waiting game now for the reviews. the design's along the lines of perlisten speakers. Also, i'm not sure why time alignment is required as most are going to use these speakers with avrs that have some sort of room correction and time alignment built in
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SVS Ultra Evolution
- Thread starter CleanSound
- Start date
The science behind the shape is time alignment of the drivers. Dunlavy used it, Duntech, Focal, many companies that have time aligned drivers other than coax, are in this configuration. When I saw them the first thing I said was "Oh, they're going for time alignment". Now test will tell if they've succeeded.
If you can time align physically, that's one less piece of DSP that's needed.....right?
OP
- Thread Starter
- #24
Because this is ASR, I will abide by the "science is king" mantra. As such, science requires scientific explanation with data and scientific evidence, so I'm going to politely ask you to kindly share the scientific study/analysis with data for this.
Particularly I keep hearing Erin from Erin's Audio Corner stating this, and I think Erin has earn his credibility (though, not full on authority. . .not yet at least).
Also, being on ASR can be a double edge sword, I have in few cases where other members made statements/claims with insufficient science and data but with a tone of authority and because this is ASR, where I naturally assumed that anyone commenting with a tone of authority are indeed legit authority. . .but to only lately fact check, they are incorrect and then they don't even reply back to my fact check.
Of course I am not accusing you of this, but I am also not buying it until demonstrated with science and data.
Respectfully yours.
It's a 90's era solution. The drivers are aligned....for one point in space. This is not special; by definition all speakers have some point in space where the drivers are playing most in-phase, ideally this point is more or less where the listener should be.
The angling of the drivers is purely scientistic. The one driver that actually should be angled, because it has narrow enough radiation to matter, is the tweeter, which is ironically the one driver which points directly out. It's probably placed too low in the smaller designs, if you really were targeting perfection. The woofers could literally be facing 90 degrees in any direction and depending on the crossover point it might not make a difference.
It is not a contemporary speaker design, it is designed to appeal to the understanding of audio consumers who read hifi magazines in the 90s. The fact that they market a 'diamond coated' tweeter but neglect to shape the acoustic loading of the tweeter says it all. At least Dunlavy made a makeshift waveguide out of felt - but Dunlavy was a true, no compromise speaker, for better or worse.
I don't care about the angling, I'm interested in the implementation of the rear firing woofers on the towers. Would love if it allowed close placement to the front wall and could fill the front wall SBIR.
I'm also not convinced a waveguide is needed for high fidelity. For example, I see no advantage here in the waveguided directivity vs. flat baffle:
I'm also not convinced a waveguide is needed for high fidelity. For example, I see no advantage here in the waveguided directivity vs. flat baffle:
In Passive designs, it’s the XO network that would be used to do this.
In theory, if they are physically aligning acoustic centers of the drivers, it should simplify some aspect of the XO.
In practice?
…We’ll see.
while, that really isnt a problem due to xo or room correction. I'm still super excited about this speakers. SVS seem to have put everything they can think of into a speaker.
no doubt these will be extensively reviewed and so we'll know soon enough as to what part of the design pays off vs what doesnt
MAB
Major Contributor
I am not clear on when Erin said this. Can you post a link? I have heard 5cm as a minimum before a rear port starts unacceptably interacting with the back-wall, for instance. Without EQ many speakers will be bass-heavy as you move them closer to the wall, but that is not a reason to necessarily keep them away.
Do you have a physical reason that leads you to believe that a port interacts with a wall at distances greater than a few times the port's radius, let alone "at least 3 feet"? I have to ask since another part of ASR is having a testable hypothesis!
I can think of two, one is a change in the effective volume of air that is in the port. The other is blocking the port in a way that introduces chuffing and other turbulent behavior.If you think about it, the wall will eventually form an extension of the port, and the mass of the air now moving and the springiness of the air is different than the port in free space. But that is really only going to happen at super close distances where the wall along with the back side of the speaker act as an extension of the port's air mass, like this:
A change in the effect mass in the port will show up in the impedance measurement and should be modulated by the distance from port to wall. The impedance measurement will neutralize any impact of room mode, SBIR, etc. as Steve Dallas mentioned.
I have two woofers in boxes, one is a Paradigm 8" woofer with a 2" diameter port, the other is a 10" with matching passive radiator, both boxes allow me to adjust the position of the port or radiator relative to a back wall. The physics of a passive radiator are similar to a port minus the port noise, with the mass of the radiator being roughly equivalent to a volume of air in a port of the diameter of the radiator (i.e. a really huge port).
First the 8" ported Paradigm woofer:
No change in impedance until the port is less than 2.5cm to the back wall.
The Seas L26 passive radiator:
No change until below 5.0cm.
I don't observe the wall loading the woofer + box resonance until the port is extremely close. I'm not surprised, hard to imagine the wall affecting the mass of air in the port substantially. Summary, I am not sure why 3 feet is a minimum for a rear-ported speaker. I have speakers with rear ports and I have never noticed an issue close to the wall.
