A7 and Bass Boost Circuits?

[notloudenough]

marshall,
Do you have the specs on a tapped horn using the 421 8-h? I also have a extra pair and would build a tapped horn given some specs.
I have two friends, one with the 902/416 combo, [he uses two long excursion 15" subs] and the other with 808/421 combo.{He swears he doesn't need any subs] That was until he heard mine. My point being the 421's will work as subs given the right enclosure. Stanley Screamers came to mind. Plus with subs, you can always turn them off, to avoid waking the neighbors. {I use mine at stadium levels when the neighbors are fighting or their kids are making noise.] Works great.

[mah]

Unfortunately, no. My post on Tapped Horns elicited most of the info that I have read. Google 'tapped horn' and you will find more.

Cheers, Marshall.

[GM]

Originally posted by 866239:
marshall,
Do you have the specs on a tapped horn using the 421 8-h?

<font size="2" face="Verdana, Helvetica, sans-serif">http://www.diyaudio.com/forums/showt...56#post1601556

http://www.diyaudio.com/forums/showt...61#post1601561

GM

[notloudenough]

Thanks GM,
Now, I'm a "gitter done" kind of guy. If you can tell me throat and mouth cubic inches and how long to make it I'll build one this weekend. My size limitation is 2'x3'13.5' Yes that's feet.

[GM]

You're welcome!

Well, alrighty then, you want the full size corner loaded conic TH:

St = ~81.84"^2
Sm = ~620"^2
axial length = ~240"

Driver at the end of both throat and mouth. You will probably want to either apply some rubber cement to the alum. DC or line the throat walls to absorb its HF. In theory it will run out of Xmax around 16.5 Hz, but probably best to digitally hi-pass it a bit higher just in case your corner doesn't load it well enough. Of course this driver can handle a bit more excursion without grenading, but being an underhung motor working ~an octave below its Fs may prove its undoing, so Caveat Emptor.

GM

[boltupright]

Originally posted by 866239:
marshall,
Do you have the specs on a tapped horn using the 421 8-h? I also have a extra pair and would build a tapped horn given some specs.
I have two friends, one with the 902/416 combo, [he uses two long excursion 15" subs] and the other with 808/421 combo.{He swears he doesn't need any subs] That was until he heard mine. My point being the 421's will work as subs given the right enclosure. Stanley Screamers came to mind. Plus with subs, you can always turn them off, to avoid waking the neighbors. {I use mine at stadium levels when the neighbors are fighting or their kids are making noise.] Works great.

<font size="2" face="Verdana, Helvetica, sans-serif">I have a pair of Stanly Screamer cabinets, they used to house a pair of 15"duplex & a large format manta ray horn & driver.
Could I get good sub bass from those with a pair of 416's?

[mah]

Still looking for comment on electronic bass boost/extension.

Marshall.

[GM]

Other than spouting formulas to calc a bunch of theoretical situations and all the caveats that go along with them, Brad's original response answered your Q, i.e. a 416 is ill equipped for using enough boost to flatten out an A7 down to its ~55 Hz Fb much less below this point without either a low average listening SPL and/or corner loading. If boost below Fb is desired, then the cab ideally needs to be tuned lower, but excursion doubles for every doubling of power (+3 dB of boost) and quadruples for every octave drop, so it takes a lot of room gain to offset this when you want to rock down low, like the amount of gain you get in a tiny 'room' such as a car's.

Going in the other direction, i.e. attenuating the horn's response allows modest bass boost to tune the cab lower, reducing system efficiency down around 93-96 dB depending on the room's gain curve or about on par with a 9846-846 respectively, which is plenty in a typical size listening room if you have enough clean power to meet the dynamic headroom (peak SPL) requirements that's based on average SPL, listening distance, room gain curve and type of playback signal.

Ideally though, you'd drive these with the same type of high output impedance amp with adjustable damping (bass boost) as they were originally designed for to 'have your cake and eat it too' so to speak as system efficiency isn't reduced nearly as much when dialing in more LF boost.

No 'free lunch' below ~0.707*Fb though, so corners would still be required to extend tuning below ~40 Hz.

GM

[notloudenough]

GM,
I'll probably build it on saturday. Hope it doesn't rain.{Testing} I'll also try to post pix.
Thanks once again.

[GM]

Originally posted by boltupright:
I have a pair of Stanly Screamer cabinets.........
Could I get good sub bass from those with a pair of 416's?

<font size="2" face="Verdana, Helvetica, sans-serif">It would depend on whether you leave the Mantaray in or not as well as the 416's specs, though at best it would need corner loading to fill in below ~100 Hz since the cab's too small for dual 416s tuned down around 20 Hz.

GM