boXem A series

[Fledermaus]

2 x 5519/N1 in the house , hooked up one of them to my country fair special PA speaker prototype - so far, so good, auto-sense works like a charm and the beast exerts a tight grip on the 15'' :

 

[bibi2000]

At home as well . Rock Solid form factor!
Hooked to 2 Kef LS50 meta with a Minidsp SHD studio (volumio) & Topping E70V + a little T-REL mini Sub.
The whole family is already Enjoying its soundstage/Clarity a lot before receiving Supra Ply 3.4 shielded speaker cables and doing a whole system fine tuning.

The Auto-sense is a nice surpise . It is a no-brainer for a smooth integration!

 

[Ruready]

20.8 and 28.8 dB for a sensitivity of 5 and 2 V in 8R.

Hello,
What does "into 8 Ohms" mean ? Is it speaker impedance ? (Please forgive my ignorance )

 

[bibi2000]

Hello,
What does "into 8 Ohms" mean ? Is it speaker impedance ? (Please forgive my ignorance )

8 ohm is for the speaker impedance.
Usually the consumer market speakers are 2, 4, 6, or 8 ohms impedance.
Beside you have the speakers sensivity given by xx dB.

 

[Ruready]

Ok thanks
If impedance must be taken into account for the calculation, What would be the optimized gain to select on the amp with 4Ohm speakers and 4V pre-amp ?

 

[bibi2000]

I am not a expert but to make it simple, it would depend on your speaker impedance, its max-min power requirement.
In addition, the sound level you want to get from your system has to be considered (ref message #50).
In my case with the DAC 4V max @XLR input and the Kef Meta LS50 power requirement (100W), the low gain is far enough with this Amp ( factor 4 for my confort ).

 

[boXem]

Hello,
What does "into 8 Ohms" mean ? Is it speaker impedance ? (Please forgive my ignorance )

Ok thanks
If impedance must be taken into account for the calculation, What would be the optimized gain to select on the amp with 4Ohm speakers and 4V pre-amp ?

Hello!
Sensitivity is the amplifier input voltage needed to get the amplifier clipping.
Sensitivity = (max_power_in_given_load * load)^-2 / gain
gain = 10^(gain_in_dB/20)
If we take 700W in 4R with 29 dB gain (high), (700 * 4)^-2 / 10^(29/20) = 52.9 / 28.2 = 1.877 V RMS
The same with gain at 22.8 dB (low): 52.9 / 13.8 = 3.83 V RMS.
edit: so in your case low gain is a no brainer

 

[makak]

How does the trigger on the A 5517/N2 combine with the audiosense feature and how is it controlled by the switch with its three settings (Stdby, On, Auto)?
I should be able to find out by myself, but I’m struggling with this. Might be a bad or incorrect trigger cable…

 

[boXem]

How does the trigger on the A 5517/N2 combine with the audiosense feature and how is it controlled by the switch with its three settings (Stdby, On, Auto)?
I should be able to find out by myself, but I’m struggling with this. Might be a bad or incorrect trigger cable…

Standby and On are directly driving the power relay.
When the switch is on Auto:
Audio + trigger = on
No audio + trigger = on
Audio + no trigger = on
No audio + no trigger = off after 10 minutes

It look like some of the first amps built have had the wrong firmware flashed in them, making the trigger unable to wake the amplifier. For whose who have such a problem, please drop us an email or a private message.

 

[boXem]

Just realized that some of you guys requested more pictures some time ago.

Inside

Back mono

Back stereo

 

[boXem]

And as bonus for the weekend, a picture of the optional "ears" for the full size chassis passing the rack test with flying colors

 

[maty]

2 x 5519/N1 in the house , hooked up one of them to my country fair special PA speaker prototype - so far, so good, auto-sense works like a charm and the beast exerts a tight grip on the 15'' :

Be careful, that loudspeaker can serve as justified cause for divorce

 

[vicenzo_del_paris]

A Boxem "A" 5517/N2 (ncx500) just replaced an Boxem Arthur 3409/N2 (nc252mp) !

Kept sourcing with Fred as I value the care he puts in his designs (thermal management, electric safety) and his value proposition (casing, auto sense)

DHL was very fast. Fred sent yesterday afternoon and I received it this afternoon

I really love the design of the new series (matter of taste), even the touch and feel.

NCX500 modules are very impressive. It can get so loud and very clean.

No sound quality difference from previous modules I had (nc252mp) but it goes much louder!

I guess the little Arthur will have to find a new owner soon

 

[boXem]

And here we go for the first amps based on the full size chassis:

2 channels NCx500 + SMPS3k from 1230 € VAT excl.: A 5519/N2
Dual mono NCx500 + SMPS1200 from 1495 € VAT excl.: A 5519/N2M
3 channels NCx500 + SMPS3k from 1535 € VAT excl.: A 5519/N3
4 channels NCx500 + SMPS3k from 1825 € VAT excl.: A 5519/N4
5 channels NCx500 + SMPS3k from 2130 € VAT excl.: A 5518/N5

We apply a 10% launch discount on these amps until the 14th of April.

 

[ubiq]

Hi Fred
Very interesting evolution of the line. Regarding the stereo setup in the full size chassis, can u explain your choice to use the smsp3K instead of the 1200, the additional power put aside ? Or is it the sole reason?

 

[boXem]

Hello!
Reason is power and the way the power limit is handled. There are combinations load/frequency that can make a pair of NCx500 shutting down a SMPS1200 (no worries, this is smooth). This won't happen with an SMPS3k.

 

[ubiq]

Great! Thx for the explanation

 

[delamelon]

Hi Fred, is it planned to do more than 5ch?
merci

 

[boXem]

First want to see how these are received. Then ...
De rien

 

[makak]

Hello!
Reason is power and the way the power limit is handled. There are combinations load/frequency that can make a pair of NCx500 shutting down a SMPS1200 (no worries, this is smooth). This won't happen with an SMPS3k.

Hi Fred,
could you please elaborate on the combinations? What role does the frequency play in this?