Obviously, I'm not testing for port non-linearities and noises. Maybe some really poorly designed ports can have enough high frequency resonances that the back wall reflections can be problematic? If so, get a speaker with a better port!
Edit: A couple typos.
Another edit: to clarify what woofer is tested!
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OP
- Thread Starter
- #30
Thank you MAB, I'll make sure to take my time to read this later. It looks like you put a lot of effort into this, so I am looking forward to reading this and learning. Erin said "typically at least 3 feet away from the wall" and 4 is even better, that has to do with with bass stacking if I remember correctly. This statement is sprinkled across several videos, I have would have to rewatch a lot of those videos and capture the timestamp, I'll see if I can look for those videos.I am not clear on when Erin said this. Can you post a link? I have heard 5cm as a minimum before a rear port starts unacceptably interacting with the back-wall, for instance. Without EQ many speakers will be bass-heavy as you move them closer to the wall, but that is not a reason to necessarily keep them away.
Do you have a physical reason that leads you to believe that a port interacts with a wall at distances greater than a few times the port's radius, let alone "at least 3 feet"? I have to ask since another part of ASR is having a testable hypothesis!
If you think about it, the wall will eventually form an extension of the port, and the mass of the air now moving and the springiness of the air is different than the port in free space. But that is really only going to happen at super close distances where the wall along with the back side of the speaker act as an extension of the port's air mass, like this
View attachment 342467
A change in the effect mass in the port will show up in the impedance measurement and should be modulated by the distance from port to wall. The impedance measurement will neutralize any impact of room mode, SBIR, etc. as Steve Dallas mentioned.
I have two woofers in boxes, one is an 8" with a 2" diameter port, the other is a 10" with matching passive radiator, both boxes allow me to adjust the position of the port or radiator relative to a back wall. The physics of a passive radiator are similar to a port minus the port noise, with the mass of the radiator being roughly equivalent to a volume of air in a port of the diameter of the radiator (i.e. a really huge port).
First the Paradigm:
View attachment 342479
No change in impedance until the port is less than 2.5cm to the back wall.
The Seas L26 passive radiator:
View attachment 342480
No change until below 5.0cm.
I don't observe the wall loading the woofer + box resonance until the port is extremely close. I'm not surprised, hard to imagine the wall affecting the mass of air in the port substantially. Summary, I am not sure why 3 feet is a minimum for a rear-ported speaker. I have speakers with rear ports and I have never noticed an issue close to the wall.
Obviously, I'm not testing for port non-linearities and noises. Maybe some really poorly designed ports can have enough high frequency resonances that the back wall reflections can be problematic? If so, get a speaker with a better port!
Edit: A couple typos.
Fwiw, I’ve talked to several designers that generally agree on 2x port diameter as absolute minimum distance to the wall.I am not clear on when Erin said this. Can you post a link? I have heard 5cm as a minimum before a rear port starts unacceptably interacting with the back-wall, for instance. Without EQ many speakers will be bass-heavy as you move them closer to the wall, but that is not a reason to necessarily keep them away.
Do you have a physical reason that leads you to believe that a port interacts with a wall at distances greater than a few times the port's radius, let alone "at least 3 feet"? I have to ask since another part of ASR is having a testable hypothesis!
If you think about it, the wall will eventually form an extension of the port, and the mass of the air now moving and the springiness of the air is different than the port in free space. But that is really only going to happen at super close distances where the wall along with the back side of the speaker act as an extension of the port's air mass, like this
View attachment 342467
A change in the effect mass in the port will show up in the impedance measurement and should be modulated by the distance from port to wall. The impedance measurement will neutralize any impact of room mode, SBIR, etc. as Steve Dallas mentioned.
I have two woofers in boxes, one is an 8" with a 2" diameter port, the other is a 10" with matching passive radiator, both boxes allow me to adjust the position of the port or radiator relative to a back wall. The physics of a passive radiator are similar to a port minus the port noise, with the mass of the radiator being roughly equivalent to a volume of air in a port of the diameter of the radiator (i.e. a really huge port).
First the Paradigm:
View attachment 342479
No change in impedance until the port is less than 2.5cm to the back wall.
The Seas L26 passive radiator:
View attachment 342480
No change until below 5.0cm.
I don't observe the wall loading the woofer + box resonance until the port is extremely close. I'm not surprised, hard to imagine the wall affecting the mass of air in the port substantially. Summary, I am not sure why 3 feet is a minimum for a rear-ported speaker. I have speakers with rear ports and I have never noticed an issue close to the wall.
Obviously, I'm not testing for port non-linearities and noises. Maybe some really poorly designed ports can have enough high frequency resonances that the back wall reflections can be problematic? If so, get a speaker with a better port!
Edit: A couple typos.
