Which design to have in-a-car-like sound pressure?

[musgofasa]

Well being an old car audio guy, I feel I may be as qualified to answer this as anyone.

In-car bass slam is between 35 and 70hz. The low vibrating bass in techno and bass tunes (IBP etc) are aroun30-35hz while the real "Slam" that makes your heart skip is closer to 60hz. These aren't particularly musical tones and if you are looking for that type of SPL to mate with cabinets or towers in a room, you will find you need a large room with PA style horns to keep up.

To get to the point, getting 135+db in a room the size of my living room (23 x 12 ft) would require quite a bit of power. Band pass enclosure is going to be the way to go. BIG band bass. My suggestion would be a down firing band pass with as many 15 or 18" woofers as your wallet will take. The power is what will cost you money. How big is the room you are working with?

I also agree with the previous post about using two enclosures, one on either side of the room. I say Band Pass because you can do a 4th order type box with a sealed rear chamber which will give you more power handling and an open, floor firing configuration which will help load the woofer to the room.

For the record, I have a really (and I mean REALLY) cheap sub built in my house. I used two 15's that cost something like $25 each and a small plate amp (dayton). At my listening position, it shakes my chairs hard enough to remind me of a car with a strong 10" woofer. I think that a much better pair of subs with10 times the power would likely bring down the walls. It runs from 20hz up to about 60 before it starts rolling off severely. Of course I have it crossed over at 70 so you can tell I was after the same thing.

When I am listening to Nora, the sub isn't playing. My mains do a pretty awesome job of getting extension and being fast, and clear. When I want to rock the house, I pump up the sub. It works great for HT too.

Of course, some people don't like the sound of it. I for one think it is pretty muddy, but I am comparing it to some full range and very high end multi-ways when I say that. All and all it is actually very pleasing the way it is and i can think of oodles of ways to make it better.

Give up some details on the room, power, subs you would prefer to work with and I can make some estimates for you on what to expect performance wise. I am sure others will chime in.

OH, one last thing. The Lab horns are pretty awesome. Big as well, but more efficient and a little more bandwidth. They do especially well with Techno and stuff like that. If you like the transients in Metal etc, I might suggest sealed or ported and a LOT of BIG woofers. See what I mean about options, lol.

Take care,
Robert

[RJ]

Originally posted by Don Bunce
"No one mentioned bass horns"

Back at post #9 I recommended a pair of Labhorns.Even one,corner loaded,will beat a stack of sealed boxes.Before I built the LABhorns,I had eight 12" HSU Research ASW1202 drivers in sealed boxes.They didn't stand a chance against the LABhorn.Ten 7" Daytons won't either...

To keep up with horn subs,you will need horns for the rest of the system.

Here is a pic of my system before I built a second LABhorn.Midbass is 1/2 space 110 hz expo horn(similar to Altec A7)with Altec 416 driver,midrange is 345 hz Tractrix horn with JBL 2441 driver,and tweeter is Fostex T925a.

Will cruise at 110-120 db without breaking a sweat...

http://img244.imageshack.us/img244/7739/0000001ix7.jpg

Huh! Missed that post. I like your system.
Too bad Parts Express doesn't sell the 12" Dayton Waveguides. I was going to build a similar system/

Yep! cruisin at 110-120dbs sounds fantastic and that's what I'm going after. The reason I like the Titan 48's is I like Eminence 15" drivers. They got some really good sounding bass. About the closest I've come across to a live concert.
I've built Bill's projects before but only the small stuff. I'm going loud this time. As for the Dayton aluminum drivers they CAN produce slam. A very very visceral feel to them. This time around I'm going 'live concert' in living room.

[RJ]

Originally posted by MaVo
The slam in the chest is around 80hz i think, maybe 70 if you are a big guy. You could google the resonance frequencies of your body parts and see for yourself. As the frequency goes down, quite funny places can be in resonance. Basslines lie around 40-80hz for typical dance music like techno, dnb, house etc. Below this are mostly special effects in movies or experimental music.

But like Sreten says, chances are, that your neighbours will complain before you really feel body resonances. Still, bass from speakers is alot more satisfying than bass from headphones, even at moderate levels.

Yep! you're right, but don't forget the 2nd and 3rd harmonics.
Like 60, 120 ,240 hz.
I forgot the European country where they were experimenting with Bary Bass if I recall correctly.
If I still have it on my hard 'drives'... I'll post the thread...

[RJ]

Another thing I liked about them line arrays was the fact at the low 80 db levels you still felt the bass. The first speakers I ever had that can do it!

[Doug Kim]

Originally posted by Don Bunce
I built a pair of thr bk16's a while back,with Fostex ff165K.They were OK ,but slam is not a word I would use to describe them.I wouldn't expect the bk20's to be much better,but I haven't heard them.

I turned the horns myself,but you can get tractrix horns from edgarhorn.com.He also sells a kit horn shell for 15" drivers.

The Altec 825/828 (A7 Voice of the Theater)cabinet will also work well,plans are available on the net.

A Karlson K15 would be a good choice,too,and has the slam you are looking for.

http://home.planet.nl/~ulfman/

Freddyi is the resident guru on Karlsons on the hi-eff speaker forum at audioasylum.com

Don,

Karlson woofers seems like a good approach since I don't like anything too big. Thanks again for the good suggestion.
And I also really liked you system.

