Passion Audio Kit A11 Amplifiers

A11

A power amplifier using SVETLANA 6550C output tubes. Push-pull, ultra-linear output stage. Printed circuit board assembly.

User Reviews (1)

Showing 1-1 of 1  
Derek Figueira   Audio Enthusiast [Aug 10, 2007]
Strength:

Due to the design, nice results can be obtained by simply replacing a minimum of one tube which makes it more affordable to experiment with NOS tubes.
Decent amount of power for higher listening levels.
Excellent speaker, RCA connectors, and tube sockets.

Weakness:

No volume remote... (I'm getting lazy)

Hard to see the dimples in volume and selector switches that indicate their positions... I filled them with white paint to solve that issue.

Schematic not included.

Straight out of the box, this amp does not impress, but after the recommended burn in period of 75-100 hours, the sound quality started to get better. Still, I felt that the music was not as rich and full bodied as I'd hoped. That's when I started doing some tube-rolling. I left the JJ KT88's alone, and instead focused on replacing just the supplied EI 12AU7 preamp tube in socket "VB5" with different brands of NOS tubes.

What a difference!! Suddenly the music was fuller, richer, more detailed, more bass, etc.! Now the fun begins! I tried several brands of NOS tubes including Telefunken, Mullard, Brimar, RCA, Amperex, and GE, and got great results, but I wanted MORE! I ordered more NOS tubes to try replacing the rest of the 12AU7's.

I haven't recieved all of the tubes that I want to try, but so far, the BEST results I've obtained is by using a BRIMAR 12AU7 in socket VB5, and by replacing two more EI's in sockets VB6 and VB8 with a couple of AMPEREX 12AU7's.

The result so far is clean bass so powerful that you can feel it, a wider deeper soundstage, focused, more detail without being harsh, and an incredible "spooky" sense of realism with the vocals!

I'm eagerly awaiting two more AMPEREX 12AU7's to replace the last two remaining EI's in sockets VB7 and VB9 to see what that does.

I hope this helps anyone else out there that either has an I-12, or is thinking of getting one.

Customer Service

Haven't required this as yet.

Similar Products Used: Vecteur I-4 Integrated amplifier.
OVERALL
RATING
4
VALUE
RATING
4
Showing 1-1 of 1  

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