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Review: Conrad Johnson CT6 Tube preamp

Category: Preamps

I have used tube preamps for about 10 years now, as I find their musicality superior to transistor designs. This is not to say they are perfectly accurate in all respects, but they remain truer to the music than their solid state counterparts in my opinion.

My listening tastes cover a wide range from classical to jazz to vocals. For critical listening and comparisons, I use mainly top notch CD recordings that I am intimately familiar with.

In sound, I hate thinness, brightness, recessed perspectives, texture, grain, bunched images.

I value musicality and naturalness, along with clarity, resolution. I want some body to the sound, without having an overbloated effect.

Feeling my preamp has been the limiting factor in an otherwise pleasing system, I wanted to move on to something new.

Conrad Johnson has been on a singular path for a number of years with their "composite triode," single gain stage, no feedback design in preamplifiers. It all started with the $15,000 ART, which was an assault on the state of the art, and which later trickled down to the Premier 16LS and 17LS designs. The composite triode design has been evolving since the ART, now the ACT2 being the top dog.

Recently, a Stereophile review of the CT5 ($8,500) gave it lavish praise, and found minimal difference between the ACT2 and the CT5, even finding some aspects of the CT5 superior.

With the CT5 out of my price range, I decided to buy its smaller brother, the CT6. Very similar to the Premier 17LS in size, weight, and tube compliment, using four 6922's, it is said to have an improved power supply and refined circuit.

If you haven't seen the huge polystyrene and polypropylene capacitors that CJ uses, you should take a look at this preamp. These caps are huge. I've never seen another preamp with capacitors this big. They are labeled CJ caps, so I don't know if they are custom made or what. They are truly impressive, and, from what I understand, account for a good portion of the parts cost of the unit, and contribute to the stunning sound quality. Overall, I was quite impressed with the beautiful finish, fit and build quality of the unit. This is quite a substantial piece.

EQUIPMENT USED: Conrad Johnson Premier 11 as a tube amp, and a Levinson 432 as a transistor amp. Northstar transport & DAC, B&W 802 Nautilus. Preamplifiers compared were Audio Research LS25, original version, the CJ Premier 17LS, and the McIntosh C2200.

Upon inserting the CT6 in my system, I noticed an immediate increase in naturalness and musicality. There was a rightness and evenness to the sonic picture that made the LS25 sound dry, artificial, over-etched, and slightly bright and irritating.

The CT6 had a wholeness to the total sonic landscape the other preamps lacked, except for the 17LS. There was dimension to each image, lacking that flat, cardboard cutout effect of the LS25. The C2200 was somewhat bright and forward, and a bit splashy, though it was a definite improvement over the LS25. The 17LS had a closer resemblance to the CT6, though it was not as nearly resolved or realistic sounding, and it had a somewhat distant perspective that did not jell together, lacking the wholeness of the CT6.

The CT6 presents voices in a natural, wholesome fashion that comes closer to the sound of a real voice singing in a space. Cellos have a rich, big, resonant character, like in reality. Piano has the harmonic complexity and weight of the real thing. Cymbals and percussion ring freely and fully, without any edge or brightness, unless poorly recorded. Brass instruments bloom out, yet still have the appropriate bite. String bass has the nice fat plucks you hear in person, without blunting or restriction.

Being familiar with the very different sound of both the Premier 11 and the Levinson 432, it was fascinating to hear how the sound of both amps was improved by using the CT6. The somewhat traditional tube signature of the Premier 11 bloomed to its finest, providing palpable, full images that were rich, but not overfat or ill-defined. Similarly, the Levinson 432 exhibited its finely-detailed and delicate treble, its slightly cool, yet somehow beguiling and natural midrange, its immense soundstage, and its powerful bass in a more favorable light than I have ever heard it before. The only area I could imagine improvement in is the bass region. Although it may have lacked the last degree of bass punch and dynamics, it was still damn good.

I must say that I am quite pleased with this amazing preamp. Gone are the days of Conrad Johnson's thick, honeyed, bloated, and colored sonics. Some prefer that sound, and find their newer products too "analytical." I can't understand how anyone could consider the present CJ sound as analytical. Rather, it's natural. CJ was able to maintain the body and soul of the music and add refinements in accuracy, clarity and naturalness.

