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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
 
Oopps, just noticed another response...Unfortunately, the sibilance and harshness are present in all cases and all recordings.
Thanks,
Dale.
audphile1's avatar
audphile1
5,119 posts
 
Dale, yes, remove the EQ for now.

I don't think running tubes some more would cure anything in a major way.
phd
1,319 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
dale_harder OP
46 posts
 
Thanks aagian for the further input. Sorry I have not been able to give too much in further results... been sick with an abcessed tooth..Ouch!
Anyway, I have rebalanced my system with the B&K Mic and RTA and achieved some better results as of late last night. Tried to remove the EQ, but did not like the room effects. Bass was overwhelming with slight high absorbtion in the 16 to 20K range. Sill only about 2 db of loss here.
In addition, I may have some further info and perhaps I am now experiencing some poor quality tubes in another component shinging through. As I said, I use a modified Jolida JA100 CD player which is tube based. Part of the mods called for changing the original Chinese tube set for New Svetlanna 12AX7's. Talking with Dr. Tube, says he believes the Svetlanna tube to be very poor quality, so much so that he has discontinued selling them or supporting them. He says, only about a 30% yield was the norm and that 30% was mediocre at best. This is confusing to me as several High end places are doing the CD mod with the Svetlanna. Something I researched before i had it done..Oh well, Cest la vie.
This may be part of the problem, since the CJ is a very revealing preamp. Perhaps it is emphisizing what these tubes are doing. They are still very new with perhaps only 10 to 15 hours use on them. Still I have some problems with other input devices producing the same type of effect, i.e. tunner, or TV audio. Though these are not that important to me, as I use the CD or Phono most.
I guess I have much to do with trying different tubes and combinations. I will post with further results. Good listening. Dale.
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