62 (EL34s) to 62SE (KT120s), musical midrange?

[decooney]

Hi All,
I'm not a regular posting member, more of a lurker admiring CJ amps. Also a prior EL34 user and current KT120/KT150 user in different brand amps. My custom speakers are 93db sensitivity @1w. I listen more at LOW volume levels, and really don't crank it up much at all. I tend to look for more musical midrange than uber detail or uber bass, as I already run dual stereo subwoofers. Having a massive sound stage is not overly important to me if it helps to describe preferences. More of a musical midrange fan. If I change amps again, would like to ask for your feedback here. Thanks in advance for your replies.

Two questions:

1. Has anyone here moved from a CJ amp using EL34s to another amp with KT120s and compared the real differences over time?

2. Let's say If you did not need gobs of power, which of these tubes do you prefer in CJ amps and why?

[Big Dog RJ]

G'day mate, from Down unda, welcome to CJO.

This very topic has been discussed at serious length on several tabs under Amplfiers, especially the section covering the CAV45. Also on numerous other posts under the MV60/se, Classic 62/se, Classic 120/se, ARTsa, and LP series amplifiers. I suggest you go through those posts at your leisure, there's very valuable info in there.

Nonetheless, just to answer on a short note, since you've provided some good insights to your listening habits: low volumes, fairly high efficiency speakers and you prefer musical midrange, plus you've got two subs, I would recommend the EL34's.

Referring to musical midrange, all tubes convey musical midrange, it's what kind of midrange you're looking for in reproduced music. Although not all recordings are perfect nor are any of them 110% flawless... you can customise the sound you want by carefully selecting the tubes to your musical tastes. The EL34's have a fast tight bass, smooth highs but not extended, and a glorious palpable midrange, where you can reach out and touch the musicians.

With the KT88, KT120 and KT150 all of these virtues are present but with far greater presence and authority. So again, it's a highly personal preference. There are many of us who have changed from EL34's to KT120's and KT150's, including myself and perhaps others will contribute...

As far as each of those tubes and its attributes are concerned, like I said all of this info has been covered in great depth based on the tabs I mentioned. It's a wonderful read!

Cheers, RJ

[decooney]

@Big Dog RJ,

Thanks for taking the time to reply. Yes, I did scan old threads for a few days prior, and year ago, including some of your replies too from the past. Got it.

The reason for the updated inquiry is more since KT150s came out and have been out for enough years - was hoping for any further updated impressions, . I referenced this same site forum to reference comparisons on KT150s when I decided to go back and retry KT120s again in my (other brand) mono block tube amplifiers. I've been back to KT120s for a year, and sort of prefer them in my amps compared to the ultra neutral KT150s which are nice, but even further away from the EL34 sound I tended to prefer in my prior strapped triode/ultralinear amp with too many EL34s in it.

After a little more research and hopefully a few more replies here, I might have some custom mono EL34 amps built and wanted to triple-check myself a bit more before doing so. My current amp designer contact believes KT120s sounded closer to EL34s to him than other tubes. In my amps, they might be 60% of the type of sound an EL34 has, maybe, imo its still not the same EL34 magic midrange sound I recall from my prior amp I reluctantly sold to try KT150s in an optimized amp design and transformer configuration designed just with higher plate voltage for KT150s. I may get the 2nd amp set and compare anyhow. We will see.

Thanks again in advance for the replies.

[admin]

I'm not sure if any of these tubes are "better" (or worse) in the classic sense. They are going to have their sonic qualities. Whether you like one over the other is really going to depend on personal taste. I use KT120's in my CJ ART amps. They sound wonderful and have no desire to change them. But that's just me.

[decooney]

I'm not sure if any of these tubes are "better" (or worse) in the classic sense. They are going to have their sonic qualities. Whether you like one over the other is really going to depend on personal taste. I use KT120's in my CJ ART amps. They sound wonderful and have no desire to change them. But that's just me.

@admin that is good to know. The primary reason I checked and referenced this CJ forum is it's the one place I could go to and read posts by folks regularly using KT120s, still today. Or, a bit more so than other brands and owners that sort of leapfrogged quickly to KT150s. In my current amps, originally I started with KT120s and realized later I unfortunately did not give them enough time to settle in on the first go-around. I jumped prematurely right back to KT150s. When I asked my amp designer/builder which of the tubes sounded closest EL34s, he told me that would likely be KT120s. So, I flipped back to KT120s, let them run in another 100hrs and they started to come into their own.

