Sound quality as a result of alignment

[badman]

Hi all:

I was doing a little pondering. One hears over and over how a driver is better suited for vented or sealed alignments (let's limit this discussion to these two). Obviously things like the response characteristic and driver design play a role here (progressive vs. linear spiders, etc), but does anybody have a theory by which the sound quality (dynamics, most specifically) changes beyond simple frequency response?

In other words, why do some drivers 'come alive' in vented cabinets where they don't boogie in sealed? The elusive 'jump factor' or 'slam' are what many people seek when doing a bass system (obviously the vented/sealed applies to midranges as well, but that's typically a little more esoteric), but what will make a driver achieve this more dynamic sound in a vented alignment beyond frequency response changes?

Let's hear some theories and maybe we can all get a little closer to the chest thumping 'live' sound

[nunayafb]

I hate to seem rude but I am always curious what people mean when they say things like "dynamic, slam, jump factor, alive, etc..." maybe you could start with your definitions of these words.

As far as your question the behavior of a given driver in vented vs. sealed there are dozens of in-depth posts on this forum that occupy hundreds of pages about the physics/merits of vented vs sealed. Please start with a search, vented vs sealed arguments spiral out of control so quickly around here.

[leadbelly]

I agree with nunayafb, you need to spell out what you mean. At a first read of your post, all that comes across is someone who hasn't read the about the basic pro's vs con's of the various alignments, and the basics of Thiele-Small parameters. Forget asking people to "theorize" about this, just read about it in one of the various speaker design books or search it out on the web. If you mean something deeper, you need to spell it out.

[Daveis]

Badman,

For deep theory get the "Loudspeaker Design Cookbook".

If I remember correctly, Qts is a big factor as to whether a driver is more suited for sealed or vented. Over .30 tends towards sealed. Under .30 tends towards vented. And there are multiple vented "alignments".

All of the commercial designs I've owned from Boston Acoustics, Thiel, NHT, B&W have used vented boxes.

All of my own DIY speaker explorations have been with LARGE sealed boxes. The reality is that you can put a driver into a grossly wrong size sealed box and still have respectable sound. This is especially true if you tune the box volume by ear and try different amounts of fill material in the box.

To me venting the box is simply an attempt to gain an extra octave or so of lower bass. The same thing can be accomplished with a large 12" to 15" sealed box sub driver. Venting requires more design finesse. Sealed is easier for the novice.

[badman]

I'm familiar with the Qts behavior and the EBP. I own and enjoy a copy of Dickasons book, but was hoping for a little more feedback. Unfortunately, the discussions here have centered around the surface of the issue, the tradeoffs in extension vs. rolloff vs. excursion at various frequencies are well known....

I should have known better than to use subjective terms. What I'm getting at is that some drivers seem to have better subjective bass transient response in a vented alignment, well above tuning, where the venting and enclosure really come into play according to what we've learned.

Searched? Sadly, threads run ON and ON and ON around here, people don't use the wiki the way they should. Oh and the search feature really sucks (nothing against the administration, I love this place). But I've reviewed the discussions of vented vs. sealed, and they generally don't do much more than the obvious and dogmatic adherence to:

A) Use the driver according to the EBP
B) Sealed is better, sealed is always better, I love sealed, can't you hear?
C) Vented is better, vented is more efficient, vented is deeper, I love vented, can't you hear?
D) Just do a TL
E) Just do a basshorn

So..... to get more specific- why does a vented driver alignment often seem to affect a driver significantly above where the alignment starts influencing amplitude response?

[sreten]

Originally posted by badman

So..... to get more specific- why does a vented driver alignment often seem to affect a driver significantly above where the alignment starts influencing amplitude response?

Hi, Intermodulation distortion (IMD), /sreten.

[Ron E]

Originally posted by badman
So..... to get more specific- why does a vented driver alignment often seem to affect a driver significantly above where the alignment starts influencing amplitude response?

I would question the premise to begin with. What evidence do you have to suggest it is so in the first place? Perhaps some toneburst listening tests compared to simulations and measurements would be useful...

[Cameron Glendin]

A) Use the driver according to the EBP
B) Sealed is better, sealed is always better, I love sealed, can't you hear?
C) Vented is better, vented is more efficient, vented is deeper, I love vented, can't you hear?
D) Just do a TL
E) Just do a basshorn

Thats funny, it does sum it up, but you did forget to buy an old altec!!!!!

At home I have sealed, ported and a voigt pipe styles,

I guess the most accurite is the large woofer in the over sized sealed box, (infinate baffle style) with the extra octive of bass by adding 4 ft wings to the side of the box or electronicly. It has the best or smoothest midrange sound (driver dependant)



Personally I like them all though bass horns look very tricky to build, I love the sound of a well built one