA7, just about the same as the Genelecs, as were the Telefunken Black Diamond EL34s I tried next.

I have fairly new Vandersteen 3A Signature speakers which are known to be on the more relaxed side of things, with hi and low crossover EQ pots. I finally settled on the current Manley factory recommendation, the Tung-Sol EL34Bs. They don't have edgy highs at all, and the bass is a tad more pronounced than the others. (I also tried a few NOS driver 12AX7 and 7044 tubes GE, Mullard, Philips--no change)
Note: None of these tubes sound significantly different from one another, keeping signal source, preamp, and speakers the same. Measure them directly on a scope output, or with a mic and spectrum analyzer in the room.
They also don't test much different from most NOS, despite all the sales hype... They sound virtually the same, except with some slight variations (like less than 2dB and that, usually only at 5000KHz+ or below 100Hz...
That said, most tube "sound" depends HEAVILY on the amp it's in. In my opinion, if you want to tweak your sound, change the DAC, the preamp, or the speakers first. And get the ARTA software, and do measurements!

I have a simple $600 Topping DAC, and a re-capped Canary Audio CA-906 (5V4 rectifier, 6V6s, 6SL7, driving 4-6SN7s) Preamp. It's a good smooth, yet well-defined system sound, with pro wall treatments and thick carpet on about 30% of the room. Anyway, hope some of that helps. I can confirm as the other writers said--'break-in' does NOT change tube sound much--except in people's imagination--not in measurements. Nope. "Break-in" is about the time it takes to initially warm up...All the best in your quest!
 
I run KT-77s in my TU-8200 and my Prima Luna Prologue. In my gear they are the perfect combination of detail and dynamic range without being fatiguing. It's strange to hear your description because it's not at all what I've experienced. I've tried EL-34s, KT-88s and 6550s. The KT-77 is just the sweet spot for me.
 
I know this is an older thread, but I just got some cryo treated KT77 Genelex Gold Lions from Upscale Audio. This is on a ST-70 variant...the Van Alstine Ultravalve amp (it's powering a set of Genesis Technologies 700's through a Schitt Freya+ with some NOS tubes). The Gold Lions replaced the stock EH 6AC7's (which I immediately liked). HOLY MOLEY do the KT77's sound harsh lol. So etchy, bright, and sharp that I had to turn the volume down because my ears didn't want it any more of it.

Of course, I'm not gonna make a decision based on my initial listening impressions because (as has been stated) it's gonna take a bit to break in. I really liked the stock tubes, but I can tell there's a lot "more" there with the KT77's...just need them to calm down a bit. I'll play them at low listening levels during the day just to get some hours on them.

It will be interesting to see how they develop because this is my first foray into tube amps, but I like what I've heard so far (minus the initial harshness of these brand new KT77's).
 
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I ran KT-77's for awhile in my ST-70. But after getting the EH-6CA7's, the KT-77's are now rolling around in the back of my tube bin with no plans to be used again.
 
I did immediately like the EH 6CA7's on the AVA Ultravalve. Have no idea how many hours are on them. I know some people say power tubes make a minimal impact on sound compared to preamp tubes, but the KT77's were noticeably in-your-face, and the highs were very harsh.

I will give them the required time to burn in given what Upscale Audio and others have to say.
 
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