3 way monitors - ported or sealed box?

[Max_Andrews]

Provided Link: pioneer 8" hd woofer (http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=290-063)


Hello everyone!
I am in the middle of building a pair of three way speakers from drivers and electronics that I purchased from parts express. But before I start cutting, I wanted to get some input on a question that's been nagging me ever since the drivers arrived about a week ago...sealed or ported?

I don't like sloppy, fuzzy bass so the low end is to be delivered by the pioneer B20FU20-54F 8" HD WOOFER that has response down to 40Hz and only 1mm of Xmax so It's going to be very snappy, tight bass. I'm not a huge fan of loud or excessive low-end, so will a ported enclosure help me much here? I'm interested in dynamics and tightness rather than "how low can I go."

If it matters, the midranges are the 2" shielded Dayton reference aluminum domes and the tweeters are dayton 1-1/8" silk domes.
Thanks in advance for any advice you can give me!
-Max

[kene]

> Hello everyone!
> I am in the middle of building a pair of
> three way speakers from drivers and
> electronics that I purchased from parts
> express. But before I start cutting, I
> wanted to get some input on a question
> that's been nagging me ever since the
> drivers arrived about a week ago...sealed or
> ported?

> I don't like sloppy, fuzzy bass so the low
> end is to be delivered by the pioneer
> B20FU20-54F 8" HD WOOFER that has
> response down to 40Hz and only 1mm of Xmax
> so It's going to be very snappy, tight bass.
> I'm not a huge fan of loud or excessive
> low-end, so will a ported enclosure help me
> much here? I'm interested in dynamics and
> tightness rather than "how low can I
> go."

> If it matters, the midranges are the 2"
> shielded Dayton reference aluminum domes and
> the tweeters are dayton 1-1/8" silk
> domes.
> Thanks in advance for any advice you can
> give me!
> -Max

The thing I see here is the Qts is quite low, which is typical for Pioneer drivers. This will not give you much bass extention. For example, your usable bass in a sealed enclosure with Qtc = 0.5 (corresponding to transient perfect tuning) won't go much past 60 Hz, and that's a LEAN 60 Hz. A ported enclosure might richen things up a bit above 60 Hz, but at the expense of response below 60 Hz.

What I'd encourage you do is both: design your box with a port on the back that you can cover up (say with a detachable plate) anytime you feel. I'm planning on doing this on a center channel speaker I'm going to start soon. What I've seen in the past (but you should double check via calculations before implementing) is that a Qts this low tends to have very similar optimum volumes for either ported or sealed designs. So just build it and leave it to your preference.

NYU eh? I graduated from Cornell. Sucky how far away I was from the city, though.

[Max_Andrews]

Very interesting...I didn;t know that the Q values had much to do with bass extension; I always thought that the lower the better :)
I bought two port tubes just in case, so I'll first build them sealed, and if I want a bit more punch I'll carve a hole in the back and add the tubes. These things should sound good either way...I'm excited!

Thanks for the help!

[Pete Schumacher ®]

> Very interesting...I didn;t know that the Q
> values had much to do with bass extension; I
> always thought that the lower the better :)
> I bought two port tubes just in case, so
> I'll first build them sealed, and if I want
> a bit more punch I'll carve a hole in the
> back and add the tubes. These things should
> sound good either way...I'm excited!

> Thanks for the help!

Too bad you picked such a limited woofer to go with that fantastic mid. You'd have been much better off with the RS225. Oh well.

[marlboro]

The xmax is actual 0.10 mm not 1(in two different places on the web). Its EBP is 137, more than suggesting a ported box. If you don't port it, you'll not like the limited amount of bass.

If you vent it, put it in a .9 box, you can keep its efficiency at about 93, at about 70hz. After that it will fall through the floor like a rock. It will be about 6db down at 55hz.

Now these are just modeled projections(WINIsD).

But in a closed box its down 3db at 108, at 70hz its down 8 db. In the ported version its group delay is only about 3.5 msec up from the closed version at 70.

Clearly this woofer was made for a vented box.

