Here's what diysubwoofers.org says:
Xmax = Linear (one-way) travel of the cone. Xmax is used to determine the
maximum linear SPL capability of the driver, and can be defined in a number
of ways. The DUMAX definition is objectively the best one, and it is
defined as the shorter of the Xmag and Xsus values, in each direction of cone
travel. This definition is more useful than the older definition of Xmax,
which was solely dependent on the length of the voice-coil vs. the length of
the gap.
Xmax = Linear (one-way) travel of the cone. Xmax is used to determine the
maximum linear SPL capability of the driver, and can be defined in a number
of ways. The DUMAX definition is objectively the best one, and it is
defined as the shorter of the Xmag and Xsus values, in each direction of cone
travel. This definition is more useful than the older definition of Xmax,
which was solely dependent on the length of the voice-coil vs. the length of
the gap.
Eminence Xmax Ratings
We always specify Xmax as one way. We calculate it by taking (VC leng- air gap HT)/2. This is very conservative; real world testing (DUMAX) often shows a bit more Xmax.
6mm on a Pro Sound 18" is pretty normal. If you need more Xmax, the Kilomax Pro18A has more and works well in a sealed box for HT. If you use the Kilomax for pro sound, go with a big ported box (9+ cft).
Thanks!
McJerry
We always specify Xmax as one way. We calculate it by taking (VC leng- air gap HT)/2. This is very conservative; real world testing (DUMAX) often shows a bit more Xmax.
6mm on a Pro Sound 18" is pretty normal. If you need more Xmax, the Kilomax Pro18A has more and works well in a sealed box for HT. If you use the Kilomax for pro sound, go with a big ported box (9+ cft).
Thanks!
McJerry
Hey, straight from the horse's mouth. At any rate, the box is already built for a Sigma Pro-18, about 7 cubic feet, calculated as per:
http://xsspl.tripod.com/Audio/KeeleBox.htm
I came up with two 4" dia. X 4.5" long ports. We'll see how the math works when the driver gets here, hopefully very soon!
Evan
http://xsspl.tripod.com/Audio/KeeleBox.htm
I came up with two 4" dia. X 4.5" long ports. We'll see how the math works when the driver gets here, hopefully very soon!
Evan
Hi there,
I've been using sigma pro18 for several years.
Picture here.
I made them 2 per side, in about 10 cubic ft cabinets in the corners. At first I tuned it to about 30Hz, but later I sealed the ports (slots) with thick foam. They sound much tighter this way. No problem going down to 25Hz in my room, and also considerable output below that.
Never worry about the Xmax, you won't touch that in the real listening in normal living space.
I've been using sigma pro18 for several years.
Picture here.
I made them 2 per side, in about 10 cubic ft cabinets in the corners. At first I tuned it to about 30Hz, but later I sealed the ports (slots) with thick foam. They sound much tighter this way. No problem going down to 25Hz in my room, and also considerable output below that.
Never worry about the Xmax, you won't touch that in the real listening in normal living space.
Evan Andersen said:
The highest Xmax of the widely used and reckognized pro-18"ers that I know of is the B&C 18TBX100 at 10mm one-way. Where did you see that a JBL pro driver had 13mm Xmax? That is p-p measurement, not one way. Not even on their bad boy, the 2242H which is udes in theaters all over the world, is 9mm.
Of course, then there is the Madison eXecutioner 18" and 21" models. They claim 19mm Xmax but I am sure they are p-p as well.
For a great performing 18" driver with good Xmax, and without breaking the budget like the aforementioned JBL, consider the Peavy Lowrider offering.
The Dayton 18" offering is actually quite the nice piece as well. Even though it "seems" limited in it's Xmax, extreme output in-home is easily attainable with not much power at all. Build a pair of them and can you say 120dB @10Hz???
Of course any of these require big boxes for lowest of octaves but hey, who buys an 18" and expects a little box.
Just my thoughts.
Noidster
re output
The type of houses people live in in the bulk of Australia give very little if any room gain, and weak standing waves. This means you have to design a subwoofer taking its anechoic responce as the in room responce.
This is a far more stringent requirement than the usual rule of thumb allowances for room gain etc. that one finds for Northern hemisphere conditions, as you very quickly end up needing 10-12db. equalisation to reach the same frequency responce.
The type of houses people live in in the bulk of Australia give very little if any room gain, and weak standing waves. This means you have to design a subwoofer taking its anechoic responce as the in room responce.
This is a far more stringent requirement than the usual rule of thumb allowances for room gain etc. that one finds for Northern hemisphere conditions, as you very quickly end up needing 10-12db. equalisation to reach the same frequency responce.
Re: re output
Alright Alright, that's enough of that talk you lucky gits
Its true that in the UK particular, the average living room is middling at best. That's probably also why we've got such a naff selection of subs, with most being the cute 8" or 10" kind that the wife doesn't mind the look of. And if your wife thinks its decor friendly you just ain't trying hard enough!
rcw said:
Alright Alright, that's enough of that talk you lucky gits
Its true that in the UK particular, the average living room is middling at best. That's probably also why we've got such a naff selection of subs, with most being the cute 8" or 10" kind that the wife doesn't mind the look of. And if your wife thinks its decor friendly you just ain't trying hard enough!
evan andersen
evan andersen
Hey there dude, I just thought that I would email you because your name is evan andersen too. I have met several evan andersens in the last few weeks. it is halarious to meet people who are named after your self, it is hard on the phone to be like, hey evan andersen, how are you and then they respond back with, evan andersen, pipe down. anyhow, bored over here, evan andersen rocks.
evan andersen
evan andersen
Hey there dude, I just thought that I would email you because your name is evan andersen too. I have met several evan andersens in the last few weeks. it is halarious to meet people who are named after your self, it is hard on the phone to be like, hey evan andersen, how are you and then they respond back with, evan andersen, pipe down. anyhow, bored over here, evan andersen rocks.
evan andersen
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