CJ PV-12 - ringing probelm solved
Posted: Mon Mar 05, 2018 1:47 pm
Hey all
I am the original owner of a Conrad Johnson PV-12, which I purchased new from a dealer about 20 yrs ago. Up until around June of last year, it was all original, incl. the tubes. One day I discovered a high-pitched clanging noise when I tapped on the faceplate, and at the recommendation of Jeff Fischel from CJ, and several members from another forum, I got new tubes, direct from CJ.
That noise still exists, but I understand now, that it's due to the monophonics of the tubes. Which probably means I didn't really need to replace the tubes, but hey - they were 20 years old, so I am not going to complain.
The reason I seek help is not for that - it's for something else. I high-pitched noise that appears from time to time (without touching the unit), which I first noticed after the tube swap. This noise might have been present before the new tubes, and maybe I just didn't notice it. Regardless, I need help now. A little history:
After replacing the tubes, and then finding this noise soon after, I had brought the PV-12 to a local electronics dealer. He cleaned the switches, and contacts, and I was hoping that would be the end of it. I get the unit home, and it doesn't sound quite right. I call Jeff @ CJ, (who by the way was helpful and nice), and he says to me, "send me the unit and I will make it like new for you".
I send the unit to CJ, and get it back not too long a period of time later. Plug it in, and now it sounds as it should. Great. But the high-pitched noise is still there. It is highly possible that due to the complete randomness, Jeff (or whoever actually worked on the unit) did not come across the noise, and therefore a clean bill of health was in order at the time.
I then purchase another pair of op tubes - Mullard 12AU7s from another dealer - just to see if the unit acts the same way with diff tubes. Which it does, meaning the issue is something other than the tubes.
I then get back w/Jeff, who tells me I might have better luck with some EAST GERMAN 12AU7’s or PHILIPS 6189’s. I got a pair of the latter, but the ringing is still there.
The other thing that Jeff told me is that it is the tubes that is the issue (the tube grid oscillating), and not the unit itself.
I was wondering if anyone here has experience in this matter, and whether or not any of you have found a resolution.
Thanks in advance.
I am the original owner of a Conrad Johnson PV-12, which I purchased new from a dealer about 20 yrs ago. Up until around June of last year, it was all original, incl. the tubes. One day I discovered a high-pitched clanging noise when I tapped on the faceplate, and at the recommendation of Jeff Fischel from CJ, and several members from another forum, I got new tubes, direct from CJ.
That noise still exists, but I understand now, that it's due to the monophonics of the tubes. Which probably means I didn't really need to replace the tubes, but hey - they were 20 years old, so I am not going to complain.
The reason I seek help is not for that - it's for something else. I high-pitched noise that appears from time to time (without touching the unit), which I first noticed after the tube swap. This noise might have been present before the new tubes, and maybe I just didn't notice it. Regardless, I need help now. A little history:
After replacing the tubes, and then finding this noise soon after, I had brought the PV-12 to a local electronics dealer. He cleaned the switches, and contacts, and I was hoping that would be the end of it. I get the unit home, and it doesn't sound quite right. I call Jeff @ CJ, (who by the way was helpful and nice), and he says to me, "send me the unit and I will make it like new for you".
I send the unit to CJ, and get it back not too long a period of time later. Plug it in, and now it sounds as it should. Great. But the high-pitched noise is still there. It is highly possible that due to the complete randomness, Jeff (or whoever actually worked on the unit) did not come across the noise, and therefore a clean bill of health was in order at the time.
I then purchase another pair of op tubes - Mullard 12AU7s from another dealer - just to see if the unit acts the same way with diff tubes. Which it does, meaning the issue is something other than the tubes.
I then get back w/Jeff, who tells me I might have better luck with some EAST GERMAN 12AU7’s or PHILIPS 6189’s. I got a pair of the latter, but the ringing is still there.
The other thing that Jeff told me is that it is the tubes that is the issue (the tube grid oscillating), and not the unit itself.
I was wondering if anyone here has experience in this matter, and whether or not any of you have found a resolution.
Thanks in advance.