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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
soundwatts
221 posts
 
What ever happened with this. Did you straighten out the issue.
elevick
2,636 posts
 
Sorry to be slow here. I'd put WXT's against Mullards any day. I have owned both. Don't care for most Amperex (except the ones made by mullard...), Telefunkens are always the best all around tube, Golden Dragons are the premium Chinese and are what I'm currently using along with Telefunkens and NOS Groove Tubes.
dale_harder OP
46 posts
 
Sorry I haven't posted any further info gentlemen, I have been out of town on a family emergency.
Regarding the original problem... I have rebalanced the room acoustics using the spectrum analyzer and put a lot more hours on the tubes. Probably 75 hours + now. It does seem to be somewhat better, but the original problem still exists. I went to cheaper interconects and OFHC 10 ga. copper speaker cable as well. Seems the silver is a little too bright.
Still I would love to find a real solution. So, I intend to do some tube rolling with older tubes and experimentation here and there. Finally, I might just return the preamp to CJ and have it gone over throughly, so at least I can have peace of mind.
Interesting on the WXT tubes.
I also have two sets of mono block tube amps that I am rebuilding and I intend to use some of the new issue matched quads of Gold Lion KT88's and 6550's. Hope these live up to expectations.
Thanks,
Dale.
maril555
619 posts
 
If you don't mine me expressing my personal opinion:
if you don't like how it sounds now, no amount of tweaking and tube rolling will make you to like it.
Any component's basic sonic signature represents approx. 90% of it's sound and the remain. 10% can potentially be changed, and not necesssarily improved by tweaking.
Do not waste your time and money, move onto something else, you'd like from the beginning. The choices are abundant.
Just a thought.
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?
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