Jump to content

K&K Audio- PP design monoblocks


Recommended Posts



I came across a set of monoblocks from K&K Audio. Here is some info: 


Two Monoblock vacuum tube amplifiers.

Push pull design using transformer coupling between all stages
(input, inter-stage, output).

Estimated 7 watts per amplifier. Can be modified for more power.

Lundahl interstage transformers

RCA and XLR input connectors.

Output transformer is a custom design rated at 90 watts.
Power Supply transformer also a custom design of excellent quality.

Tube complement (Russian NOS):
Output: GU50
Driver: 6Pi3C/6N3C (very similar to the 6L6GC)
input: 6N6p / 6H6pi

Driver stage operating point is set with current sources.
Output stage operating point is set with current sinks.
(Stable, reliable, easy to set.)

Has a custom designed soft start circuit.
Extra OP tube sockets and extra tubes.


I'm wanting a set of monoblocks and this fits the budget, but I dont know a ton about what they are selling, so I wanted to gather some thoughts here. I would run these with my La Scalas and a Erhard Audio Pre and Phono. 


Thanks for any knowledge you can drop on me here! 

Link to comment
Share on other sites

Those GU-50 are power pentode vacuum tube designed for up to 50-watt operation as a linear RF amplifier at frequencies up to 120 MHz. The tubes are typically used in hi-fi audio amplifiers in both single-ended and push-pull mode. GU-50 is a direct equivalent to Telefunken LS-50 Power Tube. I myself operate two tube mono amplifiers with Russian GU 29 tetrodes in push - pull mode. Soundwise a dream.



  • Thanks 1
Link to comment
Share on other sites

1 hour ago, Jeffrey D. Medwin said:

Holey smokes !!


I would suggest you buy them in a heartbeat.  I have no affiliation with Kevin of K and K .  


I'll tell you this :  He is one of the better designers in tube audio.  He, like me, is getting older, and perhaps he is wanting to lighten up on units on his shelves !!!!   You will likely get much much more than your money's worth, in both build quality and in performance / and in value.


The GU50s are a fine output tube !!   


Kevin knows all about the Russian small signal tubes, and he runs them conservatively, so they will last !!


MY mentor in audio runs one of his phono preamps, and it's a huge winner.  I have tons of respect for Kevin, and his work, his knowledge, whereas , usually I dismiss most audio products as being mid fi designed, and poorly implemented.  I just do not think that will be the case here. 


You should consider yourself lucky to have these monoblocks made available....from K and K.  .  It will be something to keep using until you pass them on to your grandchildren.  Please let me know how this goes for you !!! 


BTW Leave the circuit alone, and do not try for more power !! It is all you will ever need, those seven Watts on a Klipsch La Scala speaker.


Jeff Medwin 

Very cool. It sounds like the owner of this built it themselves from Kevis 32b monoblock spec. 


Yeah, I'm not going to try and make more power, givin the sensitivity of the speakers. 




Link to comment
Share on other sites

6 minutes ago, Limberpine said:



I don't know a ton about these things being new to tubes, but since reading through this I just sent the seller a message saying I'd like to buy them.

I think you have made the right decision. And if you need technical advice I'm sure that @Jeffrey D. Medwin will support and help you here.

  • Thanks 1
Link to comment
Share on other sites

He is hesitant to ship them due to size and weight, but im going to see what it costs and see if I can just have him bring them to FedEx for them to pack and ship them.


Just so I dont go crazy in the red on these. What does everybody think an approximate value is on theses? 



Link to comment
Share on other sites

54 minutes ago, Jeffrey D. Medwin said:

This is a different deal than what you led "me" to believe. I thought you were buying these directly from Kevin at K and K.  There is no telling how well these are laid out, parts choices,  and actually built from scratch, by the average DIYer. 


I would say there is far more risk involved, than I had originally envisioned.   


A DIYer's build will vary widely, from what Kevin himself may do.   I would not be so inclined to buy these "blind " as I see more and more of whats going on in this thread.  


So, I would like to alter my first post,  where I was encouraging you to act. 


What were you going to pay for these, prior to shipping may we all know?  There may be other, safer alternatives to consider.


Jeff Medwin

Thanks! He is asking $500 for them and then whatever the cost of shipping would be. 

Link to comment
Share on other sites

21 minutes ago, Jeffrey D. Medwin said:



$500 for two monoblocks is very little, almost nothing.  The price alone .....may be a red flag !!  Don't know. 


 I don't know where you and he live, but it could be $100-150 for each mono amp, for shipping, not including packing.  The external heatsink in the photo is a packing problem, for sure .


I personally would not trust the average packing shop, to pack them for you well.


Depending upon how heavy the chassis is,  and how he mounted all the components, there is a good chance that the units will be damaged in shipping.  Then you will have to get  them repaired.   


A DIYer builds the unit with the mind-frame that it won't fall apart in his living room, or recreation room. A Manufacturer designs and builds so the unit will withstand shipping drops. 


The seller is hesitant to ship, perhaps ......because he feels the unit, as built, won't safely get to you .


I am just sharing some thoughts, you get to do what ever you want to do !



Jeff. This is VERY HELPFUL!


I too thought this was a good deal at $500, so that is why I inquired.


I asked him for dimensions and weight and he has gone silent, so I'm thinking it won't work out.


If you pay FedEX to pack it, and insure it for the full value, they have done a great job for me, because it seems like they are ramping up efforts to cut down on claims.


Thanks again for your help! And I would certainly be open to chatting about Monoblocks if you want. We can message back and forth about them. My plan was to budget to buy something in about a year, and then this came up, which looked like a sweet deal!



Link to comment
Share on other sites

  • 3 weeks later...

Theses are still for sale in the Raleigh Durham area if someone wants them. The guy who built them used to work for VAC. Shipping to me in Portland would have been $350, which was just too much for me to justify. He seems like a very nice guy and is moving, which is why he is selling them.

Link to comment
Share on other sites

Just a little background information on the seller.


Kevin Carter of K&K Audio was a designer and co partner with Kevin Hayes of VAC many years ago. Mr. Hayes moved the business from NC to FLA and Mr. Carter didn't want to move so he started his own audio business. Back in 2000 Kevin Carter built a phono preamp for me that is still in my system today. He also designed electronics for Art Audio, which my phono stage is based on the Vinyl One, but with several upgrades. Kevin also repaired and upgraded two Music Reference RM9 amplifiers, one was mine and the other belonged to a friend.


I have been to Kevin's house and heard some of his amps and they are the real deal. I haven't spoken to him in years but I will reach out about these. I would have done it already but only stumbled on this thread today.



  • Like 1
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...