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Luxman SQ-N150 Review (Tube Amplifier)

Rate this amplifier:

  • 1. Poor (headless panther)

    Votes: 211 76.7%
  • 2. Not terrible (postman panther)

    Votes: 44 16.0%
  • 3. Fine (happy panther)

    Votes: 8 2.9%
  • 4. Great (golfing panther)

    Votes: 12 4.4%

  • Total voters
    275

amirm

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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.
Luxman SQ-N150 Review Valve Integrated crosstalk Tube Amplifier.jpg

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:

Luxman SQ-N150 Review EL84 ECC83 Valve Integrated crosstalk Tube Amplifier.jpg

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:

Luxman SQ-N150 Review EL84 ECC83 cage Valve Integrated crosstalk Tube Amplifier.jpg


Not much exciting in the back other than modern, beefy speaker terminals than that of vintage tube amplifiers:
Luxman SQ-N150 Review Back Panel Phono Headphone Amplifier Integrated crosstalk Tube Amplifier.jpg


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:

Luxman SQ-N150 Review Block Diagram hybrid Tube Amplifier.png


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:
Luxman SQ-N150 Measurements Integrated Tube Amplifier.png


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:
Best tube amplifier review 2022.png


Those power supply spikes set the lower bound for dynamic range:
Luxman SQ-N150 Measurements SNR hybrid Integrated Tube Amplifier.png


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:
Luxman SQ-N150 Measurements Frequency Response Integrated Tube Amplifier.png


Crosstalk does not follow the usual curve indicating some sort of resistive (?) element between the two channels:
Luxman SQ-N150 Measurements Integrated crosstalk Tube Amplifier.png


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):
Luxman SQ-N150 Measurements Multitone Integrated Tube Amplifier.png


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:
Luxman SQ-N150 Measurements Power into 8 ohm Integrated Tube Amplifier.png


Luxman SQ-N150 Measurements Power into 4 ohm Integrated Tube Amplifier.png



Luxman SQ-N150 Measurements Max and Peak Power into 4 ohm Integrated Tube Amplifier.png


Edit: forgot to post the different frequency sweeps:

Luxman SQ-N150 Measurements Distortion vs Frequency vs Power into 4 ohm Integrated Tube Amplif...png


Luxman SQ-N150 Phono Stage Measurements
The amplifier noise and distortion dwarfs the phono stage so I only checked its frequency response:
Luxman SQ-N150 Measurements Phono Integrated Tube Amplifier.png


So very good on this critical measurement.

Luxman SQ-N150 Headphone Measurements
For same reason as above, I just made a power measurement:
Luxman SQ-N150 Measurements Headphone out 300 ohm Integrated Tube Amplifier.png


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:

Luxman SQ-N150 Measurements Headphone out 32 ohm Integrated Tube Amplifier.png


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.

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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/
 

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NiagaraPete

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I'm crushed, though I knew I was going to be. I'm sure this is beautifully built but sadly even Luxman can't fix tubes.
 

juliangst

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I gave it the 'not terrible' rating because it's not broken. It's just how most tube amps perform and If someone wants to spend money on this I won't stop him.
Needless to say that objective performance is absolutly terrible and even 100€ amps like the new SMSL DA-6 give units like this a run for it's money.
 

NiagaraPete

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I gave it the 'not terrible' rating because it's not broken. It's just how most tube amps perform and If someone wants to spend money on this I won't stop him.
Needless to say that objective performance is absolutly terrible and even 100€ amps like the new SMSL DA-6 give units like this a run for it's money.
I can't be that kind and I love Lux.
 

tktran303

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Amir,

Thanks for your review. Now you know all about "synergy" and "careful system matching" that the experienced audio enthusiasts were doing in the 20thC.

An Infinity R253 with 87dB/2.83V connected to an amplifier that maxes out a just above 10W is dynamically constrained... and sounds wooly, thick. It doesn't matter whether it's this Luxman or a Tripath TA2020 based amp.

Now connect a 97dB/2.83V speaker and this amp performs like a 120W power amplifier!

With glorious overtones and the special effects, not unlike a musical instrument (pre)amplifier- it can make for an experience like no other...

Some people like this. And I get that. Musical production or re-production.
 
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EchoChamber

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It would be interesting if you could get your hands on an OTL amp from Transcendent Sound. Bruce’s designs promised greater transparency for tube circuits. But I think all tube circuits are doomed by the limitations of that technology. Subjectively, when I was into tubes, the OTL amp I had from Transcendent Audio (can’t remember the name, not a kit) paired with their pre amp was the most clean tube sound I ever got in my system.
 

sofrep811

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I had a Cayin with the same specs and always felt it was just blah compared to my solid states. It was my final journey into tubes.

Gorgeous Japanese amplifier...just beautiful. But what I pretty much expected when you'd review.

Definitely HiFi porn pics.
 

uwotm8

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I have a little experience with a garage/garbage-made ultra low power (2-3W AFAIR) single-ended tube amp and despite being technically "bad" and unable to play loud etc etc I found it's sound joyful for rather quiet and casual non-heavy genres listening. That said, I didn't get much distortion of it on my background to comfort volume levels, so overall impressions were positive with typical speakers and THEN once I hooked it to 12" fullranges and that was definitely funnier, again, YES, that's LOW-FI but who cares?
 

Doodski

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I have a little experience with a garage/garbage-made ultra low power (2-3W AFAIR) single-ended tube amp and despite being technically "bad" and unable to play loud etc etc I found it's sound joyful for rather quiet and casual non-heavy genres listening. That said, I didn't get much distortion of it on my background to comfort volume levels, so overall impressions were positive with typical speakers and THEN once I hooked it to 12" fullranges and that was definitely funnier, again, YES, that's LOW-FI but who cares?
I for the sake of just doing it ran a minty vintage Sherwood S-5500 II Integrated Tube Amp with a pair of East German RFT BR-26 speakers. Those speakers are very bright sounding and compensated for the soft tube sound. I liked having the system around for the sake of collecting a antique but eventually I lost interest and went for something a lot bigger and more powerful.
 

Doodski

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BTW-- How much does it weight and was shipping a PITA?
"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."
 

pablolie

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I am surprised that this thing gets smoked in every way by the 60 year old rusty Dynaco ST-70 I sent in.... either they don't know how to design a tube amp or they don't care about performance or maybe both.
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).
 
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