I was at a friends house recently with amps similar to mine, with GL KT77s. While my KT120s have a larger and more clear sound stage, and perhaps a little more weight and body to the sound, there is something about the midrange with EL34s, KT77s I enjoy just as much. Before purchasing a 2nd pair of mono amplifiers to run these smaller tubes, it's great to learn from folks here too and still seeing CJ amps sold with both EL34 and KT120s today.

Thanks for the feedback.

[Big Dog RJ]

Yes, that's a good point mate, and fair comparison. Certainly sounds like you've had a listen to all three types.

However, keep in mind, tubes themselves take time to settle in... typical around 100hrs or so. They need to reach optimal performance by gradual thermal temp and other parameters within spec, such as plate voltage and gain. So before allowing these elements to settle in, most people get overly excited and change tubes, without even allowing the tooobs to settle in!

I have guilt of tube rolling myself back in the day but I learned not to the hard way! So now, if I wanted to learn the differences between tubes, I would think of trying different ones only after 6 months to a year of use then I can tell the differences between types straight away. It's more tangible to ascertain.

However, as we've all advised, the type of sound coming from tubes is highly personal. There are some who prefer the 300B but others think it's too syrupy... then others prefer KT150 but some think KT150 are over bloated and KT120's on steroids! Others simply prefer the KT90-ei, which Manley Labs uses primarily in their Neo 500 monoblocks. However, Manley Labs also uses EL34's in their Neo Classic 250 monoblocks, and I've used both! I preferred the KT90-EI version but that was driving large Infinity's IRS 1B speakers.

The EL34's have been quite magical with stats, especially Quad ESL's, which I used back in the day. It was a Premier 11A configured to the XS version, which uses EL34's in Triode mode. Driving a pair of Quad ESL 63's placed on top of Gradient subs was marvellous! It had a soundstage depth and layering like no other! However, that was on that particular system.

On the Apogee Diva's driven by the Premier 8A monoblocks fitted with KT120's and Teflon cap upgrades plus the ART series 3 preamp, that was at another level that the Quads and Prem11A couldn't match. Just no comparison.

So, it all depends on your personal preference and system config. You also need to have a point of reference, such that it could be a live performance, a high quality recording played back on another top tier SOTA system or some live group with vocals and perhaps a small ensemble. This is your point of reference where you can customise the sound you're after.

Many don't have a point of reference, hence they go around in circles and tooob rolling begins...
So, what's your point of reference? If you know it and it seems like from what you're describing, the EL34's midrange is something you admire and fully engage with. In that case, stick to EL34's! After all, that's YOUR preference!

If it makes you happy and fully immersed in the presentation then that's the tooob!

Cheers mate, hope it goes well.
Woof! RJ

[decooney]

Thanks @Big Dog RJ and @Admin for your thoughts.

Since I don't have any of my EL34 amps around any more, and its, been a while since then and rotating through the larger tubes, 150, 120, and staying with 120 amps for now, I am re-questioning myself a bit if what I'm remembering was more of that eurphoric midrange sound I heard b/c my former amp which natively ran EL34s, was switchable between Ultralinear and Strapped Triode mode. I rarely ran my past el34 amp in UL mode, it was always switched to strapped Triode mode. Since then, the closest I could get with the bigger tubes is the KT120 to emulating that type of smoother and softer sound my EL34s had before.

The midrange is good on my KT120s, and perhaps think this way b/c the upper most top-end of the KT120s is a bit more rolled off than it is with my KT150s. While I greatly respect how my amps sound with KT150s,its got the best of top-end, best of lower-end, with the biggest sound stage, I'm a total MIDRANGE NUT at the end of the day, listening to guitars and piano keys a lot so I guess tend to gravitate to the more present midrange I've heard before in EL34s. I won't get rid of of my current amps designed to run dedicated KT120s/KT150s, but might get a 2nd pair of amps designed to run EL34s/KT77s to swap in/out once in a while - if that makes sense. Will try it for a while, and part with the set of amps Iisten to the least. Thinking it over now.

Folks here on the CJO forum seem to have a lot more note experience with KT120s, and still liking them a lot like I do, and compared to any other forum website I've found, which has been super helpful. Thanks again.

[decooney]

As we know, KT120s and KT150s by TungSol have become "out of stock" again of course, another factor in consideration of which tubes to follow. While we can keep spare quads around, it does make a case for amps which can also run the smaller EL34, KT77, KT88 tubes or no tubes at all. Will be buying an alternate SS amp, or picking up a 2nd tube amp to rotate in with other type tubes during these shortages and sad war events going on in the world today.

