Does anyone own the CJ CAV45-S2 Stereo Control Amplifier?

[roberto]

Hola,

The signature sound quality of Conrad Johnson is evident. You can't go wrong with it...I have a friend who has one and he is very happy with this amp.

Happy listening!

[gravetones]

Thank You. Hope all of you had a great weekend !

I did get a chance to hear a friends CJ PV11a (70W KT88) with itsPV11 pre at my home over the weekend and really liked the signature. Considering my current amp is an integrated with a passive pre, there is a Big jump in dynamics/bass presence/Midbass...everything I was looking for and the tonality which I really liked

Hoping for inputs from the collective intelligence around the CAV45 S2 passive pre and what could be lost compared to having an active pre eg has any one seen a drop in the "weight " of music with a passive maybe along with an increase in the transparency ?
( RJ, you have written about it and I do have a Reimyo Dac and a Ear 834 Phono both of which have a decently high gain to the extent the I could move the CJ PV11 Pre only one click for a sensible volume level with the EAR)

I could see a significant difference between an active and passive , although not with the CJ PV11a since i could only use only an active with it due to lack of a pre out in the passive Integrated amp, and hence wanted to be sure about the drive. I have no issues with the power section since both the 70W CJ and 20W ( 40W Dynamic) Quicksilver were able to pressurize the room.

[Big Dog RJ]

Yes, going passive on the level control is fine, provided all source gear has a high output. Especially the phonostage.

This is where I required the active linestage for that extra gain and full control/drive of the monoblocks. Plus driving CLX's is a notorious impedence curve that most powerful amps cannot handle that well.

Therefore, I believe it all depends on your source gear, power amps, speaker's sensitivity, room size and listening habits. If your preferences tick all the boxes then 50-60w from am EL34 bssed control amplifier should be more than adequate.

As I mentioned earlier, on the AG horns it was plenty loud, plus had a very smooth response, nothing of too much, not to mention the 1000w built-in amplifiers in the Duo XD's. Yet everything was quite well balanced. Similarly I had no issues with my previous ML Ethos hybrid stats being controlled by the CAV45, and this was the series 1 not the S2. Later on when I did try tge S2, that extra 10w of EL34 power delivered a tighter bass control, and managed to sound more punchy... very good sense of weight and scale. That's another thing that the S2 brings to the table.

The CAV45 is a beautiful little amplifier, it gets everything pretty much right and was an absolute joy to own. If I ever wanted a second system with higher efficiency speakers with benign loads, I wouldn't hesitate one bit to partner those speaker's with a CAV45. It's simply marvellous!

Cheers, all the best
RJ

[gravetones]

Thank You RJ, I understand that the gain in the CAV45 is 32dB and that is optimal for a passive pre . Also got a notet from Jeff@CJ who also mentioned this would not be an issue. So that looks good for now

I understand the 60W wattage is at 6Ohms..any idea on how that changes at 8 Ohms and 4 Ohms ?

For now I have a EAR Phono with telefunkens and a Reimyo DAC both have a high gain..although not sure of what the future holds

[Joe Appierto]

Are you sure that's into 6 ohms? According to the product description for the CAV45-S2:

Power
60 watts per channel RMS both channels driven into 4 ohms from 30Hz to 15kHz at no more than 1.5% total harmonic distortion or intermodulation distortion.

[Big Dog RJ]

Thank You RJ, I understand that the gain in the CAV45 is 32dB and that is optimal for a passive pre . Also got a notet from Jeff@CJ who also mentioned this would not be an issue. So that looks good for now

I understand the 60W wattage is at 6Ohms..any idea on how that changes at 8 Ohms and 4 Ohms ?

For now I have a EAR Phono with telefunkens and a Reimyo DAC both have a high gain..although not sure of what the future holds

Yes, that should be about right, especially coming from the legend himself JF!

I also know that CJ amplifiers (or at least the majority of their tube designs) are factory set for 4 Ohms, and some perhaps 6 Ohms. Whichever the rating, these are set to drive low impedences to begin with, therefore their power supplies are extremely well built, to high standards, deliver high current and well capable of driving whatever is put in front of it. That is the very reason why they factory set at low impedence.

With CJ's tube amplifiers there's no issue as impedence swings, the output rating remains pretty much the same. There's hardly any fluctuations and their output stages are rock solid! So in other words, it's basically 60w maximum output right throughout... regardless of impedence swing. They don't flinch one bit nor deviate, unless that particular tube amplifier was driven into clipping, and that's pretty loud, infact something you generally don't need to do with CJ amplification. You can really enjoy the music regardless of what level, no matter soft, moderate or loud. If you wanted really insanely loud then the ART300's are the answer.

Solid state amplifiers OTOH do fluctuate in accordance with impedence variations on the speakers, simply because they're active devices. They put out double the power at very low impedences (provided they're designed properly) and most of them run out of puff... when over stressed.

However, with tube gear that doesn't happen too often (unless driven really hard) and especially CJ amplifiers, they simply love low impedence curves. CJ's tube gear amplifies in liner operation, they're designed in such a way that they can handle the most difficult loads, and when current is in demand, CJ's power supplies deliver!

