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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 Gentlemen,
Thanks again for your responses. In answer to some more questions, I have replaced the silver IC's with generic IC's and no difference was noted. Pertaining to phase, I have phase inverted the speakers as recomended by CJ and stated in the manual. The bass is definately not suffering so I think the phase is correct. I did speak with CJ today and they informed me that they do indeed use EH tubes that have been hand selected and tested to their standards. One tube is infact a 5751. They felt that the tubes may need to burn in for awhile, but that what I am experincing is not the usual for this product. They also recomended removing the EQ for a test period. I will do so tonight, as well as try flipping the electrical plugs.
As for my system I am using several types of amps (tube based) and some solid state. The present configuration consists of a professional series BSR 4000 EQ and a Carver M1.5t magnetic field amp. I have not tried my Audio Symphony tube amps as of yet.
More later.
Dale.
dale_harder OP
46 posts
 
Oopps, just noticed another response...Unfortunately, the sibilance and harshness are present in all cases and all recordings.
Thanks,
Dale.
audphile1's avatar
audphile1
4,913 posts
 
Dale, yes, remove the EQ for now.

I don't think running tubes some more would cure anything in a major way.
phd
1,314 posts
 
I have owned the CJ PV11 & two of the things that struck me the most was the lack of bass but on the other hand it was a very revealing preamp. I think Audiophile1's comment on the lack of bass can make higher frequencies more prominent should apply here. On the other side of the coin, I don't remember the PV11 sounding harsh. You may want to remove the equalizer, if you are trying to increase the bass response try hooking up a sub to the preamp which will have the least effect on the preamp's sound.
italian
126 posts
 
Hi, I have a CJ PV12. I swapped out the Silver ICs with Zu Oxys which tamed some of the forwardness (lat a cost of a bit of detail) and I also use older tubes including Holland manufactured (my favorite sound), Mullard/Brimar, RCA clear tops, and Tungsrum. 1950/60s Sylvanias are nice also, they may fatten the base but does not provide that rich mid range that many look for in a tube preamp like the CJ. As was said, Mullard (& the Brimar 13D) is probably your best bet to help tame the harshness and sweeten up the mids. Forget 12AU7 telefunkens, cold sound. Hope this helps. Dave
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