CJ Premier 15

[wspohn]

I've been listening to my main system, but also paying attention to my second system as the sound with the ML CLS is so different and enticing. I decided to upgrade that system with a stand alone phono stage, but as I doubted I'd ever find another Vendetta like I use in the main system, I looked at alternatives.

I have been overhauling the main system and have been very pleased with the Conrad Johnson components I have used there, so looked at the Premier 15 Mk 2 as a good candidate for the second system. Found one, and it is on its way, but I am wondering if the 53 dB of gain is going to cut it with the AR SP-14 preamp, given the low efficiency of the CLS speakers.

Have been toying with the idea of installing Jensen transformers to kick that output up 20 dB so I can use lower settings on the preamp. Any feedback on those transformers? What I've read seems to be pretty positive.

[RoadDawgWest]

I have a CJ Premier 15 I use as a back up, or in a second system. The tube rush noise was a problem with low output moving coil cartridges, therefore I've used a Dynavector head amplifier versus a step up transformer. Based on my experience some type of step up should be utilized with the Premier 15 if using low output cartridges.

I personally have not utilized step up transformers, but remember an article about the Jensen 347 transformers being installed. I considered trying the Jensen transformers but did not want to mod the phono stage internally, assuming you are referencing the internal Jensen transformer mod. There are advantages to installing the transfers internally such as eliminating another pair of interconnects.

Have you considered an external transfer first?

[david k]

I've been listening to my main system, but also paying attention to my second system as the sound with the ML CLS is so different and enticing. I decided to upgrade that system with a stand alone phono stage, but as I doubted I'd ever find another Vendetta like I use in the main system, I looked at alternatives.

I have been overhauling the main system and have been very pleased with the Conrad Johnson components I have used there, so looked at the Premier 15 Mk 2 as a good candidate for the second system. Found one, and it is on its way, but I am wondering if the 53 dB of gain is going to cut it with the AR SP-14 preamp, given the low efficiency of the CLS speakers.

Have been toying with the idea of installing Jensen transformers to kick that output up 20 dB so I can use lower settings on the preamp. Any feedback on those transformers? What I've read seems to be pretty positive.

Been using Jensen transformers for a very long time and like them a lot. They're sweeter sounding than most other ones I have and musical. They work well with all cartridges I own too.
david
Disclaimer- Jensen dealer!

[wspohn]

The cartridge used in that system is a Lyra Clavis that I am quite fond of, but puts out only 0.25 mv, while my Koetsu in the main system is, IIRC, 0.6 mv, so I am sure I could use the extra gain to avoid operating the preamp at full throttle (which often seems to be noisier than lower settings, although you are removing resistance, so......)

I prefer not to add any active head amp into the chain as I think that properly made transformers are likely to be less likely to change the sound - correct me if you think that is incorrect. CJ made several pre-preamplifiers themselves but they are hard to find and add tubes (or nuvistors) to the chain.

I have no qualms about drilling two small holes in the case to bolt in the transformers, and if I ever sold the unit I'd just disclose the easily reversible mod to the buyer.

David, if you can make a buck from a sale I'd be happy to deal through you rather than direct to Jensen, if you like - contact me offline.

This is what put me onto these particular products: http://www.10audio.com/cj-p15_jensens.htm

PS - if I went for external step up, I'd probably opt for the Bryston TF-1 with which I have some experience.

[RoadDawgWest]

That is also the article I was referencing.

I cannot speak for all Lyra cartridges, but I've not had success running my Kleos through a Dynavector head amp. The Dynavector head amp amplifier current rather than voltage. I cannot confirm why the Lyra Kleos will distort through the headamp, but it's just not compatible. The Dynevaector head amplifier works well with my Dynavector XV1s, and Benz Ruby 2 through and is wonderful with the Premier 15. I discovered this a few months ago when I install my Premier 15 in my main systems as I took my BAT VP10 out for cleaning of contacts and tube pins. The Lyra Kleos has no issues running through the internal transformers of the BAT VKP10.

I just checked out the new CJ Phono stages, and it appears they are including step up transformers as well. Also the new CJ phono stage have better S/N specifications.

Even though I've had success with the Dynavector head amplifiers and the CJ preamplifier. I also would like to try a step up transformer.

[MylesBAstor]

I was just checking out the SP14s specs and the preamplifier has a gain of 20 dB, somewhat similar to cj preamplifiers that are around 25 dB. I think using the Clavis might be dodgy given the CLS's rated efficiency of what 85 or 86 dB. OTOH, Art Pfeiffer from TAS ran his CLSs with the Classic 60 and SP11 or something like that (?) and VPI HW19 successfully when I heard his system 20 or so years ago. Wish I could remember the cartridge Art was using. But am pretty sure wasn't lower than 0.5 mV.

[wspohn]

Well the unit showed up today

A couple of displeasing things. Shipped with the tubes in situ, which I hate - I like them separately boxed and protected. Oh well, I guess I shoud be happy the transit screws were installed holding the board stable for shipping.

