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VintageFlanker

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Disclaimer: This review sample was kindly loaned to me by @boXem | audio. I have no financial relationship with the brand whatsoever, nor had got paid to say anything good or bad about this amplifier. Also, my English still sucks even after being there for two years, so please be easy on that.;)


BoXem Audio Arthur 2408/N2 Review

Hey folks! Today, I'm going to evaluate as deep as I can the Arthur 2408/N2, two channels power amplifier made by BoXem Audio. For those who missed it, BoXem Audio is a newcomer company launched in October (or earlier?) this year by our member Fred Jaquot. The brand is based in Luxembourg and joins the busy list of already established custom Class D amp companies such as Apollon, Rouge Audio, Nord, Audiophonics (these ones for EU only), March Audio, VTV, and so on... Needless to say, there is a lot of competitors in this already overcrowded market.

For now, there is only one line of amplifiers available from BoXem: Arthur, which includes two models, the 3409/N2, and the one being reviewed today: the 2408/N2. Both are respectively based on Ncore NC252MP and NC122MP Class D modules from Hypex. The entry-level 2408/N2 is priced at 659€ (tax included), while the 3409/N2 costs 799€. There is no custom options available: You may only choose the front panel color between Black, Silver and Orange, at no extra cost.
Edit: There is now two models to the line just announced : Arthur 3109/N1, monobloc with NC250MP and Arthur 4614/N1 (Also monobloc, but NC500MP based).


The way I see it, not many would disagree that NC-MP line of amplifier modules are probably one of the best performance/price ratio in the entire amplification history - period. You may indeed get among the best distortion figures available today, with plenty of power for "only" a few hundred €/$. Not to mention these modules, as opposite to the regular Ncore OEM line, are all integrated with their own power supplies and buffers. You may basically build an amp by simply putting one of these in a box and call it done... Or is it that simple? Let's find out...

A word about the NC122MP module which is the heart of the Arthur 2408. I have no instrumentation to make proper objective evaluation or measurements of this amp... but we know, thanks to @amirm's reviews that datasheets from Hypex are mostly reliable. So, if you want to know more about the objective performance that the Arthur 2408 may provide, please refer to either the datasheet from Hypex, or to the review of the March Audio P122 Amp from Amir (both amps should perform very similar, if identical). Nonetheless, here are few AP datas from Hypex:

Specs.jpg



External build

Let's see how the Arthur 2408 looks:
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The unit is 224mm wide, 318mm deep and 80mm high. For me, this is the perfect form factor between more compact power amps and regular (400mm+ wide) ones from mass market companies. This will stack very easily with most DACs on top of it, such as my 20cm wide ADI-2 DAC or many from Topping, S.M.S.L etc. However, I have to mention the chassis is surprisingly light considering its size, (I would guess the weight to be around 2Kg). This does not ruin the overall stability at all, tho. The unit will stay where you put it (hopefully!). The four (tiny) feets are made of black anodized aluminum and provide a good grip despite this light weight.

PXL_20201208_175250645.jpg
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Despite the overall industrial design being some kind of "love or hate" feeling, I have to confess I personnaly like it. The front plate is made of silver aluminum (and the only part customizable for now), while the main cover is mate light grey, with its texture feeling grainy on touch. I wish @boXem | audio will add the option for black finish in the future. Let's imagine some Halloween style, combination of black main plate with orange front panel...:cool:. The quality of machined aluminum and logo engraving is nothing short of excellent.

Let's move to some closer shot at the back panel:
PXL_20201208_174954238.jpg


Overall, this looks and feels fairly premium. The binding posts are made by ETI Research (I believe to be BP-20C). Not that I imagine these would add anything to sound performance, but they are no doubt very well built. The XLR inputs are from Neutrik (as any should be). You may have noticed that the Input B is also stated as "Wake", we will talk about this soon. The IEC male input is also fairly well assembled. The power switch on top of it is the only button you will find on the Arthur. Note that the amp will run all over the world without issue, with either 100-130V or 200-264V current compatibility. Apart from these, paying attention to details: I'm glad to see CE certification, serial numbers, and the unit being proudly labelled as Handcrafted in Luxembourg.

