Review Conrad Johnson PV-11
The Conrad Johnson PV-11 tube preamplifier is used primarily for its rich, best heard to date, tube Phono Stage.
Steve Sank of Talking Dog Transducer Co, Tucson enhanced the sound of the PV-11 with a few mods - including replacing some factory Solen Caps (poor choice for a signal path) with higher quality and value Audiocap Theta capacitors and replaced one of the two ultra large black film caps off the transformer with a high value Nichicon electrolytic with great results (better bass, dynamics, soundstage, musical depth, midrange richness, more extended highs).
I also owned an did an A-B in house with the CJ PV-5, PV-9a, PV-11, and PV-12. The PV-5 was warm to the point of sounding dull to me and the PV-12 started to tip the scale toward lean and solid state to me. The best sounding was the PV-9a until the mods went into the PV-11, which made the PV-11 sound every bit as dynamic as the PV-9a and slightly warmer in the mids (and in a much more compact enclosure).
BTW, I didn't like the look of the rack arms, so I simply took them off and replaced them with some hex button bolts as you can see in the photo. Mullard Long plates with square getters (12AU7, 12AX7 where applicable) ended up being chosen in all positions of the phono stage including a Mullard 12AX7 which substituted nicely in the 5751 spot. The Mullards have stellar mids which were also pushed nicely forward which I like.
Be forewarned, Mullard short plates don't sound all that good and Mullard 12AX7 long plates are prone to be microphonic and can be extremely expensive and sometimes microphonic. For those not already initiated to micro-phonic tubes, right after you receive them, install them and have your system fully on and gently tap them to confirm that they are not micro-phonic. If one or more are microphonic, you will hear a ringing or tapping noise through your system. Sometimes just tapping the enclosure with the microphonic tube in it will do that.
A Steve Sank (moscode expert extraordinaire) partially modified (as per my budget) Moscode Super IT gave the CJ a serious run for best phono with better dynamics, blacker background (less noise), and the ability to easily handle MC Carts.
However, the CJ's ability to provide a slightly richer midrange (needed by my vinyl setup) is why I chose the CJ phono stage over the Moscode Super IT. Something gained and something lost as usual. An audiophile friend with years experience who heard both the CJ phono and modified Moscode Super IT bought the Moscode Super IT from me and loves it. Be aware that the original Moscode Super It had some dangerously borderline spec caps in it which were prone to fail and that a fully modified Moscode Super IT is supposed to be something to behold.
In general, my favorite smaller tubes (12AU7, 12AX7, 6DJ8, etc) which were chosen for best combination of musicality warmth, and detail, are Telefunken and Mullard (I occasionally throw in a RCA or Sylvania for more warmth).
I have found that in general the best tubes were usually made in the 40's, 50's, and early 60's. Tubes that I have found to be both musical and detailed in order of most detail to warmer are:
Amperex Holland & Siemens
Although many people love them, I personally found the Amperex & Siemens to be a little too detailed for my system and preference. I found Tung Sols to be detailed to the point of sounding dry and nervous to me so I left them off the list.
Although both Mullard and Telefunken are my favorite brands of preamp tubes, I found Telefunkens to have a nice combination of detail and warmth, with the Mullards offering a smidge more warmth and slightly less detail. The Telefunken 6DJ8 seemed to be a tad more detailed than other Telefunkens however.
I used Sylvanias in combination with RCAs sometimes, with the RCA being the warmest offering a rich and thick midrange, although sometimes lacking in the highs. In my PV-11, I liked to use a RCA 5751 and others to add more warmth.
Although their tubes can be a little expensive and I occasionally do not agree with them, a great resource for tube information is Tubeworld on the internet.