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Weird problem noticed last several playings...

The system: CJ PV-10AR preamp, Emotiva XPA-2 Gen3 amplifier, Yamaha BD-1060 Disc Player, Bluesound Node 2i streamer, Maggie 17i speakers,  2 Emotiva BasX10 subs. 

Fairly suddenly , over last several listenings - especially with the female background vocals on "California Dreaming" there a lack of detail, a muffled sound, and it sounds like much of the detail, punch and soundstage has disappeared on all sources. 

I am hoping (even though they are only a couple years old) it's one of the CJ tubes but does anyone have any diagnostic ideas (aside from "your system sucks, replace this or that. This is particularly galling as I have been a budget audiophile for 40yrs and the system, when right, sounds amazing and just what I want.) 
jkf011
13 responses Add your response
erik_squires
16,056 posts
 
Last thing to check is leave the cables connected at the amp, but swap the speakers they go to.
jkf011 OP
290 posts
 
A follow-up that isn't good: as above, I called Conrad Johnson and they said the tubes were well past their expiration date. So I had to wait a  week for tubes to arrive. I got them in today and, while it sounded better, something still wasn't right. I finally thought of turning the balance knob and, sure enough, when I put it all the way left there was very little output from the Maggie on that side and what output there was was very muffled and constrained. So I switched the preamp outputs and the problem stayed on the left side - which to me tells me it's the speaker, right? Could an interconnect or speaker wire cause that? I should think that would be exceedingly unlikely, no? 
jkf011 OP
290 posts
 
Because I wanted to see if people thought it was the preamp and what they thought if?t might be, duh. Why ask? 
slaw's avatar
slaw
21,402 posts
 
Why didn't you contact CJ first?
jkf011 OP
290 posts
 
CJ says it's definitely the tubes. They say I haven't replaced then since '14, but it seems sooner than that. So regardless, they are sending 2 new tubes I bought. So we'll see if that fixes it. If not I am going to send it to them for full upgrade. 
erik_squires
16,056 posts
 
If this was a tube or speaker issue it is rare they all fail at the same time.

Swapping speakers, or tubes should help diagnose, but if the problem is systemic, it's possible the regulator on the PV 10 has failed, or one of the cascaded diodes has. 
I like the PV 10, but the thing the later generations did well was to split up the voltage regulator into multiple sections so the chances of one regulator failing was rarer, not to mention offering better power supply isolation.
jkf011 OP
290 posts
 
CJ is very adamant to only buy tubes from them as they have tested and selected what they think best. I am going to call them today.
jkf011 OP
290 posts
 
Yup. There is high end on both speakers but mid-range background vocals, guitars sound muffled. Everything sounds sqiushy and no punch. 
rodman99999
6,130 posts
 
My theater system sounded just like that (playing two channel music), years back, when one of my Maggie MG12, tweeter sections failed.     Have you checked the 1.7i fuses?
roberjerman
4,319 posts
 
I'm guessing that the CJ PV10 uses 6DJ8/6922 triodes. And a SS rectifier. A good recommendation is USA - made Amperex, GE and Sylvania. Philips from Europe are also good! Avoid any present day ones (JJ, Sovtek and other Russian, Ch*nese).

Post removed 
jkf011 OP
290 posts
 
Well I think I will hope for best and get new tubes. Any recommendations or should I just get what CJ sells? 
millercarbon's avatar
millercarbon
12,531 posts
 
Fairly suddenly , over last several listenings - especially with the female background vocals on "California Dreaming" there a lack of detail, a muffled sound, and it sounds like much of the detail, punch and soundstage has disappeared on all sources.


I think we can rule out the subs. Lol! All sources, so rule out player and streamer. Amp and speakers, possible but very unlikely. Preamp tubes should last many years but in spite of that you are right, the odds-on favorite is the preamp. 

I would look at whatever tubes it uses and order a few. Can't cost much. 

If you're really cost-conscious, then if the problem is the same in both channels and you swap tubes to confirm that, then I would think rectifier tube. Anything beyond that and I'm running out of ideas. 
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