Thoughts on Tube vs SS amplification for Sony SS AR1s

No doubt that damping factor (DF) is an important variable that affects and influences the performance of an amplifier and speaker pairing. I have to imagine there are other factors at play as well. By every reasonable and trusted test bench metric the Accuphase should ’clearly’ be a far more compatible  matching amplifier for these Sony speakers than the Luxman.

Assuming that the Accuphase isn’t defective in some manner, one has to ask what’s going on? How is it possible/explainable the tubed 14 watt (Into 4 ohms) Luxman so convincingly sounds better driving the current demanding difficult impedance Sony than the (Much) higher power/current Accuphase transistor amplifier?

Can it all be written off as merely subjective preference? If so it’s fascinating that this can occur in light of test bench measurements that would suggest a far different outcome. One has to ponder that there are things listeners can clearly hear that (At least for now) aren’t being measured or maybe can’t be measured.
Charles

Hi everyone
Thanks for the follow up comments~

@tomcy6 , I know exactly what you mean and I went looking for anything simple that would explain the lack of energy in the highs (like tone controls being engaged, etc).  There was nothing seemingly out of place, and if I didn't have the Luxman to compare it with, I would likely be extremely pleased, because the low end definitely had good authority and clarity. I know I'm not describing it well, but its like the Accuphase is putting all its attention into the low and low-mid end of the spectrum, and not bringing out a ton of character/clarity in the upper ranges - there is a track we were listening to with just male vocals and a guitar: with the Luxman he's in the room with you, with the Accuphase it sounds like he's trapped in the speakers.

@petg, thanks for the recommendations (those Sony amps would be amazing to come across)

@charles1dad yeah, I just wanted to update the group because I too found it really interesting. I'm by no means a bonefied expert in any of this, but just to provide some context for the other references I've had, I've spent time with really excellent amps from Luxman and Accuphase (obviously), Hegel, Sony, Yamaha, Vincent, Technics, JP-market Denon, and a few others. The Accuphase isn't in the top 3 for me - its also possible that I had such high expectations I set myself up for some disappointment, but it is interesting that you can't tell from just the numbers how things will sound. The Luxman has stayed at the top of the list for musicality (for me). One thing I wonder if if the LX380 is sounding so good on these SS AR1s, would a higher power tube amp from Luxman also perform well? If I get a chance to find out, I'll let you know~

Pass has sounded awesome on the AR1s when I’ve heard them at shows together. Now, you can’t get the VFET amps but I’m sure X series would work well. 

I like to use the Tron soundtrack by Daft Punk at 90dbs to see how much power amps really have. Most get flattened by it. 

One has to ponder that there are things listeners can clearly hear that (At least for now) aren’t being measured or maybe can’t be measured.

In this case I don't think so.  The Luxman is able to behave as a proper voltage source within certain limits, and the 8 ohm power they are getting out of it suggests that it might be set up so that it can put out a bit more power into lower impedances. This is done by simply 'light loading' the tubes in the output section by setting the primary winding of the output transformer to a bit higher impedance. On top of that I'm pretty sure that Luxman did their homework on the output transformer and has something that is spec'ed decently in there. This all does not seem that mysterious to me- I've seen it before.

atmasphere,
I understand your point and the significant importance of the output transformer. In threads discussing tube amplifiers I consistently advocate the undeniable need for high quality transformers if one is seeking excellent sound quality from tube powered amplifiers. 

My point is if you look at the Sony SS AR1 speaker measurements they are as George and others have rightly noted, a ’challenging ’ speaker load given its impedance curve and phase angle characteristics. Armed with this knowledge the last thing you’d recommend is a 14 watt tube amplifier.

The low watt tube Luxman is doing something obviously good that can’t be surmised from assessing its measurements or those of the Sony. So again, how is this gross mismatch (Via documented measurements for both products) able to produce such high quality sound? Something is occurring that isn’t accounted for with supporting test bench numbers.
Charles