Spatial audio speakers

[ctrl]

So despite how counter-intuitive it seems to combine a 15" woofer with a (rather large) dome tweeter, the Spatial Audio M3 is imo an example of how to do it right.

Basically agree with you.

I'm just not sure how the uneven horizontal radiation will affect it.
If you compare the axial frequency response with the deg60 FR, the difference in tonality is not insignificant.
FR deg0 vs deg60 normalized FR deg0 vs deg60

Will the sound tend to be warm or too bright with a high percentage of side reflections?

 

[800]

If you can get past the subjective commentary there are some gated M3 measurements in this video at 24:50.

edit: in room at 6:40.

 

[Duke]

Thank you for finding and posting that, @ntd. Imo worth a look by anyone interested or skeptical.

 

[Alice of Old Vincennes]

To my surprise, I found no measurement results published neither on Spatial Audio website nor on their forum at AudioCircle. Frankly, I cannot believe Clayton does not measure his designs "playing it by ear" instead so to speak...

I wonder why???

 

[Alice of Old Vincennes]

Very illuminating simulation, @ctrl. I had wanted to make a similar analysis just with words, but decided not to because I couldn't back it up with graphs. Thank you very much for taking the time.

Below the crossover frequency the pattern will be the familiar dipole figure-8, with a directivity index fairly similar to what the tweeter is doing north of the crossover frequency, though the radiation pattern shapes will obviously be very different.

In my opinion the different pattern shapes above and below the 575-Hz crossover region won't be a problem. Each is wide enough to provide exceptionally uniform coverage across a 60 degree arc, which should cover the listening area and then some, given proper set-up (which includes some toe-in). There will be significant spectral variation in the individual reflections, but the average spectral balance of the reflections will be unusually smooth. The ear tends to perceive the average spectral balance of reflections over a time interval, rather than the spectral balance of individual reflections. That time interval is in the 10-15 milliseconds ballpark as I recall.

As a result the perceived spectral balance of the reverberant sound (and yes I know the use of this term is problematic in the context of small rooms) will probably track the spectral balance of the direct sound fairly closely over most of the spectrum.

So despite how counter-intuitive it seems to combine a 15" woofer with a (rather large) dome tweeter, the Spatial Audio M3 is imo an example of how to do it right.

I'll bet!

 

[FrantzM]

Are those your words or Clayton's?



You might want to wait until TheInquiring responds to my question before jumping to conclusions.

True ....

 

[JustJones]

I always thought these were interesting speakers. My eyes aren't the best and those graphs on the YouTube video were bit hard to read but it looked like they sort of fell off the map below 100hz. With those big drivers I thought they would go lower or am I missing something?

 

[abhijitnath]

For what it's worth this is what audyssey measured in room for my m3s. It's crossing them over at 60 hz, so they definitely don't fall off below 100 hz.

 

[JustJones]

The video was shaded or grayed out in the low frequencies and I was viewing on my tablet. Very hard to see it.

 

[Duke]

... those graphs on the YouTube video were bit hard to read but it looked like they sort of fell off the map below 100hz.

The greying on the charts presumably indicates that the data below 300 Hz is unreliable, which would make sense to me, given that he's using some sort of time-gated measurement (which captures the speaker's output but excludes reflections). The limiting factor is the minimum reflection path length, which determines how quickly the gating controller turns the microphone off, which in turn determines what the longest wavelength is that can be reliably captured. I use gated measurements and cannot get good data south of 300 Hz indoors.

If he raised the speaker up off the floor to increase the floor-bounce path length (for the sake of his gated measurements) then the effective size of the baffle was cut in half, as when the speaker is on the floor the floor itself effectively "mirrors" the physical baffle. The effective baffle size matters a great deal for a dipole loudspeaker's low-end response. Anyway this would further degrade the reliability of the low-end measurements. (Since he does show "grey zone" data south of 300 Hz I assume that his measurement system uses some kind of "soft" gating.)