At a glance, this is one of the best built amp I had in hands from one of these custom-amp companies. It feels rather solid and stiff wherever I put (more push) my fingers on, not any loose part anywhere. Very nice job, BoXem!

...Now let's take a look at the guts of the beast:


Internal assembly

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WOW.o_OThis seems to be close to textbook amp assembly to me. I mean... this is so clean. I honestly don't see how it may get any better than it already is. You may recognize, of course, the NC122MP module, with three house boards. Per (legitimate) request, I cannot show a closer look of the custom input board. All three are marked as BoXem Audio - Made in Luxembourg.

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Here is a closer (and unsurprising) look at the Ncore NC122MP module from Hypex. Still quite schocking to imagine how such a compact board manage to generate this amount of power.

PXL_20201207_191753689 (1).jpg

Note that the ground is obviously attached to the chassis... on the (conductive) mid plate. As we know, in a properly assembled amp, ground should not be screwed on either anodized aluminum or paint or should be ineffective that way.

PXL_20201207_193234504.jpg

Nothing to complain there either. I can't consider how these would come loose anytime soon. Note that cables are twisted under these sleeves.

Edit: I almost forgot. To get acces to the inside, you first need to deal with these six screews, including feets, maintaining the main plate underneath,
PXL_20201208_164538035.jpg


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At last, you can see is the LED Board sitting inside the front plate. The transition is readily found to talk about the next part...


Operation

At this point, some may ask: "But hey, what makes the Arthur that different from its competitors?". Apart from excellent from factor, internal and external build quality saw above: Two very simple features: Auto On/Off, and clipping indicator. "Is that all?" Yep. And I can guarantee it makes a hell of a difference under daily use. The only indicator is the front tiny LED. By the way, the aforementioned is white, and I find it to be at just the right brightness: enough to be seen under daylight, not too much in a dark room, which may be disturbing for many. Definitely a good point there.

PXL_20201208_180757573.jpg


First, the Auto Off/On function. It worked flawless during the week I had the Arthur at home. The amp simply turns on when there is any signal coming from your DAC/Preamp into it. It uses the Input B to do so. The LED starts to blink slowly and the unit is ready to operate after few seconds. With not being fed by any signal during around 10 minutes, the amp will shut down. I have to admit this is so convenient to (not) use. At least, far more than a regular 12V Trigger input. That's all. I wish this function should exist in any power amp with this specific market.

Last but not least, the Arthur comes with a clipping indicator. I don't know that much of amps providing such feature. Few in the pro world, some from March Audio, Premium Apollon amps if I'm not mistaken, and of course the mighty Benchmark AHB2. Once the Ncore module starts to clipp, the front LED will blink fast... I guess until you turn down the volume... or the unit comes into protection (?): I don't know, I did not go that far. With this funtion, you just avoid any risk to damage either your amp or your speakers. Remember: underpowering your speakers with distorted current is (almost) always more dangerous than overpowering them. Under clipping, the front LED behaves as such:
L7x07W.gif


These being said, I didn't hear any electrical/mechanical buzz noise from the module itself (as I hear from my 1200AS2 ICEpower quite significantly), nor from the speakers. This amp runs dead silent. Period.


Subjective Listening
Tricky part, isn't it? Especially on ASR... Let's do it anyway! But first, a few reminders about the NC122MP module's specs. It claims to provide up to 125W / 4Ω or 75W / 8Ω (<1% THD+N). Amir measured the power before clipping to be close to 103W / 4Ω and 55W / 8Ω. So, definitely not a powerhouse, but I guess it would be enough for most speakers under regular home listening levels. The amp works under Typical 25.5dB Gain and is supposed to reach its peak power at ≈1.66Vrms input sensitivity.

