¿Sealed or Ported?

[SupraGuy]

Hardly qualifies as all respects.

The sealed box is more flexible, is (by your own statement) smaller, leaving me more cargo space. In an automotive environment, I call those signifigant advantages.

On top of that, the horn (being basically a bandpass with a variable port) exhibits moderate to large group delays, has a steep rolloff at the upper frequency boundary which is hard to blend into the midbass or mid, and still has that nasty response drop at the low frequencies, making it hard to suit for really low bass.

A horn is a very efficient enclosure, which makes is excellent for SPL, and is cleaner than a bandpass, but still maintains some of the bandpass boxes unpleasant characteristics. For example, map phase shift vs frequency, and let's see how you plan to blend that nicely into the midbass.

Like I said before, it's all trade-off. A response graph doesn't show group delay, distortion, or other artefacts, it merely graphs SPL vs frequency. You don't get something for nothing.

[BillFitzmaurice]

The sealed box is more flexible, is (by your own statement) smaller, leaving me more cargo space.

Agreed. I don't have one of these in my own car, but I'm content with 105dB levels.

has a steep rolloff at the upper frequency boundary which is hard to blend into the midbass or mid

Not if your crossing over where you should be, at 80-100Hz, and its response is quite adequate to say the least even higher. The upper f3 of 250Hz is a good octave above where the LP crossover should be set even worst case to blend with midbasses with too high an f3.

map phase shift vs frequency, and let's see how you plan to blend that nicely into the midbass.

Again, moot with a proper crossover frequency. Those factors have no bearing in a small space with non-directional frequencies.

distortion,

SPL aside this is a horn's biggest advantage, as the power requirements from the amp and excursion requirements from the driver are so drastically reduced that distortion is well below what any other alignment is capable of.

response drop at the low frequencies, making it hard to suit for really low bass

Not at all; the response is perfectly suited to all forms of music, giving precisely the desired response for bass instruments (as a bass player with 40 years professional experience I know a bit about bass) with the crossover at 80-100Hz. For HT use setting the feed lowpass filter at 50 Hz results in +,- 3dB response from 20 to 80 Hz at 95dB/SPL/watt, which you'd be hard pressed to beat with any other speaker, especially considering the $70 build cost of this one.

You don't get something for nothing.

True. It takes some woodworking smarts and about twice the plywood that a direct radiator of the same size would use, and the willingness to lose about a grocery bag's worth of cargo space. That's compared to a direct radiator sub with 10dB less sensitivity; to get the sensitivity that this horn has using direct radiator or vented bandpass boxes you'd end up with something even larger and you'd need tens time the amp power to drive it with.

[SupraGuy]

Well, suffice it to say that I don't agree.

I've built several horns of various designs. I've found some that were quite good for home use, including a (quite large) folded horn design that worked quite well. It still had group delay issues, though. I was not able to completely get around the phase shift problem. Although the crossover frequency itself was okay, a bit above that the phase shift started giving cancellation problems with the midbass speakers, because the shift alters with frequency. At 80Hz, the response was nice, but there was a dip at 100Hz, and a bump at 125 because of the relative phase shift between the sub and midbass dreivers. This does not happen with sealed or single reflex ported enclosures. Simulate the map for both the sub and midbass.

Personally, I found the slower transient response and low rolloff characteristics to be an irritation.

With my small sealed boxes, and powering my pair of 10" subs with a total of 120W (60W/sub) I'm still getting SPL levels of 129-130 dBSPL in my car. That's NOT a lot of amplifier, and more than loud enough for my tastes.

It's a trade-off.

This is my opinion. There is no "ideal" enclosure. Horns, bandpass, ported and sealed all do certain things very well, but always at a cost.

For my purposes, amplifier power is cheap, and readily available. I do a large part of my listening late at night, and almost always watch movies after the kids are in bed, so I can't turn it up then anyways. I don't need high efficiency for a subwoofer there. (Although I'm using a slot loaded enclosure.) In my car, space is at a premium. I do a lot of driving, and often need every availalble litre of space. I don't want to have to remove the subs to carry stuff, nor do I want to drive the minivan on long highway trips. (I like my car, as you may have guessed. ) I have enough power available. I could use otherwise unusable space in the back of the car. That choice was a no-brainer.

Like I said, you'd need to prove that any one enclosure is superior in all respects. This is my opinion.

[offroadbum]

exn,
these guys have gotten over my head to the point of where I`m wondering if what I`ve been doing for the last 15yrs,could have been better.but thats another topic all together.
being the best in all respects is tough.lets look at it in another way.what type of car or truck are you putting it in?
what do you what from the system?
how much money do you have to spend on it?
how much room are you willing to give up for the box?
after 50+ systems alot of trophies and alittle money,i`ve seen alot of different systems.and in the end run the only person you have to please is you self.if the system doesn`t sound good to you then you`ve failed and you have to start all over

[BillFitzmaurice]

Well, suffice it to say that I don't agree.

I've built several horns of various designs.

None of mine, I'm sure, but that's OK. 90% of my designs are pro-sound.

Like I said, you'd need to prove that any one enclosure is superior in all respects

Agreed, that's why I have a Line Array/TL for my HT mains, a horn for my HT sub, a sealed MTM for my HT center and omnidirectional surrounds.

With my small sealed boxes, and powering my pair of 10" subs with a total of 120W (60W/sub) I'm still getting SPL levels of 129-130 dBSPL in my car. That's NOT a lot of amplifier, and more than loud enough for my tastes.

I have a single 8 incher 'invisibly' integrated into a rear quarter panel, driven by 50 watts. It takes up zero cargo space. Not everything I design is for my own tastes, but for those who want to bother the neighbors three counties away and cause cattle stampedes only a horn will do.

