Luxman SQ-N150 Review (Tube Amplifier)

[telemike]

Lookslike Klipcsch would be a good match with this

 

[ObjectiveSubjectivist]

Hmm transistor input stage but output a tube?
Kinda strange decision.

 

[wwenze]

Hmm transistor input stage but output a tube?
Kinda strange decision.

Maybe nonlinearity caused by output impedance / current draw sounds different from those caused by voltage slew

 

[Bear123]

Every now and then I run across a man who insists on cutting his lawn with a manual push reel lawn mower. They can be kind of righteous about it. So be it.
And there is that group that likes to shoot black powder old timey rifles. These Luxman integrateds are popular with the Amish. You see them advertised in Amish Ways Magazine

Yes but a big difference is that they don't pay $3,295 for the crappy manual mower while exclaiming how much better it performs

 

[Ralf Stocker]

US$3,295. Such a waste.

 

[capitanharlock]

US$3,295. Such a waste.

It depends: if you think to couple it to low efficiency speakers, then it's a waste.
If you use it with a pair of very high efficiency (horn?) speakers, it could work well.
Of course you can't have the same measures of a transistor amp with high counter-reaction (hope the English translation is correct), but you need to know if the distortion and noise of this amp at its normal power rate is audible or not.

 

[Koeitje]

Lookslike Klipcsch would be a good match with this

Depends, I don't trust all their sensitivity numbers...

 

[Vict0r]

It hurts my heart to vote "poor" on this beautiful... object? But considering its asking price vs performance, it's basically an expensive paper weight. Then again, so is a Fabergé egg, and those sell too. I don't know. Next!!

 

[DSJR]

Can we re-introduce the simulated speaker crossover please with amps like this? Stereophile do it and it's a real rogues gallery, with PrimaLuna being amongst the worst of the lot (HF ringing as well in one I recall).

This thing is an effects box basically and I don't think it's safe either, with the input control on top next to the valves. Luxman do some competent solid state integrated amps starting at this kind of price (not as elaborate as the larger models but gorgeous nonetheless).

Mind you, others at this price and higher were making far worse performing power amps back in my day with distortions in th e-30dB region and little more than the mid -40's in the midrange...

 

[Bob from Florida]

This is a review and detailed measurements of the Luxman SQ-N150 hybrid integrated amplifier with phono stage. It is on kind loan from a member and costs US $3,295.
View attachment 212863
Can you say pretty? I knew you could! Love the elegant front panel with VU meter. Nice set of balance and tone controls are provided as well:

View attachment 212864
As you can see, power amplification is provided through ECC83 triode drivers going to EL84 power tubes. Amplifier is conservatively designed and is rate at just 10+10 watts into 6 ohms. I like the look without the cage but here it is with:

View attachment 212865

Not much exciting in the back other than modern, beefy speaker terminals than that of vintage tube amplifiers:
View attachment 212866

The package is smaller than one imagines but weighs a hefty 27 pounds. Notice the AC terminal doesn't have earth ground and unit is double insulated. In testing I found no effect from earthing the unit or not.

Front-end and pre-amps are solid state:

View attachment 212868

Luxman SQ-N150 Amplifier Measurements
When I picked 5 watts as my standard for measuring amplifiers, it was usually a fraction of the amplifier power but here it is nearly half the available power! So relatively speaker, distortion plays a much strong role than it would otherwise:
View attachment 212867

The high second and third harmonics set the stage as far as SINAD (due to push-pull design) but I wish there was not so much power supply noise. Sadly the amplifier takes up the ranking of second worst amplifier I have ever measured as far as distortion+noise:
View attachment 212869

Those power supply spikes set the lower bound for dynamic range:
View attachment 212870

It is not too bad but you likely will use very sensitive speakers with this low power amplifier so the numbers may manifest themselves more than they usually do.

Frequency response is extended but shows a kink indicating some kind of filter:
View attachment 212871

Crosstalk does not follow the usual curve indicating some sort of resistive (?) element between the two channels:
View attachment 212872

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

Multitone which is supposed to resemble "music" with its 32 tone, shows strong level of "grass" (intermodulation distortion):
View attachment 212873

Hard to make a case that you are hearing more detail when so much is masked at this power level.

I don't have a 6 ohm load so used my usual 4 and 8 ohm loads for power testing:
View attachment 212874

View attachment 212875


View attachment 212876

Luxman SQ-N150 Phono Stage Measurements
The amplifier noise and distortion dwarfs the phono stage so I only checked its frequency response:
View attachment 212877

So very good on this critical measurement.

Luxman SQ-N150 Headphone Measurements
For same reason as above, I just made a power measurement:
View attachment 212878

Seems usable from power availability point of view but noise and distortion are quite high. Company specifies 16 ohm output impedance and wisely recommends against using low impedance headphones for good reason:

View attachment 212879

The headphone amplifier is simply connected to the amplifier output using the aforementioned resistor which eats up all the power. It will also change the frequency response of your headphone if it is not flat. So best to be avoided.

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.

The volume control had to be kept below 12:00 o'clock. By 1:00 o'clock distortion would start to set in and sound would start to get grungy and rough. Past 2:00 o'clock it would be rather obvious and beyond that, unusable. There was usable volume with me sitting 5 feet from the single speaker. With two speakers you could double that but it is still not enough power for me with this speaker. If an audio reviewer can't hear this level of distortion, they should give up testing audio gear. Sadly none of the reviews I read made a remark about the distortion.

It is the classic case of paying a lot more and getting a lot less fidelity and enjoyment.

