Ok then...I've spent the last month enjoying this amplifier immensely. Construction was a cinch for me. And it's absolutely gorgeous sitting on my desk (w/ no top cover )
I ordered 5 pairs of tubes from Beezar with my kit. 6J6A (Japan, UFO), 6J6W (RCA, Mid Sq), 5844 (GE), 5964 (GE, Top Halo), and the E90CC (Telefunken). I just read through the entirety of this thread and I'm surprised with how well my own impressions of the different devices match with others'. Specifically TomB's post back on page 5. From my own notes:
'Phones: Senn HD600, Ety ER4S
D/A: AMB gamma2
Other amplification: AMB CKKIII
- Definitely the most dynamic tube of the bunch. Can swing high and low without compression in either direction
- Guitars are very engaging without being overly aggressive
- Very top end is a bit less present, can seem dull with certain instruments
- Instruments have a great fluid quality, but vocals seem to be lacking the last bit of clarity I'm used to
- Soundstage is well differentiated but not what I would consider "expansive"
- Very natural and organic timbre with things like hand claps, also more 3D spatially
- Comments: Very good. Easy to listen to and engaging. Things are looking good for this amp.
- Kinda boring sounding
- Less detailed, less fluid
- Bit grainy?
- Comments: Not impressed, what I would consider a downgrade from the 6J6A. TomB mentioned this one had a "exaggerated midrange", but I hear it just as poor sounding and lacking extension in both directions. This tube kinda sounds like what the others tubes sound like when they're not warmed up yet. I keep waiting for this tube to kick into gear, but it still sounds unrefined regardless. Didn't end up spending much time with this little guy.
- More similar to 6J6A than 5844
- More spacious and longer decay than 6J6
- Bit softer and less dynamic than 6J6
- I feel the bass on the 6J6 is more dynamic, solid, and better differentiated (in terms of pitch)
- Comments: A valid sidegrade to the 6J6A I suppose. While it ups the fluidity of the amp, it does take away a certain level of microdetail and sharpness in return for a more diffuse presentation. I spent a lot less time with the 5964 than the 6J6A, which says something I guess
- Oh snap! Leagues different than any I've tried so far. More forward presentation and more microdetail!
- This tube does a better job of letting the music portray it's own character rather than impart its own. It simply lets the pacing/atmosphere/emotion through better. I know that sounds like BS and you're probably rolling your eyes, but that's just the best way I can put it. You could say that this device is less colored than the others in a sense.
- More analytical with regard to electric guitars (6J6A preferred to be fluid)
- This device seems like it's faster at tracking the input signal and recovering information in the treble. Even compared to solid-state amps
- Comments: This tube is definitely on a different level compared to its smaller brethren, as TomB said. It takes the technicalities of this amp up a few notches. You could say it's a bit leaner sounding in the bass and mids (than the 6J6A), but it's not really brighter or anything. Meaning, it's not increasing gross detail by boosting the treble, it's just inherently more detailed it's own. The only concrete drawback of this device would be that I feel it renders a slightly artificial texture compared to the 6J6A. This is outside of the lean-ness or increased detail, it's just that instruments sound less organic and natural in terms of texture (not timbre, if that makes any sense). A small niggle that I noticed.
Overall, this amp holds its own against my CKK. It is a touch warmer than the CKK throughout the the spectrum (regardless of tube choice) and has less top-end presense, but this is definitely not an uber-tubey, syrupy, drown-in-warmth sort of valve amp. It's accurate and balanced, while delivering big images and digging deep into the music. It has absolutely zero harshness in itself, but will render it if it's on the recording. At this point, the E90CC's get most of my listening time, but I'll put in the 6J6A's if I want to rock out to some metal and crank the volume.
I have yet to try the 6J6W but I'd suspect them to be fairly similar to the 6J6A's. I also have a pair of Jantzen CrossCaps on the way so we'll see if those make any tangible difference for me. Might also try the Mundorfs or ClarityCaps eventually.
Big thanks to TomB and Doug for making this amp available!