Let me tell you a little story: Once Fred from @boXem | audio first contacted me, he was supposed to sent me the bigger brother Arthur 3408 amp (NC252MP based - 250W). Then, the amp wasn't available the time I was for the review, and he mailed me "That's alright, I may send you the little 2408"... My reaction was some kind of "Meh...". Why? Because the only passive speakers I have at home right now are the Dynaudio Evoke 20s, and believe me, these are some pain in the a** to drive! Plus, I already owned a NC122MP amp from Audiophonics which was more than OK to drive my former Aria 906s, but hell, Evoke 20s are definitely different hungry monsters: 84dB sensitivity (measured) and supposed to eat up to 180W. Evaluation was done by pairing the Arthur with my RME ADI-2 DAC v2, set in Auto Ref Level mode. Then...

What a big surprise! I almost forgot that the entry-level NC122MP was so capable already. I was able to put my Evoke 20 at moderate to loud level: up to 85-90dB SPL at the Listening Position, before I got the clipping LED blinking! Depending on the track, I put the Arthur to clipping at around 1.2Vrms (4dBu) out of the ADI-2, under musical conditions. I'm the kind of crazy guy who like to listen very loud... if I may still enjoy the music free of distortion from either my electronics of speakers. That was almost the case here. I do think the Arthur 3408 would have been a better fit for the power-suckers Evoke 20s. But regarding my initial expectations, the 2408 already did great. Note that even with the LED blinking, I wasn't able to "hear" the clipping itself at this point... I mean: no audible distortion to worry about. I would be curious to know at what THD level it engages: 0.1%, 1%?

"But how does it sound?"... Well, it turns out that it sounds like Ncore. I hardly know how to describe it any further. Take this with a grain of salt, but I felt my Apollon AS1200 (basically 8-9 times more powerful) sounding a touch thicker/fuller in the bass at similar levels. But honestly, I wouldn't swear I could hear the same differences under controlled listening. For those who haven't yet experienced good Class D amps: it just feels perfectly neutral, linear and transparent, whatever the power asked or the frequency. It is free of any kind of listening fatigue or such things audiophiles are dreaming about their misconception of Class D. No joke: Put this exact same assembly in a 45X45cm, 25Kg case, call it Class A and audiophiles will suddenly love it, since they ignore it is some Class D design involved.;) Once you listen to Ncore, Purifi or IceEdge, the ultimate purpose and a amp just appears to be pretty obvious: there is no amp anymore, an amp with no sound... the so-called "wire with gain". Apart from dead flat Frequency Response, you may of course expect excellent channel separation, resulting in an accurate perceived soundstage (as long as your speakers and room may create it) and decent imaging. Yep, sorry to disappoint, but my motto is still the same after two years on ASR: Get a (powerful enough) transparent amp, get a transparent DAC and then chose whatever speakers you want, without never care about "synergy" or such mysticism. My two cents.


Competition and conclusion

Let me put this straight: The BoXem Audio Arthur 2408/N2 is a flawless power amplifier: It is well-built, it looks good (to me at least), it is powerful enough to drive most speakers, it sounds great, and its unique features may only be considered as very welcomed additions.

...But we haven't talk about its bigger problem yet... The competition and more likely, one competitor. As The Arthur 2408 costs 659€... there is another NC122MP assembled amp around, called the Audiophonics MPA-S125NC, which is priced at 369€. Well, no one will argue that this is quite a price difference. And the same applies for the Arthur 3409/N2 Vs MPA-S250NC (both NC252 based). Then, many would legitimately ask: "Is the Arthur worth to spend as much as 290€ extra?" And I would answer: it depends. If you are strictly limited by your budget, yes you will get the exact same audible performance from the MPA-S125NC, which is by the time I write this review, the biggest bargain of all Ncore assembled amps. Then, is there any advantage to pay more for BoXem?... Oh yes there is. There really is. I owned the Audiophonics one year back and I can guarantee that its overall assembly quality is nowhere near the BoXem Arthur (No offense, @Audiophonics ;)). There is not any functions to play with and the form factor (too deep relative to its wideness) make it harder to stack up. At a glance: both are equally good amps, but the Arthur is, without hesitation, a better finished product. In conclusion: Pick your poison. No good nor bad choice there.

