Why Did c-j change "small tubes" after Premier 12

[Truth71]

Looking at the history of conrad-johnson designs, it appears that in tube amplifiers,from the premier one to the premier twelve, many/most models used 5751/6FQ7 tubes.

With the Premier 140, this changed to 6922 and 6N30, and therafter most subsequent models have used exclusively 6922 in these locations.

Thoughts on reasons/effects?

[AnotherJohnson]

The 6922s sound great, are readily available, are reliable, and don't break the bank. What's not to like?

[Big Dog RJ]

Interesting topic / question.

For whatever reason may be, I was told by a very trusted source that CJ first trialed these tubes in their Art preamp.
The 6922 in fact is not an audio tube, rather it's sole purpose during its introduction was used primarily as a radio tube. It was quiet and had good stability with its operation over several tests. So a few audio companies tried them out. CJ was one of them to have developed simple circuitry around the attributes of this particular tube, and it worked really well.

So yes, as pointed out, availability and reliability was a significant factor, and now JF would obviously like to sustain this business for as long as possible. Thus, providing superb gear, and keeping customers happy is the priority, might as well play it safe rather than meddle around with some other types.

Just the update from one of my sources and he's usually right! Similar recommendations made by JF regarding the preferred output tubes for the Prem11A. Although he recommends Tung Sol 6550 reissue, if someone currently has SED 6550C tubes, those are certainly "preferred!"

However, those SED's may not be their top supplier and so Tung Sol is the preferred one...
If it was a personal preference, I think the 6550C tubes would be preferred, afterall they are absolutely marvellous tubes! I've used them in all three for may years (Prem11, 12 & 8A).

Getting back to the 6922, it also has the capability to operate as twin triodes, so sections can be used in parallel, hence it's not necessary to use more tubes for additional channels. This is another reason for the 6922, used in parallel sections = simpler circuits, shortest possible signal paths = superior results in overall performance!

Far less coloured in my opinion.

Cheers, RJ

[AnotherJohnson]

Except for specialty apps, like rectifiers, the other common small tubes are twin triodes too. This is not unique to thr 6922. The 5751, 12AX7, 6H30, and many others are twin triodes.

And as for original purposes, none of them were marked out for high end audio.

Edit: High end audio did not exist yet, but there were post WWII tube designs that were based on goals set for the audio frequency range. The 12AX7, ancestor of the 6922, for example. Note that it was a twin triode, but this was more for space saving than for stereo. In 1946 stereo was still s glimmer in the eye of the not yet fully born consumer electronics industry. :End of Edit

They were mostly designed to meet specific needs of military equipment, including radios, but also radar, sonar, etc. Amplification, power control, single direction blocking, bridge circuits, etc. The Russians and the Chinese continued to rely on tubes long after most US consumer and military applications had transitioned to solid state. So tube evolution has been concentrated in those countries.

The old tubes were all adapted to audio after WWII. The military need was diminished. TV, radio, monaural hi fi were in the offing.

6922s are great tubes and easy to source. They’re consistent from sample to sample. These are important characteristics for a manufacturer.

If a manufacturer actually believed that some highly sought after, limited availability tube was better, it would make no sense to use it since the supply chain reliability would be so unpredictable.

We still studied tubes and tube design in the EE courses that were part of my engineering curriculum over 50 years ago. But we were all much more interested in the relatively new semiconductor technology as students.

[Truth71]

Does anyone know if the switch to 6922 occurred while Conrad and Johnson were the chief designers, or was that related to JF assuming a more active role?

[AnotherJohnson]

They were using 6922s in Premier products as early as 1998 (Premier 16, and maybe earlier).

RJ probably knows exactly.

1998 was well before Jeff took over … although he was in their employ at that time.

[AnotherJohnson]

From the Premier 16LS owner’s manual.

The Premier 16LS circuit employs six vacuum tubes (V1 - V6), all 6922s. The 6922 offers low noise, low microphonics, and gain well suited to use in a zero-feedback line-stage. The brands of tubes we supply have been chosen by first selecting those brands which are known to be most reliable, then by extensive auditioning of these acceptable brands with the final choices being made solely on the basis of sonic performance. We know of no vacuum tubes available which will improve the sonic performance of your Premier 16LS. The tubes in your preamplifier have been tempered by a controlled burn-in procedure that permits them to perform for a greatly extended period without sonic degradation, then selected for minimum residual noise. Replacement tubes are prepared and selected in the same way. Therefore, we highly recommend that you purchase replacement tube sets from conrad-johnson design.

