JC3+ Anyone?
Have you checked out the Liberty B2B-1 ? Liberty B2B-1 Michael Fremer gave it a "Gruvy" Award on Analog Planet, just last week, makes me pretty happy. From its maker Peter |
Original JC3 was probably noisy (as well as being less than optimal) with many cartridges because it had outrageous amounts of gain. 68 dB on the MC input spec'd and it tested even higher than that in the Stereophile review. Parasound reduced the MC gain on the plus model to 64 dB to alleviate problems with overload which seemed to affect a number of users. 64 dB is still quite a bit of gain. Personally, I wouldn't pair a phono stage with that kind of gain with a cartridge like the Kleos which has a .5 mV output. Not a good matchup IMO. With a .5 mV Kleos I'd be looking at a phono stage with fixed gain around 56 dB or adjustable gain that could get you into that area. |
I had a Delos customer who had problems with the Parasound JC3 - the high gain gave too much signal output, which would occasionally overload the preamp. He solved the problems by building a fixed attenuator and inserting it between the JC3 and the preamp (there is a very interesting thread about this on the Steve Hoffman forums). In some systems 64dB may be too much gain for the standard output Kleos (especially if you have horns), but for most, it should be OK, and allows you the possibility to use the half-output Kleos SL version at a later date. I know from experience that 58dB will work, but 56dB may be getting close to the edge. Compatibility between phono cartridge output and phono stage gain depends very much on the gain of each component after that. The line preamp, power amp, and speakers (sensitivity). Regarding noise suppression, it is best to have as much of the total system gain as early as possible, and use less further downstream. IOW, combining a high gain phono stage, with a lower gain line preamp, power amp with even lower gain, and low-sensitivity speakers would be best if your primary goal is to minimize noise and hiss. kind regards, jonathan |
I have a JC-3 with a Denon 100th anniversary version of their 103 cartridge. I use an ARC LS-17 preamp, and I have noticed there is a lot of gain. However, my system is completely silent, and the quality of the sound is wonderful. I suspect any noise would come from the preamp. The "louder" the preamp is set, the lower it's noise will be, so if it is set too "softly" there may be noise. I think it is just an unfortunate pairing. Parasound does make a big deal about how quiet their preamp is, so that may be their standard. I did have a problem with hum until I re-stacked my components and dressed the cables. I also decided to use Kimber Sliver Streak cables and they seem like a good match for delicate low level signals. |
"Have you checked out the Liberty B2B-1" It was on my list. Only one XLR rules it out as I am not going to buy two. I do like your use of FETs. Been a fan of FETs for years. Had a Sony TA-1130 with MOSFET output devices. I also like the way the JC3+ has premium parts in the right places. " He solved the problems by building a fixed attenuator and inserting it between the JC3 and the preamp " I read that thread, one of the best forum threads ever. "half-output Kleos SL version at a later date" Always good to hear from my favorite cartridge designer. If I send my Kleos back to Japan can it be converted? It needs a complete checkup anyway. Just started seeing the SL version mentioned. Have you folks not done an official announcement? "Compatibility between phono cartridge output and phono stage gain depends very much on the gain of each component after that. The line preamp, power amp, and speakers (sensitivity)." I am testing the XLR inputs on the CDP-500. One of the many nice things about the GCPH is the switches on the back for gain and loading. It will do 66db and also has a rotary control for the output section on the front. Overload would be harshness on the loudest notes, right? I am not hearing that but I am hearing what sounds like tape compression. I played my original Telarc 1812 and the KLEOS managed to stay in the grove on the canons but the loudest orchestra sections sounded compressed. This was with the GCPH on 66 and the rotary all the way. So that's like better than 11, yeah? :-) BTW, as some might expect, the best tracking of the canons on that LP was via a Shure V15. I have a VxMR and I believe I had a V15III when I bought the 1812. Thanks Folks, Robert A. Ober |
Robert, The reason for only one XLR input is that the B2B-1 becomes a fully balanced amplifier when using the XLR inputs, and setting internal jumpers accordingly. Running it in this mode will of course require two for a stereo setup, however in my totally biased opinion :-) well worth the effort. Good Listening Peter |
"Robert, The reason for only one XLR input is that the B2B-1 becomes a fully balanced amplifier when using the XLR inputs, and setting internal jumpers accordingly. Running it in this mode will of course require two for a stereo setup, however in my totally biased opinion :-) well worth the effort." Yep, I get that:-) |
Hey Again Folks, This testing is interesting. I may bore you with some of it later. In the mean time, I am not convinced I have the azimuth of the Kleos correct yet. As I recall, there is a method of setting the azimuth using a voltmeter. Anybody know of a good article on how to do this? Thanks, Robert A. Ober |
