boXem A 4216/E2 Stereo Amplifier Review

[Human1]

Yeah the connector has a springy action and just won't seat.

I am no expert though, it could be user error. Edit - yeah I'm dumb and couldn't push it in properly . . . something about "that's what they said" too . . .

I wonder if the shorter inner clasp would work with it see 4:38 of this video

 

[SKNG]

Yeah the connector has a springy action and just won't seat.

I am no expert though, it could be user error.

I wonder if the shorter inner clasp would work with it see 4:38 of this video

U need to apply a little bit more force to push it in to properly "lock in",the front part will retract make it harder to connect.
I have a hard time figuring how to connect it when I first got it many yrs ago also.

 

[Human1]

Oh my friggin gawd . . . need to edit my post . . .

 

[boXem]

The interest of such a connector is that GND connects first, preventing accidents when the amplifier was inadvertently left ON.

 

[Endibol]

I am also very interested to see the Wiim Amp Ultra tested by Amir, although I realize that Erin already did, see link.
Looks like a great powerful unit with lots of software functionality as well.

WiiM Amp Ultra Streaming Amplifier Review

WiiM Amp Ultra Streaming Amplifier Review

www.erinsaudiocorner.com

@amirm : I just got the confirmation from WiiM in the USA that they will reach out to you about sending a WiiM Amp Ultra for reviewing..

 

[amirm]

@amirm : I just got the confirmation from WiiM in the USA that they will reach out to you about sending a WiiM Amp Ultra for reviewing..

Thanks. They did so last night.

 

[ninja1]

Back to boXem... Uncle Arthur (4216/E2) is on the way....

 

[Willem]

For Boxem, it says "Tax included" for me.View attachment 470259

You would be buying from within the EU, and in that case it is mandatory to include VAT (at your local rate) in the pricing.

 

[ptw]

Note that the xlr to rca cable sold by boxem will not work with the wiim ultra unfortunately. I didn't realize these things have different lengths for the connectors. I'm using cheap amazon xlr to rca and they work fine.

No problem for me with boXem xlr to rca cable and my wiim ultra.

 

[Stinga]

Fred, whats the difference std binding posts and the wbt version.
My speaker cables front R and L use male wbt connection, with others bare wire or banana, what do you recommend pls?
Thanks!
Al

 

[boXem]

The tightening system from the WBT 708 is it's major strength for it's reliability over time. But the WBT are lacking a hole to maintain raw wire during tightening.
So I would say, for spades, WBT, for banana whatever, and for raw wire, choose your devil between simpler installation and better reliability.
But speakon rules them all.

 

[ninja1]

Hi Fred,

what is value of impedance relative to 3 gain settings ? Or it is similar for all?
Thx

 

[boXem]

20 10 k for the A series, 94k for Arthur. Whatever the gain setting.

 

[ninja1]

Thank you

 

[Fledermaus]

20 k for the A series, 94k for Arthur. Whatever the gain setting.

Nicer than, as some do, bypassing the input buffer for low gain, which lowers impedance fair bit

 

[Oniiz86]

20 k for the A series, 94k for Arthur. Whatever the gain setting.

@boXem I was curious why there was a revision to the input impedance, I believe it was 10k for the A series & 100k for the Arthur series when the 4216/E2 was initially released?

Your follow up post " Bias current is contained within the amp and the few hundreds ohms from high output impedance devices would anyhow not change anything to the DC caused by the bias current. 100k causes a pop noise that is not nice, 10k makes the pop noise caused by DC almost inaudible."

I guess why my amps have a moderate pop noise when powering on is soley because of the use of the OPA1612 & its 20k input impedance, if it were a composite design like your Arthur series utilising the best of both worlds OPA1656/OPA1612 everything would most likely be fine.

 

[pma]

Nice amplifier.

 

[boXem]

@boXem I was curious why there was a revision to the input impedance, I believe it was 10k for the A series & 100k for the Arthur series when the 4216/E2 was initially released?

View attachment 472643
Your follow up post " Bias current is contained within the amp and the few hundreds ohms from high output impedance devices would anyhow not change anything to the DC caused by the bias current. 100k causes a pop noise that is not nice, 10k makes the pop noise caused by DC almost inaudible."

I guess why my amps have a moderate pop noise when powering on is soley because of the use of the OPA1612 & its 20k input impedance, if it were a composite design like your Arthur series utilising the best of both worlds OPA1656/OPA1612 everything would most likely be fine.

It's indeed 10k, I don't know why I typed 20k. I corrected my post now.
Pop noise at startup shutdown is often due to DC voltage, created by input buffer due to the association of relatively high opamp bias current and too high input resistors, or due to the upstream components.
The OPA1612 is not optimal concerning bias current, thus 5k resistors per each of the 2 legs for the A series, or 2 x 47k + post buffer DC filtering for Arthur.

 

[rsg]

I have the E4 version of this amp and I've been pleased with its performance. Some things I don't like:

1. No on/off switch that is provided with the Arthur series.
2. No front LED indicator showing power is on.
3. Since the power supply and Purifi modules are placed down facing, the feet in my opinion aren't high enough to dissipate heat. I replaced them.

 

[ninja1]

I think on new Arthur there is on/off switch on the back...

and also a small led in front (in the center)