Conrad-Johnson Premier 350 discussion
 

This thread is for discussion of the famous Conrad-Johnson Premier 350 amplifier:

From the C-J website:
Hybrid Solid-State Circuit.
The Premier 350 benefits from an interesting hybrid of solid-state technologies. The distortion characteristics of an amplifier are dominated by it's voltage gain stage. We have selected FETs for this application, because, like tubes, and unlike bi-polar transistors, they produce almost no strident odd-order harmonic distortion. The output stage of an amplifier must efficiently couple the high amplitude signal produced by the voltage gain stage to the loudspeaker system to assure the power and control needed to produce a musically accurate response. Bi-polar devices have been specified for the output stages of these amplifiers because they offer about 1/4th the output impedance of a MOSFET, resulting in much better control of the loudspeaker. This is most noticeable in faster, more solid bass response.

Zero Feedback.
Negative feedback is an engineering technique used to reduce measured distortion. While feedback does achieve this goal, it also introduces aberrations in the tran-sient response characteristics of the circuit. The Premier 350 uses conrad-johnson's unique auto-linear gain block for the voltage gain stage, which achieves low distortion with zero loop feedback by exploiting the symmetrical distortion properties of n and p channel fets.

Solid Power Supplies.

Power supply circuits present a parallel signal path to the audio circuits. Ideally this signal path provides ac signals with a zero impedance path to ground. Any deviation from this ideal is reflected in the reproduced audio signal. Thus the power supplies are as important to audio performance as the audio circuits and must be accorded equal attention in design. The Premier 350 features a discrete dc regulators to power the critical voltage gain stage.

Quality Parts.

As with all Premier components, the Premier 350 is constructed from the highest quality, carefully selected parts for unrivaled sonic performance and reliability. The circuits employ polypropylene and polystyrene capacitors extensively, except in the main power supply storage, where special high-speed electrolytics are used because of the extremely high capacitance required. The audio circuit and related power supplies utilize precision low inductance laser-trimmed metal foil resistors. The obsession for parts quality extends to the high quality, gold plated input jacks and output connectors - even the internal wiring is chosen on the basis of its sound quality in its specific application.

Thoughtful engineering, specification of the finest available component parts, and painstaking care taken in production make this an audio amplifier without peer in music reproduction. We invite you to arrange an audition with your conrad-johnson dealer to confirm for yourself the extraordinary musical performance of the Premier 350.

Gentlemen, start your engines...

We need Coppy to chime in...he's got a Pr350 IIRC....

Nov 2011. Unpacked brand new PR 350. I am living in a special time space continuum.



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dpod4....congrats! How did you manage to get a brand new one?

Dealer's bro in law had one in storage never opened. Nixed home theater room. I did major outreach at right time. Talked to CJ and confirmed unit was new and authorized. Seller even double boxed and did 2 day fed ex. I am so grateful. I feel very fortunate.

Here is system it is going into.

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Major score! Very nicely done :thumbsup:

Congrats...it looks beautiful...that's a major coup.

BRAVO, beautiful and great amp, well done:thumbsup::tresbon:

Sweet and lucky buy to get nos.

Will be iteresting how they drive the maggies.

This review for the et-250 had trouble with his martin logans

http://www.dagogo.com/View-Article.asp?hArticle=815

Should be good on the Maggie's; I think the issue with MLs is that their impedance goes way low at some point....

Maggie 3.7s are stable at 4 ohm so PR 350 should effortlessly handle them.

Another shout out to ToneAudio and AA which really incented me to join the CJ family. Same music-first, holistic, equipment with loyal fan base as I read in Shindo forums.

I'm here... just tuned in to this thread. You folks know how I feel about this AMP, it's an incredible bargain for this level of performance... can't let it go. Some say it's a bit delicate but I've not had any issues although I'm careful not to connect/disconnect anything while it's on or has been on. Those big caps inside retain a good deal of their power long after it's shut down. As has been said, be careful not to short the outputs... ever. I think some folks at dealers who are constantly pulling equipment in and out for demo have had difficulty when they were too casual about connections.