[Big Dog RJ]

Yes mate, I agree! The world in it's current state is absolutely topsy-turvy. Apart from the consequences of climate change... we're faced with unexpected economic pressures and every household is feeling it. On top of that, looney Putin continues to bomb away! I guess that's his motto now, fire as many missiles as possible and bomb anything in the way, regardless of life circumstances.

Sometimes when I look at it, the audio issues we're talking about are luxurious problems, they really are! However, I do sincerely believe listening to good quality music, is a form of therapy and it's what keeps us sane! I figure many of those harming others are not happy and obviously not enjoying the music!

That's why, I always believe in enjoying those fine tunes!

It's very handy to have amplifiers that can safely accommodate different types of tubes... you can't do this with SS devices, tubes rule!

Cheers, RJ

[roberto]

hola decoony,

All tubes have their own signature sound quality. I had for long time in love with the EL-34/6CA7s. Then I started to use SS, and did a long journey with different well known brands in the SS words until I went to a friends house where he was using a CJ One Twenty SE with the KT-120s. His speakers: JM Labs Utopia. I am into the electrostatic speakers since 1987, and let me tell you that I can't forget his quality sound. The bass was well defined with real authority, incredible stage presentation and very non fatigue highs. He really had a wonderful enjoyable sound system.

Then I entered again into the tube world. At that time I had Levinson and acquired a VT-100 MK II by ARC and because this amp is easy to work into its electronic, I modified it for the KT-120 tubes. I did change all the carbon resistors for a Vishay metal resistors and some caps. I did use mostly the same value of components that I did change, only a little more power dissipation. I was very happy the result. The sound was a big step forward.

Since 1982 I have a new friend: Lew Johnson. He respected me that I was trying to listen different goods in my system, but the truth is that my heart belongs to Conrad Johnson. A friend came and bought my modified ARC about 7 years ago, and I got the Classic One Twenty SE. It was a Lew recommendation. I remember his words: This unit has almost the same quality sound the our top of the line mono blocks. Same quality for a fraction of their price? I was very interested and bought it.

I know that CJ has better goods than my 120SE, but my Martin Logan CLXs are very happy with it. I really find the authority in the bass section a control that I never spect to have with a tube gear. The KT-120s are a wonder to have. And the recipe of the design of this marvellous power amplifier (marvellous for me) is breath taking. The signals to noise ratio is my system is fantastic. Even having your ears against the CLXs panels are dead quiet.

I did made some changes and got the ET-7V2. I did an unfair comparison with my previous ET-7. My truth is that perhaps I did not have the version 2 enough time with me and I said to myself, why are you going to a change if you have a such wonderful sound too coming from your ET-7?...and I did not do the change. Now I do regret all the time that I had lost, the V2 is a big step forward of the quality sound, stage and harmonic texture over the V1. Where I do find the big differences are in the micro dynamics and the harmonic texture. The bass is profound and very well defined. A wide stage and pure sound is what I am enjoying, of course the highs are extended to beyond hearing threshold. Another big change that I did is the Holo May KTE dac.

At this moment, I don't want to change even a screw with the quality that I am getting through CJ and my CLXs. It is for me, the best system that I ever own. Period!

My advice to you: get the 62SE and have two or three days of listening. It is a hidden monster there. Don't worry about the power, it is capable to produce a lot of super clean steady sound. Highly recommended.

Yes, I do know that out there are far better goods too. But I am happy as never before in all my audiophile time.

Happy listening!

[decooney]

@Big Dog RJ, @Roberto -

Thanks for sharing your journey and story. Some day I would like to try CJ. I'm a Cary Audio. Quicksilver Audio, and Pass/Forte' amp owner now. Each offers its own signature of sound. What I'm also interested in is how each of these output tubes can sound different within one amp designer's vision to the next. EL34s sounded amazing in my Cary amps, the KT150s and KT120s sound really good in my Quicksilver amps. I have not heard the EL34 or KT120 in a good CJ amp yet, only with 6550s. Would love to hear one some day with the custom speakers I designed and built for myself. Will look for.a western US dealer and hopefully can check out both of these amp in person. Thanks again.

[Big Dog RJ]

No worries at all mate. Just tell us what you're after and we'll help you spend your money!

Always willing to help,
Woof! RJ

[roberto]

Yes, we are here for helping others with our experience and our love for Conrad Johnson products. As the slogan says : "Conrad Johnson sounds right!"

Happy listening!

[decooney]

Does anyone here have a general idea of the more common low/high range for KT120 tube bias with CJ amps? 50,60,70,80ma per tube?

...just curious how hot CT recommends as min/max limits in their amps.