Marlboro

[Max_Andrews]

The 0.1mm xmax is definitely a recurring typo that may have been on the pioneer spec sheet. My printed parts express catalog lists it at 1mm, not 0.1mm, and there is obviously more than 0.1mm of response if I gently push down on the dustcap. it seem a bit less travel than the 1.5mm xmax dayton pa drivers i've used in the past, putting it at about 1mm. There's no way 1 0.1mm xmax driver could have listed response down to 40hz. If it IS only 0.1mm xmax i'll return it immediately.

I understand where you guys are coming from, but I don't like my music the way most do. I really really dislike high excursion drivers because they just feel too sloppy to my ears. They compress the air too much for my taste and the clear punch that I want to hear always leaves something to be desired. But, I built a portable system this past summer with the dayton full range PA 5 1/4" drivers, and with their response at 70hz and 1.5mm of xmax, they really put out a strong, clean punch. So I looked for a speaker with similar characteristics but a deeper response and of course, a larger size. The 93db efficiency doesn;t hurt one bit either.

And of course, i'm probably dead wrong. If it sounds crappy, no big deal...I'll pick up some different 8" drivers and swap them out. In either case I'll let you guys know. I'm more concerned with these speakers sounding good than the intricacies of xmax and qts which I don't know enough about, and as such I'm willing to experiment.
Thanks for running those calculations as well, very helpful.
Thanks again!
-Max

[kene]

> I built a portable system this past
> summer with the dayton full range PA 5
> 1/4" drivers, and with their response
> at 70hz and 1.5mm of xmax, they really put
> out a strong, clean punch. So I looked for a
> speaker with similar characteristics but a
> deeper response and of course, a larger
> size. The 93db efficiency doesn;t hurt one
> bit either.

Well that does help to clear some things up. The numbers we're throwing up at you may seem intimidating, but as you get familiar with things you realize they're very useful.

I've only had experience with Pioneer drivers once and things didn't quite turn out as I had hoped. It's all up to what you like of course, and the high-efficiency of these Pioneers may help, but IF you end up feeling the same way, and let's say you have a bit of a budget to throw around, here's an alternative approach.

Start with a 1 cubic foot sealed enclosure. If the Pioneers sound way too thin and un-punchy, porting may not take you in the direction you want. I'm all about ports, but if you're prioritizing on punch, leave your enclosures sealed, and instead substitute another driver.

Those Dayton RS drivers as suggested by Pete are fantastic values, and the 8" model he's suggesting can be transplanted into your sealed enclosure in brainless fashion, no new cuts or anything needed. Their bass extention will be more flexible, and keeping the enclosure sealed will help emulate the sense of tautness I think you're after. Like Pete, I've used these drivers in some of my own projects and can attest to their resolution. And as Pete's already alluded to, they'll be a natural fit with the mids and tweets you've chosen.

But if you're honestly just looking for that rock-concert punch, I mean it's your absolute first priority, you may want to stay in the original line you used for your previous project. The 8" Pyle Dryver Pro looks like it has an accordian surround, right? That'll be punchy, and again it'll be a brainless transplant sticking it in a 1 cu.ft. sealed enclosure. They won't get as deep as the Dayton References, though. But I've met some that honestly do prefer the sound of concert-style equipment. Nothing wrong with that.

Before making further suggestions, maybe we need to know more about the system and listening context you're shooting for. What kind of amplification will you be using, what kind of music, how big of a room, do you have to worry about roomates, etc. Or you can stick with the 1 cu.ft. plan for now and get back to us later. At any rate, have fun. I like your willingness to experiment.

[damkor]

My printed parts express catalog
> lists it at 1mm, not 0.1mm, and there is
> obviously more than 0.1mm of response if I
> gently push down on the dustcap.

Just FYI: Xmax is not the maximum travel before the voice coil hits the backplate or pops out of the gap. It's the maximum distance the voice coil can travel and STILL be under maximal, ideal control of the motor system, i.e. the magnet. So, a driver can exceed Xmax, and still be under perfectly good control, by virtue of the spider and the suoorund.

Anyway, I would go for a ventedf box.