K&K 6C33C Mono Blocks

Captainhemo · « **on:** 1 Nov 2016, 05:15 am »

My buddy finally took delivery of his "one off" ( 4 pairs in existece) k&K 6C33C P/P monos today and being he's speakerless at the moment, they are playing n my room

These use 2 6J49P input tube and 2 6C33C output tubes per amp. Power, ,output, and interstage Lundalhl transformers. Each amp is about 70 lbs, they are beauties. Best of all, they just sound amazing.... HUGe sound stage and extremely rich with a ton of depth. Been listening for a few hours and I'm just wowed . Very nicely done Kevin (K&K Audio)

Will try and post some more details soon, gotta get back to listening right now
jay

FullRangeMan · « **Reply #1 on:** 1 Nov 2016, 10:02 am »

Wow what heavy transformers!
I hate you Hemo. Any specs details?

Dieterle Tool · « **Reply #2 on:** 1 Nov 2016, 12:20 pm »

Very nice Hemo. Although I have no experience with Kevin's amps, his "Maxed Out" phono has put an end to chasing gain devices for me. With the potential upgrades to circuit and features, I don't think I will ever pursue another phono device.

How long was the lead time from ordering to delivery?

Dieter

Mike B. · « **Reply #3 on:** 1 Nov 2016, 02:50 pm »

I met Kevin when we both were starting our businesses. He helped me with a transformer output for a CD player. Nice to see he has put all his knowledge into a variety of completed components.

Captainhemo · « **Reply #4 on:** 1 Nov 2016, 07:00 pm »

Quote from: FullRangeMan on 1 Nov 2016, 10:02 am

Wow what heavy transformers!
I hate you Hemo. Any specs details?

Gonna kill me when these go up to don's place, man they sound good !
A few specs
30-35 wpc
Zero neg feedback
20 db gain

Will post more when I have them, will also get another pic or two

Dieter, the lead time was "signifigant but totally worth the wait ! Kevin apparently also has a new pre that is supposed to be most exellent

Mike, yes I've heard a couple of his pieces now and I'm impressed, outstanding

jay

FullRangeMan · « **Reply #5 on:** 1 Nov 2016, 07:08 pm »

What is the OPT core/Laminations?
C core, HiB, nanocristaline? etc

KevinC · « **Reply #6 on:** 1 Nov 2016, 07:24 pm »

The output and interstage transformers are silicon iron. The input transformer (for balanced input) is cobalt amorphous core. The use of amorphous iron in the interstage transformer was an option. I found that the amorphous core transformers provided more access to superfine details, but thinned the sound out a bit as a trade-off. I preferred the body over the superfine details. Instruments seemed better integrated (but not smeared) in the soundstage with the silicon iron IT.

There are four pairs of these amps in existence at this point; the pair Hemo is "borrowing" is the best sounding as there were changes to the power supply that improved the sound in that pair. I had no plans for making more if these, but could be persuaded otherwise if there was significant demand. They are a physically challenging build, with 3 separate 250VA Lundahl power supply transformers each and a 12 pound C-Core output transformer.

bigmuck · « **Reply #7 on:** 1 Nov 2016, 07:32 pm »

New to Audio Circle. I have built the 6C33C PSE monoblocs using components from Kevin and constructed my own chassis'. Finished my amp build in January and then built Kevin's new Mir linestage that uses the 12P17L. The amps are superb sonically and the Mir linestage only adds to the magic. The synergy has taken the system to a higher level. I incorporated mesquite and aluminum for the chassis' construction on the amps and linestage. I will include pictures in a future post.

poseidonsvoice · « **Reply #8 on:** 1 Nov 2016, 08:03 pm »

Quote from: FullRangeMan on 1 Nov 2016, 07:08 pm

What is the OPT core/Laminations?
C core, HiB, nanocristaline? etc

Lundahl Amorphous Core baby!

But Kevin's circuit design is not to be undermined, he really knows his stuff! His 6C33C amps are on my todo list along with an EML 300BXLS design.

Best,
Anand.

Dieterle Tool · « **Reply #9 on:** 1 Nov 2016, 10:17 pm »

^ Yah, what Anand said. I was interested in the Lundahl T's and in searching, the K&K site provided all the info. I needed to make a commitment. Money well spent.

Mike B, I regret not being aware of your work, would you care to elaborate on your cdp design? I did a diy project with the CS4398 "Lampucero" board (Ebay) and replaced the op amps with a toroidal T. It improved clarity and dynamics a bit. I can only imagine what the Lundahl's would achieve...

Dieter

saygrr · « **Reply #10 on:** 2 Nov 2016, 01:32 am »

Dieterle Tool I have the Maxxed Out phono stage also, and it has ended my search to. The previous stage was more expensive by a couple thousand but the Maxxed Out beat it in every way.

Captainhemo I can see why you like the amps. Kevin is definitely a perfectionist. What speakers are you using? What speakers would you recommend with these amps?

Thanks for sharing your experience. I know Kevin is working on a line stage did not know about these amps.

Captainhemo · « **Reply #11 on:** 2 Nov 2016, 01:57 am »

Quote from: saygrr on 2 Nov 2016, 01:32 am

Captainhemo I can see why you like the amps. Kevin is definitely a perfectionist. What speakers are you using? What speakers would you recommend with these amps?