Last time I heard Erin mention his preference in a video, it seemed much further in the room, like 2-3’; preference is of course different than minimal functional difference.
MAB
Major Contributor
Got it.Fwiw, I’ve talked to several designers that generally agree on 2x port diameter as absolute minimum distance to the wall.
Last time I heard Erin mention his preference in a video, it seemed much further in the room, like 2-3’; preference is of course different than minimal functional difference.
Is his preference due to concern that the port somehow has odd behavior in proximity to a wall?
I hear speaker placement warnings and guardrails so often, I often don't know who said what!
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Focal shape without the bright colors. As for measurements, you don't know until you try.
My take has been that it is subjective preference based on what created the best SQ in his rooms.
It would be interesting to know if he ever does REW or OmniMic measurements in room just as a reference point. I’m certain that’s the last thing he wants to do while also running the Klip.
Can’t say as I blame him, either!
Steve Dallas
Major Contributor
Easy, although a bit imperfectly...
Here is an in-room FR graph of a rear-ported Philharmonic BMR placed just to the right of a front-ported F206. Both cabinets are of similar depth, and both have ~3" ports. The port tuning frequency is lower in the BMR. Both speakers were placed with the back surface of the speaker 6" from the front wall. This is a bit imperfect since they were next to each other, and the BMR was closer to the right side wall, ~28" away, whereas the F206 was ~37" away. Had I carefully replaced one with the other, all of the room modes and nulls below Schroeder of 213Hz would align nearly perfectly (I have tested that before, and it was a near perfect match.)
As you can see, the 47Hz mode lines up almost perfectly with very little difference in amplitude. (Perfectly level-matching speakers in a room is very difficult, therefore the relative amplitudes are not exact) The next peak at 85Hz shows some difference, but it is shifted and amplified in the BMR by side wall proximity. Imagine a summation of sorts of the two F206 peaks, and the two speakers would again align almost perfectly. SBIR is at ~152Hz, and the speakers begin to track very well as they fall into the SBIR region beginning around 120Hz. There is no significant difference here than cannot be explained by differences in side wall proximity considering the wavelengths involved.
Where is the sonic boom that is supposed to be realized by pushing a rear-ported speaker close to the front wall? It exists in the same realm with silk dome tweeters sounding soft and silky, metal dome tweeters sounding hard and metallic, ribbon tweeters sounding airy, pulp cone woofers sounding woody and reedy, polyester film capacitors sounding plastic-y, etc. That is to say in false internet lore. It simply is not true.
The only way it happens is when the rear-ported speaker is pushed right up against the wall where the space between the rear surface of the speaker and the surface of the wall becomes and extension of the port and changes the tuning frequency. That situation is rare, and the simple solution is to pull the speaker out a few inches.
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OP
- Thread Starter
- #37
I don't know if this is a good test to prove front ported vs. rear ported speaker makes no difference, the fr is based on two different speakers, granted both measured relatively very flat.
And if you take the same rear ported speaker and measure it with different distance from the wall, the measurement will naturally changed due to the room.
I don't have enough expertise to say this method is neither good nor bad.
Steve Dallas
Major Contributor
- The myth states, "You cannot place a rear-ported speaker close to the front wall, because the bass will be too boomy."
- The hypotheses is there is no real difference; boundary gain and cancellation will be similar, because these are dictated by physics, not what someone on the internet thinks will happen.
- The test proves there is no significant difference in boundary gain nor boundary interference--even in an imperfect comparison.
- The conclusion is the myth is busted.
How did this test come about? I have heard the myth repeated hundreds of times, yet in setting up dozens of sets of speakers for people in listening rooms, home theaters, project studios, etc. I never once found it to be true. So, while I had 2 speakers that were similar enough side-by-side in the same room, I decided to test it as well as possible without dislodging the main speakers. I make no claim this is a great scientific test. It simply is good enough to prove to ME that no further investigation is necessary.
I understand your desire to appeal to authority, but no expert is correct about everything. They are open to the power of suggestion just like everyone else.
OP
- Thread Starter
- #39
Very logical and fair enough.
MAB
Major Contributor
Yes, we both showed different aspects of the same thing. The impedance characteristics of the port's contribution isn't problematic until very close to the wall, like a few cm or a couple port diameters, and that Genelec and other advice that it is 5cm is totally consistent. The impedance misses the response but factors out the room. Your traces evaluate no problems with the response, but do have to deal with the room. While neither of us can say what the optimal distance is or the exact minimum, the absurd (and it is a bit absurd) assertion that a port needs to be 3 feet from a wall is... absurd. After all, most ports are less than 3 feet from the floor, which is no different than a back wall.
The problem is people come here and expect science and measurements to be clean and devoid of any real-world artifacts. They get others to measure or represent data, then pick it apart, ignore obvious things (like how a port works), and often run with their own conclusions.
edit: typo
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