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SUPPORT FORUMS FOR DECWARE SPEAKER PLANS >> Wicked One Support Forum >> Multiple Drivers Instead Of Big Drivers?
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Message started by Matthew on 12/09/06 at 11:52:22

Title: Multiple Drivers Instead Of Big Drivers?
Post by Matthew on 12/09/06 at 11:52:22

Whoa, I was looking up instrument loudspeakers on google and came by this:

http://www.instituteofbass.com/product_spotlight/

This makes me wonder if something tricky can be done with the WO as well.

At first glance, this makes no sense to me. This theory may work in cylinder heads, where 4+ smaller valves amount to more flow than a single large valve, but I thought one of the necessities of creating lower frequencies was starting with a cone surface that could create them to begin with! Low frequencies seem lower pitches when played very loudly, but... well you get my drift. What is really going on in those cabinets with all the 5" drivers?

All I can figure is they're using multiple drivers to create larger SPL since there is as they said more effective cone area, but making up for the lack of actual low frequency reproduction from the driver cones by using a transmission line or folded horn of sorts.

Title: Re: Multiple Drivers Instead Of Big Drivers?
Post by 60ndown on 12/09/06 at 16:45:08

not sure about the speaker design thing, but theres a few cds there i want to get.

Title: Re: Multiple Drivers Instead Of Big Drivers?
Post by Jet-Lee on 12/10/06 at 01:46:42

You can't compare speaker output to valves in an engine.

Valves in an engine optimize air velocity and flow. For SPL you want acoustic pressure.

On that page, I see a setup that has an 8x4 array of what I assume are these 5" 'woofers'. That's roughly 628 square inches of cone area in about 960 square inches of space. We could put 6 12" speakers in that same amount of space but have about 678.5 square inches of cone area. That's 50 square inches more cone with less wiring headache.

20hz from an 18" speaker is a lot different than 20hz from a 10" speaker.

Title: Re: Multiple Drivers Instead Of Big Drivers?
Post by Matthew on 12/10/06 at 04:40:58

You obviously didn't read my post correctly. I wasn't ruling in that manufacturers favor. I was pointing out that if we were talking about valves, having more, smaller valves would make for some form of benefit, whereas I don't really see how having several more small drivers can equal the output of less, larger drivers. The little cones cannot reproduce low frequencies adequately.

I did take it for granted, though that their claim about having more total effective cone area was true. But then their basis for comparison was silly because I don't see those drivers having an adequate xmax or power handling to be a real comparison. Oh well. keke! ^_^ I don't really feel that four 5" drivers placed in a tight square are going to have the same output as a single 10" in their place... even with the help of a folded horn or transmission line. I think chucking their product for a bass-bin with an 18" would be TEH WIN!

Title: Re: Multiple Drivers Instead Of Big Drivers?
Post by J_Rock on 12/10/06 at 05:10:07

Well-

Lets look at the 4 x 8 array. It says it uses 5 inch drivers. We can assume these drivers ar emounted as close as possible in lines, meaning each 5 inch speaker is mounted in a 5 x 5 square. This means the 32 5 inch speakers use up 800 sq inches of space, and create 628 sq inches of radiating area.

Similarly, we could fit at most, 4 12" drivers (in the 800 sq in and in lines.) These 4 12s would have a radiating area of 452 inches.

That means the 5 inch speakers have more radiating surface then the 12s.

The 5s will play higher frequencies easier and sound better doing it, plus they will displace more air then the 12s at the same excursion.

Problem is, the 12s will have a higher excursion, therefore equal or exceed the displacement of the 5"s. The only real benefit is a somewhat similar output with higher more controlled frequency response.

Title: Re: Multiple Drivers Instead Of Big Drivers?
Post by colinreynolds on 12/11/06 at 04:27:04

I've seen some wild stuff done with lots and lots of 5"s in ported boxes in extended cab trucks. Not as low, but loud I bet. And as said, the louder you play low frequencies, the lower they sound.

I wonder if you mix and match drivers that are the same size but are different drivers (like Steve did with the Imperials) that one could play just a bit lower than the other one. This would make the bass sound much much lower. This is how the Waves Maxxbass works as best I can tell.

Title: Re: Multiple Drivers Instead Of Big Drivers?
Post by Adrian D. on 12/11/06 at 12:48:05

colinreynolds wrote on 12/11/06 at 04:27:04:

And as said, the louder you play low frequencies, the lower they sound.

i tought it was the lower the frequency, the louder it seems to the ear

Title: Re: Multiple Drivers Instead Of Big Drivers?
Post by musgofasa on 12/11/06 at 17:24:52

Psychoacoustics are fun aren't they?
Colin is right though. The louder a low frequency is played the lower we think we here it. A 40hz tone played at 90 or so DB sounds pretty natural, but because it is low enough to feel when played very loudly we perceive it to be lower when played at say 135db. Blast it on up to 150db and it seems to us to be playing way lower. In reality the sound has not changed, but due to the fact that we feel it, our minds want to process each wave and make it slow down.
Psychoacoustics are weird. Now if you listen to the same through headphones you can really tell what is going on. It can be hazardous to the equipment though lol.

I have seen very large installs done with small drivers. There was a van with 56 8" drivers at one time touring the IASCA circuit that seemed like it could play anything the vans with 15s could. There was also a Volkswagen with 24 6.5" drivers that was doing a pretty amazing job. Perception is reality folks.

Now when we measure stuff with a mike and take away our pyscho brains from the equation, physics won't go away. Cone area and displacement equal SPL, but they do not affect sound quality. Quality is reproduction. Depending on your goals in your project one attack may work much better than the other. Everything is relative. EVERYTHING.........

Title: Re: Multiple Drivers Instead Of Big Drivers?
Post by Jet-Lee on 12/14/06 at 06:31:50

J_Rock wrote on 12/10/06 at 05:10:07:

Lets say these 5" speakers have a peak-peak xmax of 1 inch. That means on one single peak to peak stroke (- to +) of all speakers at the same time moves roughly 418.46 cubic inches of air with the 1 inch stroke and 1 inch deep cone. Now those four 12's would move roughly 597.15 cubic inches of space if they had a 2inch xmax and 2inch deep cone.

Now, my math could be wrong, as it's 1:30am, but the same formula (wrong or right) was used on both examples, so it still stands that the 12's would move more air.