Sub excursion vs ESL panel

[GranteedEV]

So if I'm understanding things correctly (correct me if I'm wrong), you take that 12" woofer, put it in a box, in a room, and that 70mm excursion figure disappears.

It becomes about 26mm peak-to-peak. In other words - Xmax = 13mm

You then add in room gain at low frequencies and that 5mm peak-peak excursion ESL panel is starting to look worse for wear?

Assuming the ESL panel can actually pull off an excursion of 2.5mm/5mm Peak-to-peak. Who knows if that's even a safe assumption???

Plus, as you mentioned, the roll-off profile becomes very steep at very low frequencies for the panel, vs the monopole sub.

18db/oct for a dipole or cardioid, and 12db/oct for a sealed monopole.

A vented or tranmsision line enclosure will roll off 24db/oct eventually but will extend response much lower than sealed before that happens.

The cardioid and sealed will benefit from room gain. The vented and TL will benefit from room gain down to its tuning but not below. The Dipole will not benefit from room gain.

So in reality, you take that 28mm total movement, add in all the factors above and it's much closer than he made it out to be?

Yes. ESLs might have great sounding bass above 100hz. But they are at a big disadvantage to a monopole below that range give or take.

 

[Vaughan Odendaa]

It becomes about 26mm peak-to-peak. In other words - Xmax = 13mm

How did you calculate that?

 

[GranteedEV]

How did you calculate that?

I threw it into Linkwitz SPL_Max worksheet. I might have made an error here or there because I don't quite understand what the effective path difference exactly is. But i'm pretty confident that if I'm wrong, it would be LESS in favor of the dipole to the extent that the monopole then only needs 6mm instead of 13.

 

[Vaughan Odendaa]

So 26mm peak travel is sufficient for a monopole sub to match the ESP panel until frequencies go very low, then room gain takes over and it's a walk-over, pretty much.

 

[Vaughan Odendaa]

These are the speakers apparently :

Pretty darn big. It would be interesting to calculate the 18 dB drop point, but I would imagine it's at a pretty low frequency given the huge baffle size.

 

[GranteedEV]

Yes they are 20" wide which on paper would lower their dipole frequency nicely. But they are also only around 82db/w/m. How much power can they handle thermally? Do they ACTUALLY have 5mm of peak to peak excursion or is it closer to 2mm?

 

[Hocky]

Looking at my ESL panels, I highly doubt that they even have 2.5mm xmax, let alone 5mm. They don't play well deep, so there is no reason to even compare them at that. Throughout the rest of the range, my panels are quite dynamic, reasonably sensitive, and will play louder than I have ever cared to turn them up in to in my large room.

 

[pureiso]

The issue I have with this comparison is it is set up to fail. Any open baffle setup for lower frequencies needs to have 2-4x the normal amount of woofer area due to the issues explained in here. Since you will not have porting or sealed cabinets helping to get down low, you have to do almost exactly what he is asking for which is more surface area.

However, to get extremely low in LF response on an open baffle you need both surface area and extreme amounts of watts (or higher sensitivity), which ESLs fail the last part. The benefits of an open baffle of course is it has less room interaction, which for low frequencies is not a bad idea. Those are really hard to treat, so instead of accepting that you add 4x the cost and a really heavy amp.

Hopefully this is not off topic, but it makes sense to me to clarify some of the issues with the initial argument.

 

[Irvrobinson]

For ESLs to reach low, you need really big ESLs, like these Sound Lab 945PX.

Still, they don't play nearly as loud as cone speakers in cabinets that cost only half as much. And they look much bigger in person than they do in a picture.

 

[Vaughan Odendaa]

Yes they are 20" wide which on paper would lower their dipole frequency nicely.

You probably wouldn't know at what frequency roll-off would occur at 18 dB per octave?

 

[Vaughan Odendaa]

That same guy rebutted with :

ESL panels, or to be specific - Acoustats for sure - do not have the steep roll-off that most "box" speakers do. They can (and, given the correct room coupling - WILL) play very low. In the rooms (mine... :'() that do not couple well in the low(est) range, one would naturally consider adding a sub because due to ESL placing constraints, unless you get them to couple, you ain't gonna have bass, period.

 

[Steve81]

That same guy rebutted with :

With respect to his original comments: it's not really a matter of how low ESLs can go; it's a matter of how much output they can deliver.

I mean, the original comment was that you'd need a 12" subwoofer with ungodly xmax to keep up with an ESL panel. GranteedEV linked to a quite respectable but nonetheless affordable 12" driver, and I've provided measurements of what kind of output it can deliver in a sealed box.

Now think about that this for a minute: the subwoofer in question can deliver 109dB of clean output at 32Hz outdoors (1/2 space) at 2 meters. That (in theory) equates to 127dB at 1 meters, corner loaded (1/8th space). To take it out to 4 meters corner loaded, and you'll get a potential of 115dB output at 32Hz at listening position.

Now this is maximum output and the driver is going to be going nuts, and maybe this just rubs you the wrong way regardless of what the actual measured overhang is. But lets face facts here: few (if any) ESLs are going to be keeping up at these kind of output levels, and few people listen at these volume levels. So what happens at a lower level? Every 6dB drop in output reduces driver excursion by half. If you only want peaks of 109dB at the listening position, the driver excursion is one half of where it was at full power. Peaks of 103dB? A quarter. And let me tell you: to most people, 80dB average levels at the listening position and a crest factor of 20dB is pretty loud. We're not talking "elevator music" here by any means. Further, this is just a single affordable 12" driver in a sealed box.