just a guy said:
I made this point over at Audio Circle and got a very condescending response from proponents of small corner horns. The fact remains that if you want to do a single driver speaker and get any SLP above "polite" levels, you have to have at least an 8"er to get any semblance of "slam" for modern pop music. I have built 6"ers that are very, very good at "polite" music, but they start to compress early in the game. My 8"ers are much better for "slam", simply because they are moving half again as much air.
However, if you really must do metal at concert levels, you are going to have to go to a 2-way woofer + mid-tweet arrangement. Then you can consider a 4"er for the top.
Bob
Agreed, although IMO, if you want to take little drivers down low, a decently designed big box or corner horn will be more effective at it than small one, all other things being equal (not that they ever are). But whatever you do, they'll never have the 'slam factor' -with a cone that size, it's just not going to happen. That's why the good Lord invented 15in woofers. 
I saw the ac thread, but haven't followed it. I already know (theoretically) the pros and cons, and how strongly those involved feel about their choices. I basically knew this experiment would turn out the way it did, I just needed to try it out and form my own personal point of view.
FWIW, from what I did read of the ac thread(s), they seem to center around the hornshoppe horn design vs everything else, and my inverted bibs are tuned a full 20 hz lower than the horns. I still have high hopes for the frugal horns I am making, and hoping ~60 hz tuning is not too much to ask of these 4 inch fostex drivers.
That's kind of assuming that all horns are equal, when they're not. With the FH & others, you're getting a better loading on the driver than you'll get with a simple pipe-horn. The latter is basically a linear (nee conical) expansion; very rapid initial expansion, which is great from the POV of low distortion; however, because throat resistance rises very slowly, LF loading isn't as good as, say, a hyperbolic with its much slower initial expansion rate, and which will hit the ~optimal much more quickly.
60Hz isn't too much to ask. Hell, 30Hz isn't too much to ask if you can cope with the size (and add a tweeter as the very high damping on the cone provided by a horn this big will cause HF roll-off): extension is rarely a problem if you can go big enough, but the old slam factor is with small units, whatever you do with them.
60Hz isn't too much to ask. Hell, 30Hz isn't too much to ask if you can cope with the size (and add a tweeter as the very high damping on the cone provided by a horn this big will cause HF roll-off): extension is rarely a problem if you can go big enough, but the old slam factor is with small units, whatever you do with them.
Understood. I'm not trying to make any sweeping statements here, just saying I won't be trying to get real fullrange extension out of 4 inch drivers anymore - I'll be using a sub. And with that in mind, I have great expectations from the frugals. I'm thinking they will meet my (subjective) criteria for size vs spl vs lf extension.
The thing about corner horns is that that have to be in corners. Also, your stereo pair have to be in adjacent corners and reasonable close together if you want any center fill, which implies that the room is going to be on the small side. Given a small room, you can reasonably expect to excite all of the room modes, and may well get some meaningful pressurization. Look at the amount of bass those sorry little speakers in a pick-up truck can create.
While a 4" driver might produce some bass with the help of corners and room modes, you are still not going to move much air in the 80-100Hz range where "slam" is. Removed from a corner, they become just another run-of-the-mill BLH with poor bass and lots of ripple. Even BiB's loose a lot removed from corners. The real world that I live in requires that the speakers be well away from corners in moderate sized rooms. Hence, my designs do not require support from the walls. A little room lift does help, though.
Bob
While a 4" driver might produce some bass with the help of corners and room modes, you are still not going to move much air in the 80-100Hz range where "slam" is. Removed from a corner, they become just another run-of-the-mill BLH with poor bass and lots of ripple. Even BiB's loose a lot removed from corners. The real world that I live in requires that the speakers be well away from corners in moderate sized rooms. Hence, my designs do not require support from the walls. A little room lift does help, though.
Bob
Scottmoose said:
But whatever you do, they'll never have the 'slam factor' -with a cone that size, it's just not going to happen. That's why the good Lord invented 15in woofers.
Not true! The FR125S actually has excellent specs for a corner loaded 'ideal' BLH with a ~23 Hz cut-off, but the trade-off is you'll need another in a sealed cab to fill in above a few hundred Hz and bi-amped to level match due to it being so highly damped and huge acoustical gain.
Really, it would be neat to use one as a 'sub' horn just for freaking out folks trying to figure out what big driver(s)/'x'kW amp are hidden in it when you point to a dinky little driver over in the corner as the source.
GM
Bob Brines said:
As presented, not true! The BLH I just mentioned reduced in length, hence reduced size mouth to something that will fit in a typical corner and room size limited to a ~12.5 ft long room due to Hornresp's max mouth size limitation, 1 W, 1 mm excursion/60 Hz:
GM
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Same horn with an optimum minimum path-length and folded to load two corners in a ~20 ft long room, though again, a longer room will load it lower, though at these frequencies the room needs to be really massive such as a below grade poured concrete (all surfaces) basement:
GM
GM
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I still haven't taken the time to research his revised BLH sheet yet since lately this 'old dog' has been having a hard time learning new 'tricks'.
Prof. Leach:
Vf = 20.997"^3
St = 6.288"^2
M = 0.583
Based on some early production driver specs:
Fs = 67.4 Hz
Qes = 0.684
Vas = 0.197162 ft^3
Anyway, you have to be able to either spec the 'M' (AKA 'T') factor as well as make it big enough to load all the way to ~23 Hz. The sim I did in the earlier version only allowed an expo flare, so while very smooth, it didn't load all the down even with a full WL path-length into half space to try to make up for corner loading:
GM
Prof. Leach:
Vf = 20.997"^3
St = 6.288"^2
M = 0.583
Based on some early production driver specs:
Fs = 67.4 Hz
Qes = 0.684
Vas = 0.197162 ft^3
Anyway, you have to be able to either spec the 'M' (AKA 'T') factor as well as make it big enough to load all the way to ~23 Hz. The sim I did in the earlier version only allowed an expo flare, so while very smooth, it didn't load all the down even with a full WL path-length into half space to try to make up for corner loading:
GM
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