• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). Come here to have fun, be ready to be teased and not take online life too seriously. We now measure and review equipment for free! Click here for details.

About the "sweet spot"

Theo

Active Member
Joined
Mar 31, 2018
Messages
241
Likes
132
#22
Yeah, you're right, it should come from the sides. You can find a list of all (not many) of the recordings using Qsound. A lot of crap, but now I need to get hold of some of them.
Yeah, it does work somehow after I moved my chair around to the exact "sweet" spot in my room. The effects are indeed wider than the speaker geometry but, in my system, not beyond 180° (nothing in the rear...). I found that the best way to test the process is to use the Qsound demos. Quite immersive actually. Work with my headphones too.
I've had a look at the artists using Qsound and I noticed that most of the records predate year 2000. Obviously, these effects have not been the recording engineers preoccupation recently, probably not adapted to the loudness war trend?
 

jackenhack

Active Member
Patreon Donor
Joined
Oct 25, 2018
Messages
190
Likes
411
Location
Stockholm, Sweden
#23
I've had a look at the artists using Qsound and I noticed that most of the records predate year 2000. Obviously, these effects have not been the recording engineers preoccupation recently, probably not adapted to the loudness war trend?
I think the reason the technology never caught on is that it only works when sitting in the sweet spot. But it's a cool party trick.
 

Sal1950

Major Contributor
The Chicago Crusher
Joined
Mar 1, 2016
Messages
5,379
Likes
2,707
Location
Central Fl
#24
At my main seating area they are 75 degrees apart. I can move to 90 degrees or move backward until they are 40 degrees.
Seems to me the Qsound is more consistent and works best at speaker angles of no more than 60 degrees.
Can we have a chart on that please?
Speaker angles from 0 degrees being straight ahead?
I'm so confused. o_O
 

Krunok

Major Contributor
Joined
Mar 25, 2018
Messages
3,205
Likes
1,557
Location
Zg, Cro
#25
I think the reason the technology never caught on is that it only works when sitting in the sweet spot. But it's a cool party trick.
Sure, it cannot possibly compete with raising loudness technology as that works in the entire room, thus a logical choice from todays recording engineers. :p
 

Blumlein 88

Major Contributor
Joined
Feb 23, 2016
Messages
5,987
Likes
5,219
#26
Can we have a chart on that please?
Speaker angles from 0 degrees being straight ahead?
I'm so confused. o_O
Ok, okay.

The primary LP in my video system has the speakers right and left of the center line by 37.5 degrees or 75 degrees total. At this point the speakers are aimed about at the nearest shoulder of the sweet spot listener. I didn't change any of that listening to the Q sound Roger Waters.

I took a chair and moved forward closer to the speakers so they subtend an angle of 45 degrees each side of the center line or 90 degrees total.

I've got two rows of primary seating as its mostly for theater purposes so the second row is just about a 60 degree total angle for the front speakers.

I've room enough to place a chair further back to the point you get a total angle of only 40 degrees or 20 degrees between the center line and each speaker.

So what I did was simply moving closer to or further from the speakers effectively changing their angle vs my listening position.

Does that make sense?

As as well as subtended angle I effectively changed if the speakers direct line cross in front of, on or behind the listening position.

In any case Q sound didn't seem to work well if the speakers were wider than a 60 degree total angle, and seemed most stable and noticeable at narrower angles.
 

svart-hvitt

Major Contributor
Joined
Aug 31, 2017
Messages
2,244
Likes
1,052
#28
@svart-hvitt, I remember you posted a link to a Genelec presentation on this topic that I'd been meaning to watch but have now lost... Do you remember what it was I was talking about?
@andreasmaaan , sorry for taking so long to reply. I wanted to elaborate on this but I will have to make it «short». I think also @Cosmik may have interest in this answer (from another thread where I didn’t come back to him on the same topic).

It will take a bit of time for you to go through it all but I hope you’ll get my point.

First, take a look at the horizontal/vertical directivity plots of Genelec’s The Ones:

https://www.genelec.com/sites/default/files/media/Studio monitors/SAM Coaxial Studio Monitors/gen_theones_brochure_210x279_12pager_lowres_0.pdf

See how symmetrical they are, and how flat the curves are. The Ones are Genelec’s attempt at point source.

Then, take a look at the same diagram for 8260, page 10:

https://www.genelec.com/sites/default/files/media/Studio monitors/SAM Studio Monitors/8260A/genelec_8240_8250_8351_8260_opman.pdf

8260 was Genelec’s first attempt on coaxial point source and the speaker is a predecessor of The Ones. The mid and tweeter are coaxial but the woofer is mounted below. The diagrams are no longer as beautiful, are they?

