Luxman SQ-N150 Review (Tube Amplifier)

[MAB]

I had forgotten that Stereophile reviewed this amp and JA measured it. Please note that I am not arguing for this amp's ultimate value to anyone, and I wouldn't buy it (speakers aren't efficient enough), though I have used and enjoyed tube amps in the past (currently use a Benchmark ABH2), but there are many nuances involved that make simplistic statements like "piece of SH#*" and "money grab" not completely applicable. Also, if I were gifted one I would listen and enjoy the heck out of it, even if it ended up as part-time only.

JA's measurements can be trusted, I feel (I know many prefer Amir's Klippel measurements to JA's, I am thinking of source components/amps in this instance). In this case, his experience shines through. All of Amir's measurements could be calculated from JA's and JA's provide the needed additional information to add the nuance described above and a better understanding of what is going on with the amp in actual use. This doesn't even include the squarewave measurement with accompanying explanation I mentioned earlier.

"Look at how early THD+N starts to rise with output power too" was written above

I actually look at the graph and see likely inaudible distortion up to at least 1 watt. Ok, not terribly impressive, but.....

Klipsch sensitivity figures were doubted earlier. That is justified. But, JA also measured the Klipsch the reviewer used and found that it's sensitivity was 95.2 db/2.83V. Not considering music's crest factor for a moment, when the reviewer was listening at 95db, THD was 0.04%(not accounting for distance, but also not counting that two speakers playing at 95db = 98db). What is your typical in-room listening level? Mine certainly isn't 95 db (again, excluding transients). Amir's might be, seems he listens loud!

Look at the above graph in terms of the following (and the corresponding numbers for a more popular/typical-here speaker of say 86 db/2.83V- and many of those are actually nominally 4 ohms, so their true sensitivity for 1 watt is 83db). Think of your typical listening level:

83 db output for the Klipsch, (86 db for a pair) requires 62.5 milliwatts. Typical speaker for 83 db requires 500 milliwatts (62.5 milliwatts into the typical speaker yields 76 db)
89 db output from the Klipsch requires 250 mW, the typical speaker 2 watts
95 db output from the Klipsch requires 1 W, clearly, the typical speaker 8 watts. (then 98db= 2 and 16, 101db= 4 and 32, 104db= 8 and 64, etc. etc.)
98 db = 2 and 16 W respectively

So then you say at 1-2 watts the Luxman THD is approaching audibility. But it has been shown over and over again that distortion spectra are vital when determining audibility (total THD, measured for ages is incomplete at least, more likely misleading). 2nd and 3rd are very difficult to perceive until levels are fairly high (especially what y'all are used to seeing), where higher orders are much more audible. Also, distortion in the low frequencies is very hard to detect and should be measured. JA also helps us with this. First the second feature:

The blue and red traces are into an 8 ohm load at 2.83V, or 98 db from a pair of the Klipsch. Increasing distortions in the low frequencies (transformer), but less audible, but pretty darn low through the most critical (ear's most sensitive) range.

Now the harmonic spectra of a 50 Hz (see above) signal at 3 watts (102.5 db from the pair of Klipsch):

A 1 khz wave being produced at the same 102.5 db:

Someone mentioned (I don't know how to multiquote....) "The boominess that you mentioned could very well have been caused by the typical Ohms-law interaction between the speaker's complex impedance curve and the amplifier's output source impedance. I did not see that you measured the amp's output driving impedance, and I think you should. With tube equipment this becomes especially important as it has a major impact on sound. Some tube amps have flat FR when driving a resistive load but drive a speaker and I have seen ± 6 dB variation in output! You're gonna hear that! Amir, you're an engineer, you should know this. Please, measure the output impedance of this amp- it's simple enough to do."

Certainly I agree- not about the marked possible variations with this particular amp (not the case), but the need for additional measurements. Impedance relationships are almost never addressed in the measurements here. How can you measure a passive volume controller out of the low output impedance and into the high input impedance of the Audio Precision, show the frequency response, and think you are done?? It is presented authoritatively, but is almost meaningless. One must factor in the two impedances in their system to know what frequency response they will get. It is simply ohm's law.