On "setting azimuth with a voltmeter". You need a high quality voltmeter and a test LP that has bands with signal in R channel, only, and in L channel, only, respectively. Preferably the frequency of the signal is 1kHz, but you will get slightly different results at different frequencies. For accuracy in reading the meter, you will probably need to measure voltage at the output of the phono section vs the output of the cartridge, which would be more ideal. Then you play, let's say, the R channel 1kHz signal and measure its amplitude in terms of signal AC voltage in the R channel. Take note. Play the R channel signal again and measure any AC voltage that appears in the L channel. Take note. Then do likewise with the L channel 1kHz test band; measure voltage in the L channel, and ideally at this point you need to set it to be equal to the voltage you saw for the R channel signal in the R channel, perhaps by use of a balance control. Once that is done, play the L channel signal again and measure VAC in the R channel. The voltage in the L channel when playing the R channel, and the voltage in the R channel when playing the L channel, represent "crosstalk". Some people like to adjust crosstalk so it is equal in both channels. Others like to adjust crosstalk to obtain the minimum values possible. (The two goals will not be arrived at at the same azimuth angle.) There are good arguments, either way. Also, keep in mind that azimuth has very very little effect on channel balance (a difference in output between R and L). Don't use azimuth to correct channel imbalance. |
Great summary by Lewm. Having done that many times with many cartridges, I eventually learned that I could adjust azimuth just as well, and far more quickly, by listening. Choose LPs (ideally mono) that have a higher register instrument or voice (think soprano or upper register of the clarinet). Acoustic instruments or non-amplified vocals, please, not electronified hash. If the LP is stereo, the instrument or voice should be in the center, not off to one side. Listen for the azimuth setting which makes this voice/instrument sound as tight/small/non-bloated as possible. A clarinet is not 4 feet wide, and shouldn't sound so. Some sopranos... oh, never mind! The point is, minimizing/equalizing crosstalk (as Lewm described) results in the most focused imaging. It's essential that you're sitting in the sweet spot and that your speaker/room setup is well adjusted for pinpoint imaging. (If it isn't, you're wasting your time fussing with azimuth anyway.) Listen to a few CD's with the kind of music I described to give yourself a baseline. Crosstalk with any decent digital media is lower than with even the best vinyl rig, so it can provide a good baseline for comparison. IMPORTANT: the adjustments to optimize azimuth, by any method, are incredibly tiny. Make the smallest adjustments that you possibly can. The window for optimum setting is very narrow. Get outside that window and you'll hear and/or measure little if any change. Start with the stylus visibly vertical when riding in the groove and tweak in tiny increments from there. |
I had a high output Ruby, .7 output, and with the JC3. I had an overload problem. While I could use the MM input, I had to run the Ruby unloaded. The JC3 worked fine with a regular Ruby 3, .35 output. I believe the sensitivity of the line stage is also a factor. The JC3 worked very well for me with MC's in the .2-.4 range. Dead quiet and great sound. Above that, and depending on your line stage, overload could come into play. I'm sure the reduced gain of the JC3+ was designed to make it more compatable with medium output MC's. |
Alternately from the methods described by Lew and Doug, one can use software, which takes the rest of the system out of the equation, among other things. I have been using the Feickert software ever since it came out and am able to quickly converge upon the correct azimuth setting every time, but there's definitely a learning curve. Every cartridge is different, even the same model. |
Hey Robert, sorry i I got to this post so late. I Owned a DV P75 Mk III and then moved up to the JC3+. I agree with your assessment of it. I have the VPI Prime with a Dynavctor 20x2 low output MC cart. Mind, I have Thiel speakers too and any thinness would be noticeable. I find the music natural sounding. |
Hi - Not sure anyone is still paying attention, but I'll give it a try. I am considering a move from a LehmannAudio Black Cube SE II to a Parasound JC3+. Running a Thorens TD160 Super and a Dynavector 20x2L, with a Parasound Halo Integrated amp. Hoping for a little more cartridge matching flexibility (the Black Cube can only be set at a gain of 56 or 66 for MC carts). Good move? Thanks to anyone who may be listening! |
I got a chance to have JC3+ for a week to test in home. It was being actively used by my dealer for well over 6 months so it was ready to go when I got it. I used it with a ART9 cart so that is .5mV the same as your Lyra. Sounds on the JC3+ are very good. Tonally it sounded correct with very good high extension, Bass was good, with forceful impact when needed. Mids were detailed, which tends to leads to slightly more prominent vocals but it never sounds too much. Overall it was an excellent premap, really if you are looking at a Preamp under $3K It's about as good as you are going to get, it sounds great,. It has lots of options, variable loading, 12v trigger, inverted polarity on the AC input, defeatable front panel illumination, balanced and unbalanced outputs. It does have some high gain though, I think some of the good dynamics it is able to get has to do with the high gain that the preamp delivers. Although I never had it overload anything, my system definitely played loader with the JC3+ in it than with some other premaps I have had. If you can demo it, I would. Even if you have to buy it outright, as long as you can return it think you will probably end up keeping it. It is really an excellent premap for the price. HTH |
