BOXEM Audio | Arthur 4215/E2 Purifi Amplifier | Owners' Thread

[Hayabusa]

That's fine. My comment wasn't directed at you specifically, but there's been page after page of off topic cable debate in this thread at this point.

Do you have anything to say in regards to Boxem's 4215/E2?

You are right I was off-topic..

But I have (a Boxem) question:
The purify modules have an i2c interface that allows for detecting of clipping in the voltage and current domain.
I know that buckeye cleverly add this functionality to its builds by a multi color led.
Anyone knows Boxem also has this?

 

[imdamo]

You are right I was off-topic..

But I have (a Boxem) question:
The purify modules have an i2c interface that allows for detecting of clipping in the voltage and current domain.
I know that buckeye cleverly add this functionality to its builds by a multi color led.
Anyone knows Boxem also has this?

I don't know anything about that. But it does remind me of another question I had regarding this amplifier, since they are mentioned in the same sentence on Boxems website.

"Arthur 4215/E2 input buffer board was designed in-house. The challenge has been to fit in a relatively limited space the buffer circuits for two channels, the gain management switch, the audio sense circuit, the I2C bus communication with the amplifiers and finally the supplies for analog and digital circuits, all this while obtaining the performance at the same level as the amplification modules."

My question is: What digital circuit? I thought this amplifier was all analogue?

Hopefully Fred will swing by at some point and clarify

 

[MCH]

I don't know anything about that. But it does remind me of another question I had regarding this amplifier, since they are mentioned in the same sentence on Boxems website.

"Arthur 4215/E2 input buffer board was designed in-house. The challenge has been to fit in a relatively limited space the buffer circuits for two channels, the gain management switch, the audio sense circuit, the I2C bus communication with the amplifiers and finally the supplies for analog and digital circuits, all this while obtaining the performance at the same level as the amplification modules."

My question is: What digital circuit? I thought this amplifier was all analogue?

Hopefully Fred will swing by at some point and clarify

I2c is a digital communication protocol. Probably the amp sends some information via i2c (as @Hayabusa mentions just above, clipping events or whatever) to a microcontroller to shine a led or take whatever action. Probably the audio sense function goes through the microcontroller as well. I imagine that all this, and maybe some other things going on under the hood, is what is referred to as the digital circuit.

 

[imdamo]

I2c is a digital communication protocol. Probably the amp sends some information via i2c (as @Hayabusa mentions just above, clipping events or whatever) to a microcontroller to shine a led or take whatever action. Probably the audio sense function goes through the microcontroller as well. I imagine that all this, and maybe some other things going on under the hood, is what is referred to as the digital circuit.

So the amp has some level of ADC on board to send status messages? That's neat.

 

[MCH]

So the amp has some level of ADC on board to send status messages? That's neat.

I have no idea, but in principle I don't see the need for an ADC. Sometimes is enough with an analog circuit to bring high or low a pin of the microcontroller.
Example: if you are curious how an audio sense circuit works (probably the one in the Boxem is more sophisticated), see here:

Audio Sense schematic needed

Hi, I am considering building a power amplifier and want it to have audio sense. I have searched a while, but could not find any solution suitable for my project. I do know Rod Elliot's Signal detecting circuit but this is a fully analog circuit that does not fit my needs...

www.audiosciencereview.com

 

[imdamo]

I have no idea, but in principle I don't see the need for an ADC. Sometimes is enough with an analog circuit to bring high or low a pin of the microcontroller.
Example: if you are curious how an audio sense circuit works (probably the one in the Boxem is more sophisticated), see here:

Audio Sense schematic needed

Hi, I am considering building a power amplifier and want it to have audio sense. I have searched a while, but could not find any solution suitable for my project. I do know Rod Elliot's Signal detecting circuit but this is a fully analog circuit that does not fit my needs...

www.audiosciencereview.com

That's really cool, but I wouldn't call that a digital circuit?

 

[Hayabusa]

I don't know anything about that. But it does remind me of another question I had regarding this amplifier, since they are mentioned in the same sentence on Boxems website.

"Arthur 4215/E2 input buffer board was designed in-house. The challenge has been to fit in a relatively limited space the buffer circuits for two channels, the gain management switch, the audio sense circuit, the I2C bus communication with the amplifiers and finally the supplies for analog and digital circuits, all this while obtaining the performance at the same level as the amplification modules."