Thanks for sharing your experience. I know Kevin is working on a line stage did not know about these amps.

Have them driving a pair of NX-Otticas (3x/94db) which are paired with a set of triple OB H-frame servo subs. these amnps are showcasing just how good these speakers really are

They'll eventually be driving a pair of the NX-Tremes just haven't built a set out yet

Quote from: KevinC on 1 Nov 2016, 07:24 pm

The output and interstage transformers are silicon iron. The input transformer (for balanced input) is cobalt amorphous core. The use of amorphous iron in the interstage transformer was an option. I found that the amorphous core transformers provided more access to superfine details, but thinned the sound out a bit as a trade-off. I preferred the body over the superfine details. Instruments seemed better integrated (but not smeared) in the soundstage with the silicon iron IT.

There are four pairs of these amps in existence at this point; the pair Hemo is "borrowing" is the best sounding as there were changes to the power supply that improved the sound in that pair. I had no plans for making more if these, but could be persuaded otherwise if there was significant demand. They are a physically challenging build, with 3 separate 250VA Lundahl power supply transformers each and a 12 pound C-Core output transformer.

Thanks for chiming in Kevin, most appreciated and informative.
As I mentioned in an email to Kevin yesterday "both of us are thoroughly impressed. The layering and accuracy of images is amazing, and what tone, everything is so "real".
Interesting that Kevin mentions the body and fullness, I've commented several times when listening regarding that exact characteristic, it's stunning just how much presence there is

jay

FullRangeMan · « **Reply #12 on:** 2 Nov 2016, 07:41 am »

Quote from: KevinC on 1 Nov 2016, 07:24 pm

The output and interstage transformers are silicon iron. The input transformer (for balanced input) is cobalt amorphous core. The use of amorphous iron in the interstage transformer was an option. I found that the amorphous core transformers provided more access to superfine details, but thinned the sound out a bit as a trade-off. I preferred the body over the superfine details. Instruments seemed better integrated (but not smeared) in the soundstage with the silicon iron IT.

There are four pairs of these amps in existence at this point; the pair Hemo is "borrowing" is the best sounding as there were changes to the power supply that improved the sound in that pair. I had no plans for making more if these, but could be persuaded otherwise if there was significant demand. They are a physically challenging build, with 3 separate 250VA Lundahl power supply transformers each and a 12 pound C-Core output transformer.

Thanks Kevin for the complete details, you most kind.

bigmuck · « **Reply #13 on:** 8 Nov 2016, 02:44 am »

A few pictures to share of my version of the 6C33C PSE amps from K&K. My amps are slightly larger than the chassis that Kevin uses. Powder coating was done by a local paint shop. Power transformer is potted with a marine grade epoxy. Wood on the sides of the amps are re-sawn and book ended to match on each amp. The front plates as you can see are book ended as well. Hook up wire for the power supply is 20 ga. fine silver and signal wire is 22 ga. fine silver. Components are mounted on a mid -plate that allows access to top and bottom of the circuit boards.

poseidonsvoice · « **Reply #14 on:** 8 Nov 2016, 02:55 pm »

Gorgeous

Thanks!
Anand.

Captainhemo · « **Reply #15 on:** 8 Nov 2016, 03:50 pm »

Wow, very nice

jay

ludimagis · « **Reply #16 on:** 8 Nov 2016, 04:05 pm »

Totally agree with all, I'm really impressed!
Just love what the 6C33C does for SQ.
I owned Audio Mirror SET amps that utilized 6C33C tubes in parallel that I thoroughly enjoyed.
Now I have to check out the K&K website.

Dieterle Tool · « **Reply #17 on:** 17 Nov 2016, 01:53 pm »

bigmuck, talk about "ending the chase", those are gorgeous. Thanks to you and Kevin for chiming in.

Dieter

sledwards · « **Reply #18 on:** 2 Dec 2016, 01:41 am »

I thought I would share another one of Kevin's excellent designs with the group. This is one of his KT-120 based, push-pull Class A1 monoblock amplifiers I recently completed. I mounted the Lundahl output transformer and choke externally in Lundahl housings. The main power transformer is a custom toroid designed by Toroidy http://sklep.toroidy.pl/. Separate filament transformers are located inside the chassis. I will let Kevin chime in on the operating details and design. In a nutshell, I am thrilled with the sound of these amps. Since I live in the RTP area, I was fortunately able to audition the KT-120 and 6C33C amps at Kevin's shop on his system. Both of these amps sound wonderful, and really boils down to ones personal preference and your output power requirement. At approximately 20 watts rms, they easily drive my current 87 dB efficiency speakers to adequate listening levels for my taste. Yes, in a few cases I have found some tracks recorded at lower levels, requiring full volume on the preamp. Soon I will be building the same NX-Otticas Jay previously mentioned which are much more efficient and will giver me the desired headroom with the amps. A word of warning: Once you start building Kevin's audio equipment, it is hard to stop. Next up for me is Kevin's single-ended line stage preamp "Mir" http://www.audiocircle.com/index.php?topic=146892.0. I have one of the prototypes running in my system now and it's a definite keeper.

FullRangeMan · « **Reply #19 on:** 2 Dec 2016, 07:14 am »

Quote from: sledwards on 2 Dec 2016, 01:41 am

Once you start building Kevin's audio equipment, it is hard to stop.

Do you are a tube amp builder?