Tubes, which are supposedly new, consist of four JJ ECC803S, and a couple of Northern Electric 12AX7s to make up the total of 6 of that type (according to the tube store, the ECC803s are not suitable for use in phono stages as they can be noisy; the ECC83S is preferable).

The rest of the complement is made up of a pair of Sylvania 6GK5s.

Not exactly the new tube set claimed, I fear. Any recommendations on replacement 12AX7s (I have a bunch of alternate 6GK5s from retubing the preamp so should be fine there).

I was going to try this unit in my main system just to confirm that all is well, with the Koetsu and ample gain for the speakers in that system. Interesting that when I opened it up the two channels were set for wildly different input impedances. Ah well, I'll confirm that it at least works and will then see how bad/noisy the tubes are in the upstairs system before deciding if I need more gain and pursuing additional boost from transformers.

[MylesBAstor]

Well the unit showed up today

A couple of displeasing things. Shipped with the tubes in situ, which I hate - I like them separately boxed and protected. Oh well, I guess I shoud be happy the transit screws were installed holding the board stable for shipping.

Tubes, which are supposedly new, consist of four JJ ECC803S, and a couple of Northern Electric 12AX7s to make up the total of 6 of that type (according to the tube store, the ECC803s are not suitable for use in phono stages as they can be noisy; the ECC83S is preferable).

The rest of the complement is made up of a pair of Sylvania 6GK5s.

Not exactly the new tube set claimed, I fear. Any recommendations on replacement 12AX7s (I have a bunch of alternate 6GK5s from retubing the preamp so should be fine there).

I was going to try this unit in my main system just to confirm that all is well, with the Koetsu and ample gain for the speakers in that system. Interesting that when I opened it up the two channels were set for wildly different input impedances. Ah well, I'll confirm that it at least works and will then see how bad/noisy the tubes are in the upstairs system before deciding if I need more gain and pursuing additional boost from transformers.

IIRC the 83S here is the real frame grid tube.

I would check with cj. Usually there is a pair of tubes in the circuit that are more important than the others in order for the unit to sound its quietest. So in essence you can play around with four of the tubes.

Last I remember, cj was supplying New reissue Tungsols; they sounded pretty good in the TEA phono. At one time, before their source dried up, cj used prewar Ei ECC83s. The Ei tubes were very good sounding, if just a touch soft. Nice mids, almost like a Mullard. Problem was they didn't necessarily stay quiet for long enough. One of the two triodes in Ei ECC83 also tended to be microphonic and ring like a bell. So getting a useful pair took a lot of selecting. Plus the sound of what was left of Ei ECC83s on market was all over the place. Bought a quad ages ago that had no low end for whatever the reason.

You might also look for some vintage Tesla tubes. They sounded pretty good in my older Doshi phonostage.

[wspohn]

So - decided that while I am waiting for a phono stage input jack on the SP-14 to be resoldered, I'd try out the Premier 15 in the main system.

Set it up, then listened to an LP over the Vendetta and switched to the Premier 15. Then immediately had to weed out a microphonic 12AX7 in that unit which was causing a major buzz. After that though, the sound was quite good. It isn't up the standard set by the Vendetta - it lacks the same bass extension and the detail at top end of that phono stage, but is nonetheless very decent.

We'll see how it makes out with the Lyra Clavis which is lower output, in the upstairs system as soon as the SP-14 comes back.

[JCOConnell]

So - decided that while I am waiting for a phono stage input jack on the SP-14 to be resoldered, I'd try out the Premier 15 in the main system.

Set it up, then listened to an LP over the Vendetta and switched to the Premier 15. Then immediately had to weed out a monophonic 12AX7 in that unit which was causing a major buzz. After that though, the sound was quite good. It isn't up the standard set by the Vendetta - it lacks the same bass extension and the detail at top end of that phono stage, but is nonetheless very decent.

We'll see how it makes out with the Lyra Clavis which is lower output, in the upstairs system as soon as the SP-14 comes back.

monophonic 12AX7 or microphonic 12AX7?

[wspohn]

Just following up - I ended up replacing the old SP-14 with a dead quiet Bryston BP-17 preamp with sufficient gain to use the CJ 15 with no issues.

[RoadDawgWest]

So the Lyra Clavis, is working well with the CJ Prem 15?

[wspohn]

Yes - quite nicely.
That system is used for acoustic music - you aren't going to want to listen to deep organ notes on the CLS. Magic with strings, piano etc.

[RoadDawgWest]

That's great, and I'm glad it's working out for you. Never heard the CLS, but they do have a following.
Did you ultimately deploy the step up transformers, or run the Lyra direct?
I recently pulled my Prem 15 out of storage, and my Dynavector XV1s doesn't have enough gain for my liking.

[wspohn]

I am running direct.
The CLS are low efficiency - 85 db (some sources say even less) but for the sort of music I use them for, the 15 has sufficient gain. I tried the 15 in the big system, mostly to measure it up against the Vendetta, and it has tons of gain, but then the main system speakers are 92 db efficient.

Although a very capable unit, the 15 falls short of the Vendetta, but that was no surprise.