P.A. sub project

[juxta]

Hey I'm looking at drivers for a P.A. sub project

Freq range needed:30hz to 100hz

Spl needed: Greater than 100db 1w/1m

I've seen a few around but thought someone with experience may be the best bet for finding good info..

I am open to any design suggestions

Sub to be used outdoors for electronic music

Any thoughts, info, stories, pics would be a great help

Thanks

 

[WithTarragon]

Well, your requirements are tough ones. If it could be done, the cabinets would be huge and they would probably require corner loading.
You may want to re-think you requirements.

 

[powerflux]

i'd put the -3dB at 45 Hz, this is way low enough for PA and much easier to accomplish.
30 is also doable but with laaaarge cabinets.

labhorn anyone?

 

[davygrvy]

As before in the other threads: many small horns with a cheap MCM 55-2421 acting with great mutual coupling.

 

[littlemike]

I have posted a simulation of a quad 55-2421 driven tapped horn that meets these criteria over in your other thread.

 

[WithTarragon]

As before in the other threads: many small horns with a cheap MCM 55-2421 acting with great mutual coupling.

Hmmmm, many small horns and mutual coupling. That can add up to a huge box or footprint. Some of the TH designs that go down to 30Hz assume a corner loading. Do PA setups have the flexibility of an "available corner"?.

The criteria are still going to force you to build something huge that may also need corner placement.

 

[davygrvy]

The criteria are still going to force you to build something huge that may also need corner placement.

We're assuming 1/2 space. Huge probably, but many boxes move and pack easier.

 

[juxta]

I have posted a simulation of a quad 55-2421 driven tapped horn that meets these criteria over in your other thread.

Thanks mike I decided to throw the doors open to any suggestions in case horn loading wouldn't happen.. Not that I don't have hope
Becoming a bit of a messy threader!

 

[juxta]

Hmmmm, many small horns and mutual coupling. That can add up to a huge box or footprint. Some of the TH designs that go down to 30Hz assume a corner loading. Do PA setups have the flexibility of an "available corner"?.

The criteria are still going to force you to build something huge that may also need corner placement.

I've been thinking about building a collapsible corner but how much building do you need to get effect?
Would subs with fake corner still produce?
Feels like a wacky scientist thing to say, i'm prepared to be embarassed.....

 

[juxta]

Is it impossible to get 30hz to 100hz and 100db 1w/1m from a sealed or ported normal box sub?
I've used some 18' box subs an they've been good with only my battered ears as testers, are they actually doing very little hz and db wise?
BEHRINGER VP1800S 18" 1600 are only $300 but only reach 40hz I think they say....

 

[davygrvy]

I've been thinking about building a collapsible corner but how much building do you need to get effect?

Boundaries need to be greater than a half wavelength, I think. That's 19 feet for 30Hz and needs to be very solid, so consider masonry blocks. Or maybe ice

 

[juxta]

Boundaries need to be greater than a half wavelength, I think. That's 19 feet for 30Hz and needs to be very solid, so consider masonry blocks. Or maybe ice

Ha ice looks fun but a bit messy an a bit hard to drive up the mountain every party we have!!!

Have had ideas of building a flying booth with deflection for subs in front but could only be 4 foot high and 10 feet wide...

What do you mean by 19 feet? 19 square or wide or high?

Littlemike said I should be looking for 30hz but is it even possible?

 

[davygrvy]

What do you mean by 19 feet? 19 square or wide or high?

19 feet from the point of origin. Like an eighth slice of the earth, but only two sides

Littlemike said I should be looking for 30hz but is it even possible?

Sure, mouth area of the whole thing might be around 16sqft. Whole thing doesn't mean one monster cabinet. A whole bunch in a BFM style V-couple array with a roof. Follow with what jbell is doing with his 'bass stick' in his FLH thread. Eight of those would be 5 feet tall with a mouth area looking to be well over 16sqft. With super cheap drivers!

 

[juxta]

Sure, mouth area of the whole thing might be around 16sqft. Whole thing doesn't mean one monster cabinet. A whole bunch in a BFM style V-couple array with a roof. Follow with what jbell is doing with his 'bass stick' in his FLH thread. Eight of those would be 5 feet tall with a mouth area looking to be well over 16sqft. With super cheap drivers!

Ok

BFM V-couple array + roof

jbell's bass stick

An what drivers are we using?

Cheers

 

[davygrvy]

I'm really only asking you to consider the idea of many small boxes to become greater than a single monster. It could be the Titan39s, or Jim's bass stick, or maybe a big pile of AutoTubas. The AutoTubas couple well, but can't do that V-couple trick for a monster mouth. The Titans have the classic BFM 1/4 wave response which means hot in the 100, rolling down to 40. More in the pile makes the response smoother, louder because of multiple sources [10*log(number of sources)=dB gain], and Fc becomes lower. The roof to it smooths it more and drops Fc even more. But you might not want the 1/4 wave response, as you've mentioned electronic music. Live kick drum, snare and bass guitar are the big eaters of your power and surprisingly that's up in the 80-120 area, not the 40. A system to get you 30 at rock levels, around 136dB(SPL) at 1 meter will be expensive in terms of size of the whole. Which doesn't have to be large regarding the individuals of your pile.

Here's how to calculate max SPL:

maxSPL = sensitivity + power gain + sources
maxSPL = 96db(SPL)1W/1M + 10*log(300W) + 20*log(6 cabs)
maxSPL = 96 + 24.77 + 15.56
maxSPL = 136.33 dB(SPL)

 

[polviggen]

don't you have to count in power compression too ?

 

[davygrvy]

don't you have to count in power compression too ?

Not likely when you use the continuous power rating or baring any bad behaviors of the horn. But that's really something you have to measure with the end result.

BTW, 20*log(number of sources) is for coherent sources, of which mutual coupling is, not the incoherent calc using 10*log(sources)

 

[Xoc1]

Would a bandpass cabinet fit the requirements for a 30 to 100hz cabinet?
I was thinking specfically about Rog Mogales Design on speakerplans.com
Speakerplans.com
-3db points are 31 to 119hz @ 102db/W.
Personally I dont like the sound of 6th order bandpass cabinets in PA systems, In my opinion they have poor bass timing.

Funktion One use some sort of ported bandpass design in the Infrabass 218 to extend the LF of their horn systems.
I assume the Infrabass 218 is a 4th order bandpass cabinet,which would compliment their bandpass horn designs.
They also make a add on horn that fits to the front of 2 Infrabass 218 cabinets. thats 4 x 18" drivers. they do sound very impressive but they are ony effective for one octave from 30 to 60hz

 

[littlemike]

I have posted a simulation of a quad 55-2421 driven tapped horn that meets these criteria over in your other thread.

This was a 2pi simulation, no corner loading needed.

It is a big cabinet, but it is still smaller than Jim's 3015-LF Tapped Horn.

V-plate two of these - it will get interesting.

 

[juxta]

This was a 2pi simulation, no corner loading needed.

It is a big cabinet, but it is still smaller than Jim's 3015-LF Tapped Horn.

V-plate two of these - it will get interesting.

I can't find the sim mike would you mind posting it up again please?

What do you mean by v-plate too ?

I still have a hard time imagining 8"s or 10" producing more bass than my 15" Klipsch's but the proof is in the pudding..

Thanks guys for the input