My question is: What digital circuit? I thought this amplifier was all analogue?

Hopefully Fred will swing by at some point and clarify

The Purifi module has a microcontroller on board to check all kind of things.
It monitors temperature/voltages/currents, and must have one or more adc's

 

[n00brx]

So nice you can upgrade your binding post
Should have know this we can do it

 

[imdamo]

If anyone wants to dim the LED on this thing, I put one of these little semi-transparent stickers over the LED:

Light Dimming Stickers for Electronic Displays

LightDims are light reducing stickers for electronic devices, screens and LED lights.

www.sleepsolutions.com.au

The black sticker completely disappears on the black face-plate and I'm left with an LED that's about 25% as bright as it was.
Perfect solution in my opinion.

 

[whislai]

Just got my boXem audio Arthur 4215/E2, first impression is clean detailed transparent neutral sound, thought that it lack of color might not everybody's cup of tea, nevertheless I do think that it perform well in scientific score.

 

[whislai]

Ok further impressions on the amp, after few weeks of critical listening I starting to like this amp, especially when pairing with the S.M.S.L SU-1 DAC the sound I hear is on another level of details, even my Wharefedale Denton 80 never sounded so crisp, I'm not going to complain just because it sounded a bit bright on some recordings, I gain experience in a new way, yes sure you will hit listening fatique if you listen to some poorer recording with higher noise and less than perfect mastering. Another thing I noticed is watching movie is on a whole new level of experience because of accurate sound reproduction. I can't compare with the NAD M22 power amp since I sold it, but then judging from my memory for volume loudness level the power output should be roughly the same, include tax it's cheaper than the NAD, and also smaller, temperature wise it run just slightly hot but ok. I dunno suddenly I feel like I'm listening like a super critical musician/audiophile (which is ok) instead of casual daily listener, next I will try with some cheap preamps from AliExpress, one coming would be the Accuphase C3850 clone.

 

[boXem]

Is it possible you have NCx500 components inside the case instead?

Case is not ready for screwing an NCx500 inside and since the modules are firmware controlled, they would not even start .

 

[whislai]

My Boxem Arthur 4215/E2 runs cool as a cucumber in the fridge. It never gets hot even after hours of use. Is it possible you have NCx500 components inside the case instead? Or maybe the build design is different mounting the Purifi module to the top case?

Nope, I'm in Malaysia, I open aircond just slightly cool, not sure that's the reason, actually it's not hot until boiling egg like my Class D Audio SDS-470C, which I open the case and put few coins on the heat sink, the boXem amp just not cool, just a bit of heat, perhaps rougly less than 50 degree celcius if on high power load which sometimes I did crank for some music:

 

[Bobesku]

Ok further impressions on the amp, after few weeks of critical listening I starting to like this amp, especially when pairing with the S.M.S.L SU-1 DAC the sound I hear is on another level of details, even my Wharefedale Denton 80 never sounded so crisp, I'm not going to complain just because it sounded a bit bright on some recordings, I gain experience in a new way, yes sure you will hit listening fatique if you listen to some poorer recording with higher noise and less than perfect mastering. Another thing I noticed is watching movie is on a whole new level of experience because of accurate sound reproduction. I can't compare with the NAD M22 power amp since I sold it, but then judging from my memory for volume loudness level the power output should be roughly the same, include tax it's cheaper than the NAD, and also smaller, temperature wise it run just slightly hot but ok. I dunno suddenly I feel like I'm listening like a super critical musician/audiophile (which is ok) instead of casual daily listener, next I will try with some cheap preamps from AliExpress, one coming would be the Accuphase C3850 clone.

My BOXEM amp runs cool as well. Even after a 6-8 ours party with hard electronic music and a VERY loud volume, it was just warm. Not hot.
Maybe yours is in an enclosed cabinet? Maybe check your connections -some stray wires touching themselves? Or you are really listening at EPIC levels?

 

[whislai]

My BOXEM amp runs cool as well. Even after a 6-8 ours party with hard electronic music and a VERY loud volume, it was just warm. Not hot.
Maybe yours is in an enclosed cabinet? Maybe check your connections -some stray wires touching themselves? Or you are really listening at EPIC levels?

Yeah it's warm, not really that hot, quite amazing the efficiency of this Purifi board

 

[boXem]

Fred - have you ever seen an Arthur 4215/E2 run hot? I can't imagine how I would get mine to run anywhere near as hot as my Denon 4700 or my Buckeye NC502MP amps. With two Revel F328Be powered through RME ADI-2 DAC FS to Arthur 4215/E2 I can barely get the amp above room temp.