Then, take a look at Genelec’s brand new S360, a two-way with compression horn (for high SPL) and a 10 inch woofer, page 9:

https://www.genelec.com/sites/default/files/media/s360_operating_manual.pdf

Even if this is a two-way, which means information summation is easier, it’s clear that the information summation is not as robust off axis as on axis.

Then, take a look at Genelec’s flagship, 1236 (page 7):

https://www.genelec.com/sites/default/files/media/Studio monitors/SAM Studio Monitors/1236A/1236a_operating_manual_0.pdf

This is a full-range speaker, but the off-axis directivity diagram is not beautiful at all.

What we learn from this tour of diagrams is that information summation becomes a problem as soon as you diverge from the point source design. This is not a big problem in a studio where one man sits in sweet spot, and where the room is dead in terms of reverberation from walls. However, in domestic situations, you wish for a wider sweet spot both on and off axis, and you want as little colouration from reflecting sound, right?

In theory, point source is ideal. These diagrams show that Genelec’s point source implementation works. So colouration is minimized, the radiated and reverberated sounds are robust.

Interestingly, very few are interested in point source. And those who use mathematics and physics in other situations, resort to undocumented psychoacoustics («colouration from reverberated sound doesn’t influence perceived sound», etc.) to continue their love affair with traditional driver design. However, if you use a microphone to record the sound in the room - both from a traditional three-way speaker and a point source speaker - you would easily hear how a traditional three-way design colour off axis sound.

Because theory (on point source) and empirical tests (recorded sound in room) support the case of the point source idea, I am baffled that so few wish to hear the sound of a point source and instead continue using legacy design.

Legacy design with conventionally mounted drivers is the ELEPHANT IN THE ROOM.
 

Blumlein 88

Major Contributor
Joined
Feb 23, 2016
Messages
5,987
Likes
5,219
#29
It does. How are your speakers aimed (toed-in)?
Just noticed this question.
The speakers axis would cross somewhere between the 75 degree listening position and the 60 degree listening position. So they cross behind the listener at 75 degree LP and in front of all the others.

Also the speakers in this case are Revel F12s. So they have relatively good directional characteristics though not point source.
 

Krunok

Major Contributor
Joined
Mar 25, 2018
Messages
3,205
Likes
1,557
Location
Zg, Cro
#30
Just noticed this question.
The speakers axis would cross somewhere between the 75 degree listening position and the 60 degree listening position. So they cross behind the listener at 75 degree LP and in front of all the others.

Also the speakers in this case are Revel F12s. So they have relatively good directional characteristics though not point source.
Interesting.. My LP has a total angle toward speakers app 50 degrees and speakers are toed-in to cross at a point which is app 1 meter behind LP. MY speakers are app 4m away from each other and LP is a little more toward each speaker hence the angle is app 50 degrees.

I would like to have my LP at an angle like yours, at 60 degrees or a little more, but it is not possible do to the shape of the room and furniture.

Btw, how are you satisified with Revel F12? :)
 

Blumlein 88

Major Contributor
Joined
Feb 23, 2016
Messages
5,987
Likes
5,219
#31
Interesting.. My LP has a total angle toward speakers app 50 degrees and speakers are toed-in to cross at a point which is app 1 meter behind LP. MY speakers are app 4m away from each other and LP is a little more toward each speaker hence the angle is app 50 degrees.

I would like to have my LP at an angle like yours, at 60 degrees or a little more, but it is not possible do to the shape of the room and furniture.

Btw, how are you satisified with Revel F12? :)
The F12's are fantastic. They get a large portion of the Harman magic. I purchased these, made in the last month of production for a very low price on ebay. They are efficient, very well balanced, and sound good over a wide listening angle. I have a Wyred4Sound ST-500 driving them. Harman is onto something with their design process.
 

Krunok

Major Contributor
Joined
Mar 25, 2018
Messages
3,205
Likes
1,557
Location
Zg, Cro
#32
The F12's are fantastic. They get a large portion of the Harman magic. I purchased these, made in the last month of production for a very low price on ebay. They are efficient, very well balanced, and sound good over a wide listening angle. I have a Wyred4Sound ST-500 driving them. Harman is onto something with their design process.
I thought so. :)

Have you applied room EQ with them?
 

andreasmaaan

Major Contributor
Patreon Donor
Joined
Jun 19, 2018
Messages
3,517
Likes
2,702
#33
@andreasmaaan , sorry for taking so long to reply. I wanted to elaborate on this but I will have to make it «short». I think also @Cosmik may have interest in this answer (from another thread where I didn’t come back to him on the same topic).

