Audio Research REF2 MK 1 Vs. MK 2

I've had a Ref 2 mk1 for several years and love it. Because of the input/output stages are all tubes, (along with the 6922's) the sound is very "tubey". Lots of bloom. Mk2 uses a different tube set and jFets on the input stage. Sounds more crisp and clean than the mk1, but with less bloom.

The Mk I has an all vacuum tube audio circuit. The Mk II has an all solid state audio circuit (not just the input stage....all) with only a single cathode follower at the output. The Mk I has all the best sonic qualities of tubes while the Mk II sounds more like a solid state unit, albeit a very good one. Take your pick based on your personal preferences. I vote for the MK I. To me, its sounds more like what I hear in life.

05-01-08: Hjp
The Mk I has an all vacuum tube audio circuit. The Mk II has an all solid state audio circuit (not just the input stage....all)

This is not correct. The input stage uses J-FETs followed by 6H30 tube for the 2nd gain stage and another 6H30 as a follower/output driver. That's why there are four 6H30 tubes (two per channel).

Dave, I thought there were 6 6H30 tubes in the REF2MkII.

The REF 2 MK II has 6) 6H30's, 1) 6L6, and 1) 5AR4. The only reason for a "tubey" sounding REF 2 MK I is "tubey"(microphonic) tubes. If the tubes are rolled for accurate/transparent, NOS 6922's, the sound will be also. Siemens and Telefunken CCa's will both provide a clean, accurate, non-tubey presentation. As with any pre-amp, mic or phono stage: Tubes MUST be screened for noise before purchased. The CCa's were a specially selected, low-noise 6922 variant, but that doesn't guarantee all will be quiet enough for your pre-amp. A less expensive, but still excellent option, is the Siemens E188CC. I had them in a couple ARC pieces I owned(very extended, lucid and transparent). I'm using 6) Siemens CCa's in my VK-D5 now, and love 'em.