And re. the quote, JA has given us these measurements- output impedance and response into a simulated load. Again, it is ohm's law (look at the impedance curve of your speakers and that will be the trend in FR with increasing output Z).

"The Luxman amplifier's output transformers have a single tap, which is optimized for a 6 ohm load. The output impedance from this tap was relatively low for a tube design at 0.7 ohm at 20Hz and 1kHz, rising to 0.83 ohm at 20kHz. As a result, the modulation of the Luxman's frequency response with our standard simulated loudspeaker was a modest ±0.5dB (fig.1, gray trace)."

Luxman SQ-N150 integrated amplifier Measurements

Sidebar 3: Measurements Nostalgia struck when I unpacked the Luxman SQ-N150 and hoisted it onto the test bench. This compact integrated amplifier uses a pair of EL84 tubes for each channel's outputI used to own a sweet-sounding Vox AC30 guitar amplifier back in the 1960s, which also used a...

www.stereophile.com

I like to read Amir's measurements, that's why I come here. In many cases there are good. But....nothing in this world is perfect, and he has some gaps. To look at something's SINAD without understanding the nuances and immediately rush to an absolute judgement (joining the bandwagon of increasingly dismissive derision) is simply not based on what is known, and frankly isn't that smart. After going through the above, is it possible that the Stereophile reviewer heard a transparent reproduction via the Klipschs'.

Bill

P.S. I hope I got all my db match correct!

Really interesting. I appreciate your perspective for sure.
But, I thought Luxman could do better on the things that Amir did measure.
And, I am under the impression that Luxman has done better in the past, but I may be mistaken.
As far as a first-Watt optimized design for enthusiasts with specific speakers, this seems sub-par. Maybe I am naïve to what should be expected here.

 

[ta240]

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

I liked my mower like that. Sharpening wasn't fun but it really wasn't that hard to use and I guess I could have got a self propelled mower and a gym membership instead
Plus, no messing with gas or recharging batteries and it took up a fraction of the space.

 

[Deleted member 34304]

Amir has his fun. But couldn't he have just left it at the poor measurement results?
Amir actually plugged a 10 watt amplifier into his poor efficiency speakers and then turned up the volume to his favorite volume?
Why does he do that?
Does he understand what he is doing or is he just trying to make fun of us?
I am not experienced when it comes to the right combination of speakers and amplifier.
But amir has absolutely no idea, or is he just kidding?
Do any of you give a damn and if amir does it is science?
Actually it's a shame and it makes everything audiosciencereview.com stands for completely ridiculous. Now those out there think it's an advertising portal for china-cheap stuff that just has to measure up well in the lab and doesn't care if after 13 months the volume control is faulty.
Gladly I leave you and log off here. Farewell you scientists...

Translated with www.DeepL.com/Translator (free version)

 

[SIY]

We can figure out a few interesting things about their implementation of a very old but solid topology. The overall gain is 27dB (or x23), so let’s remember that.

To take the output stage into clipping should require roughly 8V of drive to each EL84 grid. Clipping commences at 12W into 8R, which is 9.8V. Call it 10V for calculational ease. So that means 9.8/23 = about 0.5V in to clip. So input stage gain after feedback is effectively 8V/0.5 = 16 (24dB). Now, open loop, the very highest gain you’re going to get from a 12AX7 is maybe 80-90, and that only with a CCS load; more typically, you’re at 60 or so (36dB) because of the tube’s high plate resistance and limitations on the size of the plate resistor because of supply voltage. And the tube will not be running particularly linearly (a 12AX7 can be superbly linear in a circuit better designed to accommodate its peculiarities).