[eXn]

offroadbum,
I will be putting it in a chevy suburban. Im not goin for competition quality necisarily, but i dont want it to sound bad. I want it to be loud and still sound good. I have heard some peoples systems and the bass is loud as hell but it sounds crappy because it is all distorted.

[SupraGuy]

Loud is in the ear of the beholder.

A suburban won't have the same kind of cabin gain that my Supra has, because it's much larger.

Good sound will also depend on what kind of music that you are listening to. For most types of music a basic ported enclosure should work well in your Suburban. So will a horn. A sealed enclosure might need to be a bit larger than "recommended" but not that much.

Amplifier power is going to make a lot of difference, as well. Good clean power will always sound better (And let your woofer last longer, too) than nasty clipping power. A quality amplifier will make a large difference.

You're not exactly space limited in the Suburban, so it also depends on what kind of speaker you're going to load into it. A single 15" will work well in just about any kind of enclosure.

The next question is who is building the box. If you have an experienced box maker building the box, then you can go with a more complicated design. A sealed box is a good project for a beginner, and can more easily use fibreglass to make a nice curved panel, or fit into tight spaces for maximum use of space in the vehicle. A ported box needs more precisely measured volumes, and therefore requires a more experienced builder. While a ported box can use fibreglass construction techniques, it is exponentially more difficult to get it just right. A horn or bandpass box needs to be very precise, and is not recommended for beginners to even attempt. Use of fibreglass panels for these is practically unheard of, due to the exacting nature of volume calculation required for it to work. (It can be done, but would be very hard -- expensive if you get a pro to do it.)

The right combination of speaker, enclosure, vehicle and amplifier can always be made to sound good, regardless of the enclosure TYPE. Some types of enclosure do some things better than others, but no type is superior in all respects. And of course this is all good in theory, but in practice, someone has to actually BUILD the thing, and if that's you, you should go with what you can actually build well. A poorly made enclosure will always sound poor.

[djQUAN]

and don't have the nasty habbit of leaving my subs at high excursion whenever I drive up or down some of the long hills that I've been known to drive over. (I can get out of the car at the top of a hill, get out and open the back of the car and SEE the subs pushed out for about a minute or so after I get to the top. That box is SEALED.

that's why basic box building instructions say you need to have a tiny hole somewhere to equalize inside and outside pressure. a pinhole will do and will not affect tuning.

Not at all; the response is perfectly suited to all forms of music, giving precisely the desired response for bass instruments (as a bass player with 40 years professional experience I know a bit about bass) with the crossover at 80-100Hz. For HT use setting the feed lowpass filter at 50 Hz results in +,- 3dB response from 20 to 80 Hz at 95dB/SPL/watt, which you'd be hard pressed to beat with any other speaker, especially considering the $70 build cost of this one.

is this about the horn? can I see some box plans/ cross section look of the horn (the one in the picture)?

For my purposes, amplifier power is cheap, and readily available. I do a large part of my listening late at night, and almost always watch movies after the kids are in bed, so I can't turn it up then anyways. I don't need high efficiency for a subwoofer there. (Although I'm using a slot loaded enclosure.) In my car, space is at a premium. I do a lot of driving, and often need every availalble litre of space. I don't want to have to remove the subs to carry stuff, nor do I want to drive the minivan on long highway trips. (I like my car, as you may have guessed. ) I have enough power available. I could use otherwise unusable space in the back of the car. That choice was a no-brainer.

I don't think amplifier is cheap (well, I don't think so over here. ) I have to build myself a P68 monoblock driving into 2 ohms just to have more power for my subs than what I have presently.. besides, I need the extra power when needed.

but i dont want it to sound bad. I want it to be loud and still sound good. I have heard some peoples systems and the bass is loud as hell but it sounds crappy because it is all distorted.


BillFitzmaurice

same here! some people I know tell me that they hear other people's systems distorting so badly, they just turn it up to "show off".

since this is a car sub topic....what do you guys think about my box? I just thought this box config would go loud and I built one for my SUV. works quite well, about 170 watts per sub and I get to around ~130db with the windows open . www.djquan.angelcities.com/ride.html

[SupraGuy]

that's why basic box building instructions say you need to have a tiny hole somewhere to equalize inside and outside pressure

Heh. There actually was a 1mm hole drilled in the back of my sub boxes, but I accidentally plugged it when I installed the box in the back of the car. I've been MEANING to get around to fixing that, but I just haven't done it yet. It's not a problem when the subs are playing, there's just enough air leakage around the sub itself to allow it to equalise.

can I see some box plans/ cross section look of the horn

I also agree. I'd be willing to build a horn enclosure for listening tests, at least.

I don't think amplifier is cheap (well, I don't think so over here. ) I have to build myself a P68 monoblock

Hmmm... Within a good stone's throw of my office, I could buy a dozen car amplifiers of 500W or more. Many of these would actually cost me less to buy than it would cost me to build a P68 for home use.

For my car, I can get to 130dB SPL, and that's with plain sealed enclosures, with the windows down, (It actually makes no difference in my car) but my car is a lot different from an SUV. I'm running 60W/channel to a pair of 10" subs (120W total)

While testing a friend's 10" DVC in a bandpass, I got 138dB SPL on the same amp, which goes the show the efficiency gain that a bandpass enclosure is capable of! (Too loud for me.)

[eXn]

djquan,
how about some plans for the enclosure that u have built? Would i be able to get a hold of those. and there are plans for the horn for sale online at billfitzmaurice's website i cant remember it. please post for the others