[AnotherJohnson]

It was even before 1998. The 1996 released Art Preamp used the 6922s too.

So … I think that anyone who might be attributing the switch to 6922s as an ill-advised effort to find something cheaper, or a compromise compared to older tube designs is not on the right track. Bill and Lou certainly were “in on it,” and maybe even “behind it.”

In any event, last night I got out Ralph Smith’s 50+ year old book that summarized the state of EE (at the dawn of Solid State’s displacement of hollow state). I turned to the chapter on audio amplifier design, and was greeted by many “sound” ideas about ways that distortion gets introduced in an amp.

I came away even more convinced that when people prefer one tube over another, it is likely to be because the preferred tube is introducing or reducing some distortion that they like (first case) or don’t like (second case).

Because of the Fletcher Munson studies, we know that ALL of us hear differently, so choosing tubes is a personal choice.

I feel lucky that the 6922s are so satisfying to my ears. Someone else may feel the same way about 6H30s.

FWIW, unless you’ve spent a lot of time listening to live music, and are using that as your reference, it’s all subjective (even beyond Fletcher Munson) anyway.

[Big Dog RJ]

So relating to the question/ topic: change of small tubes after Prem12... is mostly focused on power amplifiers.

This is where we also had a chat to LJ about this exact topic. Back then when we took delivery of the ART preamp, we noticed straight away the multiple array of 6922's (I think there were 10 in total, 5 tubes per chassis). I clearly remember then the 6922's were EH, and these always had a sense of fine musicality.

Taking into consideration the MV series power amps and PV series preamps, they were so musical, you could literally see and taste that caramel syrupy sound. Tubes used in those designs were of a different type, including the power amps. Then they introduced the new Premier series amps; Prem 11, 12 & 8, the overall presentation was quite different to any MV series or earlier Premier product. They had much larger trannys, higher current capacity and more Class A output before switching into Class AB. The primary output tubes were 6550's whether type C or A being used at the time, these amplifiers retained that level of musicality, along with plenty of power according to the user's speakers.

If it was an efficient load then the Prem11A was most suited. For inefficient speakers and notorious impedence swings, the much more powerful Prem12 & 8A was more suited, and well capable to handling such loads. Owners were thrilled with these top of the line Premier standard versions, that CJ offered yet another level of fine musicality by offering these power amps in triode mode, referred to as XS versions using EL34's. The output power rating would typically halve, yet they had a highly palpable midrange that was totally engaging and highly addictive, almost like a drug! Once this level of performance was experienced, it was actually quite difficult to venture back towards 6550's.
The EL34's delivered a holographic image and soundstage depth that was mind blowing! It was truly top of class.
This was pretty much the standard CJ set, and it easily became a reference standard that many other brands looked up to but couldn't quite match it.

Lower powered amplifiers, typically between 30w to 60w, tended to sound more musical compared to higher powered versions. Many other brands, such as ARC and VTL were designed around brute force, able to drive virtually any load but they didn't quite have that musicality factor compared to CJ. We all agreed that these small signal tubes and 6550's used in earlier gear, were the result of that golden glow, caramel effect whatever they termed it then, and it was most enjoyable.

Fast fwd another 20yrs, and now things are quite different. The preferred standard is now KT120's along with 6922's being mostly Genalex, which I can tell is quite neutral. Then comes the new ART series amplifiers and the KT150 tube is the preferred choice, apart from the ART27A. These larger ART amplifiers have much larger trannys, capable of greater current and higher Class A bias, they are capable of reproducing the live event! So by all means, the goal is to recreate the live event, getting the most from your recordings without any artifices, in the most natural way possible. The GAT and ART do exactly that!

Probably the reason why I really didn't settle for a GAT. The ACT2 didn't use 6922's unlike the original ART preamp. It used 6H30P / 6N30P tubes, which still have a bit of that golden era, to me at least. I had two ACT2 preamps. The first one worked fine and it was sold to a happy mate. The second one was an ACT2 S2 but it had issues. Maybe I should have just kept the series 1. Apart from a few tech issues, both of then had a significant amount of hiss! I could distinctively hear it from the listening position and it was bloody annoying! With the CT5 none of that hiss is present, absolute silence. Maybe due to the number of tubes used in the ACT2 (4 6N30P's, vs only 2 6N30P in the CT5)... I'm not 100% sure but I think these extra tubes caused unwanted hiss probably due to higher gain perhaps.