So since the output stage is not far off from unity gain (accounting for the output transformer), most of the open loop gain comes right here. Consequentially, there’s only 12dB of feedback available. And that why the distortion is not great. A high gain cascode or pentode is a much better choice for the voltage amp, or the 12AX7 can be run with a CCS plate load. In the former case, something like a 6AU6 can give you 200-ish (46dB) for gain, the 12AX7 100-ish (40dB) for gain, yielding feedback of 22dB and 16dB, respectively, which would very much help the amp’s performance. The optimized 12AX7, despite 6dB lower feedback, might give a better distortion performance because it starts out so linear.

I would also predict that the source impedance of this amp will be pretty high and get even higher in the top octave or two. Curiously, that’s not measured here despite the fact that it will likely have the greatest impact on sound…

 

[ta240]

Listening to a 10w tube amp, using low efficiency 87db Infinity loudspeakers is going to get the exact results Amir got: it sounds awful.

And it will do nothing to convince anyone that it isn't a good item to purchase because it will be dismissed as tested in a way that anyone that buys that amp would not do. No matter how much the mantra we hear is about educating people it often comes down to doing what will show the other side as being wrong.

My job is to stress test the devices I test. When you get to do what I do, you can take the side of manufacturers and baby the products in your testing....

You see it as taking the manufactures side; others may see it as using the item as it was designed to be used. It is great to throw the stress testing into the mix but most everything in the review is just preaching to the converted. Everyone else will just take it like a review of a Porsche Cayman that says "It was really crowded with 3 people and I had to leave the lumber I bought at Home Depot because it wouldn't fit."
I still wonder how the LGK would do with a subwoofer crossed at 120 and played at lower levels. I doubt it would be worth the price even then but it would be interesting to have the info.

 

[ta240]

Amir has his fun. But couldn't he have just left it at the poor measurement results?
Amir actually plugged a 10 watt amplifier into his poor efficiency speakers and then turned up the volume to his favorite volume?
Why does he do that?
Does he understand what he is doing or is he just trying to make fun of us?
I am not experienced when it comes to the right combination of speakers and amplifier.
But amir has absolutely no idea, or is he just kidding?
Do any of you give a damn and if amir does it is science?
Actually it's a shame and it makes everything audiosciencereview.com stands for completely ridiculous. Now those out there think it's an advertising portal for china-cheap stuff that just has to measure up well in the lab and doesn't care if after 13 months the volume control is faulty.
Gladly I leave you and log off here. Farewell you scientists...

Translated with www.DeepL.com/Translator (free version)

I don't know if it makes everything ridiculous but it is a tiny example of the modern world. Don't try to understand the other side; dismiss it, poke fun at it and gather the information that most makes it look wrong. Ironically, even if reviewed with the speakers and levels that an actual buyer of it might use it could still be said to be lacking for the price. Instead that gets buried in the 'why would anyone ever...." that is so common today.

I get the desire to listen to really clear music at higher volume levels. I also get that the cleaner the sound the less 'loud' it sounds. But I also understand that others enjoy listening at lower levels. Some of my most enjoyable listening happens when everyone else is asleep so the levels are low; I don't need to feel the music to 'feel' the music. My desktop listening level rarely goes over 65 db at 2' so what works for me in that situation would be far different than someone looking for 85+ in the same setting.

 

[Bill Brown]

Really interesting. I appreciate your perspective for sure.
But, I thought Luxman could do better on the things that Amir did measure.
And, I am under the impression that Luxman has done better in the past, but I may be mistaken.
As far as a first-Watt optimized design for enthusiasts with specific speakers, this seems sub-par. Maybe I am naïve to what should be expected here.

Thank you.

I understand your thinking in the second and third lines. Below you, SIY makes some excellent points re. fundamental design issues. Having read him and tons of other stuff on the tube forum of diyaudio.com for years and years, it isn't a design I would follow for a personal build (or purchase).

I do think it is reasonable for a first-watt optimized design (in a very high-sensitivity system), but again, not the one I would choose. I think there are better.

