2. vintage
  3. 166885-152909

Harman Kardon TA5000x pre-amp tubes

I had a scratchy sound that I deduced was the 12AU7 in my pre-amp section (discovered by the near-source soldering iron test) .  I had an old one that I expect is weak (i have reasons) but works; it fixed the scratch.  I m considering changing out the full set of pre-amp tubes (4x 12 AX7, 1x 12AU7) and I'm willing to spend about $20 per tubes.  I was looking at some of the less aggressive Groove Tubes and would like some advice.  Is this worth doing for the $100 or so I'm willing to spend and are Groove Tubes a good pick?  
wgh64
dekay's avatar
dekay
5,855 posts
 
If you use the phono section the (2) 12ax7's on the front/left (when facing the unit) should be low noise phono grade.

I think that a pair of phono grade Soviet 12ax7LPS may be around $40-$50/pair.

The other tubes just need to test well.

Sorry, not very familar with new production signal tubes but did once try the LPS's in the phono section of an old Pilot integrated (nice and quiet).

DeKay
jasonbourne52's avatar
jasonbourne52
2,863 posts
 
Tube Doctor sells 12AX7s of various grades. And 12AU7s. I bought a pair of 7025s there. That's a low-noise 12AX7  Recommended for use in the phono stage!
russ69's avatar
russ69
3,579 posts
 
Try a Tung-Sol or Mullard reissue. (I use upscale audio, my trusted source).
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