2. amps-preamps
  3. 150003-132470

So I bought a Pro-ject Pre Box RS... (Valve suggestions?)

The Pre Box RS comes from the factory with Electro Harmonix 6922, on the output stage. All I have read about this pre has suggested a linear power supply upgrade and tube rolling gives
significantly better results, so the linear PSU is already done (19VDC from a HDPlex 200W).

I've already got some tubes I bought for my old old DAC (it's now 9 years old).
I have a pair of Amperex P.Q 6922 [VCM 163 tested], and a pair of
Phillips E88CC SQ [1109] with writing on the box [12500-12750 and 12400-12500 on the other box] What do those hand written numbers mean?

Anyway, which valves should I likely go with? (I am hoping for longevity as well as quality)



 
128x128rixthetrick
tomcy6's avatar
tomcy6
2,598 posts
 
Heerlen tubes are usually described as having a lively sound and especially good in the midrange.  The American Amperex are also considered very good tubes, maybe a little more subdued than their Dutch brethren.

These are just generalizations though, and the only way to tell how they'll sound to you, in your system, is to try them out.  Differences may be subtle, but both pairs are considered very good tubes, so roll them in and enjoy!
rixthetrick's avatar
rixthetrick OP
1,060 posts
 
I am still burning it in, as it came from factory.. It turned really muddy, but I am leaving a signal run through it, even if not at usual listening levels.
Currently it is either sounding better than it was out of the box or my audible memory is shot (left myself wide open, even chambered the bullet). I'll tube roll after burn in is completed.. a few hundred hours aught to do it? Should be about a fortnight, or so.

Thank you for so much information, much appreciated.


rixthetrick's avatar
rixthetrick OP
1,060 posts
 
tomcy6
I'm flying back to visit family in Australia, and while I'm gone I was seriously considering cryo treating my speaker cables and interconnects.
Should I send the valves in with it? Had any experience with doing that?
tomcy6's avatar
tomcy6
2,598 posts
 
No I don't.  Can't help you there.
zina2005
2 posts
 
hi Rick, I have the Pre Box as well. How did you connect the Linear power supply you bought? Were you able to source a connector or did you run cables into the box to connect t? 
More to discover