Luxman SQ-N150 Review (Tube Amplifier)

[VintageFlanker]

Crosstalk does not follow the usual curve indicating some sort of resistive (?) element between the two channels:

Normally the issue is capacitive which causes the two reference lines you see.

That is definitely uncommon. Thanks, I'm glad to finally have an explanation after measuring the same behaviour for the Audio-GD NFB-11...

Stereo crosstalk​

Right​	Left​
Crosstalk at 100 Hz, dB	-73​	-73​
Crosstalk at 1000 Hz, dB	-73​	-73​
Crosstalk at 10000 Hz, dB	-73​	-73​

 

[soccermommy]

This is why I only keep tubes in the preamp section.

 

[DMill]

Good review. Pretty meh on that amp. I lIke my Cary SLI80 sig. way more. I’m sure It doesn’t measure great either but at least I can get 40 watts triode and 80w ultra linear out of it. And it has subwoofer outs. Don’t know why they went solid state pre. Wouldnt a tube lover want all tubes? Nice meters I guess and a phono stage. Disheartening for us who still like to dabble with valves in a system.

 

[levimax]

I don't think this is the plausible explanation. They probably designed this based on what worked on some key groups that like "pleasant" harmonic distortions paired with highly sensitive speakers. I'd never buy it myself, but there's a market there, and having listened to such systems, they work with some music in a different but not unpleasing way... Chopin piano, string concertos, classical guitar... in a different way like I said, but I have enjoyed it (when it's not my system :-D).

Do you really think that this amp with all the PS noise and distortion would sound "better" to anyone than a competently designed hybrid tube amp which should be able to achieve a SINAD of 70 or more quite easily? The only tube amps I have used are "vintage" so they perform much better than modern tube amps like this. To me I can't tell the difference between a decent tube amp and a SS amp.

 

[MacCali]

What is the best measuring tube amp? pure tube.

Wonder how a prima luna will do and if that dude at Upscale audio Kevin is just lit or a vapor ware salesman o.o

 

[pablolie]

Do you really think that this amp with all the PS noise and distortion would sound "better" to anyone than a competently designed hybrid tube amp which should be able to achieve a SINAD of 70 or more quite easily? The only tube amps I have used are "vintage" so they perform much better than modern tube amps like this. To me I can't tell the difference between a decent tube amp and a SS amp.

I clearly stated - not my cup of coffee. This or "hybrid" either. Nope thanks. I was just providing a theory based on some systems I have heard - not mine nor my preference. I voted "poor".

But Luxman knows how to engineer great amps. Too cumbersome and big given my preference these days though. Which is what makes me think this in engineered to the preferences to a very targeted audience with certain preferences you or I don't get.

 

[MacCali]

I clearly stated - not my cup of coffee. This or "hybrid" either. Nope thanks. I was just providing a theory based on some systems I have heard - not mine nor my preference. I voted "poor".

It really varies person to person. I have heard some really good tube amps, or so you would suppose/assume based on the price tag. Not really a good factor to consider when it comes to performance. But I do prefer the warmer and darker signature or however you wish to describe it.

That's why I think class A has been the perfect balance of both worlds Edit: for me

 

[levimax]

What is the best measuring tube amp? pure tube.

@SIY has designed and knows of some very good performing tube amps... maybe he can answer

 

[Bill Brown]

Frequency response is extended but shows a kink indicating some kind of filter:

Huh? I suspect that you are seeing the natural roll-off the amplifier then a resonance (likely the transformer) at 80-100 khz. Trying running a 10 khz square wave through it and you will likely see the ringing. The peak isn't huge, so I suspect it will be reasonably damped. O/W, the bandwidth suggests a good output transformer.

Bill

 

[pablolie]

@ SIY has designed and knows of some very good performing tube amps... maybe he can answer

I haven't ever seen or heard about a tube amp that doesn't have serious harmonics going on - whether you see it as a virtue or a weakness is up to any consumer to decide. Certainly the perfectly accurate match of input to amplified output signal is neither the strength or the design goal of a tube amplifier.

But this thread shouldn't be about our opinion of tube vs class A or D. We seemingly all agree this amp doesn't measure that great, my only point is that Luxman designed it to cover that exact market niche.

PS: If I preferred over-engineered, large, heavy and classic integrated amps I'd kept my Accuphase E306v. To me *personally* the time of these amps passed. They are exquisitely designed mechanically, but there are more efficient ways to get stuff done these days without measurable SQ penalties(if you prioritize accuracy).

 

[amirm]

Huh? I suspect that you are seeing the natural roll-off the amplifier then a resonance (likely the transformer) at 80-100 khz. Trying running a 10 khz square wave through it and you will likely see the ringing. The peak isn't huge, so I suspect it will be reasonably damped. O/W, the bandwidth suggests a good output transformer.

Bill

Yeh my mind was not there as far as this being transformer coupled. Thanks for the correction.

 

[LTig]

Luxman SQ-N150 Listening Tests
My lab speaker is an infinity R253 which has a sensitivity of 87 dB. I connected it to the SQ-N150 and started to listen. I had to immediately acknowledge the lack of power as the volume control not only maxed out but there was so much distortion as to cause crackling noise. I backed off to moderate listening level and the sound was OK but I noticed boominess in the lows as if you have more room modes than you do. To confirm, I switched to Topping PA5 amplifier on my bench and boominess was gone. Likely the harmonic distortion of the amplifier is hitting on more room modes causing extra bass/boominess. I can see if your speakers/setup lacks bass that you experience a bit more of it.

I rather think the boominess is caused by too high output impedance of the power stage.

 

[SIY]

The high second tells me that either the output stage is pretty unbalanced or the loading on the input 12AX7 is too low. Or both. The 10 dB difference between channels on 2nd suggests the former is a major factor.

My PP EL84 amp is in the 0.03-0.05% THD range at this power, and that was not optimized for lowest measured distortion. Lux can do better in this form factor and price point.

Literally going in I said "2 EL84s per channel? No way that's doing more than 10 watts."

15 watts is not uncommon, and using the hack I learned from Roger Modjeski, 25-40 watts is easily obtained.

 

[MakeMineVinyl]

EL-84s in push pull should be more like 15 watts with less distortion. Something is not optimized somewhere. I'm not saying this amp should be super clean, but I'd imagine it could be cleaner than it is.

 

[SKBubba]

Bet it sounds great playing Dark Side of the Moon on Klipschorns in the, uh, "right" frame of mind.

 

[Mojo Warrior]

This review of a competently designed and built tube amp clearly demonstrates why the electronics industry overwhelmingly embraced transistor technology, because it was far superior to vacuum tubes.

So much for nostalgia and so called "golden ears audiophiles"..

 

[fuzzychaos]

Not sure if ASR has ever tested the Luxman L505ux ii, but I loved it when I owned one. Would love to know how it measured.

 

[digicidal]

If these weren't so expensive, even in the used market, I'd love to gut one and convert it into a simple in-line VU meter display with some LED's under-lighting the tubes. Then in the body cavity of the chassis, put the guts of some of the "cheap and ugly but great" Chinese electronics hidden inside. Best of both worlds IMO.

 

[Vini darko]

Transistor front end tube power out. Surly this is the wrong way round.

 

[AndreaT]

What is the best measuring tube amp? pure tube.

Wonder how a prima luna will do and if that dude at Upscale audio Kevin is just lit or a vapor ware salesman o.o

McIntosh 225