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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
uberwaltz's avatar
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uberwaltz
4,946 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
938 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.
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stereo5
2,766 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. 
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uberwaltz
4,946 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.
jetter
1,035 posts
 
My all tube system sounded great with the morrow interconnects.  But when I switched my tube amp for a SS it resulted in a buzz coming through the speakers, which was immediately eliminated when I switched to another brand interconnect.  Perhaps it is the insulation used? You may be experiencing a milder case of this that manifest itself as a duller sound.
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