So, you've got nothing to worry about in terns of impedence swing. Just sit back and enjoy those fine tunes!
Cheers, RJ

[AnotherJohnson]

It is probably rated into 4 Ohms.

The advice is to leave it on 4, even if nominally your speakers are 6 or 8.

Most speakers rated at 6 or 8 can dip to 4 or lower.

Most people I’ve known who insisted on changing the taps end up back on 4 based on listening experiments.

[Big Dog RJ]

Checking in on Gravetones:

Did you get the CAV45 S2 as yet...?

Was just wondering how you went with it and whether you managed to finalise on one. Let us know, always good to hear from new members systems and performance improvements by adding in CJ gear.

Cheers, RJ

[arnel]

Just bought a cav45s2. I have a vinyl rig and I’m concerned about the lack of line stage. What do you guys use for phono preamp? Is a step up device necessary? Thanks in advance!

[AnotherJohnson]

I use a TEA1. Also have TEA2MAX as a spare until need presents.

Step up transformer need is determined by the cartridge and the gain of the phono preamp.

[arnel]

Ah, I should of mentioned I use a soundsmith othello for a cartridge. But in the future would like the ability to use a low output MC cart as i get deeper into this hobby. I have been eyeing a EV1 and premier 15. Both have a fixed gain, 47 and 53. I believe I’d need a step up device for use with MC carts with the cav45.

[JoshT289]

As AJ said, it depends on the cartridge and on the phono preamp you use.

There is no phonostage built into the CAV45 at all, so you will need to get an external phono preamp no matter what. If that phono preamp includes settings for LOMC cartridges, then you won't need a step-up transformer. This is not specific to the CAV45 but applies to all preamps and integrated amps without built in phono stages. The EV1 is a stand alone phono preamp.

Some people swear that LOMC cartridges never sound great unless used with a step up transformer because the active amplification stages used inside phono preamps are inherently noisy and can sound grainy. With my Rogue Audio RP-5 preamp, that is partly true. I have a LOMC Dynavector, and while I really like the sound of the Rogue's built-in phonostage, it definitely is noisier than the line stage inputs on its high gain settings. I've considered getting a step up transformer so I can use one of the lower gain settings, but I understand that step up transformers can be hum monsters if not perfectly placed.

So if you have a HOMC (or iron) cart now but think you will get a LO one in the future, you should either get a phono preamp that can do both and has lots of settings, or plan to get a step up transformer if you don't.

[JoshT289]

By the way, congratulations on getting a CAV45. I'd love to hear about your overall impressions, phono stage aside. It's an amp that has always intrigued me, as was the CAV50 predecessor, and yet I've never heard one in any setting!

[arnel]

Thanks for the clarification. Yeah, neither the EV1 or premier 15 have variable gain settings. With my current cart I won’t need a SUT, but i see with these phono preamps I will also be searching for a SUT when I get into LOMC cartridges.

[JoshT289]

Thanks for the clarification. Yeah, neither the EV1 or premier 15 have variable gain settings. With my current cart I won’t need a SUT, but i see with these phono preamps I will also be searching for a SUT when I get into LOMC cartridges.

Ah, got it. Sorry, I was confusing the Premier 15 with the Premier 14 I think and thinking it was a line stage preamp, but I just looked it up and understand. The gain might be high enough for some LOMCs even without a SUT (unless you get a super low output cart)? Probably not the EV1 though. Enjoy!

EDIT: I just changed my reference to "Premier 12" to "Premier 14," which is what I meant!

[AnotherJohnson]

At 53 dB of gain, the Premier 15 should have plenty of gain for LOMC cartridges, but will probably run out of gas for the ultra low output genre.

53 may struggle even with LOMC if the speakers are also inefficient.

And, of course, the room may be a factor too.

The Premier 15 appears to be the direct ancestor of the TEA2. It does allow resistive load choices via internal dip switches.

I think it would be a cool unit, but I can’t remember ever seeing one for sale … not that I watch for them.

[Big Dog RJ]

Yes, with a CAV45 you will need a dedicated phonostage with high gain.
In one of my posts I have mentioned this in detail... regarding my experience with it, driving Martin Logan hybrid stats at the time. If the speakers are very efficient (90dB and above) with a phono gain of above 53dB you should be fine. However, that means the cartridge should either be medium or high output as well, most probably anything between 0.5 to 0.8mv would be better, especially of realistic scale and a certain level of dynamics.
That was the combination with my BM Glider and the CAV45.

However, I would have to turn things up quite a bit even having the TEA2SE set at 55dB, which was the high gain version. Whereas, the Rega Aria was perfect! It had selected gain settings all the way upto 70dB. So, driving TT rig with the Aria was effortless compared to the CJ unit, and that's simply because the CAV45 has no active linestage, as you already know.

If you're thinking of very low output MC carts, either a SUT or phono pre with high gain is much required. Also depends on your listening habits and level setting preferences. The size of the room will depend a lot, no doubt but your personal preferences will determine what type of level you want playback to be at, low- moderate - high...

Hope it goes well, cheers
RJ

[warnie7]

I use a EAR 834P phonostage with a Ortofon Quartet Bronze MC and a SUT. I dont have any issues with this set up