Do programs such as winisd calculate efficiency including baffle step loss?, what happens in terms of effiency below 80hz? Should i be taking off 6db from efficency?
The wavelengths of sub frequencies are much longer than typical baffles, so the baffle step doesn't exist for most subs.
I know that, but a normal spekaer would roll off from a 2pi to 4pi radiating space, loosing 6db in the process, does a subwoofer loose 6db at all frequencies as it is radiating into a 4pi space, as opposed to a 2pi space as it may be measured on an infinate baffle?
They calculate in 4pi space and assume the efficiency is measured in 4pi space also (they have options for room loading/cabin loading ect which would be pointless if they didn't start from 4pi space).
Actually, you should look at the individual program as they are not all simulating into 4pi space. Subwoofer simulator simulates 2pi space:
http://www.geocities.com/f4ier/newsubsim.htm
You need to subtract 6db to get 4pi in this case.
No simulation program is really going to tell you the actual SPL you will get out of a subwoofer. Room gain and modes are too unpredictable for a start and they will have a big impact.
Also power compression is not normally allowed for.
Also what you simulate at 1m takes no account of the size of the room.
If anyone can come up with a comprehensive simulation/calculation of the actual max SPL achieved and then verify it with measurements, and be accurate within 3db, I'm impressed (or they are lucky).
Regarding driver efficiency, as far as I'm aware they are normally measured quasi-infinite baffle, which would be 2pi space ...
http://www.geocities.com/f4ier/newsubsim.htm
You need to subtract 6db to get 4pi in this case.
No simulation program is really going to tell you the actual SPL you will get out of a subwoofer. Room gain and modes are too unpredictable for a start and they will have a big impact.
Also power compression is not normally allowed for.
Also what you simulate at 1m takes no account of the size of the room.
If anyone can come up with a comprehensive simulation/calculation of the actual max SPL achieved and then verify it with measurements, and be accurate within 3db, I'm impressed (or they are lucky).
Regarding driver efficiency, as far as I'm aware they are normally measured quasi-infinite baffle, which would be 2pi space ...
Most subs work in 2PI or PI so not an issue and BS doesn't exist in subs. Room loading and the gain control is your friend. 😉
Have a look at the manufacturer's data sheets and will sometimes mention the testing method.
Do you have a particular application worry or just a general question?
Have a look at the manufacturer's data sheets and will sometimes mention the testing method.
Do you have a particular application worry or just a general question?
Noodle, think about this for a second.... Yes manufacturers could show efficiency in 2pi however that would be a heck of a baffle... Consider the actual size of wavelengths: at 20hz you would need a baffle over 56.5 ft to keep the driver in 2pi.
Even at 150 hz the baffle size would need to be over 7.5 ft wide.
Hmmm, makes me think anyway. Is this why low freq drivers are always quite a bit lower in effeciency than mid and high freq drivers?
Then it also comes down to the integrity of the manufacturer. Car amplifiers are a prime example of this. Manufacturers of cheap car amps will subject their units to 18+v in sub-zero temp conditions for fractions of a second to be able to put overexaggerated power ratings on the amplifier so the un-wise will buy.
Ethan
Even at 150 hz the baffle size would need to be over 7.5 ft wide.
Hmmm, makes me think anyway. Is this why low freq drivers are always quite a bit lower in effeciency than mid and high freq drivers?
Then it also comes down to the integrity of the manufacturer. Car amplifiers are a prime example of this. Manufacturers of cheap car amps will subject their units to 18+v in sub-zero temp conditions for fractions of a second to be able to put overexaggerated power ratings on the amplifier so the un-wise will buy.
Ethan
paulspencer said:
If you can get a baseline performance of a "reference" subwoofer in the intended location it's pretty straight forward to get a model of the response of whatever design you intend to use in that environment.
For example, I've measured the cabin gain of various vehicles with different sub locations and configurations of sub enclosures, I can then model a design and super impose the cabin gain on it to see how it would perform in the car (see attachment, note my measurements only cover 20-100hz hence the abrupt jump)
It's simply a matter of getting sufficient data.
Attachments
I am just curious, i would doubt that i can get over much more than about 110db at my listening position (2-3 meters from the sub) with my adire tempest EBS. This is fine for home use but i would like more output capability for parties etc, i think i will go with a horn subwoofer of some type.
JJ, I have plans for a 35 Hz horn for the tempest driver that were on the adire website in the past, I can send it to you if you like. If you don't mind changing the driver over from time to time then you don't even need to buy a new driver.
Yeah i have those plans, I have been fiddling around with horn resp etc, i have about 800 bucks or so to spend, my options are either to build stereo XLS/XXLS subwoofers at home (or some other sub driver). Then build the tempest horn. I could also build a horn subwoofer or two using lower quality drivers and keep them for that sort of use. The sound quality of the horns does not concern me very much, i primarily want a 40hz cutoff and high efficency, both of which are easy enough obtain i think.
A nice combo would be a bass horn to cover 40-80 Hz then use it also at home to go in between your EBS and mains. Not so much for output at home but as a bonus it will give very low distortion in the mid to upper bass, if it's a good horn it should sound quite a bit better than the tempest in that range. How big can this thing be?
Hmm with my amp that would be easy enough to do (2x450wrms into 4 ohms) Biggest dimensions are about 1000x1400x800 or so total (so it'd fit in the car) however i'd rather build a 2-4 of something this size:
http://diy.cowanaudio.com/hornsubjr.html
Unsure of what sort of driver to use though (looking for suggestions, pointers here).
While using this stuff in a PA arrangement i would be using some PA main speakers with whatever sort of horn subwoofer i decide to go for, having better quality bass down to 40hz is just a bonus.
http://diy.cowanaudio.com/hornsubjr.html
Unsure of what sort of driver to use though (looking for suggestions, pointers here).
While using this stuff in a PA arrangement i would be using some PA main speakers with whatever sort of horn subwoofer i decide to go for, having better quality bass down to 40hz is just a bonus.
- Status
- Not open for further replies.