AV123 / GR Research X-Voce Speaker Review

[Mnyb]

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.

I think you nailed the main problem

 

[Robbo99999]

Oh no, this GR Research stuff keeps going from bad to worse or worse to bad, can't remember the applicable order!

 

[hmt]

Huh?

Crap speaker can’t get a decent score no matter what you do so the model is bad?

How did you even reach that conclusion?

The EQ no Sub score on this speaker is 7.8. So yes, the model does not apply for EQed speakers. I did not write that the model is wrong. EQed speakers were not in the sample of the Toole/Olive paper which derived this model.

 

[Fidji]

On the other hand - it is safer, when people like Danny work in audio, where nobody gets killed because of bad FR or directivity errors.
Just imagine, he would be upgrading motorcycles ….

 

[Elvom]

I have this center speaker paired with the x-statik fronts(same woofers) and while i really love the x-statik with audyssey eq ive never been happy with the center channel, i guess its time to play around, throw some towels on top of it lol.

(btw x-statik without audyseey sounds boomy too, ive been blaming my untreated room for that)

 

[Ajax]

Linn and Naim was always regarded by our service engineers as very expensive for what was inside.

A true UK story follows and this set the scene for their ludicrously high pricing now - In the early to mid 80's, we being one of the three largest Linn and Naim dealers in the UK at the time, had a number of 'foreigners here on holiday' wanting to buy the gear and take it back to their home countries. Worst of all were European types who were bypassing the local distributors and said distributors started to complain. Letters were sent out reading 'us' the riot act and in Linn's case, not even LP12 update kits were exempt!

So, what to do? As of '85 to '87 or so, the price lists of both Linn and Naim began to have huge increases way over inflation and I think over three years the retail prices od Linn's products increased by around 25%. Naim (and maybe Linn too) continued to have automatic price rises inline with inflation every April 1st (surely not coincidence) for decades after and of course with both makes, a new model was almost always far more expensive than the unit which preceded it, despite prices of components falling as I understood it to be. The reputation of said brands kept the sales going and by the time that vinyl 'died' as a mainstream format in the late 80's, both makes had digital sources (Naim) and electronics with digital on the way (Linn). Things were moving fast with domestic audio here and I was still young enough to regard a year as quite a long time lived. I have to whinge at the Akito tonearm, which started life at around two hundred quid in the late 80's or thereabouts and finished off at nearly SIXTEEN HUNDRED a couple of years ago, albeit supposedly made with better materials than the 'plasticine' originals, the pillars of which being easily crushed (by us ignorant dealers taught to overtighten everything) which knackered the bearings...

Linn didn't really enter the high end 'B&O Catchment' market with solidly milled-out ally cases and so on until the mid noughties by which time I'd left the retail side of the industry. their speakers began to have the tweeter 'array' and the CD12 player had just come out (whatever happened to that £12,000 product and can you get one serviced?).

The above are memories of my experience in the UK scene of course and hopefully reasonably factual. The Linn guys told me in 1987 how bad vinyl was (although their crap was better than everyone else's crap in their opinion) and proved it to me too!!! - But obviously they've improved their vinyl source no end (they really have) with extremely lucrative upgrades every few years to keep the largely now retired but 'comfortably off' faithful on board.

Apologies for going so far off topic. GR Research has little to no presence here apart from Youtube as far as I know.

Hi DSJR,

Thanks for the insight.

I came to London on a working holiday from Aus in 1982 and was one of those that purchased a Linn LP12 together with a small 40W Naim Nait amp. A couple of years later I upgraded to a Linn L1 & L2 amp combination.

I remember going into Grahams HiFi and listening to Dire Straits "Love over Gold", while sitting in these lovely big chairs, and being absolutely smitten by the sound. It is unbelievable how easily I was led to spend GBP3,000 to buy something I couldn't afford. I was naive to the extreme, but loved the system and when I got back to Aus I hooked it up to a pair of huge Tannoy Arden speakers that my brother had built for him by Krix (who were just starting out and are now a large Aus speaker manufacturer). The Arden had the 15" concentric drivers.

Tannoy | Not Found

www.tannoy.com

I was in London for a year and worked as an engineer for a demolition contractor in Tottenham Court rd, which only just covered my rent so I coached tenis at night

Thanks for reviving some great memories.

Ajax

PS .. apologies for the off topic

 

[lc6]

Danny does not seem to use any sophisticated measurement tools like Klippel to evaluate non GR Research speakers that he aims to "improve" by redesigning their crossovers, "upgrading" the caps (from the "dismal" electrolytic ones), inductors (from "awful" iron core ones for midranges and tweeters), interior wires (from "bad" PVC insulated ones), binding posts and nuts (from "unacceptable" steel ones, claiming dubious audible deterioration of sound due to their "magnetic" properties), etc. All this brings into question any value of his work. It seems like a niche effort to peddle "upscale" components at a substantial markup. And, based on this review, this approach seems to have propagated into his own product.