Now that's said, enjoy the dynamics... the P350 will drive just about anything. And it's response is dead flat. It's still a reference amp for reviewers overseas. It's difficult for them to use our beloved tube amps as the don't always match speakers. Here's a ToneAudio review if it comes through on this post...
/Users/rbc7/Downloads/review_premier350_j_dorgay_ta.pdf

Hmm... maybe not. Got to figure out how to add this PDF file. In the meantime, enjoy the music.

Stephen... how are the KT120s doing?

:music:

Coppy,
The KT-120s are doing great, and the interesting thing is they seemed to have created a wonderful synergy with the CT-5. I spent the evening listening to the CT-5 last night with my Rega P5 and I'm going to have to rethink things. The fuller, weightier, and punchier presentation of the KT-120s has filled in some of the gaps I've always felt the CT-5 had compared to the Premier 17. Namely, while the CT-5 was quieter, faster, more detailed and transparent, it was thinner, leaner, flatter, more neutal and smaller in presentation than the Premier 17.

The KT-120s seems to have really brought the CT-5 to another level in terms of these gaps. Gotta say, the CT-5 sounded REALLY good last night. The other remarkable thing is how good the Rega P5 is compared to my much more expensive Michell/SME V/Koetsu UV.

Interesting thing to think about, about how a power tube in an amp can create greater synergistic results with a preamp.

It never ceases to amaze me how simply getting properly matched equipment together makes such a huge difference in the sound. Some of the world's best equipment can be so disappointing paired badly together. And, it's not at all obvious why that is or how to match things except trial and error. Why do Transparent cables work well with Wilson speakers? Certain interconnects work better in certain systems? There are a few obvious electrical issues like impedance and damping factor but look at what a tube change in your amp did for the amp/preamp combo. The output of the CT-5 was probably always there but only now can your amp fully express it. Maybe we need a thread on just this subject. Glad to hear everything is working so well for you.

Bob

Bob,
Yes, I think we need a new thread on just this subject! ;)

I'm listening to the CT-5 right now again, and it sounds fab; it's strikingly quiet for a tube preamp.

Just plugged my CJ350 in, after listening to my reference CDs thru my VAC 300.1a amp. Wow, I guess that's what bass and punch is supposed to sound like thru my Magnepan 3.7s! I kid you not, I muted and unmuted my Velodyne DD15+ and could no longer hear the subwoofer...my Magnepans are now taking over the low end via the Premier 350. I was bracing myself for loss of delicacy at the top, but right of the box, first 1/2 hour turned on the CJ is much better in the mids and highs than I was expecting -- not overly bright nor rolled off. Nice to know the spatial soundstaging inherent in my VAC preamp carries over to the SS amp. Other thing I am noticing is incredible combination of macro and micro dynamics.

Sounds like you have a winner. Congrats!!

Lets get a CJ Premier 350 re-issue group buy going !!! I'm in!

I'd be with ya, Joe, but they'd never do it....

If we wish it, it will come true :thumbsup:

When I called CJ a few weeks ago they said it would be $15-16k + to build that amp today. From initial listening I am not surprised. Not quite as liquid smooth as my VAC (not broken in tho) but sheer force and presence is mind boggling.

:scratch2: Maybe an ET250S might be good enough :D

Gee guys

I almost wish I did not sell my prem350 a few years back.

that said, my prem 8a's are the better sounding amplifiers, especially with 3d floating image, tone and upper frequency extension and "air"

still, would have been nice to use during summer :-)

Agree it is tough to beat tubes for nonfatiguing natural fluid holographic mids and highs. I can't imagine selling my VAC 300.1a

dpod my friend... I should add two more suggestions:

First... as you doubt already know, that thing is a heavy 85 lb. and is not a well balanced lift. The left side is so much heavier than the right. It's a hoss to move around... and please be careful. The cooling fins on the left side all have sharp edges and will show no mercy to your forearms.

