Can I use this in an E.B.S.?

[mikee55]

Hello Everybody,
I have a Longmill 10" woofer and found the following spec

Re = 3.6 ohms
Zmax =50.3 ohms
Fs = 27Hz
Qms = 4.3690
Qes = 0.3368
Qts = 0.3127
fc= 77.5hz
Vas = 99.94 L
E.B.P. = 80.1662

At the mo, its in a basic reflex enclosure. I've learnt to build a sealed box and the reflex, now I want to try the Extended Bass Shelf.
Please can you give some pointers.

Cheers

Mike

 

[richie00boy]

Any driver that works in a normal vented box you can also use in EBS as EBS is just a vented box made 'oversize' and tuned to suit.

What application is this Mike? In the house?

 

[316a]

Just run it and it looks good to me Lowish Qts drivers like yours seem to model best with an EBS alignment

cheers

316a

 

[mikee55]

Hello

Hi Rich,

Got some scrap wood, so thought I'd play whilst waiting to move. I'll stick it in the car, house is a mess at the mo. How big would the box be?

Cheers

Mike

 

[GM]

Re: Hello

How big would the box be?

Greets!

EBS dates back to when you tuned the cab to ~what we now call Vas when the vent was tuned to Fs, though up to ~0.7*Fs is fine, so ~100 L tuned to as low as ~19 Hz works for me.

GM

 

[sreten]

Hi,

TBH EBS in a car is not box volume friendly.

An EBS type alignment is shown below.

/sreten.

 

[sreten]

Hi,

an even bigger box is needed for a more pronounces shelf.
Not recommended IMO.

/sreten.

 

[mikee55]

Big

Yeah I aimed for 100l andtuned for 27.Bit too big me thinks

Mike

 

[GM]

Hi,

an even bigger box is needed for a more pronounces shelf.
Not recommended IMO.

/sreten.

Greets!

Can't comment about your locale, but around here the extended shelf works very well WRT ~mirroring a typical room's gain and ultimate 'bleed off' down very low assuming the driver allows a low enough tuning frequency and has a fairly low Qts. Never built any true subs for cars though, so not sure if this applies to them.

GM

 

[sreten]

Greets!

Can't comment about your locale, but around here the extended shelf works very well WRT ~mirroring a typical room's gain and ultimate 'bleed off' down very low assuming the driver allows a low enough tuning frequency and has a fairly low Qts. Never built any true subs for cars though, so not sure if this applies to them.

GM

Hi,

not recommended for in car use IMO, half the size and
an amplifier with low bass boost would be better IMO.

/sreten.

 

[mikee55]

Hi sreten

Hello, I'm using a 40l box with the driver now and thats quite big in my Vauxhal Corsa. I just fancied learning the design and using it in the car, because I already know how the reflex sounds, I could easily identify its differences. I suppose a Transmission Line would be as big, and a horn not possible with this driver type? Just leaves the Bandpass then?

Cheers

Mike

 

[GM]

not recommended for in car use IMO.......

Greets!

OK, wasn't sure what you were disagreeing about.

After reviewing some old data I had on car audio it appears a decently sealed car will have a near ideal cabin gain below the first mode, so if the distance between the base of the windshield and rear window (typically the longest parallel distance) is ~8 ft, then a driver with specs that yields a ~T/S max flat sealed alignment or reactance annulled FLH down to ~70 Hz should theoretically be flat to the lowest signal reproduced, though apparently many vehicles still have a fairly high Fs, so below this point it will act as a steep acoustic low pass filter.

This implies that a seriously under-damped (large) EBS will work well to go really low, but it would be so obnoxious for anyone nearby that I imagine you'll get more than you bargained for from irate motorists, pedestrians and any law enforcement within shouting distance.

GM

 

[GM]

Re: Hi sreten

I suppose a Transmission Line would be as big, and a horn not possible with this driver type? Just leaves the Bandpass then?

Greets!

Hmm, forgot about a max flat impedance TL if the driver's specs work for your vehicle's cabin gain curve and should be closer to a sealed alignment in size. Yeah, BP is apparently car audio's de facto sub alignment.

GM

 

[mikee55]

Okay

Hello GM

This implies that a seriously under-damped (large) EBS will work well to go really low, but it would be so obnoxious for anyone nearby that I imagine you'll get more than you bargained for from irate motorists, pedestrians and any law enforcement within shouting distance.

This sounds like fun, could a sensible sized Bandpass be as good, and how difficult are they to design?

Cheers

Mike

 

[GM]

Greets!

Around here it could get you shot, or worse.

As good as what? The ridiculously large EBS, a good EBS, or?

Anyway, the BP would be pretty small at ~40 L (net), so will need a TL length vent for a low vent mach even with as little as 100 W (creating its own distortion), so I imagine it will need to be heavily stuffed which will require some chamber Vb adjustments that no program I have can predict.

Then again, IIRC Dan W. (Adire) did one using a plastic dryer vent coiled up and this combo reduced its self generated pipe harmonics enough without any, so as always YMMV.

GM

 

[boydon_lepasci]

I modeled a ~30Hz tapped horn for a 12" I was asked to help with. It folded up to a reasonably tolerable profile and the rolloff was prime for the cabin gain of a typical vehicle. You would need to derive or measure some additional parameters to plug into Hornresp(freeware) for modeling.