At last, I would like to personally congratulate Fred (@boXem | audio) for his courage to launch his company under such circumstances: As 2020 draws to an end, most of us will agree that it was a completely messed-up year, and certainly not the best one to start a business, especially on an already overcrowded market, with many competitors able to give similar performance at every price points. But the BoXem Arthur is an accomplished piece of gear which has a lot to offer and may put to shame many amps from mass market. Let's face it: some big brands may have put the exact same amp in a fancy case and would not feel ashamed to ask 1500€ for it (don't look at me, TEAC...). From that perspective, I do find the final price more than adequate for what you get at the end. Bravo!
 
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Ilkless

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Beautiful, beautiful internals and thoughtful industrial design. What I see justifies the premium on the bargain options, without resorting to the ridiculous premium mainstream brands are charging for nCore. I actually really like the row of slotted vents at the top of the rear panel and the typography on the logo. I know Fred received some feedback against it in his original vendor thread here, but I really like it.
 

boXem | audio

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Thanks a lot for this review @VintageFlanker . You put there an impressive amount of work!
Concerning the competition, I will add that our pricing is more or less aligned to the one from the usual suspects in nCore amplifiers production and that we consider that we offer more for the same price.
And we will keep the idea of the pumkin amplifier :)
 

boXem | audio

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Beautiful, beautiful internals and thoughtful industrial design. What I see justifies the premium on the bargain options, without resorting to the ridiculous premium mainstream brands are charging for nCore. I actually really like the row of slotted vents at the top of the rear panel and the typography on the logo. I know Fred received some feedback against it in his original vendor thread here, but I really like it.
Thanks for the nice words. To be honest, we are able to reach this price to quality ratio because we operate in a really lean way and do direct distribution. It would be impossible with the infrastructure from the big guys
 

ririt

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In my opinion, Boxem Audio and March Audio are offering the best Ncore premium offers. Features are slightly different: March offers trigger control while Boxem has Auto on/off, both offer Clipping indicator. Built quality is top-notch for both. Then comes the question of the amp aesthetic which is a question of taste! Personally I like both with a slight preference for the sleek design of March Audio.
Price wise, depending where you leave, one can be cheaper than the other.
I should add that I have been in touch both with Alan and Fred. The quality of their feedback and support is amazing. They are clearly not only entrepreneur but also passionate about hifi!
We are very lucky to have such kind of companies to provide us with SOTA devices to enjoy our music!
 

Willem

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Thanks for this view of the new Boxem amplifier. It is very attractive indeed. I like the esthetics (just like I love the March design). I think the auto on/off is an appealing feature. I currently use a master/slave power strip with my Quad 606-2 and that works too, but auto on/off is just that little bit more elegant. And since this is a class D design, it will stay cool enough to allow you to put it out of sight, for the ultimate minimalism. For my own use, I would want a more powerful implementation than what is currently on offer, but I am sure that will come.
 

boXem | audio

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Thanks for this view of the new Boxem amplifier. It is very attractive indeed. I like the esthetics (just like I love the March design). I think the auto on/off is an appealing feature. I currently use a master/slave power strip with my Quad 606-2 and that works too, but auto on/off is just that little bit more elegant. And since this is a class D design, it will stay cool enough to allow you to put it out of sight, for the ultimate minimalism. For my own use, I would want a more powerful implementation than what is currently on offer, but I am sure that will come.
Would 270/500/400 W @ 8/4/2 Ohm monoblocks suit your needs or is it still not for grown men? ;)
...
To @boXem | audio : congrats! Are there plans for amps with pre-amps functions in the future? with several inputs?
Yes. Need to decide which one is first between the integrated (pre+amp) and the preamp only.
 

