2. amps-preamps
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Conrad Johnson PV11...Extreme sibilance, harsh sou

Hello everyone,
I have an issue and was wondering if I might prevail upon the community to help me out. I am a seasoned audiophile, I would like to think, but I am sure this old dog can still learn a few tricks.
I have recently acquired a CJ PV11 preamp that is basically in mint condition and came with a brand new tube set from CJ. The tubes were installed around 7/10 and I received this amp on 7/28/07. (strange though, they used Electro-Harmonics tubes)
Anyway, After I installed the preamp, I now have very serious issues with harsh mid range and extreme Sibilance issues that I never had before.
My system is very revealing. I use NEW Walsh drivers based on the Ohm Acoustics design of the model "F" and "A". In fact I have both. These units I make and build myself.
I have not even attempted to use the phono section of this preamp yet. Just the line stage.
While I have never encountered this problem before, I have it now, so much so that I can barely stand to listen to my system. Nothing in my system has changed except the preamp. I intend to rebalance the room and speakers using my calibrated mic and high quality RTA. And even though I am a purist at heart, I do use a high quality graphic equalizer just to cope with some room acoustic issues, but it is set to a very low and flat curve and mainly compensates for low end reflections from my omnidirectional speakers.
I have read about the usual tube rolling, try different interconnects and ac conditioning, but most of that seems very subjective, even to those that suggested it.
I do use dedicated 30 amp lines and separate grounds for my system and even have an ac conditioner, but found the conditioner caused hum issues, strange as that might seem. So I took it out and run direct to the line.
My speaker cables unfortunately are long runs of 25 feet by necessity, but are high quality OFHC braided cables with a 10 ga. size. I also use silver interconnects that I have designed.
Does anyone have any ideas? I have put into CJ for help, but no response yet. (Holiday) and have also been in contact with Dr. Tube.
I would appreciate any help.
Thanks in advance.
Dale
dale_harder
dale_harder OP
46 posts
 
Hello to all,

Sorry I have not been on lately. I have been caught up in the whirl-wind we call life. I need to get back to the tunes.

Regarding some of the posts I missed. I have to say that my CJ PV-11 is now doing very well and apparently most of my original issue was simply tube break-in. It is now quite listenable and very, very quiet.

I also added a PS Audio Power Plant to my system, (I tried other products but none like the PS) and it made such an unbelievable difference it was beyond words. I like to call these my "Ah Ha!" light switch moments. Like someone flipped a switch and then there was magic. I really hate it when I have to strain and hem and haw...did that really make a difference? You all know what I mean.

Thank you JMO for the upgrade info too. I also found Bill Thallman of Music Technologies. 703-764-7005. They are an Apogee Ribbon dealer and specialize in upgrades for CJ and some other high end stuff.

Thanks again for all the interest and responses.
Dale
PS our new web site went on line last week. www.hhr-exoticspeakers.com
bondmanp
1,816 posts
 
Glad to hear things are looking better. I retubed my PV11 (tubes from C-J). Still having channel balance issues, and I am beginning to suspect room acoustics or even my power amp.

However, even though I installed the new tubes with C-J's supplied dampers, I have been hearing a lot of microphonics (I think). Sounds like a very high frequency ringing or feedback-type noise. It comes and goes, and can be pretty annoying. Plus, the pre is pretty noisy. It got a tad quieter when I plugged it into my PS Audio Quintet, but I wonder if that's just a price to pay for a tubed pre, or perhaps my PV11 needs servicing?

Any thoughts on this would be very much appreciated.
jmo
115 posts
 
Bondmap,

You have nothing to lose contacting Bob & Gary Backart, my PV12 sounds much better then it did when it was brand spanking new... Current age 16 years of old. :O)
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