Conclusions
The high level picture here is very clear: wonderful looking, and presumably well built amplifier. The problem is using tube technology and producing so little power. I see no advantage to it, euphonically or otherwise. But it is possible for some people the bass impact is a positive. But at what cost? So much spent with so little dynamic capability due to lack of power.

Needless to say I can't recommend the Luxman SQ-N150.

------------
As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

Interesting results from Luxman, especially contrasted against my solid state Luxman - ux507ii.
If we take the schematic as accurate a couple of things stand out. The use of solid state on the input takes care of the phono stage and supports the tone controls. The output stage, as shown, is Pentode operation with adjustable fixed bias. Only one pot for both tubes which means your output tubes need to be well matched to cancel power supply noise in the output stage. I did not see a bias adjustment pot in the pics, so likely internal which makes it inconvenient to get the bias right for matched tubes. Pentode operation needs more tubes in parallel or sufficient feedback to get low enough output impedance to have a decent damping factor. McIntosh and Quicksilver Audio used the Unity-Coupled output stage to solve for lower output impedance. Ultralinear output would help when only using 2 tubes in push pull with better control of the bass. Somewhat puzzling that Luxman would not do better.

 

[raindance]

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.

In ultralinear mode with manual bias, yes. However 10 watts per channel is exactly what I'd expect from a self or cathode biased design running UL.

 

[FrantzM]

Hi

Let's not bend backwards to try to justify what speakers this piece of sh##!@ , sorry, audio jewelry, would work with. This is an overpriced, poorly performing amplifier. One can spend 1/10 of the price and get similar performances. e.g. this Nobsound amplifier

or many others... Come to think of it , I might ....... Nah!!

What is really appalling is that, there are in the HEA (High End Audio) countless worse exemples of amplifiers similar to this Luxman, at multiple times the price. Those-who-believe-their-ears-and-their-gurus/reviewers, would actually feel lucky to have this Luxman, at this price !!!!!; serious, and this reinforces that false notion so dear to the High End Audio Industry, that high quality audio reproduction can only be achieved with large amount of money. Thank God there is ASR and its effect is being felt throughout the Hi-Fi industry and provoking some tremors in the HEA. Now we all know and have been proven that, at the price of this POC (Piece Of Crap, I am nice), one can build a complete good sounding system....

Keep it up ASR.


Peace.

 

[anphex]

Kudos to the members who ship gear worth thousands for testing.

 

[nyxnyxnyx]

Hi

Let's not bend backwards to try to justify what speakers this piece of sh##!@ , sorry, audio jewelry, would work with. This is an overpriced, poorly performing amplifier. One can spend 1/10 of the price and get similar performances. e.g. this Nobsound amplifier

For that price and to have many features and to look like that I think many of us won't mind if it measures horribly. My concern about brands like Nobsound is their business used to be 'unclear' and 'misleading' sometimes, not sure about now but I hope they got better.

 

[tomtoo]

Kudos to the members who ship gear worth thousands for testing.

Especally when your reward is a feeling like kicked in the balls.

 

[anmpr1]

Hey, those lawn mowers are great for small city lots. I used one for years until a good battery-powered mower came my way. Way less of a pain than a gas mower, and way less garage space too.

Every now and then I run across a man who insists on cutting his lawn with a manual push reel lawn mower. They can be kind of righteous about it.

Here's the thing: unlike a tube amp which will never give you better specs than you'll get with SS, a multi-blade rotary mower will offer a much better cut than you'll get from a spinning blade. Probably not a push one, but gasoline powered for sure. The downside is, like a tube amp, initial cost is higher, and it will require more maintenance (blade sharpening).

I suggest that anyone with who can afford a low wattage Lux tube amp (and the associated horn loudspeaker), consider a Swardman Edwin 2.1 for lawn upkeep. Both will offer satisfaction--one subjectively and the other objectively. And while your neighbor might scratch his head after finding out what you spent on your hi-fi given what you got, he will definitely admire your landscape.

 

[anmpr1]

Hmm transistor input stage but output a tube?
Kinda strange decision.

You encounter that occasionally, but the other way around is more common. When 'hybrids' became a big thing (or at least when I remember them becoming popular) you had designs like those from George Kaye (NYAL) and Michael Elliot (Counterpoint). I believe those featured tube input stages with MOSFETs doing the heavy lifting.

The latest and greatest Bascom King amp is like that. However, with this topology you don't get the 'look at this' WOW factor, because the tubes are generally hidden away, often not sticking out from the top of the chassis. People like to see tubes sticking out of the top of the chassis.

 

[anmpr1]

Depends, I don't trust all their sensitivity numbers...

You always need independent confirmation. This little amp will drive a Klipschorn fine. The La Scala is going to be a bit less sensitive. From Richard Heyser's teardown:

 

[anmpr1]

Especally when your reward is a feeling like kicked in the balls.

Who would 'feel' that way? If one enjoyed the amplifier to satisfaction on Monday, read about its bench performance on Tuesday, what would they think on Wednesday? Will the Goddess of Disenchantment visit them? I mean, nothing has changed with their amplifier.

I am often perplexed when folks live with an item, like it, but then read a review and change their mind about it. What is anyone really thinking when they buy something like this? That it will have great specs on the analyzer? Why would anyone think that?

I agree that the owner should be commended for sending it in, for review.

 

[Godataloss]

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

I have an Dynaco ST 35 that makes 17 wpc pp with EL84. I'm surprised the Luxman has such terrible numbers dialed back that far.