It will take a bit of time for you to go through it all but I hope you’ll get my point.

First, take a look at the horizontal/vertical directivity plots of Genelec’s The Ones:

https://www.genelec.com/sites/default/files/media/Studio monitors/SAM Coaxial Studio Monitors/gen_theones_brochure_210x279_12pager_lowres_0.pdf

See how symmetrical they are, and how flat the curves are. The Ones are Genelec’s attempt at point source.

Then, take a look at the same diagram for 8260, page 10:

https://www.genelec.com/sites/default/files/media/Studio monitors/SAM Studio Monitors/8260A/genelec_8240_8250_8351_8260_opman.pdf

8260 was Genelec’s first attempt on coaxial point source and the speaker is a predecessor of The Ones. The mid and tweeter are coaxial but the woofer is mounted below. The diagrams are no longer as beautiful, are they?

Then, take a look at Genelec’s brand new S360, a two-way with compression horn (for high SPL) and a 10 inch woofer, page 9:

https://www.genelec.com/sites/default/files/media/s360_operating_manual.pdf

Even if this is a two-way, which means information summation is easier, it’s clear that the information summation is not as robust off axis as on axis.

Then, take a look at Genelec’s flagship, 1236 (page 7):

https://www.genelec.com/sites/default/files/media/Studio monitors/SAM Studio Monitors/1236A/1236a_operating_manual_0.pdf

This is a full-range speaker, but the off-axis directivity diagram is not beautiful at all.

What we learn from this tour of diagrams is that information summation becomes a problem as soon as you diverge from the point source design. This is not a big problem in a studio where one man sits in sweet spot, and where the room is dead in terms of reverberation from walls. However, in domestic situations, you wish for a wider sweet spot both on and off axis, and you want as little colouration from reflecting sound, right?

In theory, point source is ideal. These diagrams show that Genelec’s point source implementation works. So colouration is minimized, the radiated and reverberated sounds are robust.

Interestingly, very few are interested in point source. And those who use mathematics and physics in other situations, resort to undocumented psychoacoustics («colouration from reverberated sound doesn’t influence perceived sound», etc.) to continue their love affair with traditional driver design. However, if you use a microphone to record the sound in the room - both from a traditional three-way speaker and a point source speaker - you would easily hear how a traditional three-way design colour off axis sound.

Because theory (on point source) and empirical tests (recorded sound in room) support the case of the point source idea, I am baffled that so few wish to hear the sound of a point source and instead continue using legacy design.

Legacy design with conventionally mounted drivers is the ELEPHANT IN THE ROOM.
Thanks @svart-hvitt.

Actually, I recall us having this discussion before now! I'm not quite as sold on coaxials as you are, mostly because I think the disadvantages often outweigh the advantages.

I think I've mentioned before that I might prefer coaxials where there are strong early vertical reflections, e.g. when the speakers are sitting on a desk, but that in a properly setup room I'd probably tend to take a good non-coaxial design for the (all else being equal) lower distortion and higher SPL. YMMV though.... :)
 

svart-hvitt

Major Contributor
Joined
Aug 31, 2017
Messages
2,244
Likes
1,052
#34
Thanks @svart-hvitt.

Actually, I recall us having this discussion before now! I'm not quite as sold on coaxials as you are, mostly because I think the disadvantages often outweigh the advantages.

I think I've mentioned before that I might prefer coaxials where there are strong early vertical reflections, e.g. when the speakers are sitting on a desk, but that in a properly setup room I'd probably tend to take a good non-coaxial design for the (all else being equal) lower distortion and higher SPL. YMMV though.... :)
Genelec go through the history and drawbacks of coaxial designs in the link below. Are there any drawbacks you had in mind that were not addressed in this technical paper from 2009?

https://www.genelec.com/documents/other/Genelec 8260A Technical Paper.pdf

EDIT: I added an AES paper on the Genelec coaxial driver design: https://www.genelec.com/sites/default/files/media/About Us/Academic_Papers/aes_142_makivirta_et_al_paper_95_2017-04-03_v_1.0.2.pdf
 
Last edited:

Theo

Active Member
Joined
Mar 31, 2018
Messages
241
Likes
132
#35
In theory, point source is ideal.
In theory, most certainly. However, the engineering seems far from obvious. Several manufacturers have tried, Tannoy, Cabasse, Devialet to name a few that come to my mind. They don't seem to attract a lot of praise, do they? The Genelec Ones are though. Anyone has tried them?
 

andreasmaaan

Major Contributor
Patreon Donor
Joined
Jun 19, 2018
Messages
3,517
Likes
2,702
#36
In theory, most certainly. However, the engineering seems far from obvious. Several manufacturers have tried, Tannoy, Cabasse, Devialet to name a few that come to my mind. They don't seem to attract a lot of praise, do they? The Genelec Ones are though. Anyone has tried them?
I've hear the Genelec 8531s and also took a few (not comprehensive) measurements. Very capable speakers I thought, although TBH it wasn’t really my cup of tea.
 