[admin]

I don't know if there is a "range" but more of a set point. On my ART amps you basically bias the tubes to a specific set point (indicated when LED go on/off). I'm sure there is some variation of the currents with different temperatures and loads. As for what this "set point" value is, that I am not sure.

[decooney]

I don't know if there is a "range" but more of a set point. On my ART amps you basically bias the tubes to a specific set point (indicated when LED go on/off). I'm sure there is some variation of the currents with different temperatures and loads. As for what this "set point" value is, that I am not sure.

Thx, I probably should have posted the question in a tech/repair section, and was referring to those who might be checking internally during a service check - using a meter vs led. I run different amps, and using a meter and realize different amp/designs with different circuit designs will run different voltages and therefore different bias settings, and so where the range question comes into play. In general across different amps designs it seems very few run the KT120s less than 40ma, found several at 50ma, a few at 60-70ma, and few rarely mention biasing upwards of 80ma per tube. The interesting part is a periodic mention of a point of diminishing return going above 60ma, sound getting brighter and not necessarily sounding better. If anyone here happens to check with a meter when the LED is fully lit on your 62SE amp, would be curious to know what a single tube measures at with that amp. Thx

[roberto]

Hola,

If my mind does not tricked me, I think the proper bias current is 57.5mA for each power tube. The ARC use 65mA for a pair of power tubes while you are adjusting the bias, and this the factory recommendation.

I can't say that the set up of the bias in Conrad Johnson is that value, because you are allow to adjust the current on each tube by a Led. When the Led goes off, that's the bias value from the factory. And also it is wise to check this adjustment at least every 6 months, because the tubes get old, and the bias current might vary.

A very valued member Another Johnson perhaps might have this exact value.

Happy listening!

[decooney]

re: KT120 -

@Roberto If my mind does not tricked me, I think the proper bias current is 57.5mA for each power tube.

If this seems "reasonable" and not too far out of bounds, or too hot, I may try 60ma per tube with KT120s in a different amp. My Amp Designer [different brand] use to recommend up to 65map for 6550 tubes and 60ma for KT150s in his older version amps. He's become more conservative over the years showing as low as 40ma for KT150s in the operations manual for my current amps. I'm now with KT120s sampling others with different brands to see if there is a general idea of what is "safe" and not too hot for KT120s, but want to push it a little closer to 60ma. I don't want to cause damage to the amp. My mono amps have huge transformers, and I just upgraded the main power caps with larger quality Nichicon power caps too.

Recently upgraded one of my other solid state amps to full Class A with a local pro tech. Love how it sounds in full Class A mode 50w. Super nice. It has me reanalyzing my mono tube amps, wondering if I'm not running my KT120 or KT150s in their optimum range down at 40ma per tube right now. Tried it once with KT150s at 50ma, did not hear a lot of difference. Now using KT120s in these same mono amps. May try 60ma per tube each. Thanks for the notes.

[decooney]

Looping back on this and bias setting for my [other brand] amps with KT120 output tubes -

Found out my amps run 600v at the plate, and the designer was running the tubes "in the COOL zone", intentionally, to increase longevity.

However, barely running anything close to 70% plate dissipation, not "in the window" or optimum operation for sound. So, what to do.

Doing calculations and checking formulas realized I could easily jump from from 40ma per tube up to 50-60ma without even breaking a sweat, Found others running upwards of 70-90ma with KT120s and similar plate voltage. Wow 90ma?, more than double than my initial starting point.

Tried 50/60ma and the stage opened up more, more detail, more revealing and slightly more analytical. Backed off to 50ma, seems to be nice without prematurely burning up the output tubes. Got it covered now with my current KT120 pentode push pull amps.

-----------

CJ / Next to try:
Anyhow, was attempting to reference this forum for feedback - also in case I try a CJ amp in the future, likely EL34s or KT120s. I do like the sound of EL34s in my prior amps. Not sure how EL34s or KT120s sound in CJ amps set up in "ultralinear vs. triode" configuration. Feedback appreciated about this. Also have a friend looking at trying an older MV-60 starting in ultralinear and may reconfigure to triode to see how it sounds, pros/cons of each. CJ owner feedback appreciated about UL vs. Triode configuration (pros/cons) in these amps when paired with more efficient horn speakers, like Klipsch Hersey or Klipsch Forte 4s?. What do you like, why?

[roberto]

IMG_4797.jpeg (378.74 KiB) Viewed 1301 times

This is what Mr Manley states regarding the bias on his very good sounding professional studio power amplifiers.

Happy listening