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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
audphile1's avatar
audphile1
5,119 posts
 
Dale, I suggest you either borrow a different preamp same in class as the CJ or take the CJ to check in another system to see if the sibilance problem is there as well.

I agree with Maril555 about tube rolling. Applies to cable changes as well. The sonic foundation of the unit will always prevail does not matter the tubes or cables. Especially with a sibilance problem. I doubt you will get rid of it completely by rolling tubes or changing cables.
Also, I think sending the pre back to CJ may be a waste. If it is working, not making any strange noises but just does not sound right to you, sending it back to the factory won't do a thing. Most likely it is fine.

just I said before, I believe the only way to check the pre is to either insert it into another system or borrow another hi-rez preamp to try in your system.

Also, is the sibilance problem you get on particular recordings or is it on every recording?
dale_harder OP
46 posts
 
Thanks for your comments guys. I tend to agree with you. Unfortunately, there is no one close by whom has a stereo with higher quality components to test the CJ in, so that is not an option. I also tend to agree regarding the checkout at CJ. They look for the obvious, such as complete malfunction or noise. As far as tube rolling, I would simply try other sets of tubes I already have here. I certainly wouldn't purchase any more. Finally, I just don't have the money to turn over the CJ and try something else. It took long enough just to save up and buy this one, let alone the WAF. I guess I will have to live with it for awhile, though I must admit it is a big disappointment.
jimmyred21's avatar
jimmyred21
2 posts
 
I have had a PV 11 for 15 years and love it.
I had to do some work on my PV 11 about 10 years ago and sent it to CJ. Call them and ask them, they are great to work with and can I think can still service the PV-11 or just advise you. could be tubes.
ps bought a used ART-2 last year and in heaven.

Good luck
Jim
dale_harder OP
46 posts
 
Thanks, Jim. I appreciate that.
A litttle update... the preamp is starting to sound much better since the tubes have burned in. The exagerated sibilance is softening and not nearly as extreme. I would say I have about 150 hours on the EH tube set now. Otherwise, little else has made much of a difference. Talked with CJ twice and they had little to offer except to return the preamp and check it out.
Dale.
fredtroy
8 posts
 
Bit late reading this thread. Have PV11, actually PV8 modified to PV11. Changed output coupling caps to PIO's, that made the difference in mine.
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