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Summer projects

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Posted on August 16, 2014 at 08:41:35
KevinC
Manufacturer

Posts: 2984
Location: NC
Joined: April 19, 2001



I've been busy with a couple of new projects this summer, both of which were begun earlier in the year.

The first of these is a new phono preamp (called the "Trio"), which will be offered as a kit. The Maxxed-Out Phono Preamp has become much more complicated to build in its latest revision (alas, the complication resulted in better sound), so I decided that a simpler phono preamp was needed that wouldn't sacrifice too much of that K&K Audio sound. The Trio uses three 6922 type tubes in a three stage configuration with split RIAA EQ. In order to minimize the number of coupling capacitors, the third stage is directly coupled to the second stage and the output transformer (LL1689) is series fed, eliminating the "parafeed" cap. To further remove capacitors from the circuit, the first two stages are operated LED (fixed) bias, removing the bypass capacitors. Good capacitors are expensive and my goal was to reduce the cost without reducing the sonic value. The plate load and the shunt regulator boards will be preassembled and tested to make success more attainable, as well. Both MM and MC cartridges will be accommodated in much the same way as they are in the Maxxed-Out Phono Preamp. The prototype is complete and I am very pleased with the way it sounds. I just need to get PC boards and chassis and it will be available. Stay tuned...

The other project I've been working on is a parallel single-ended 6C33C amplifier design. The topology is fundamentally the same as the stereo amplifier's described earlier this year, but with some interesting twists. More info will be available later, but suffice it to say that while the stereo SE 6C33C amp is a very fine performer, indeed, the parallel SE 6C33 monoblocks are just what my speakers needed to give the music the "bloom" and "grunt" that more closely resembles live, while treating the less descriptively masculine parts of the music with the delicacy they require.

I have also developed a monoblock version of the single output tube SE 6C33C amp and will be offering PC boards for input stage and power supply soon. (these boards could potentially be used for any amplifier design, not just 6C33C) I am not planning on offering chassis, but I could be convinced to do so....by orders for them.

Decidedly good stuff!

Kevin Carter
K&K Audio
www.kandkaudio.com

 

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RE: Summer projects, posted on August 16, 2014 at 22:09:32
What is the power output of the monoblocks? I've moderately efficient loudspeakers on the way (87dB, 4ohm nominal) for which these amps may be a nice mate.

 

RE: Summer projects, posted on August 17, 2014 at 04:34:01
KevinC
Manufacturer

Posts: 2984
Location: NC
Joined: April 19, 2001
The parallel SE monoblocks are 35w/ch, while the single tube SE monoblocks are 16w/ch.

Kevin Carter
K&K Audio
www.kandkaudio.com

 

RE: Summer projects, posted on August 17, 2014 at 12:34:18
pistoljoe
Audiophile

Posts: 269
Location: cambridge, ma
Joined: February 19, 2003
Kevin,
Are the mic preamps still in queue? Love to hear more about this!
Joe

 

RE: Summer projects, posted on September 5, 2014 at 14:53:51
Cpwill
Audiophile

Posts: 1096
Location: DC
Joined: December 22, 2003
Contributor
  Since:
October 24, 2008
What set-up x-former for MC will the Trio use, and any idea on price point yet?
"Anyone who understands jazz knows that you can't understand it. It's too complicated. That's what's so simple about it." - Yogi Berra.

Cpwill

 

RE: Summer projects, posted on September 5, 2014 at 17:00:58
KevinC
Manufacturer

Posts: 2984
Location: NC
Joined: April 19, 2001
The Trio will have two options regarding input gain, MM only or MM/MC, like the Maxxed-Out Phono Preamp. I will use the same back panel PC board for the Trio, so the LL9226, LL1678, LL1931, or LL1941 will be accommodated, all with or without MC cartridge load switching.

All is not yet final (only got the PC boards on Wednesday), but I am trying to hold the MM-only to $1250. Although this is only $100 less than the Standard Maxxed-Out at current pricing, the Standard will be discontinued and the Premium Maxxed-Out prices will all go up when the Trio is introduced, reflecting the fact that I've held prices steady for 3 years. It's also important to keep in mind that the Trio sounds better than the Standard Maxxed-Out, so it's a deal by comparison.

For those of you who might build the Trio Kit, there are 5 "plug-in" daughter boards that will be preassembled and adjusted to spec included in the kit. These boards house the plate loads for the first and second stages and the power supply shunt regulator. In the past I've found that these parts of the circuit are the most difficult to assemble and adjust correctly, so I've built the cost of completing that operation here at K&K into the pricing to make the chance of successful construction substantially greater.

I'm really pleased with the sound of the Trio. I've worked on this phono preamp on and off since the Christmas holidays, so I've had time to try and sonically consider many options for coupling and biasing. The result has been a set of compromises that minimizes the effects of less expensive components on the sound quality, resulting is a really fine product that is simple enough to assemble without breaking a sweat.


Kevin Carter
K&K Audio
www.kandkaudio.com

 

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