K&K Audio / Lundahl Transformers

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4P1L linstage

Posted on November 30, 2016 at 14:31:06
Jim D.

Posts: 730
Joined: October 26, 2000
April 6, 2002

It's alive! I powered up the prototype last night and it sounds marvelous. It's still burning in and a work in progress. Picture is audio circuit. Power supply is a basic tube rectified LCLC design (not shown). Kevin's boards are very good quality and have very nice test points to make it easier to set values.



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RE: 4P1L linestage, posted on November 30, 2016 at 17:57:00

Posts: 2911
Location: NC
Joined: April 19, 2001
The 4P1L and its sibling the 12P17L are very special sounding tubes. There is detail aplenty, but there is also excellent bass extension/tautness and midrange presence. These provide the most "live sounding", compelling reproduced music I have heard in my years of chasing that goal. In addition to the SE 4P1L preamp on plywood, I have built both SE and differential preamps using the 12P17L and they are both excellent, although somewhat different from one another in character. They interface extremely well with either PP or SE amplifiers built using the amplifier kits.

Thanks for sharing your build. Your plywood prototypes look better than mine, for sure!

Kevin Carter
K&K Audio


RE: 4P1L linestage, posted on December 1, 2016 at 06:21:17
big muck

Posts: 126
Joined: December 31, 2000
I've been enjoying my 12P17L linestage since February. Originally I was going to use the 4P1L but made the switch to the 12P17L and eliminated the need for the additional circuitry necessary to the tame the 4P1L filaments. The new linestage mates well with my 6C33C PSE monoblocs that are Kevin's design as well. Soundstage is deep and wide with players assuming their place in that space. Music has a body, air and texture that is very engaging, leading to many late night, wee hour listening sessions. While a parts tweak here and there is inevitable (audiophile disease symptom), I do believe that my sound system is one item on the bucket list has been achieved. Many thanks to Kevin for his assistance in the journey. I wouldn't have made it this far without it.


RE: 4P1L linstage, posted on March 10, 2017 at 22:36:25

Posts: 1851
Location: Alberta, Canada
Joined: October 24, 2004
What type of wood do you have tubes mounted in?
It looks like black walnut. Many have used extreme measures for mounting the sockets because of microphonics.
I have thought mounting in wood could solve the problems, as it will absorb the vibration much easier. I bet it sounds very nice!


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