Bill

 

[Deleted member 34304]

Thanks ta240!
Right now I enjoy fine music although the house is already asleep. 4 watt amplifier. Where my hypex from apollon disappoint, even cheap tubes (pcl86) are better.
If someone now declares me crazy, although he himself transfers money to his church, then he should admit it.
Church has quite bad measurement results in this world.
Unfortunately, my other post was deleted.
But if we want to be taken seriously outside of audiosciencereview.com, then we must not wander around here like groupies. Please do not try a 10 watt amplifier on 87 dB speakers! Please, please ...

 

[DMill]

I don’t consider an 87db speaker that inefficient. Actually pretty average.

 

[MAB]

Thank you.

I understand your thinking in the second and third lines. Below you, SIY makes some excellent points re. fundamental design issues. Having read him and tons of other stuff on the tube forum of diyaudio.com for years and years, it isn't a design I would follow for a personal build (or purchase).

I do think it is reasonable for a first-watt optimized design (in a very high-sensitivity system), but again, not the one I would choose. I think there are better.

Bill

Got it. Very helpful. I appreciate the explanation from SIY.

 

[levimax]

I had forgotten that Stereophile reviewed this amp and JA measured it. Please note that I am not arguing for this amp's ultimate value to anyone, and I wouldn't buy it (speakers aren't efficient enough), though I have used and enjoyed tube amps in the past (currently use a Benchmark ABH2), but there are many nuances involved that make simplistic statements like "piece of SH#*" and "money grab" not completely applicable. Also, if I were gifted one I would listen and enjoy the heck out of it, even if it ended up as part-time only.

JA's measurements can be trusted, I feel (I know many prefer Amir's Klippel measurements to JA's, I am thinking of source components/amps in this instance). In this case, his experience shines through. All of Amir's measurements could be calculated from JA's and JA's provide the needed additional information to add the nuance described above and a better understanding of what is going on with the amp in actual use. This doesn't even include the squarewave measurement with accompanying explanation I mentioned earlier.

"Look at how early THD+N starts to rise with output power too" was written above

I actually look at the graph and see likely inaudible distortion up to at least 1 watt. Ok, not terribly impressive, but.....

Klipsch sensitivity figures were doubted earlier. That is justified. But, JA also measured the Klipsch the reviewer used and found that it's sensitivity was 95.2 db/2.83V. Not considering music's crest factor for a moment, when the reviewer was listening at 95db, THD was 0.04%(not accounting for distance, but also not counting that two speakers playing at 95db = 98db). What is your typical in-room listening level? Mine certainly isn't 95 db (again, excluding transients). Amir's might be, seems he listens loud!

Look at the above graph in terms of the following (and the corresponding numbers for a more popular/typical-here speaker of say 86 db/2.83V- and many of those are actually nominally 4 ohms, so their true sensitivity for 1 watt is 83db). Think of your typical listening level:

83 db output for the Klipsch, (86 db for a pair) requires 62.5 milliwatts. Typical speaker for 83 db requires 500 milliwatts (62.5 milliwatts into the typical speaker yields 76 db)
89 db output from the Klipsch requires 250 mW, the typical speaker 2 watts
95 db output from the Klipsch requires 1 W, clearly, the typical speaker 8 watts. (then 98db= 2 and 16, 101db= 4 and 32, 104db= 8 and 64, etc. etc.)
98 db = 2 and 16 W respectively

So then you say at 1-2 watts the Luxman THD is approaching audibility. But it has been shown over and over again that distortion spectra are vital when determining audibility (total THD, measured for ages is incomplete at least, more likely misleading). 2nd and 3rd are very difficult to perceive until levels are fairly high (especially what y'all are used to seeing), where higher orders are much more audible. Also, distortion in the low frequencies is very hard to detect and should be measured. JA also helps us with this. First the second feature:

The blue and red traces are into an 8 ohm load at 2.83V, or 98 db from a pair of the Klipsch. Increasing distortions in the low frequencies (transformer), but less audible, but pretty darn low through the most critical (ear's most sensitive) range.

