AV123 / GR Research X-Voce Speaker Review

[IAtaman]

I suppose it threw in the towel at the end

Ha!
Or maybe decided to hitchhike around the galaxy.

 

[HarmonicTHD]

To me the bass response looks like what would happen if you apply a higher order low pass filter an octave or two above woofer resonance without doing impedance compensation. The circuit then "rings" at the resonant frequency. Easy enough to model in PCD...

edit: and if thats the case; fairly easily and cheaply fixable with a couple of caps and inductors (the bass response)

Danny will probably make a business out of it and selling a „Premium Kit“ to the owners which fixes his fixes.

 

[VintageFlanker]

Thank you @amirm.

Would you consider a new rating indicator, ...below the Headless Panther?...

 

[sweetchaos]

 

[HarmonicTHD]

Thank you @amirm.

Would you consider a new rating indicator, ...below the Headless Panther?...

You mean one which is cut off at the hip? Boy that’s dark.

 

[MZKM]

Reserved.

 

[ctrl]

Wow!...

Even if the design flaw in the low frequency range around 90Hz would not exist, there is a second frequency range (200-600Hz) that causes problems. It's caused by the open baffle design using a "resonator chamber".

Source: gr-research, in blue added by me

One of the most important frequency ranges of a loudspeaker is the 100-1000Hz range, as this is practically the fundamental tone of all voices and instruments (of course, e.g. with an organ the range is much wider - you know what I mean).

As a small reminder, a woofer (no XO) in a typical open baffle design would radiate as follows (0°-90°) - the FR has been normalized to the on-axis FR:

It is precisely this dipole radiation behavior that makes OB speaker so fascinating.

Now take a look at the horizontal and vertical radiation behavior of the AV123, especially in the frequency range 200-600Hz (I have smoothed the FR considerably and only show the 0,30,60,90 deg FR in order to better recognize the problem):

(In the horizontal plane, inter-driver cancellations occur above 500Hz, which is of no interest to us here)
If we look at the hor and ver FR normalized to the on-axis FR, we can see the problem better:

The "resonance chamber" amplifies the SPL in a certain frequency range and different radiation angles in an undesirable way and thus prevents the desired OB dipole radiation. The reflected sound from the side walls and ceiling deviates considerably and "abruptly" from the direct sound in the frequency range 200-600Hz.
The "resonance chamber" is also evident in the CSD in Amir's opening post due to delayed decay in 200-500Hz range.

This also explains why Amir's "audiophile towel" was so successful, as it significantly dampened the radiation of the resonances in the 200-600Hz frequency range. This makes the fundamental frequency range sound more natural again.

The NX-Series speakers NX-Otica and NX-Treme show similar problems (using V-frame open baffle), only with multiple resonance ranges - more details here.

 

[voodooless]

Ha!
Or maybe decided to hitchhike around the galaxy.

 

[August]

Worried about amirm's back.

 

[IAtaman]

[IMAGE]

Danny would be a good cast for Paranoid Android role indeed

Amir, I don't know where you find the energy and the motivation to deal with the likes of GR Research, but I appreciate that fact that you do.

 

[vkvedam]

To me Danny comes across as Ray Samuels of good old Head-Fi days

 

[Soria Moria]

Worried about amirm's back.

Come on! He's not that old yet.

 

[HarmonicTHD]

Wow!...

Even if the design flaw in the low frequency range around 90Hz would not exist, there is a second frequency range (200-600Hz) that causes problems. It's caused by the open baffle design using a "resonator chamber".
View attachment 326537
Source: gr-research, in blue added by me

One of the most important frequency ranges of a loudspeaker is the 100-1000Hz range, as this is practically the fundamental tone of all voices and instruments (of course, e.g. with an organ the range is much wider - you know what I mean).

As a small reminder, a woofer (no XO) in a typical open baffle design would radiate as follows (0°-90°) - the FR has been normalized to the on-axis FR:
View attachment 326538
It is precisely this dipole radiation behavior that makes OB speaker so fascinating.

Now take a look at the horizontal and vertical radiation behavior of the AV123, especially in the frequency range 200-600Hz (I have smoothed the FR considerably and only show the 0,30,60,90 deg FR in order to better recognize the problem):
View attachment 326545 View attachment 326546
(In the horizontal plane, inter-driver cancellations occur above 500Hz, which is of no interest to us here)
If we look at the hor and ver FR normalized to the on-axis FR, we can see the problem better:
View attachment 326547 View attachment 326548
The "resonance chamber" amplifies the SPL in a certain frequency range and different radiation angles in an undesirable way and thus prevents the desired OB dipole radiation. The reflected sound from the side walls and ceiling deviates considerably and "abruptly" from the direct sound in the frequency range 200-600Hz.
The "resonance chamber" is also evident in the CSD in Amir's opening post due to delayed decay in 200-500Hz range.

This also explains why Amir's "audiophile towel" was so successful, as it significantly dampened the radiation of the resonances in the 200-600Hz frequency range. This makes the fundamental frequency range sound more natural again.

The NX-Series speakers NX-Otica and NX-Treme show similar problems (using V-frame open baffle), only with multiple resonance ranges - more details here.

Wow. Nice. Thanks.

 

[uwotm8]

Well well

“A towel, [The Hitchhiker's Guide to the Galaxy] says, is about the most massively useful thing an interstellar hitchhiker can have. Partly it has great practical value. You can wrap it around you for warmth as you bound across the cold moons of Jaglan Beta; you can lie on it on the brilliant marble-sanded beaches of Santraginus V, inhaling the heady sea vapors; you can sleep under it beneath the stars which shine so redly on the desert world of Kakrafoon; use it to sail a miniraft down the slow heavy River Moth; wet it for use in hand-to-hand-combat; wrap it round your head to ward off noxious fumes or avoid the gaze of the Ravenous Bugblatter Beast of Traal (such a mind-boggingly stupid animal, it assumes that if you can't see it, it can't see you); you can wave your towel in emergencies as a distress signal, and of course dry yourself off with it if it still seems to be clean enough.”​

 

[AscendDF]

By this time, the conversation with Danny had gotten ugly with him claiming that my measurements are not high resolution

His Clio vs a Klippel NFS, did he seriously say this to you?

 

[Guralex]

GR Research customer support be like

 

[Lunafag]

He doesn't measure below 200Hz so he never saw that.

 

[Penelinfi]

It actually reminds me of a more extreme version of a small Wilson speaker with the ~100Hz peak and lack of baffle step compensation

 

[Soniclife]

That dumpster should be on fire .

This is how I'd rate it.

 

[RickS]

Thanks Amir!

Seems Danny now has a higher priority than that Jamo “upgrade” he still has not resolved.