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boXem ARTHUR 2408/N2 Teardown (Class D Amp)

amirm

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I recently reviewed the boXem ARTHUR 2408/N2 class D stereo amplifier. This is a follow up teardown of the unit. A handful of screws keep the case together making it easy to take apart:
boXem ARTHUR 2408 N2 Teardown Class D Stereo Amplifier.jpg


I must stay, this is a beautiful looking build. Starting with power plug, we see the whole thing has been covered with heatshrink tube, highly minimizing the danger of terminals coming loose and making connection to the chassis. A proper earth safety terminal is connected to bare chassis as it should be.

The amplifier has auto turn-on so a sense board is used to detect the signal from the XLR connectors to the input of the Hypex NC122MP which is a combination stereo amplifier and switching power supply. Paint/anodization has been removed from most of the chassis to allow for better heat transfer. Many holes are drilled which increase the surface area of the case to allow better convection cooling.

Output wires are tidy and go the shortest distance to the speaker terminal and kept away from each other, aiding in its great crosstalk measurments. Likely that custom board helps with that as well.

Cable for the front panel clipping and power on indicator has been nicely tie wrapped to the case rather than using stick on clamps which come unglued easily.

Everything within the control of the builder has been done to create a nice and clean amplifier around that Hypex module from safety and performance point of view.

Conclusions
It is easy to dismiss the roll of companies building amplifiers around these hypex modules. Yet we usually see a lot of missteps which potentially make the devices less safe and performant. The opposite is the case here. Clearly the designer paid attention to everything including adding custom modules/features to make the device more than just the bare amplifier. This is a model of how it should be done.

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Xyrium

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So, is that board with "Boxem Audio" on it, simply an IO board, connecting the amp module to the output?

Edit: ...and is the silver under the boards a large strip of aluminum tape, or is the case unfinished in that area?

Thanks!
 

boXem

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So, is that board with "Boxem Audio" on it, simply an IO board, connecting the amp module to the output?

Edit: ...and is the silver under the boards a large strip of aluminum tape, or is the case unfinished in that area?

Thanks!
Yes, it is an io board.
First version of the case was fully painted but my tests shown that the isolation layer created by the paint was creating some thermal issues with higher powered amps. So goodbye paint.
 

enricoclaudio

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WOW.. It looks clean and neat in and out. Very well done, @boXem | audio !!!
 

Digital Mastering System

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I too am very impressed. All the Dutch engineers I 've worked with (at Philips) have impressed me with their skill and knowledge. The Boxem ARTHUR 4215/E2 is what I would like to see tested; it is built exactly as I would do it, with OPA1656s and high power Purifi modules (if I could get them). I have always planned on building a Purifi amp, but now I see Boxem has built the one I want: ARTHUR 4215/E2.
 

Ron Texas

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The challenge with putting a Hypex module in a box is not to snatch defeat from the jaws of victory. It should be simple enough, but somehow people manage to screw it up. Thank you @amirm . These guys managed to get it right.
 

trl

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Totally love the inside guts.

I've also seen ARTHUR 4215/E2 that benefits of an adjustable gain, so I'd love to see it "in action" on Amir's desk. I think that it may measure better than 2408 on the lowest gain (also, probably the different NCore modules will help a bit here as well).
 

TimoJ

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Starting with power plug, we see the whole thing has been covered with heatshrink tube, highly minimizing the danger of terminals coming loose and making connection to the chassis.
That is not heatshrink tube, it's a rubber insulation boot made specially for IEC connectors. Various models are available, highly recommended also for DIY builds.
 

restorer-john

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That is not heatshrink tube, it's a rubber insulation boot made specially for IEC connectors. Various models are available, highly recommended also for DIY builds.

Yes, there is a single IEC boot, plenty of heatshrink on the ends of every loom/cable and runs of PET expandable woven flex sleeve.

The only thing that seems odd is the two screws and spacers missing on the input/wake board. We can see Amir's white light showing through, so we know there's holes lined up. @boXem | audio probably decided they weren't needed as the pin header and XLR screws were sufficient I guess.
 

boXem

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Yes, there is a single IEC boot, plenty of heatshrink on the ends of every loom/cable and runs of PET expandable woven flex sleeve.

The only thing that seems odd is the two screws and spacers missing on the input/wake board. We can see Amir's white light showing through, so we know there's holes lined up. @boXem | audio probably decided they weren't needed as the pin header and XLR screws were sufficient I guess.
Not only it is sufficient, but using the additional screws created a stress on the connector solder that didn' t make me confident on long term reliability.
 
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