April 3, 2012

• Small Signal Tubes

  I realized that although I’d provided a link to my system that lists what equipment and accessories are currently being used, I thought it’d be worthwhile to show the small signal tubes being used during the course of my power tube reviews.

   

  conrad-johnson Premier 16 LS2 Preamplifier:

  This preamp uses six (three per channel) 6922/E88CC tubes.  I’ve found that 6DJ8/ECC88, 7308/E188CC and 7DJ8/PCC88 tubes also work very well in this unit.

  My current tube of choice is the 1960’s vintage Lorenz 7DJ8/PCC88 made in their Stuttgart, Germany plant.   Its sound is very similar to the Telefunken 6DJ8/ECC88 and 7DJ8/PCC types from the same time period, but I prefer the Lorenz by a small margin for its across-the-board excellence.  Of all the tubes that have been rolled through the 16 LS2, these get out of the way more than any other while still ticking all the audiophile approved boxes including sound stage palpability.  They’re clear and detailed without ever sounding sterile and are as close to not being there as any I’ve heard.

   

    

  conrad-johnson Premier Eleven A Amplifier:

  This amplifier uses a pair each of 6FQ7 (you can also use the 6CG7 type) and 5751 tubes.

  I’m currently using GE tubes in both of these positions.  The Eleven A was originally voiced by conrad-johnson using GE tubes in all positions, including GE 6550A power tubes.

   

  GE 6CG7

  The tubes in the amplifier are actually the earlier model of the 6FQ7, the 6CG7, and include the central electrostatic shield that was later eliminated in the 6FQ7 model.  conrad-johnson doesn’t ground pin 9 which is connected to the shield so I guess, in theory, these two types shouldn’t sound any different in the Eleven A. 

  This picture shows the central silver/chrome shield but because it's reflective, the shield appears to be the same color as the outside plates, dark grey.

   

  This is a double mica tube, with one mica layer above and the other below the vertical plates.

   

  GE 5751

  These are GE triple mica, black plate 5751 tubes and date to sometime in the 1950’s.  The vendor I purchased these from has them listed as triple mica, grey plates but they certainly look black to me.  For that matter, although it may be difficult to tell from the photograph, they also appear to have double mica plates (therefore four in total) below and above the central, vertical plates.

  

   

  Here are all the little guys lined up for the last shot.  To their right in the photo, you can see the Shuguang KT 88-98 power tubes that will be the subject of my next meanderings.

  

   

   

  • 9:28 am
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