Last edited:

Sal1950

Major Contributor
The Chicago Crusher
Joined
Mar 1, 2016
Messages
5,379
Likes
2,707
Location
Central Fl
#37
In theory, most certainly. However, the engineering seems far from obvious. Several manufacturers have tried, Tannoy, Cabasse, Devialet to name a few that come to my mind. They don't seem to attract a lot of praise, do they? The Genelec Ones are though. Anyone has tried them?
Coaxial's seem to be making a minor comeback. The KEF LS50 variations have been very successful and the HSU CCB-8 has been well reviewed.
Time will tell if this resurgence with be long term successful.
 

oivavoi

Major Contributor
Joined
Jan 12, 2017
Messages
1,221
Likes
643
#38
Briefly on dispersion pattern: My experience so far is that there might be a trade-off between laser sharp imaging and wide dispersion/ambience/envelopment. I say "might" because there is very little research on this, and the research that exists points in different directions (some studies claim that early reflections degrade imaging, while others don't find any such effect). I believe that Geddes is about to publish a study on this though.

The trade-off then becomes this, according to my anecdotal experiences: With wide imaging, you can move around without the tonality changing too much, there's a nice and enveloping ambiance to the music, and with true omnis you can get a stereo image between the speakers almost from anywhere in the room. When sitting exactly in the sweet spot though, the stereo image becomes more "airy" and a bit less sharp. With narrow dispersion and/or heavy acoustic treatment, the stereo imaging and often the tonality collapses when you move outside the sweetspot. Music is also more dry and less enveloping. But when sitting exactly in the sweet spot, imaging is more precise.

So what to choose? I think it partly depends on personal preference, and partly on the kind of music one mainly listens to. I listen 80 percent to classical and jazz, and on that kind of acoustic music I find that narrow dispersion and/or no reflections feels sterile and wrong. On electronic and processed studio recordings though, which 99 percent of audiophiles mostly listen to these days, I find that more narrow dispersion feels more correct.

The obvious choice is therefore to have two different systems, one wide and one narrow! Or to choose a boring compromise with speakers that are neither true omnis nor narrow-dispersion speakers. Or multichannel, as has already been pointed out.

PS: I'm also still waiting patiently for the Morrison omnis which I ordered a long long time ago... but which have become heavily delayed due to health issues for the two guys in charge. Everybody who have heard them seems to think that they image just as well - or even better - than narrow-dispersion speakers. We'll see what I think when I finally get them :)
 

Sal1950

Major Contributor
The Chicago Crusher
Joined
Mar 1, 2016
Messages
5,379
Likes
2,707
Location
Central Fl
#39
The obvious choice is therefore to have two different systems, one wide and one narrow! Or to choose a boring compromise with speakers that are neither true omnis nor narrow-dispersion speakers. Or multichannel, as has already been pointed out.
Looks as though the latest path is to use DSP to offer both or multiple options via switching on the same speaker
 

oivavoi

Major Contributor
Joined
Jan 12, 2017
Messages
1,221
Likes
643
#40
Looks as though the latest path is to use DSP to offer both or multiple options via switching on the same speaker
Yap, that's the simplest solution - but also expensive (though two systems also add to the cost as well...). I'm not sure it's a perfect solution, though. Different directivities will frequently require different speaker placements in the room. So to get the most of either speaker-mode - narrow vs wide - the speakers would probably need to be placed differently.

Btw, I've listened extensively to Beolab 90 in narrow, wide and omni mode. I think it's a far better speaker in narrow mode - it's like it's optimized for that kind of dispersion. In wide mode it's ok. In omni mode it's horrendous. That's because the omni dispersion becomes very uneven, and it basically just splashes the sound around in a chaotic manner, unlike proper omni speakers like MBL, German Physiks, Morrison etc. So I have yet to hear a speaker I think is equally adept at narrow and wide dispersion.
 

Similar threads

Top Bottom