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Conrad-Johnson PV 11 preamp tube dilemma

I recently made changes to my system that altered the character of the sound.  After installing Morrow MA4 interconnects between preamp and DAC, and preamp and amplifier, the sound became duller.  By switching from two 12AU7 Telefunken tubes to Amperex tubes in the line section of the preamp, CDs started sounding wonderful. The problem is the phono section still sounds very dull.
In the tube section I’m currently using two Electro Harmonix 12AX7’s, one JJ-5751 tube and one Mullard 12AU7.
Can anyone suggest a tube complement that would brighten the sound of the phono section?
128x128rvpiano
lowrider57's avatar
lowrider57
5,417 posts
 
Nice cart, I like the Grado sound. OK, so you do need to open-up the phonostage with some dynamics and detail. In addition to my advice above, I’ll add that you don’t need a Mullard in your analogue chain.

Some other 12AX7’s; Siemens (good extension, but Tele’s are better), Sylvania (dynamic, transparent and airy on top), Amperex/Philips (same factory, many different choices). There are Sylvania 12AX7 and also 5751’s. The 12AX7WA Sylvania military is a popular tube. Some Sylvania’s can sound bright, so they should be mated with a less extended tube.

uberwaltz's avatar
uberwaltz
13,381 posts
 
I guess I have to ask the obvious but if changing to the morrow ic caused such a dissapointed sound result that you felt you needed to start tube rolling might it not have been better to just have put the original ic back in the system?

Or were you changing ic because you disliked the sq anyway?
rvpiano's avatar
rvpiano OP
2,696 posts
 
uberwaltz,

What prompted me to use a Morrow cable in the first case was that another piece of equipment I had, benefitted from a Morrow product.  
Then, since that cable (between the preamp and the DAC) worked so well, I installed another identical cable between the preamp and amplifier.  That’s when the dullness occurred.  I happened to have a couple of Amperex 12AU7’s tubes lying around.  I knew them to be brighter than the  Telefunken, so I thought I’d give them a try.
Voila!, the sound opened up.
stereo5's avatar
stereo5
6,480 posts
 
I would go back to the original cable and return the Morrow cable and tubes.   Use the money for a nice dinner out or buy more music. 
uberwaltz's avatar
uberwaltz
13,381 posts
 
Got you OP.

I hate when an "upgrade" turns into a downgrade!
Its times like that you wish you could just be content to leave well alone. Which is not likely to happen to any of us anytime soon.....lol.
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