Now the harmonic spectra of a 50 Hz (see above) signal at 3 watts (102.5 db from the pair of Klipsch):

A 1 khz wave being produced at the same 102.5 db:

Someone mentioned (I don't know how to multiquote....) "The boominess that you mentioned could very well have been caused by the typical Ohms-law interaction between the speaker's complex impedance curve and the amplifier's output source impedance. I did not see that you measured the amp's output driving impedance, and I think you should. With tube equipment this becomes especially important as it has a major impact on sound. Some tube amps have flat FR when driving a resistive load but drive a speaker and I have seen ± 6 dB variation in output! You're gonna hear that! Amir, you're an engineer, you should know this. Please, measure the output impedance of this amp- it's simple enough to do."

Certainly I agree- not about the marked possible variations with this particular amp (not the case), but the need for additional measurements. Impedance relationships are almost never addressed in the measurements here. How can you measure a passive volume controller out of the low output impedance and into the high input impedance of the Audio Precision, show the frequency response, and think you are done?? It is presented authoritatively, but is almost meaningless. One must factor in the two impedances in their system to know what frequency response they will get. It is simply ohm's law.

And re. the quote, JA has given us these measurements- output impedance and response into a simulated load. Again, it is ohm's law (look at the impedance curve of your speakers and that will be the trend in FR with increasing output Z).

"The Luxman amplifier's output transformers have a single tap, which is optimized for a 6 ohm load. The output impedance from this tap was relatively low for a tube design at 0.7 ohm at 20Hz and 1kHz, rising to 0.83 ohm at 20kHz. As a result, the modulation of the Luxman's frequency response with our standard simulated loudspeaker was a modest ±0.5dB (fig.1, gray trace)."

Luxman SQ-N150 integrated amplifier Measurements

Sidebar 3: Measurements Nostalgia struck when I unpacked the Luxman SQ-N150 and hoisted it onto the test bench. This compact integrated amplifier uses a pair of EL84 tubes for each channel's outputI used to own a sweet-sounding Vox AC30 guitar amplifier back in the 1960s, which also used a...

www.stereophile.com

I like to read Amir's measurements, that's why I come here. In many cases there are good. But....nothing in this world is perfect, and he has some gaps. To look at something's SINAD without understanding the nuances and immediately rush to an absolute judgement (joining the bandwagon of increasingly dismissive derision) is simply not based on what is known, and frankly isn't that smart. After going through the above, is it possible that the Stereophile reviewer heard a transparent reproduction via the Klipschs'.

Bill

P.S. I hope I got all my db match correct!

My issue with this amp is not that it will not sound fine with the right speakers but rather that a well known company with all the latest design tools comes up with an expensive design that underperforms (noise, distortion, power) by a very wide margin amps that are 60 or more years old using the same tubes. While OK for some applications it could be better and it wouldn't really cost any more except possibly for a little more testing and design work.

 

[amirm]

Does he understand what he is doing or is he just trying to make fun of us?

Do you understand what I am doing? Because it seems not.

I have explained this three times. So here is the fourth time. I tested with the most sensitive speaker I have at around 86 dB. Typical speaker tests at around 82 dB. So that is 4 dB better. Then I listened to the speaker near arm's length. SPL drops by 6 dB by ever doubling of distance. If you sit at just double of where I listened to, the effective sensitivity of the speaker I listened to already becomes 92 dB.

I also made consideration by testing the amp at very low volumes and reported little distortion.

And don't go grabbing sensitivity numbers from random people or even measurements. There is no one sensitivity number. CEA-2034 had an averaging one which is what I stated above but even that is wrong for reasons I won't go into here.

 

[amirm]

I had forgotten that Stereophile reviewed this amp and JA measured it. Please note that I am not arguing for this amp's ultimate value to anyone, and I wouldn't buy it (speakers aren't efficient enough), though I have used and enjoyed tube amps in the past (currently use a Benchmark ABH2), but there are many nuances involved that make simplistic statements like "piece of SH#*" and "money grab" not completely applicable. Also, if I were gifted one I would listen and enjoy the heck out of it, even if it ended up as part-time only.

