I think I have found the End Game Amp


For the past couple of years I have been searching for a power amp that plays well with the highly resolving nature of the Esoteric K-01XDSE source and the Rockport Atria II speakers.

How do I get a mid-range to captivate without losing the sense of air and space?

The K-01 and the Atrias deserved something great in between but I could not bring myself to spend $25k - $50k if I went all out on both pre and power.  Building an amp is surely easier than building transducers?

The closest I came was with a Cary SLP-98 pre - with NOS RCA 6SN7s and the Elekit 8900 running Black Plate 2A3s.  There was not quite enough power, slight sounds of strain at fff and not quite the warmth in the mids.

I was enamored of the 2A3 sound and wondered if there exists a PP or PSET 2A3 amp, so I discovered and contacted Frank Ng at Triode Labs.  He had recently found a pair of Tamura OPTs and Tango chokes and had built a pair of the PP 2A3 GT-C amps that I could have immediately!  Working with Frank was an absolute joy, getting a story of his constant search for the Tamura OPTs, and seeing his views on various tubes.

He gave me great price (he supplied only the 6SQ7s) and I was able to pay through PayPal - I rounded up (dividing by .96) to cover the fees.  I got him to autograph the base plates!

The shipping boxes were superbly protective but easy to unpack.

Even cold out of the box I could hear something special; there is just a natural quality to the sound.  The amps now have about 30 hours and Frank expects break in to be about 200.

Everything I play sounds - I am not sure of the word - but "right" seems to fit.  I have played everything, from Angela Hewitt's Goldbergs - you can clearly her management of tone from her Fazioli piano - to Simon Rattle's Mahler 7 (Bavarian Rundfunk).  Also the Borodin recording of Shostakovitch quartet 9, the Beethoven op.132, the Sveshnikov Rachmaninov Vespers with Klara Korkan's haunting mezzo, Hilary Hahn playing Bach.  AMAZING!

There will be some tube rolling to fine tune (!) everything but at this time the SLP 98 has coin base a 6SN7 gain stage, Tung Sol buffers.  The GT-C has Motorola branded 6SQ7s, Smoked glass RCA 6SN7s, JAN Black Plate 2A3s and Sophia 274B rectifiers in the main amp..

 

 

 

retiredaudioguy

I thought about addressing that comment regarding high efficiency speakers. I currently own high efficiency speakers and I hear no degradation in sound from the numerous pairs of speakers I have owned that were lower efficiency. That includes the Avalon’s I owned with almost identical specs to your Rockports. I think my current speakers are the best I have owned and will be my last speakers. The other thing is that I can use a 60W parallel SET amp that uses two 845’s per channel (parallel), a 300B driver, a single 6SN7GT and two 6SN7GTB input tubes. This combination of four different tube types of the best sounding tubes ever made for audio gives massive ability to fine tune. That said, even the 60W’s on very efficient speakers, I feel us slightly outperformed by a 300W SS muscle amp capable if driving any speakers on the planet. I am guessing the massive difference in headroom cor the amps contributes to this to some degree. None of the presence, transparency and life like presentation are lost when I switch to the SS monos.

@posbwp55 what are your speakers?  My experience is probably out of date as it is at least 25 years since I heard anything with much over 90dB, and back then there seemed to be colorations - a "boxy" sound.

I do remember hearing Avalons (dk which) and being impressed, though the floor standers were out of my price range at the time - probably still are.

I certainly do not want to denigrate any other audiophile's choices, I guess I am feeling defensive as there have been remarks (not from you) that my speakers cannot sound good with my electronics.  And I appreciate all your comments and advice.

@retiredaudioguy 

No, I cannot shake the walls at 92 dB, but I live in a log home and it would take a bulldozer to move them anyway!

Unfinished exposed logs for the side walls? Free diffusion! Nice. 

@retiredaudioguy Much of my listening is chamber music and choral works where "bass slam" and other artifacts requiring power are not relevant

I find it very interesting that you’re taking the very transparent but average efficiency Atria to use in limited frequency range of your preferred music genre. Likely most others would get stronger amps to reach the frequency extremes which you don’t need. While you use both a tube pre + tube amp to tune in your desired Sonics, I took a different route.

After demoing the very best I could find at many audio shows and audio stores, my sonic preference was Magico or YG and their accompanying electronics. Unfortunately with my modest budget it was a major struggle in finding an affordable combo. Luckily I ended up with a Vimberg Mino D driven by Audionet Humboldt integrated.

To check out tube midrange magic, my second system is anchored by a highly egg 100db Volti Rival which I chose for its neutrality, clarity, and performance so I can hear tube amplification better. I’m starting with flea watt SET amps.

It is not that easy to find high efficiency speakers that don't have midrange coloration or harshness.  It is also hard to find modern conventional speakers that don't sound flat and lifeless compared to the better high efficiency speakers.  The few high efficiency speakers that do avoid major tonal issues tend to be expensive and large.  I really like a number of custom-made horn systems--using vintage horns and compression drivers--but these are not generally available to most shoppers.  Among more common horn systems that are quite good, I like Volti speakers even though they are not the last word in bass integration.  I also like some systems built around full-range drivers, such as Charney Audio and Songer Audio speakers.

For my taste, the best sounding compact, reasonably efficient, and easy to locate in the room speakers are those made by Audio Note and Graham.  

The 2a3 amps I've heard (and owned) tend to be a bit lean, though very tight, in bass response.  This would not be an issue with chamber music.  Choral music can be surprisingly demanding on low-powered amplifiers if one tries to achieve realistic listening levels.  I noticed this with my parallel single-ended 2a3 amp playing large choral works--the music does not sound obviously distorted but it becomes slightly compressed (the music does not fully swell at peak volume levels).  Still, I am not surprised that a 2a3 amp can do such music so well.  I love the clarity and low-level dynamics of 2a3 amps.