Dear CKKeung, likewise it's great to hear from another HK-based audiophile. Thanks for your post and photos - wow, that looks more like a wizard's cave (than a dedicated listening room)! Reading the instruction manual for the AVAAs, they specifically advise against stacking them, as well as placing multiple units in close vicinity to each other, because of potential negative feedback consequences, as well as they physics of standing waves which are best dealt with multiple corners and locations in a distributed layout. Why then is your friend going against recommendations? Has he had the chance to experiment with multiple configurations? Also, it appears that the room size/volume is insufficient to accommodate high amplitudes of deep bass produced by the four 18" drivers which in turn result in gigantic amounts of pressure, especially at boundaries where velocity go to zero. Why are subwoofers even necessary, when the horn speaker system (presumably) already has its own bass units? I very much doubt that even twenty AVAAs can neutralize the incredible (and excessive) amounts of standing waves. BTW the local dealer of the AVAAs have submitted their unit(s) for review by an audiophile magazine and currently can't do a demo. I'm highly interested in buying at least two AVAAs for my room, but I guess I'll have to wait a bit longer for a chance to check them out.
Dear CKKeung, likewise it's great to hear from another HK-based audiophile. Thanks for your post and photos - wow, that looks more like a wizard's cave (than a dedicated listening room)!
Reading the instruction manual for the AVAAs, they specifically advise against stacking them, as well as placing multiple units in close vicinity to each other, because of potential negative feedback consequences, as well as they physics of standing waves which are best dealt with multiple corners and locations in a distributed layout. Why then is your friend going against recommendations? Has he had the chance to experiment with multiple configurations?
Also, it appears that the room size/volume is insufficient to accommodate high amplitudes of deep bass produced by the four 18" drivers which in turn result in gigantic amounts of pressure, especially at boundaries where velocity go to zero. Why are subwoofers even necessary, when the horn speaker system (presumably) already has its own bass units? I very much doubt that even twenty AVAAs can neutralize the incredible (and excessive) amounts of standing waves.
BTW the local dealer of the AVAAs have submitted their unit(s) for review by an audiophile magazine and currently can't do a demo. I'm highly interested in buying at least two AVAAs for my room, but I guess I'll have to wait a bit longer for a chance to check them out.
Why my friend installed such a huge horn with gigantic subwoofers inside a relatively "small room"?
I guess he had trusted the local dealer and that those horn+subwoofer was a set.
He did mention to me that he regretted to have bought them and it took him huge amount of energy and time and further investment to make it to the current reasonably listenable state.
The obvious lesson to learn is : don't be too ambitious.
The AVAA local dealer is in fact his friend and both of their offices are nearby.
Using 4 AVAAs seemed to be agreed by the local dealer.
You may ask the dealer why 4 are needed and why they are in stacked placement.
I think your plan of using 2 AVAAs at the front corners is a very good starting point.
Please update WBF members on the improvement they bring about.
I bought two AVAAs (in white), and have placed them against the front wall behind the loudspeakers at its rear perimeter. Relative to the bottom woofer’s surround, the units sit 3-4 ft laterally, and 5-6 ft rearward - or about 6-7ft diagonally. Immediately apparent was the cleansing of the full spectrum of sound from top to bottom, with cleaner articulation of vocals and even percussion instruments in the mid/high frequencies. And for the low frequencies, WOW! Bass instruments were released from their anchor of being localized to the general vicinity of either the left and right loudspeakers. It was now free to occupy a location and size/volume naturally appropriate for the recording, not just laterally between the two speakers, but also in depth, width, and incredibly, even in height ! The boundaries of the soundscape now extend ever more deeply behind the speakers, expanded into an imaginary space with a volume which has now doubled.
The beauty of these AVAAs is that they are small, unobtrusive, and maintenance-free; essentially, just turn them on, place them in a spot where pressure is high, and just forget about them.
As more units are added around the room’s corners, I believe their benefits become additive in perhaps an exponential manner, rather than marginally or even just linearly, as the benefits of standing wave removal reinforce each other.
I’m inclined to purchase two more units, to be placed along the rear wall of my listening space. They are that good, even in a initial placement which was rather haphazard.
Yes, the user's manual doesn't really explain the subtleties of intermediate settings on the rotating potentiometer, only that as long as there aren't signs of feedback, one should peg it in the maximum position. One of the benefits of the reduction of standing waves is that bass articulation improves just about everywhere in the listening room - not just in the sweet spot. Instead of an omnipresent and amorphous blob/rumble which is typical of a room with no dedicated (tuned) bass traps, one can actually hear, feel, and follow tuneful low frequency notes in most all of the room as they anchor and drive the music along. Too bad the MSRP for the AVAA has crept up since its introduction, from US$2,000 at its debut in 2016 to what is now about US$2,700 now. One needs to evaluate whether US$10,000 is a worthwhile expenditure, as I think in a decent-sized listening room, four are needed. As with many things audiophile-related, it may boil down to the cost/performance ratio. For my system, the AVAA brings me so much closer to the proverbial Holy Grail, so it's worth it!
What is the ceiling height in your listening space?
Perhaps not so surprisingly, a lot depends on the physical space - the smallest dimension, the ceiling height, sets the stage for the peskiest of resonances - standing waves in the upper bass and its multiples which reach into the midrange, as well as floor-to-ceiling “bounce”.