Secondly... although this may be a good thing as you already like the sound...this was one of the first units in which C-J used proprietary teflon caps. I don't remember a break-in issue but the sound should only get better for you with time. I've never found the sound at all fatiguing and none of the reviewers that I've read did either. Is it as holographic as my LP140 tubes, probably not but it sure is faster with tighter lows. Back to the Ravens.

Enjoy the champaign beast! :yes:

Bob

Bob

Where does it say it has teflon caps?

certainly not in the spec's

If it will come through, here is an excerpt from Roy Gregory's review in HiFi Plus of the P350 referring to the teflon caps: /Users/rbc7/Desktop/Screen Shot 2011-11-24 at 10.50.27 PM.png. Got to figure out how to add this stuff here, but maybe you can look it up on their site. There were reviews in both HiFi+ and ToneAudio. I might also have the original C-J product flier someplace. If so I can e-mail a picture to you.

I can remember discussing the caps with Tor Sivertsen (then sales manager for C-J) when I bought the 350 some years ago.

Bob

Here is the link to the Roy Gregory HiFi+ review of the Pr350:

http://www.conradjohnson.com/It_just...HiFi+PR350.pdf

It does mention the use of Teflon caps....

Thanks, Bob. I had read where most of the weight was on the left side so I was super careful lifting and placing it. Thanks for the good counsel. CJ and others have also advised about the burn in for Teflon caps - 300+ hours to hit their stride so I will be certain to listen for changes although I think it sounds awesome out of the box. Your description is very accurate. The sound is very fast. I feel like all veils have been lifted without any glare or edginess being present (I'm very sensitive to overly strident or etching sonics). Cheers.

And the manual and brochure that came with it references the Teflon caps.

Now all you need is a C-J preamp! :thumbsup:

thanks Gents.

bizzare how the cj web site spec's say nothing.

Congrats on your purchase dpod4..........I own this amp as well

I'm amazed that in your short time with this amp....you have experienced and written in your post the best qualities of the Prem 350SA.............Enjoy

Thanks!

dodp4,
How is the Premier 350 settling in?

Thanks for asking. I now know why this component has a cult following and why Jeff Dorgay encouraged me to be patient and find one. It is amazing. Just noticed tonight listening to a Naim cd recording on my modwright 5400es that the Pr350 is sounding even better - more richness and meat on the bones. I sent an email today to CJ stating how happy I am (a portion pasted below). While my (broken-in) VAC 300.1a amp has a hard to equal, impossible to beat holographic harmonic magic to it, the CJ is pleasing in similar and different ways and better in others like micro/macro dynamics etc. I could not be happier (unless the loud startup pop wasn't part of the circuitry). The fact I landed a NOS in-perfect-condition unit makes me even more grateful. Sorry to gush but this 350 is perfect for my Magnepan 3.7s and my ears. I'm now a CJ fan for life. Thx to die-hard CJ loyalists on AA as that incented my search.

In part, sent to CJ earlier today and was told it was being forwarded to mssrs Conrad and Johnson:

"....I hooked up the Premier 350 into my high-end 2 channel audio system and let it compete against my tube amplifier. It held its own in a big way and that was right out of the box! The sweet, delicate nature of this amplifier is matched by its deliberate grip and dynamic finesse. It is a perfect solid state amplifier, delivering the power and speed of solid state, and the spatial imaging, delicate mids/highs and non-fatiguing sound of tubes. My favorite piece of equipment has been my Benz Micro LP-S moving coil cartridge. I think it was just displaced by the Premier 350. Amazing, amazing, amazing. Hard to believe after it breaks in it will sound even better...."

That's wonderful, dpod4 (BTW, what is your real name?); you have a lot of us envious here. I'm sure Bill and Lew will like to hear of your review.

Sign me up for one. Let's get the petition going and deposits ready. Congratulations! Glad you are enjoying an amazing piece of history. I don't think the lottery would have been any better!

Thx. From what I'm told you are in for the same treat with the ca200!!