 

[poxymoron]

What a mess, but what an effort @amirm ,thank you.
I'm an architect with no speaker building experience, and I do okay, but I've made my decision. I'm going to build speakers.

 

[Elvom]

now i remember someone saying inverting the speaker improved the sound(grill at botom covered by the stand), now it makes some sense

 

[rynberg]

Then again, this is a center channel mainly for intelligibility..............

Sigh, that wasn't even true in the early '90s during the Dolby Pro-Logic days. For film/TV, the center channel carries more content than any other channel, including virtually all dialog and a lot of full-range music and effects. For multi-channel music, obviously the center must have the same fidelity as the L+R.

 

[DSJR]

Hi DSJR,

Thanks for the insight.

I came to London on a working holiday from Aus in 1982 and was one of those that purchased a Linn LP12 together with a small 40W Naim Nait amp. A couple of years later I upgraded to a Linn L1 & L2 amp combination.

I remember going into Grahams HiFi and listening to Dire Straits "Love over Gold", while sitting in these lovely big chairs, and being absolutely smitten by the sound. It is unbelievable how easily I was led to spend GBP3,000 to buy something I couldn't afford. I was naive to the extreme, but loved the system and when I got back to Aus I hooked it up to a pair of huge Tannoy Arden speakers that my brother had built for him by Krix (who were just starting out and are now a large Aus speaker manufacturer). The Arden had the 15" concentric drivers.

Tannoy | Not Found

www.tannoy.com

I was in London for a year and worked as an engineer for a demolition contractor in Tottenham Court rd, which only just covered my rent so I coached tenis at night

Thanks for reviving some great memories.

Ajax

PS .. apologies for the off topic

Ah, Tannoy 'Ard-ons' - big and LOUD I remember...

 

[defec1]

Hi, did you happen to check if either of the woofers had any coil rub?

 

[Jon AA]

The EQ no Sub score on this speaker is 7.8. So yes, the model does not apply for EQed speakers. I did not write that the model is wrong. EQed speakers were not in the sample of the Toole/Olive paper which derived this model.

There's no reason the model wouldn't apply to EQd speakers exactly the same way it applies to any speaker--provided the speaker is physically measured with the EQ in place. Many speaker flaws, like cancellations, do not respond well, if at all, to EQ. So a nice smooth line in REW may never actually happen in the real world.

That's why I would be very skeptical of EQ scores, particularly in cases like this, as that not how it is usually derived when people cite it.

 

[Blumlein 88]

I don't know about the emperor, but Danny has no clothes.

Way to go on this one Amir!

 

[Endibol]

I was thinking the same thing, I have gotten rid of two things that tested badly. I always feel kind of bad for the very generous person that sends something in and it warrants scorn. You can even see your beloved center speaker in a dumpster. Good photoshop BTW. Perhaps if this is in your system and it's all you know it might sound pretty good to you. Until you get something that is actually really good.

Who says it was photoshopped?

 

[thewas]

The EQ no Sub score on this speaker is 7.8

I see 7.8 score with both sub and EQ? https://www.audiosciencereview.com/...rch-x-voce-speaker-review.49563/#post-1776516

 

[hmt]

There's no reason the model wouldn't apply to EQd speakers exactly the same way it applies to any speaker--provided the speaker is physically measured with the EQ in place. Many speaker flaws, like cancellations, do not respond well, if at all, to EQ. So a nice smooth line in REW may never actually happen in the real world.

That's why I would be very skeptical of EQ scores, particularly in cases like this, as that not how it is usually derived when people cite it.

The model has not been tested with EQed speakers so there is all reason to doubt. Btw one reason is that the on axis response is weighted quite heavily in the score. The rationale is that uneven response and jaggyness is seen as a proxy for resonances. That assumption does not hold when you use EQ. You would have to use a more complicated indicator for resonances. This is not new. The doubts of the model wrt EQ have been discussed before.

 

[hmt]

I see 7.8 score with both sub and EQ? https://www.audiosciencereview.com/...rch-x-voce-speaker-review.49563/#post-1776516

Typo. Of course I meant w sub.

 

[amirm]

Hi, did you happen to check if either of the woofers had any coil rub?

I just did and there is no rub of any sort.

 

[defec1]

Thanks Amirm, I figured that it was worth checking due to being a older used speaker.