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

[gaburko]

He told me hopefully sometime in March.

Thank you! I was about to pull the trigger on the current one but I guess I can wait a few weeks

 

[storing]

new, more powerful Purifi amp

What system do you have that would need even more power than the current line has?

 

[boXem]

Thank you! I was about to pull the trigger on the current one but I guess I can wait a few weeks

FYI, these will be monoblocks.

 

[VintageFlanker]

I might try to put a tube pre (freya+?) in between when it sound overly analytic or harsh.

It won't.

 

[gaburko]

FYI, these will be monoblocks.

Ah, this is quite important info. In that case I will stick with my plan and get the Arthur 4215. Btw, on the website you mentioned that deliveries will re-start around mid Feb? What are the current delivery times if i place an order this week?

thanks!

 

[RDSChicago]

What system do you have that would need even more power than the current line has?

Sonus Faber Extremas. They are driven best with gobs of solid state power. I’m not too technically inclined but some say they need a lot of power due to the following - maybe someone here can explain:

From the Stereophile review:

A first-order crossover can be achieved, not with a series capacitor but with a single inductor, this connected in parallel with the tweeter. The parallel inductor connection terminates the high-frequency driver well, helping to control its natural fundamental resonance. For the inductor to give a defined filter characteristic, however, there must be a series impedance; in the case of the Extrema, a resistor (fig.B). This resistor/inductor combination appears wired across the speaker input terminals; it will dissipate power over the speaker’s entire frequency range, mainly according to the resistor value.

image: https://www.stereophile.com/images/archivesart/sfefigB.jpg

Fig.B Conventional first-order high-pass crossover filter (top) vs "Sine-Cap" filter (bottom).
In the case of the Extrema, the series resistor for the treble section is typically 20 ohms. This provides the required source impedance for the crossover inductor, and also correctly attenuates the treble unit by the required 4dB or so. Yet with the Extrema’s nominal 8 ohm drivers, the total system impedance does not fall below a 4 ohm minimum—it is nominally a 5 ohm-rated design.
Read more at https://www.stereophile.com/standloudspeakers/915/index.html#C1tSeYjx17owvP01.99

 

[EdW]

Sonus Faber Extremas. They are driven best with gobs of solid state power. I’m not too technically inclined but some say they need a lot of power due to the following - maybe someone here can explain:

From the Stereophile review:

Looks like Sonos Fabre Extremas speakers are a very benign load to drive. The 1ET400 (Arthur 4215) and the 1ET7040 based amplifier would have the ability to give identical drive voltage to these speakers, with very marginally lower distortion from the lower current drive capability 1ET400 based amplifier. Now if boXem manages to make the 1ET7040 based amp bridgeable then we’re really talking high power. Plus boXem gets to sell you 4 mono blocks

 

[boXem]

Looks like Sonos Fabre Extremas speakers are a very benign load to drive. The 1ET400 (Arthur 4215) and the 1ET7040 based amplifier would have the ability to give identical drive voltage to these speakers, with very marginally lower distortion from the lower current drive capability 1ET400 based amplifier. Now if boXem manages to make the 1ET7040 based amp bridgeable then we’re really talking high power. Plus boXem gets to sell you 4 mono blocks

Bridging 1ETx modules with separated power supplies doesn't seem to be a good idea, beside the mess in wiring.
Bridging a 4215/E2 is fairly easy with this cable: Calogrenant "Bridger"

 

[bloodshoteyed]

FYI, these will be monoblocks.

you've got my attention...

 

[Mnyb]

Hi @boXem | audio .

Wonderful products btw . Like the gain settings ( essential feature in any amp ).
And for not offering flawor of the month buffer stages that “sounds different” proves that you dont consider your customers fools, thankyou very much.

Other purify builders differentiate with having EMI/Rfi filtered inputs . Vera and March and ofcourse claims that it’s necessary ?
Most brands does not have this ? Any thoughts ?

 

[gaburko]

Hi @boXem | audio .


Other purify builders differentiate with having EMI/Rfi filtered inputs . Vera and March and ofcourse claims that it’s necessary ?
Most brands does not have this ? Any thoughts ?