I can't imagine what the CT5 must sound like. I don't want to hear it, as it is now $8,500, and way out of my budget. With that in mind, I'm very pleased with my purchase, and I consider the CT6 one honey of a preamp.

Associated gear
B&W 802 Nautilus
Conrad Johnson Premier 11 amp
Mark Levinson 432 amp
Northstar transport and DAC

Similar products
Audio Research LS25
Macintosh C2200
Conrad Johnson Premier 17LS
zear
zear OP
69 posts
 
In a forum thread asking about what the CJ sound is, I posted the following, which I thought would be helpful to post here as well:

I compared the 17LS to my new CT6. The 17LS was definitely more distant sounding, and not in the same league sonically to the CT6, which was much better. I can't speak to the 17LS MkII, which some here claim is superior to the original 17LS.

Read my review on the CT6. It does not have a recessed sound at all, yet it has a deep soundstage, deeper than any of other preamps I tried or owned. One of CJ's biggest strengths is how it recreates a 3-D image of each instrument, where you can hear the air and space around each instrument. This paints a wide and deep soundstage that separates images in a clearly-defined and natural way that sounds correct and easy-going. This results in a much less electronic, constricted, flattened presentation of other preamps.

The CT6 is not dark or lacking sparkle. There is detail, but not achieved by overetching or brightness. The midrange has some weight and body, which is a hallmark of the CJ sound. I find this combination closer to reality than other brands, and is bringing me much musical enjoyment.
zear OP
69 posts
 
Saxo, I used the Acoustic Zen Matrix in the past, and thought it a good cable, but moved on to other things, so I couldn't comment on it now. I certainly have found that interconnects make a huge difference in the ultimate sound.
saxo
98 posts
 
Zear- you're right about cables. Some friends & I tried a bunch of cables and each one gave a markedly different result. I guess the elegant simplicity of the CT (composite triode) design creates such a clear window on the sound that it reveals the characteristics of each cable. It was interesting, too, that one fellow brought his CT5 over, and I thought my CT6 sounded very, very similar to his CT5. The CT5 almost sounded overdynamic with an almost overpowering bass. Don't get me wrong - the CT5 sounded great, but I was surprised at how similar the sonic character was of both pieces.
zear OP
69 posts
 
I, as well, was able to find a local fellow with a CT5 who was willing to make a comparison. We listened back and forth to each with several selections, and did this two times before he needed to leave. I agree with you that both units have a similar sonic qualities and presentation, but there are differences.

The CT5 is quite dynamic, so I can understand how you may have felt it almost overpowering. This is not to say the CT6 is not dynamic; it is quite dynamic, just not to the degree of the CT5.

My feeling is that the 6H30 tube has different sonic characteristics than the 6922/6DJ8. It tends to be quite punchy and dynamic, have a powerful bass, and image exceptionally. This takes away a bit from the sparkle and air in the high end, which is still there and quite good. However, I hear more air and sparkle in the CT6. That said, I think this is system dependent. Also, one could tailor the sound with different IC's, etc. The soundstages are very similar, with the CT5's being slightly larger, with even more authority.

I went away from this comparison feeling good about the sound of my CT6, and consider it very good value when the price differential is considered. In fact, I'm going to go listen to it some tonight. It has brought me much musical pleasure, presenting music in such a natural, coherent way, more so than any other preamp I have owned.
saxo
98 posts
 
Zear, I heard the same thing in the highs on the CT5. I remember reading comments about BAT preamps where people were arguing that the top end did or didn't have the treble extension the extreme highs, and these were specifically models that use the 6H30 tube. Can't determine much from that though, because I would think the implementation of the tube in the circuit design makes a big difference. It's clear the 6h30 is a dynamic and big sounding tube. I don't know how anyone can call it sterile. It certainly didn't sound sterile in the CT5. If anything, the midrange was quite robust. Your suggestion of tailoring the sound with interconnects and wires is a good one.
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