Planning to build a 1000w bass horn in the summer!

[bob123]

Hi,

I have intentions to build a 1kw bass horn in the summer.
Idealy i would like the below charicteristics:

1000w(rms)
bass extention 40hz
Max SPL = 130db+
Not too bothered about the quality or the transient responce as it is for drum and bass.

Does anyone have any plans based on these parimeters?
Is it worth designing the horn myself? I am very competent in mathematics but have only recently discovered the concept of a bass horn (i am 17 years old).

I will have a budget of about £300

I also would consider building 2 if this will improve outside performance.

These horns will need to withstand an absolute hammering! 1000W of DRUM AND BASS from 10pm to 6am LOL

[pinkmouse]

The only drivers that I know from practical experience will handle 1KW constantly are the precision devices PD2150 and PD2450. Both drivers, on their own, are well above your total budget for the whole enclosure, and with your criteria, I wouldn't recommend anything but pro drivers. What amp will you be powering this with?

[Tenson]

Have a look at the Eminence LAB 12 subwoofer driver page here - http://eminence.web.iglou.com/eminen...ab12/lab12.htm

Take note of the application notes to the left as there is a design for a bass horn.

BTW, why do you need 130dB? That is a dangerous level. Even a short exposure at that level will literally pop your ear drums. Not fun at all, even for someone who likes drum and bass. The only way I can see of achieving that level is with multiple speakers and that will cost over £300. A pair of lab 12 will give you A LOT of bass though. Just probably not 130dB.

Hmm you know since all you drum and bass people are mad about volume I think you should hire out Wembley for a evening and club there. They have a 60KW system.

[bob123]

TOA P-1090d - got it for £50 of ebay LOL (500w x 2 - 4ohms)

Ok so a single driver is out of the question. I was looking at the eminence delta 15 and it seems that 2 bass horns with a driver in each could delvier in excess of 131db.

How big would the horns have to be to "tune" to 40hz?
What would the gain of building the horns be instead of a bass reflex enclosure?

[bob123]

"Hmm you know since all you drum and bass people are mad about volume I think you should hire out Wembley for a evening and club there. They have a 60KW system."

NO id rather hire out the valve sound system. 52 bass bins with a total of 95kw. That was a good night out LOL

130db is within 1m of the speaker but as you well know that decreases by 6 db as you double the distance also due to the frequency being quite low the dammage is either less or less noticable - i havent figured out which one yet!

[Tenson]

How did you calculate that MAX SPL for the Delta 15?

[bob123]

101db + 10log800

[Nigel Goodwin]

Originally posted by bob123
TOA P-1090d - got it for £50 of ebay LOL (500w x 2 - 4ohms)

Ok so a single driver is out of the question. I was looking at the eminence delta 15 and it seems that 2 bass horns with a driver in each could delvier in excess of 131db.

How big would the horns have to be to "tune" to 40hz?
What would the gain of building the horns be instead of a bass reflex enclosure?

They would be massive! - do they need to be portable?.

The advantage of horns over bass reflex is much greater efficiency, a horn is basically an acoustic transformer, it matches the mechanical impedance of the cone to the mechanical impedance of the air.

A guy I knew many years ago used folded horns for his disco, placing the cabinets pointing into corners of the room using the walls to make the last section of the folded horns. He used to run only TEN WATTS and it was plenty loud enough, more so than people running 100W or 200W.

[bob123]

yea they need to be somewhat portable - i think i could make £100 a night at uni hiring them out. Or if i get bored with them just sell them on ebay for a profit!

What is an average gain for a horn?

[Tenson]

Originally posted by bob123
101db + 10log800

Ahh okay, I only asked is because you said that in horns they would reach that level and I didn't know a formula to work out the extra efficiency a horn gives I would suspect that all horns are different, but they will definitely give you more output.

I may not be helping to answer your original question but…

The drivers efficacy drops to 97dB @ 200Hz and I'm sure it keeps on dropping the lower you go. I’m afraid that doing the Max SPL calc like that fails to take into account the linear exertion of the driver. If you stick within this limit for low distortion then the SPL will be lower. I’m not sure how to calculate a drivers max SPL within linear exertion though. Anybody? Scott maybe

What sort of environment will they be used in? As you probably know room gain adds a fair few dB depending on placement so that is good from your point of view. Corner placement would be good.

Also, two drivers gives you 6dB more than one driver in output and (I think) another 3dB efficiency as well. So with two drivers and going by 97+10*log800 (97dB efficiency @ 200Hz) you would get more like 135dB @ 200Hz You can then add room gain. Using the amp in bridged mono mode you will get 900watts into 8Ohms which will likely double into 4Ohms (two 8Ohm drivers in parallel) so you can indeed give 800watts to each driver.

BTW, where in the UK are you?