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-   -   1 Or 1.5 Cu. Ft. Sealed Cabs? (http://www.diyaudio.com/forums/wild-burro-audio/166567-1-1-5-cu-ft-sealed-cabs.html)

Karl71 9th May 2010 12:56 AM

1 Or 1.5 Cu. Ft. Sealed Cabs?
 
Has anyone tried the Betsy-K in a sealed 1 or 1.5 cu. ft. cabinet? I haven't yet implemented my drivers. I have the "itch" but not the space at this time to set up such "large" enclosures. I would pair them experimentally with domes, ribbons, and planars.

Have you tried it, Paul?

Regards,

Karl

pjanda1 9th May 2010 01:09 AM

Karl,

I honestly haven't gone that small sealed, but I have advised others to try it! I think it would work well in a moderately sized room placed close to the walls or corners. I'd think in terms of a wide baffle/shallow cabinet. Maybe even a Mapleshade style placement, very low and tilted back.

If you are planning a more traditional "bookshelf", (narrow baffle, stand, out in the room), then I'd use BSC. (Of course, there are plenty of folks out there who are happy with fullrange bookshelves and no BSC, but I like a little more bass). If you have a large room, you might want a sub with the sealed option. In smaller rooms, the room modes often extend the sealed cabs low enough to be pleasing. The nice thing is that if you do need a sub, only one is needed. Many other fullrangers in sealed boxes won't get low enough for a single sub.

I have used slightly larger sealed boxes, and I think the excursion reduction vs. a vented cab is well worth it (the lower distortion sounds nicer to my ear).

If you are looking for a small footprint, consider the skinny TL/TQWT I have yet to post plans for. 12"x13" footprint, 44" tall. I'm listening to a pair right now! They are a simple build, and you don't need to find stands. I spent some time thinking about these. Now if I could only get the dimensions exactly right in SketchUp. . .

Paul
Wild Burro Audio Labs - DIY Full Range Speakers

Karl71 10th May 2010 05:26 PM

Paul -

What do mean by placing a cabinet "low"? How much of a tilt? What are the benefits and detriments of such placement?

Regards,

Karl

pjanda1 10th May 2010 06:03 PM

Karl,

Here is what Mapleshade says. The benefits are mainly that you get plenty of mid and low bass with no BSC. There are, of course, some downsides. Even with the speakers tilted back enough to be listening on axis with the fullrangers (or tweeters), the soundstage will be very low. You also have the potential for midrange reflections off the floor, but larger fullrangers won't be as much of a problem as smaller midranges (due to the directivity of the 8" fullranger). And if your bookshelf speaker has BSC, then you will end up with too much bass.

When I was using smaller sealed and vented boxes, I placed them on big concrete blocks. I had the blocks sitting on their smallest end, and the U shape provided adjustable tilt. I didn't care much about scratching those cabinets. I had them quite close to the wall.

Some folks like the sound with shelved down midbass/bass. The midrange really comes forward and puts vocalists in your lap. There are plenty of mini-monitors that use this trick. The lack of BSC also creates that distinctive forward midrange in the filter-less commercial fullrange vented bookshelves.

So, before you buy BSC parts, try it without. And then try the low placement. If you like the tonal balance of the low placement but find that you don't like the low soundstage or hear some reflection problem, then you can start to play with BSC.

Of course, another option is to use subs as your speaker stands ala the Bottlehead S.E.X.y speaker. You wouldn't need two with the BetsyK's, but those Parts Express pre-built subs are cheap enough that you may as well!

Paul
Wild Burro Audio Labs - DIY Full Range Speakers

Karl71 10th May 2010 09:31 PM

Paul -

How large have been your sealed cabinets? While I love tight and well-defined bass, transients are very important to me. How do your TLs do in that department? Did you model the TLs? Do you have a hand-drawn sketch that you could post here?

Regards,

Karl

pjanda1 10th May 2010 09:54 PM

1 Attachment(s)
Karl,

I modeled the TL's in Horn Response. I worked the original design out as a regular tapered TL, then I tried some models with various steps to see how that might affect it. It works very much as I expected, which is to say, great! The transient response sounds excellent to me. How the cabinet effects transients will depend on exactly what you are asking out. The TL's midbass lacks the "slam" I got from the BIB's, but I'm sure it will exceed a sealed box in that regard. It has been awhile since I tried a sealed box, but I suspect that the midrange on up isn't entirely different. If anything, I'm sure the TL is better as the speaker has more room to breath, and likely is being asked to work less hard.

If you are looking for "slam," that will always be a challenge with a little, low excursion woofer. I'd pick the biggest enclosure you can stand to give it as much help as possible. If you are looking for speed and microdynamics in the midrange and treble, I'd stick to 1.5 cu ft at a minimum. You don't want to have to stuff the enclosure too much and "choke" the dynamics. I haven't tried it myself, but if you go to a very small (1 cu ft or less) sealed box, you should be able to stuff it enough to get the bass in line (not too warm), but those micro-dynamics will the the first thing to suffer. The flip side is that the smaller sealed box will restrict excursion more, so the maximum dynamic range should be greater.

I attached an image from SketchUp. This is the TL with no sides, so you can see the internal folding and get the basic idea. The dimensions are a little off, and I can't figure out what I'm doing wrong. That is why I'm not showing all of them. If you needed this to go flat against a wall, you could face the terminus forward. As long as you've got an inch for them to breath, the rear vent is probably the way to go.

Paul
Wild Burro Audio Labs - DIY Full Range Speakers

Karl71 10th May 2010 10:33 PM

Paul -

I would like to build your TL. When do you think you could post the complete plans here or on your site? What about stuffing?

Regards,

Karl

pjanda1 11th May 2010 01:34 AM

Karl,

I'll try and get it to work. If all else fails, I draw in the dimensions and mail them to you. The design is really pretty simple, and also fairly flexible. If memory serves, I'm using a pound and a half of polyfill per enclosure. I stuffed only above the folds, denser towards the top, tapering off to the first bend.

Paul
Wild Burro Audio Labs - DIY Full Range Speakers

dwk123 11th May 2010 04:41 PM

Hi Paul,
My Betsy K's are still in their boxes - I'd been thinking of trying 1cf sealed, but then realized just how big that is for a computer speaker and thought better of it. The mini-tl looks great for my alternate application though, and I'd be very interested in the plans for your cabinet as well.

Godzilla 12th May 2010 02:06 AM

2 Attachment(s)
I have heard the Betsy in three different cabinet designs. An open baffle with bass support, a 1.3L sealed and a .5L sealed (but lossy) box. In sealed all by themselves they sound fine with detail galore. If you look carefully at the pictures you will notice i have a pair of beautiful wizzerless Betsy's. In the sealed box there are piezo's on the rear. On the open baffles are small compression drivers crossed around 11k.

Godzilla


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