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New power amp input stage and power supply kits!

99.178.170.125

Posted on June 23, 2015 at 10:55:17
KevinC
Manufacturer

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



The K&K Audio website will soon feature a variety of PP and SE input stage kits, as well as tube power amplifier power supply kits to make the construction of first class amplifiers easier/faster. The input stage kits are based on circuits that we've worked with for the last 18 months using high transconductance pentodes connected as triodes. The high gain of this class of tubes makes it possible to build 2 stage amplifiers and still have enough gain for good volume with average sensitivity speakers, even without a line stage. Both the SE and PP input stage circuits can be constructed with either capacitor or interstage transformer coupling. The power supplies come in two voltage-capable levels and with and without the soft start feature. They feature FRED rectification and time-delayed application of high voltage, and can be configured for LC or CLC filtering. They are also flexible enough to be used with either traditional center-tapped or modern power transformers. While these designs are significantly less complex than my previous designs, they sacrifice nothing sonically when implemented properly. I've been listening to two different SE 6C33C amps built using this topology for the past 1.5 years, and I am a "converted" two stage amp guy now, where the output tube of choice lends itself to this use. Output tubes such as the 6C33C, and all of the usual audio tetrode/pentode output tubes that can be triode connected are great candidates for being driven by these input stages. Build better-sounding amplifiers with less time invested and have more time to listen to music!!!

-- A picture of the assembled SE input stage board shows one of the three input stages, this one with the facility for either capacitor or IT coupling on the board (although, of course, the IT is too big to solder to the board (:+)).

Kevin Carter
K&K Audio
www.kandkaudio.com

 

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RE: New power amp input stage and power supply kits!, posted on June 24, 2015 at 18:01:06
Brinkman
Audiophile

Posts: 52
Location: Pacific Northwest
Joined: December 4, 2007
Looks promising Kevin!

I've seen solid state monoblocks that incorporate oversized extruded aluminum heat sinks as elements of the chassis layout (i.e. side panels). Knowing that adequate heat dissipation within the footprint of an ST70 chassis was an operational constraint on your prior power amp offerings, is off-board mounting of transistors a possibility with these new kits?

Best regards.

 

RE: New power amp input stage and power supply kits!, posted on June 25, 2015 at 06:01:11
KevinC
Manufacturer

Posts: 2984
Location: NC
Joined: April 19, 2001
The key heat generating element in these Class A1 designs is the cathode current source for the output stage. That isn't formally part of the new kit line-up, but existing current source kits attached to a chassis mounted heat sink will handle that. You are certainly correct about the need for a largish heat sink for something like a PP KT120/150 monoblock! The current sources can readily be located away from the output tubes in this sort of configuration. The ST-70's limitation was chassis space. There was no other place for a heat sink than the PC board.

Kevin Carter
K&K Audio
www.kandkaudio.com

 

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