Also, he mentions a "resonance" that "disappears" when the microphone is below the tweeter axis. My understanding is that a resonance does not "disappear" in the off-axis measurements, and especially not in a slightly off-axis measurement, as that is one way to identify which on-axis anomalies are resonances and which are not. So if a small on-axis glitch disappears in a slightly off-axis measurement, I really don't think it was a resonance.

 

[Putter]

For what it's worth this is what audyssey measured in room for my m3s. It's crossing them over at 60 hz, so they definitely don't fall off below 100 hz.

It is my understanding that Audyssey doesn't determine the crossover frequency. Rather it's the maker who sets it up in their software. I have JBL E20 speakers in my desktop setup which have 5 inch woofers and a -3db point of 68 hz as per JBL and around 88 hz as per a Sound and Vision test. However my Denon AVR-1610 sets it at 40 hz which I manually reset to 100 hz. This has been my experience with other AV receivers I have with Audyssey and it is mentioned in the Audyssey FAQ.

 

[abhijitnath]

Well, the graph clearly shows that there is output below 100 hz (pre correction) no? Also, I've tried other mains before that it crossed over at 80, so presumably the speaker's response determines the crossover inside Audyssy somewhere?

 

[sfdoddsy]

For what it's worth this is what audyssey measured in room for my m3s. It's crossing them over at 60 hz, so they definitely don't fall off below 100 hz.

Whilst your measurements are obviously from the listening position, they are consistent with those from the review I posted earlier and what I'd suspect from my listening, ie a dip right around the crossover point.

But lets not be overly harsh. I've run some form of open baffle for past 20 years or so, mostly DIY, and you can take it from me how difficult it is to measure them in the way you would a normal speaker.

For example, here's the FR (in Red) of my current open baffles when measured close and EQed to create the sort of response we look for in a box speaker. From the listening position you'd expect even lumpier bass, rolled off treble but the same basic pattern.

Instead, you get the response in Green.

The nasty lower mid-range dip is caused by dipole roll-off of the mid-range which isn't apparent when measured close.

The nasty dip around 1K is caused by over-EQing the dipole peak.

The Harman (or Klippel) theory of flat anechoic response leading to a smooth in room response is problematic with OBs due to the way dipoles interact with the baffle and the room.

The Spatials would be even trickier to measure because, due to the width of the baffle, they are only dipole below about 700hz.

For me the choice with open baffles has always been do you measure and EQ at the traditional close spot, or at the listening position.

Assuming the drivers I use are basically flat, I personally work out the theoretical EQ needed depending on baffle width, drivers and crossover point and then do room EQ at the listening position.

 

[Jokerbre]

Does anyone have a crossover schematic or a picture of a m3 sapphire speaker crossover?

https://www.myaudiophrenia.com/spatial-audio-m3-sapphires/

 

[Jokerbre]

Work in progress...

 

[squeedle]

I'd also love to see proper measurements of Spatial's M or X series. I was able to audition the M3 recently and while I know my opinion is subjective and worthless to most of you, I felt the speakers sounded frigging fantastic. I'm really eager to audition the X series for comparison and then am considering pulling the trigger on one or the other.

 

[Jokerbre]

I played a little and simulated something like this.
2xDeltaLite2515 and Tymphany da32tx00-08
I have DeltaLite2515 when I find some time I will do some proper measurements.

 

[TheInquiring]

I was able to audition the M3 recently and while I know my opinion is subjective and worthless to most of you, I felt the speakers sounded frigging fantastic.

In absence of the proper measurement results, your anecdotal report would be much appreciated. Please chime in!

I'm really eager to audition the X series for comparison...

Please do keep us posted!

 

[sarumbear]

Is there any measurment based on CEA 2034 standard of Spatial auidio speakers ( open baffle speakers from Utah designed by Clayton Shaw) ?

What is a “spatial audio speaker”?

 

[squeedle]

What is a “spatial audio speaker”?

https://www.spatialaudiolab.com
They make open baffle speakers.