I used none of those terms in my review. People who use amplifiers for what they do, simply amplify, rightfully are puzzled why people pay thousands of dollars for what is a noise and distortion factory. Nothing you showed from JA's measurements changed this. As to me measuring more, the purpose of my evaluation is to do just enough to assess the products of engineering and fidelity quality. It is not my job to help reverse engineer a product, dig into its design, etc. Yes, comments are made here and there but I am not here to turn every review into a science project. Unlike JA, I have tons and tons of gear waiting to be tested. I rather get through those than to give you this and that other measurement. No other conclusion could have been reached with more testing than what I did.

Now look at JA's conclusion:

Who do you think got it right? You think his measurements show excellence? If so little power and so much noise and distortion is excellent, what on earth is not?

You really have lost the plot with your commentary.

 

[Ken1951]

I haven't used a tube amp of any sort for decades, but did once upon a time. It seems to me that a company like Luxman could have done a better job of designing this unit. Especially for the price. But what do I know?!

 

[amirm]

So then you say at 1-2 watts the Luxman THD is approaching audibility. But it has been shown over and over again that distortion spectra are vital when determining audibility (total THD, measured for ages is incomplete at least, more likely misleading). 2nd and 3rd are very difficult to perceive until levels are fairly high (especially what y'all are used to seeing), where higher orders are much more audible. Also, distortion in the low frequencies is very hard to detect and should be measured. JA also helps us with this. First the second feature:

More important than the spectra is having the training to be able to hear distortion. There is massive difference between people when it comes to their ability to hear non-linear distortion. This is why I included listening tests and my impression of such. You didn't hear such comments from other reviewers because they simply are unqualified to evaluate such gear.

As to above chart, I always run a much better of it for my amplifier tests. I did the same here but just realized I forgot to put it in the review. It is there now:

 

[Doodski]

I haven't used a tube amp of any sort for decades, but did once upon a time. It seems to me that a company like Luxman could have done a better job of designing this unit. Especially for the price. But what do I know?!

It seems to me that not even the bare minimum was provided in the amp for the price they ask for it. Eye candy yes but otherwise it's a cash grab.

 

[amirm]

On bias, company says it is not user adjustable. They set it in the factory and say it does not need changing. They say they tubes are designed to last 10 years. If someone changes tubes, they apparently send them instructions on how to do it.

 

[amirm]

It seems to me that not even the bare minimum was provided in the amp for the price they ask for it. Eye candy yes but otherwise it's a cash grab.

They are doing as everyone else is doing. There are no checks and balances as far as noise, distortion, etc. in this industry We see how JA concludes with praise for measured performance. Likely majority of people just run with that as does the company instead of looking and comparing measurements to others. So why change or do better?

Now the looks, everyone sees that so much investment is put in that.

 

[Bacchusoo7]

Has anyone bench tested any of the Manley tube products? I know for recording their EQs and such are amazing. They know tubes, but recording and playback are two different animals.

 

[MAB]

More important than the spectra is having the training to be able to hear distortion. There is massive difference between people when it comes to their ability to hear non-linear distortion. This is why I included listening tests and my impression of such. You didn't hear such comments from other reviewers because they simply are unqualified to evaluate such gear.

As to above chart, I always run a much better of it for my amplifier tests. I did the same here but just realized I forgot to put it in the review. It is there now:

One more question.
Given this unit has large amount of power supply noise, is this even a good candidate for the use condition?
Harmonics, I guess you can make a case for being part of the experience.
Regarding my earlier question... It seems you are in semi-agreement this isn't the best implementation on the planet. And it seems that the measurements confirm, not the best.

I do think it is reasonable for a first-watt optimized design (in a very high-sensitivity system), but again, not the one I would choose. I think there are better.

Bill

Back to my head-scratcher, PS noise on an amp that is best paired with sensitive speakers? Lots of discussion about missing measurements or methodology. But this amp just doesn't seem OK to me. And it seems like we are all saying almost the same thing!!!