It seems that while the 48ft dimension (presumably the width) is quite adequate to support fundamental wavelengths as low as 24Hz.
The 18ft dimension (presumably the depth) is equal to a full wavelength of a 63Hz, which seems a wee bit constraining.
If by chance your ceiling height is 9ft, that would be an exact multiple of 18ft, which can potentially propagate some really nasty standing waves.
My listening space is quite complex - essentially, my system is placed along the long wall of a large space which includes the living room, study room, and dining room.
Apart from structural walls, pillars, and beams, the entire area is "open", ie. there are no walls which trap the sound into an area smaller than the largest perimeter which circles all of the living, dining, and study areas.
So I'm lucky to have a tall ceiling of nearly 10 ft. (a rarity in space-constrained Hong Kong), a decent depth of 22 ft., and a generous width of 32 ft.
Some say that the absence of side walls, as well as side wall symmetry will not support good soundstage imaging, but I have not found that to be the case - perhaps due to the extensive treatment of all near field boundaries with generous amounts of Quadratic diffusors (P-17 for the front wall, and P-13 for the ceiling), as well as diaphragmatic bass absorbers tuned to 40-80 Hz for the immediate vicinity of the loudspeakers, as well as others on the ceiling tuned to 80-120Hz. Collectively, the quadratic diffusors and diaphragmatic absorbers on the front wall which can be seen on my profile photo weigh over a ton; the ceiling diffusors and absorbers, together with the mounting lattice of I-beams, weigh another ton. It seems that few audiophiles actually put this much effort into engineering their listening space for optimal acoustics as I have.
A picture is probably worth a thousand words, but in its absence, here are some dimensions (the major dimensions are in BOLD):
Ceiling height throughout: 9.94ft
Depth of the listening space (front wall to back wall): 22.0 ft
Width of the porous semi-enclosed listening space (study area) which the speakers "fire" into: 13.9 ft
Width of the listening space (inclusive of the balcony extension seen to the R from the listening seat): 19.4 ft
Additional width of the listening space (inclusive of the space to the entrance door, seen to the L from the listening seat): 12.6 ft
Full width of the space (immediate lateral L and R boundaries seen by loudspeakers): 32.0 ft
The sofa (listening spot) is placed at a distance equal to 2/3 (from the front wall) and 1/3 (from the rear wall), ie. 14.666 ft and 7.333 ft
All rooms have nodes, just stand in any corner of a room to hear.
As a simple exercise, use this calculator to approximate your room as a rectangle to see what nodes are present. Purely mathematical, it obviously won't take into account any furnishings or complicated shapes. It will however let you gain an insight into how sound is behaving in your room.
Accurate measurements are the key once your system is set up.
QuadD, I've managed to wrangle as good a raw space as I could reasonably hope for.
18' wide, spkrs 8' apart, 3.5' to each side wall, 9' to front wall.
I sit 12'-13' from the spkrs, and so 15' to back wall (room 38' deep, plus 10' extra alcove to one side).
My complexity, if it indeed is one, is my ceiling. The room is in my roof space, hence I have 30 degree descending eaves R and L.
My midline apex max ht is 9' dropping down each side to 4' high side walls (18' apart).
What's fascinating is that what I strongly suspected might have been a massive disadvantage to SQ ie the descending eaves, may well have actually contributed to what has turned out to be very good SQ indeed.
My sound is infinitely better than my old harsh and strident 27x22x13 space.
And with my subs FINALLY dialled in properly, I'm not overanalysing my sound at all anymore.
I have been told in no uncertain terms that my eaves by definition must be detrimental, yet I'm really not picking up on that.
Similarly, w my subs going into 20's Hz, and the sheer size of my room suggesting the need for corner bass management, yet my sound being the best it's ever been in the lower frequencies, I'm at a slightly unsure juncture in how I should go from here.
How envious! Given your layout, it’s less likely that problematic standing waves will develop; the non-parallel geometry of the sloped ceilings, and the massive spacial volume which allow bass pressure to vent away. Try crawling around on your knees to locate problematic wall/floor junctures (with bass warble tones playing on repeat in the background). Two AVAAs may be all you need, if any at all.
QuadD, my current room, even in its "raw" untreated state, proved to be vastly superior to my old room that had multiple GIK bass traps and side walls reflection points panels.
And 18 months into getting to know the room and fine tuning my system, it's not immediately apparent that the room needs treating.
But the good news is I can probably get a couple of AVAAs on a trial basis and just play w them.
My idea is to, if needed, have a couple of bass traps in the front corners, either these AVAAs or ASC tubes, maybe a 6'x6' area of diffusers on the central front wall, side walls reflection points, and reflection points on eaves.
I don't want to do anything to overtreat or compromise an already warm and expressive acoustic.
Received my third and fourth AVAAs; pretty happy so far, having placed them around multiple corners in my asymmetric listen room. Initial impressions were that the quantity of bass decreased moderately (as expected). Remedied it by increasing my speakers' bass output by +1dB through their active bass amp. Next step: using my Trinnov Amethyst to measure the magnitude of decrease in bass energy through the reduction in bass hangover, and apply a new correction filter using the fresh room measurements.