Harmonie

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Thank you @VintageFlanker for this nice review.
I appreciate the quality of wiring inside Arthur (much better than some I could see thanks to ASR without naming).
I didn't expect the housing to be U shaped. But it's probably cheaper to produce.
Certainly the Auto on/off is a must feature and the clipping indicator too.
My nearly 3 decades amps have such function with Red led warming up and Green Led when Audio operating. It's so convenient, I wouldn't go back.
 

Willem

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Would 270/500/400 W @ 8/4/2 Ohm monoblocks suit your needs or is it still not for grown men?
My speakers are Quad 2805 electrostats (plus a sub), and my current power amplifier is a completely refurbished 2x140 watt Quad 606-2. The room is large (about 75 sqm) so I need a lot of power, but I should be a bit careful because the Quads cannot take too much. Until recently I was playing the power amp full range, and had the sub connected at speaker level. I had the distinct impression that the sound was hardening a bit when I played at higher levels. So I have now connected the subwoofer at line level (out of the RME ADI-2), with a passive 80 Hz high pass filter, to relieve the power amp and the speakers of the really heavy lifting. It does sound as if I now have more headroom.
So if I were to buy a new amplifier, I would want some more power than the Quad 606-2 can offer (but preferably in one rather than two boxes). What I would also like is an adjustable high pass filter like the one on my son's Yamaha P2500s pro audio amplifier. I think using subwoofers is a great way to improve the sound, and since most subwoofers do not have an inbuilt high pass filter, it would be nice to have one in the power amplifier. In fact, even those who use full range speakers without subwoofers would probably benefit from the reduction in distortion and undesirable background noises in the recording.
 

boXem | audio

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Thank you @VintageFlanker for this nice review.
I appreciate the quality of wiring inside Arthur (much better than some I could see thanks to ASR without naming).
I didn't expect the housing to be U shaped. But it's probably cheaper to produce.
Certainly the Auto on/off is a must feature and the clipping indicator too.
My nearly 3 decades amps have such function with Red led warming up and Green Led when Audio operating. It's so convenient, I wouldn't go back.
There were several reasons behind the choice of sheet metal instead of machining
- I don't like the idea of throwing away 80% of raw material when building something
- I talked about "lean operation" in a previous post. This includes very limited storage surface. By just changing front and/or back-plate we can do stereo, mono, integrated, pre... with parts variants that can be stored in a drawer
- Machining such a shape would be quite complicated
- It allows a large contact surface between the chassis and the cover, substantially improving the cooling
I believe a machined housing with a manufacture-able shape would have a similar cost.
 

boXem | audio

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My speakers are Quad 2805 electrostats (plus a sub), and my current power amplifier is a completely refurbished 2x140 watt Quad 606-2. The room is large (about 75 sqm) so I need a lot of power, but I should be a bit careful because the Quads cannot take too much. Until recently I was playing the power amp full range, and had the sub connected at speaker level. I had the distinct impression that the sound was hardening a bit when I played at higher levels. So I have now connected the subwoofer at line level (out of the RME ADI-2), with a passive 80 Hz high pass filter, to relieve the power amp and the speakers of the really heavy lifting. It does sound as if I now have more headroom.
So if I were to buy a new amplifier, I would want some more power than the Quad 606-2 can offer (but preferably in one rather than two boxes). What I would also like is an adjustable high pass filter like the one on my son's Yamaha P2500s pro audio amplifier. I think using subwoofers is a great way to improve the sound, and since most subwoofers do not have an inbuilt high pass filter, it would be nice to have one in the power amplifier. In fact, even those who use full range speakers without subwoofers would probably benefit from the reduction in distortion and undesirable background noises in the recording.
This is an interesting suggestion. Will keep it in mind, maybe a bit higher in the list than the pumpkin amp.
 
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