That's an interesting thought, I was just reading a interview snippet with Alan March from March Audio who said:

“I won’t be specific – but some of them don’t know what they’re doing,” he says. “They don’t have the background knowledge of electronics, signal integrity, and so on. Practically every single competitor to us does not even put r.f. filters on the front of the amplifier, they just connect them straight out to the outside world… and with Class-D, that’s a problem, because r.f. noise getting into the amplifier can intermodulate with the switching signal, and then you get ‘birdies’ and noise in the background. So it’s having a deeper fundamental understanding of electronics and signal processing and signal integrity that helps us differentiate ourselves.”

March Audio P452 review

A powerful, compact, award-winning Aussie stereo power amp

www.whathifi.com

 

[Mnyb]

That's an interesting thought, I was just reading a interview snippet with Alan March from March Audio who said:

“I won’t be specific – but some of them don’t know what they’re doing,” he says. “They don’t have the background knowledge of electronics, signal integrity, and so on. Practically every single competitor to us does not even put r.f. filters on the front of the amplifier, they just connect them straight out to the outside world… and with Class-D, that’s a problem, because r.f. noise getting into the amplifier can intermodulate with the switching signal, and then you get ‘birdies’ and noise in the background. So it’s having a deeper fundamental understanding of electronics and signal processing and signal integrity that helps us differentiate ourselves.”

March Audio P452 review

A powerful, compact, award-winning Aussie stereo power amp

www.whathifi.com

Yes but March does not have user selectable gain , you have to decide when ordering.

VERA’s offer is very complete, but pricing is eye watering so boXem is still high on my list

 

[gaburko]

Yes but March does not have user selectable gain , you have to decide when ordering.

VERA’s offer is very complete, but pricing is eye watering so boXem is still high on my list

Oh, no question. For me personally the killer feature is the auto wake-up as well

 

[boXem]

Hi @boXem | audio .

Wonderful products btw . Like the gain settings ( essential feature in any amp ).
And for not offering flawor of the month buffer stages that “sounds different” proves that you dont consider your customers fools, thankyou very much.

Other purify builders differentiate with having EMI/Rfi filtered inputs . Vera and March and ofcourse claims that it’s necessary ?
Most brands does not have this ? Any thoughts ?

Thanks for the nice words!
I have spent countless hours in EMC chambers for my previous job. So I do not communicate on the input filtering because, well, that's obvious in my mind. Seeing what others do, maybe I should ...

 

[Mnyb]

Thanks for the nice words!
I have spent countless hours in EMC chambers for my previous job. So I do not communicate on the input filtering because, well, that's obvious in my mind. Seeing what others do, maybe I should ...

Nice . It seems like a differentiation worth mentioning as apearenlty some builders basically just appears to stuff boxes.
You seems capable of understanding your own product another “ necessary feature “ suppose you can design an amp yourself but choose to build with these modules, it’s a very rational choice .

 

[boXem]

Nice . It seems like a differentiation worth mentioning as apearenlty some builders basically just appears to stuff boxes.
You seems capable of understanding your own product another “ necessary feature “ suppose you can design an amp yourself but choose to build with these modules, it’s a very rational choice .

It's not just a rational choice, there is also a fact of life: Bruno P. is an incredibly talented person having worked on post filter feedback self oscillating class D amplifiers during almost 2 decades. Pretending to compete with him on this very specific subject is ambitious, to say the least.

 

[HansH]

I just received my Arthur 4215/E2 and I'm extremely happy with it. Unbelievable what difference it makes compared to my Lyngdorf SDAI 2175 on my JBL Ti6k speakers.
It is connected to a RME ADI2 DAC fs which received its data over usb from a SoTM sms-200 Neo through Roon.
From all class D amps, only the SPEC RPA W3EX sounded better, but then again, for the same cost, I could run 6 Arthurs in bridge mode to tri-Amp my speakers
So happy customer

 

[JensenW]

Bypassing would imply changing the input impedance, which doesn't comply with the target of having an "easy to drive" amplifier. So flow through.

May I ask what the input impedance and the crosstalk @1 kHz of the Arthur 4215 is please? Thanks.

 

[boXem]

May I ask what the input impedance and the crosstalk @1 kHz of the Arthur 4215 is please? Thanks.

Sure, 94 kOhm.

 

[JensenW]

Sure, 94 kOhm.

Wonderful! Any approximate figures for the crosstalk too? Thanks!