The question here is the definition of hot.
Amp temperature is always an offset added to the room temp.
Room temp at 20 degC (68 degF) with an offset of 10 degC will be slightly warm to the touch (30 deg C - 86 degF) while with the same use profile with a room temp at 30 degC will make the amp will feel hot (40 degC - 104 degF).
PS: before writing this I never realized how much the Farenheit scale complicates the understanding of simple stuff.

 

[Doodski]

PS: before writing this I never realized how much the Farenheit scale complicates the understanding of simple stuff.

We dealt with Imperial measurement for a long time. From liquids to distances and physics calculations requiring additional calculations it made life more busy for sure. Now we have metric and things are better. (Canada)

 

[whislai]

Quick update with the Arthur power amp experiment, my AliExpress C3850 preamp clone arrived today, it seem it sound a bit of bass hump with several gears matching in the process with best matching surprisingly is a MOTU M4, I don't know I feel this gear has very light sound based on my impression could be due to the OP-AMP implementation, after some testings and critical listenings, I finally feel best go with the Gustard H16 preamp set at full volume, DAC is SMSL C100 serve as preamp volume control with remote, my guess is the Gustard acts as a lightweight limiter to "screechier sound" for high frequency at higher volume, at extreme volume I think also can sound a bit bright. Few things I don't like the Gustard until I wanna sell it (now I'm keeping it as it's best matching I have now) is mechanical stuff like clicking sound when turning the volume, no way to turn off headphone while listening to preamp, not so impressive volume knob, well something like Khozmo design is sophisticated, though plan to look for another "Gustard" preamp house sound though...

 

[Firespeed]

Hello everyone,

I take the liberty of intervening in this subject, having recently acquired an Arthur 4215/E2 (second hand for the price of the LA90 - a bargain!).

Up until now, I've had an LA90 Descrete, which I've been very happy with. I have nothing against Topping, really. It represents an important step in the quality of my system.

But now I understand the importance of power in an amplifier...

Indeed, my speakers (rated at 6 ohms minimum) are not difficult to power, but they're not the most efficient in the world, and since Arthur's arrival, they've come into their own!

I haven't noticed any difference in terms of transparency, neutrality and reproduction quality, but I can easily hear the difference in terms of spatialization and stage depth. It's incredible to feel the sound so wide and so deep! Crosstalk is also far superior, and that's certainly the first thing I heard when I first listened to it. This crosstalk is extremely pleasant, and it's fun to follow the movements from left to right on some tracks or in some films. Like others here, I also found punch in the attacks and percussion of mid basses. It's jubilant.

In short, I'm a witness to the quality of Purifi modules, the excellent integration of Boxem craftsmen and, from now on, the importance of having power in reserve to hold speakers properly.

I can now consider changing speakers if the mood strikes me!

A question if you don't mind me asking: what would a dedicated preamp bring me between my DAC and Arthur? At the moment, volume management is handled by the DAC (E70 Velvet configured at 5V max and Arthur's gain set to medium).

Finally, I wouldn't have got here without ASR and its experts, who contribute to all these subjects, and I'm naturally thinking of Amir, Boxem founder, Vintage Flanker and all those I'm forgetting who participate with their clear, educational explanations.

Thanks again, and happy music-listening to you all!

 

[Firespeed]

If you use the RME ADI-2 DAC FS with the Arthur 4215/E2 the "Loudness" function can offer you a new level of sound quality. You can individually adjust the bass and treble frequency settings to match your desired sound quality and they automatically adjust as the volume level changes. It's quite remarkable. If you thought you noticed a difference adding the Arthur 4215/E2 wait until you connect the ADI-2 DAC FS and learn to adjust the "Loudness" controls to fit your listening needs. There is absolutely nothing like the control it offers discriminating listeners.

The recently added computer remote app for the ADI-2 DAC FS makes learning how to use the "Loudness" controls easy. You can dial in the exact sound you desire while listening to your favorite music tracks. Want more definition to the sound? What more bass thump? It can do it. Want to match the sound you have on another system? It can do it. ADI-2 DAC FS loudness control offers an amazing toolbox for speakers, all at the touch of your PC/Mac or iPad.

Thank you amper42 !!!

Will have a look...