Beyond the Ariel

[Antripodean]

Originally Posted by cuibono

But I'm finishing a design that has a 11" by 13" footprint, need no EQ, is almost as sensitive, has more output, and lower distortion, for almost the same cost.

I would be interested to know how this turns out

[CLS]

Originally Posted by gainphile

To OB proponents here, do you find the lack of physical impact disturbing?

....

No, with T-bass circuit and 4 18".

[Pano]

Originally Posted by Lynn Olson

Panomaniac can speak to what these kinds of speakers can do, since he re-worked the big Altecs in Paris.

Well, yeah. The Altec 825/828 cabinet built right is the most natural sounding bass I've ever heard. Sounds like real, live music - even to someone who hears real live music every day. But it is not easy to build right and it's BIG. So not a likely candidate for this project.

So bass reflex, done right, can be better. OB is easier, that's all. Gary's V-Bass is a nice approach if you can throw some power and EQ at it. That's easy to do these days. A big system should have separate bass amplification anyway.

Lynn, hope to see you at RMAF. But I'll be very busy and doubt I'll get much time out of the room. (Marriott Tower 2032)

[Robh3606]

I know there's "vibrator" equipments out there. I wonder if it makes impact if I install it on my sofa.

Hello Gainphile

Tried a demo with the shackers in a sofa and it just didn't work for me. They had some cube speakers as the audio source. Yeah the sofa did shake but there was no preasure wave with it. There is no substitute for the real thing.

Rob

[gedlee]

Lynn

I strongly disagree with much of what you are saying.

In a typical room, the lowest mode will be in the 30-40 Hz range. Below this is "room pressureization". Modal effects in the room will then be from 30-40 Hz up to the Schroeder frequency which is typically about 120 -150 Hz in most home sized listening rooms. It can be as low as 100 Hz in a larger well damped room and as high as 200 Hz in a small car, but typically it is about 120-150 Hz. Above this frequency "modes" are not a factor as the density is too high. So you have the three regions, but at dramatically different frequencies than you quote. Below 30 - pressure mode (only a monopole can do anything here); 30-120 - modal region (multiple spaced subs are the answer); and above 150 Hz where room shape and modes are virtually irrelavent (except as regards early reflections).

As to your test for box resonances, that test proves nothing. It's the sound that radiates to the listeners position that counts NOT what you hear when you place your ear against the box. The two things are dramtically different. Put your ear to a port and thats all you will hear, but at the listening position its quite another thing.

Finally, most drivers ARE NOT flat in the region below 800 Hz because. The cone may be rigid, but the drivers structure, frame and magnet as well as things like the spider, have resonances in this range and there are often effects form these resonances.

[Curly Woods]

Originally Posted by gedlee

Finally, most drivers ARE NOT flat in the region below 800 Hz because. The cone may be rigid, but the drivers structure, frame and magnet as well as things like the spider, have resonances in this range and there are often effects form these resonances.

Can an accelerometer be used to measure spider/frame resonance of a mounted driver in its cabinet correctly? I realize that the cabinet will be a big influence on this measurement, but curious if this would help to address driver/cabinet resonance to a higher degree of accuracy, or will it matter?

[Pano]

Originally Posted by gedlee

As to your test for box resonances, that test proves nothing. It's the sound that radiates to the listeners position that counts NOT what you hear when you place your ear against the box.

I think you might be missing Lynn's point. Doesn't he mean that pressing your ear against the box is a good way to know what the box sounds like? Once you do, you will easily notice it at the listening position.

Once you know what an oboe sounds like, or a major 7th chord, you'll notice it - you can pick it out. The visual domain is similar. Hearing it and noticing it are not the same thing.

[john k...]

Originally Posted by panomaniac

I think you might be missing Lynn's point. Doesn't he mean that pressing your ear against the box is a good way to know what the box sounds like? Once you do, you will easily notice it at the listening position.

Depends, as usualy, on relative levels. Put your ear against a wall and you can hear what us being said in another room, but sitting in the center of a room what is said in the other room may well be inaudible. I have to agree with Earl here. Not to say that boxes don't color the sound, but it is not necessarily revealed by ear agianst box. Tap lightly on your skull. You will hear it. Someone across the room will not.

You can make the same comment about OB's. Place your ear against the baffle and you will hear what vibrations are transmitted to the baffle. Mounting a "vibrating device" on any surface or box will impart vibration to that structure.

One other minor point to Earl. Monopoles are not unique in excitng room pressurization. Any source which has finite volume displacement below the room fundamental will cause some degree of pressurization. Cardior woofer systems fall into this catagory.

[Speedskater]

Originally Posted by gedlee

(snip)
As to your test for box resonances, that test proves nothing. It's the sound that radiates to the listeners position that counts NOT what you hear when you place your ear against the box. The two things are dramtically different. Put your ear to a port and thats all you will hear, but at the listening position its quite another thing.
(snip)

But Stereophile magazine tries to correlate every loudspeaker coloration or defect to cabinet box resonances.

[gedlee]

Originally Posted by Speedskater

But Stereophile magazine tries to correlate every loudspeaker coloration or defect to cabinet box resonances.

Wow! It must be real then! We all know how accurate their assesments of audio quality are.

I'm not saying that all boxes and all box resonances are unimprortant, they are important, I'm just saying that with some good structural design they can be made negligable. And consider this. There is a big difference in box audibility between a low efficiency loudspeaker that sends sound in all directions and a high efficiency one that focuses the sound in the forward direction. The audibility of the low efficiency speakers box could easily be some 10-20 dB greater than the high efficiency one.