The 6922's used right throughout in all of CJ's designs are the standard now, along with much higher grade parts, solid power supplies and discrete circuits to deliver a far more neutral type of sound. By this, you can actually "see" into your music, and it's something truly remarkable!

OTOH, a bit if CJ old school is still preferred..., and by carefully matching that old school signature with slightly newer amps, you can create a custom sound that's really special. I'm pretty much in that camp!

I guess as AJ pointed out, it all depends on personal preference and once you know the type of sound you're after, that's all that matters as long as you're truly enjoying it!
Cheers, and enjoy those fine tunes!
RJ

[AnotherJohnson]

Those small tubes in the amp are either used for switching (regulating) or an early amplification stage. The big tubes are trying to transfer power to the load (the speakers), via the output transformers (for impedance matching, which improves efficiency).

I do think that the earlier in the path that the tube swap occurs, the more sensitive the whole thing is to the change, unless an out of spec tube is serendipitously replaced.

Meanwhile ... it is personal preference. Different strokes for different folks. I think as a company, the focus has to be on designing the amp so that the output signal is as close a replica, except for amplitude, as it can be to the input signal. The 6922s seem to have become favored as CJ shifted to what you call their current sound.

To me it sounds more realistic, not that I didn't enjoy the old sound too. I have said it before, and I do believe it, that in every era CJ has tried to build components that would be faithful to the source. It just sounds right.

[Big Dog RJ]

That's a definite!
Very good point, definitely just sounds right, without a doubt! In order for it to just sound right, everything must be in the balance. The right amount of tonal accuracy, tonal weight, scale factor, and realism. Nothing too much of anything, and I firmly believe this is what makes it just sound right. I also noticed once it does sound right, every track or type of music you play will sound different. This is the greatest thing, where the system remain neutral for the most part and allows more of the actual recording to flow. It's easier to follow and understand, and you begin to really appreciate it even more. Every singer / vocal is different, along with the accompanying musicians.

I've heard some very lofty setups where nearly every piece of music sounds the same! Simply because the gear has taken over and is delivering their usual signature/ house sound. Initially it's OK but towards more listening it really gets boring. Nothing seems to change but the owners think it's great because it's cost an awful lot! I've been trying to explain to them about this phenomenon but sometimes they just don't get it.


It's a marvellous thing when you can hear every type of music in its most natural form possible, and this is where CJ just sounds right.

Cheers, and enjoy those fine tunes!
RJ

[roberto]

Chicos,
Another advice is: try to listen live music. Please, unplug music. I have to admit that the sound that I listened at the National Stadium here in Costa Rica with Roger Waters (Pink Floyd bassist) the quality sound was impecable. Clean highs with outstanding dynamics, but with the right level. Not too loud, just enough for all the Stadium. I really was impressed by this.
Usually the recording studios are as they were playing in front of us. Not in a big place. So, here is where I beg for you to have a listen carefully a live piano, guitar, drums, voices, wind instruments, all musical instruments but no amplification. Just the instruments for you. Like if you where in a living concert hall. Here will tell you how close you are to the real thing.
Conrad Johnson is seeking this. The naturalness of the musical instruments and voices. The recording quality has to do too. In a general way of speaking, the quality of the recordings have improved to a point that we are listening things that we thought they will never show up, as an example, the timbre of the cymbals. These percussion instruments are very difficult to achieve the naturalness, and today we have incredible clean highs with outstanding cymbals.
Happy listening!

[roberto]

In my system, a hiss came out. Not too loud but enough for my ears to detect it. It was coming from the SS three channel power amp Anthem brand. My stereo system is so quiet now that I could hear this hiss. Now I am turning off the Anthem while I am listening to stereo. I am 90% with stereo music. And really enjoying the musician(s) each day better.

I was able to get two Bel Canto transports. One, is the model CD2 and the other is the model CD3T. The CD2 has an upsampling mode by factory default, so I have 96KHz always with this transport. The other is normal config. Both are great to have too.
Happy listening.

[roberto]

The 6922 tubes are nice to have. They exhibit a naturalness with a great S/R too. I did some tube rolling and now I am very happy with the Genalex. I only have 4 tubes 6922. There are many options and also from different manufactures.

The 6922 is very neutral. It seems that it does not touches the signal. I love this.

Happy listening!