Doug

[Doug Kim]

Originally posted by musgofasa
Well being an old car audio guy, I feel I may be as qualified to answer this as anyone.

In-car bass slam is between 35 and 70hz. The low vibrating bass in techno and bass tunes (IBP etc) are aroun30-35hz while the real "Slam" that makes your heart skip is closer to 60hz. These aren't particularly musical tones and if you are looking for that type of SPL to mate with cabinets or towers in a room, you will find you need a large room with PA style horns to keep up.

To get to the point, getting 135+db in a room the size of my living room (23 x 12 ft) would require quite a bit of power. Band pass enclosure is going to be the way to go. BIG band bass. My suggestion would be a down firing band pass with as many 15 or 18" woofers as your wallet will take. The power is what will cost you money. How big is the room you are working with?

I also agree with the previous post about using two enclosures, one on either side of the room. I say Band Pass because you can do a 4th order type box with a sealed rear chamber which will give you more power handling and an open, floor firing configuration which will help load the woofer to the room.

For the record, I have a really (and I mean REALLY) cheap sub built in my house. I used two 15's that cost something like $25 each and a small plate amp (dayton). At my listening position, it shakes my chairs hard enough to remind me of a car with a strong 10" woofer. I think that a much better pair of subs with10 times the power would likely bring down the walls. It runs from 20hz up to about 60 before it starts rolling off severely. Of course I have it crossed over at 70 so you can tell I was after the same thing.

When I am listening to Nora, the sub isn't playing. My mains do a pretty awesome job of getting extension and being fast, and clear. When I want to rock the house, I pump up the sub. It works great for HT too.

Of course, some people don't like the sound of it. I for one think it is pretty muddy, but I am comparing it to some full range and very high end multi-ways when I say that. All and all it is actually very pleasing the way it is and i can think of oodles of ways to make it better.

Give up some details on the room, power, subs you would prefer to work with and I can make some estimates for you on what to expect performance wise. I am sure others will chime in.

OH, one last thing. The Lab horns are pretty awesome. Big as well, but more efficient and a little more bandwidth. They do especially well with Techno and stuff like that. If you like the transients in Metal etc, I might suggest sealed or ported and a LOT of BIG woofers. See what I mean about options, lol.

Take care,
Robert

Robert,

Thank you for all the nice answers to my question. Size does matter in this case, doesn't it?

I got a question. When you experimented with your system, how fast did you think the bass is? I think the biggest difference in bass quality between car-audio and (not so well set up) home-audio is not just their bass quantity but also their speed.

Doug

[RJ]

Originally posted by Doug Kim



I think the biggest difference in bass quality between car-audio and (not so well set up) home-audio is not just their bass quantity but also their speed.

Doug

Speed;
http://acousticreproductionofpercussion.blogspot.com/

[musgofasa]

Admittedly,
My sub is not fast at all. In fact it can be downright muddy sounding to me. I have heard cars with far worse, true, but in comparison to the mains, it isn't nearly as musical.

In reference to that last post, I agree with one of the statements about "off-axis" response. I am an omni lover, lol. I have heard a few "good" omnis and nothing seems to be as forgiving to me. I have heard great standard styled speakers and even good OBs, but nothing has given the same "speed" as the omnis from anywhere you listen. That is why I am trying to work on a set now. I have a tiny set for my computer and the difference is amazing.

As far as comparisons to car audio though, it is really a different animal. My favorite subs for low extension and transients have been horns. The Labs do a terrific job of this with good drivers. I bet the Eminence would be wonderful. The only issue I have had with horns is room size. Sometimes they are not forgiving in small rooms and end up sounding "choked" somehow. I prefer band pass in small rooms because the waves are already spread out before they hit the listening area. The only problem then becomes transients. Inherently BP designs aren't quite as fast as direct radiating ones. Again with the floor firing. If you can load them to the room, it is like coupling in a car. Anyone who has ever made a false floor in a trunk or hatch knows they get more gain in car that way. Likewise, bolting a sub to the frame and firing the speakers at the trunk floor inherently gives you more gain as well but usually at the cost of some transient ability. Like anything there are trade offs.

Which interests you more? Quality or Quantity? If you must have both, you may find your wallet in dire straits. Previous posts recommended going with comparable driver/ enclosure volume as compared to a vehicle. This would mean something like 20 18" drivers in a normal sized living room. Granted that might be a bit exxagerated, but it still makes sense.

Robert

[sreten]

Hi,

Slam as far as I'm aware is accurate bass transients + bass extension,
e.g. the leading edge sound of a garage door being shut or similar.

/sreten.

[musgofasa]

Sreten,
You are probably right on with that assessment. I have to say that my itty bitty 4" sub in my office does a great job of giving the "sound" of slam and I know it isn't producing any real SPL.
I think most car audio guys get more from the "feeling" of the vibration from the thing than from the sound of it. Such a subjective thing to try and replicate. Sometimes I am glad there is subjective reasons for sound and others I just wish we could do the math and achieve perfection.

Somebody has a signature (sorry don't remember the author) that says, "Making something simple is the most complicated thing you can try to accomplish".

I tend to agree.

Take care,
Robert