queston re: statements

[BeerParty]

I plan to build the sealed version with an integrated sub in a base cabinet, and wonder about the option of either SIDE MOUNTED OR DOWN FIRING sub driver. My plan would be to use the crossover in my receiver around 40-60hz. In either case using a 10 or 12" driver in sealed configuration. Should have about 1 CF of volume. I've never built such a design so wonder about the plus or minus that each might offer. I would think the downfiring sub might offer a little more impact and might help lower the F3 of the driver.

My thought was to power both sub drivers from a common plate amp. If the drivers are 4 ohm I will have to wire in series, unless suitable 8 ohm drivers are available?

If you are not experianced in designing subwoofers, your best bet would be to pick an existing design and built it. There are several places that have designs, I like the Master Index of DIY Subwoofer designs over at AVS

[AdelaaR]

It should be exactly 7.231654743168746486332" give or take a foot or so...
-Close enough for government work... :B

C

I assume that isn't a joke but the exact outcome of the equation that you used to calculate the bass reflex system, right?

I live in Europe and so I will be purchasing bass ports in millimeters ... this will give me some rounding errors but I hope that won't matter too much.
If I understand correctly the inside diameter of the ports is 3 inches which gives me 3 x 2.54 = 7,62 centimeters ... I'm hoping a 7,5cm tube will do the trick.
Do I have to adjust the length to compensate this difference?

Could the statements have ports on the front and did anybody try this yet?

[WaterMark]

"Stick with the designated driver. If you change the driver you will need to redesign the crossover for the speaker, and then it is no longer a Statement."

While I appreciate the response, adding a little more displacement and lower F3 can't be a bad thing can it?
The electrical parameters and the response chart look very close for the RS225-8 and the RS270-8. The Statements woofer xover looks to be a simple 2nd order with no contour network or traps so I assume it should work fine. Both drivers exhibit a broad peak around 6k

If I build the sealed statements using the 2-10" drivers in the sealed boxes as currently drawn up (about 60 liters) the F3 should be around 46 and if I use the 2-8" and reduce the volume to 40 liter the F3 would be around 55hz
I like the idea of crossing to my sub as low as possible.
Mind you I am just using the manufacturers specs and some free box software.

[cjd]

Mind you I am just using the manufacturers specs and some free box software.

Clearly. Your F3 on the RS270 should be around 30Hz or you're going WAY too small. Yes, the box should be rather huge.

That said, the sensitivity difference, acoustic center difference, and those small but important additional electrical differences (which is probably all you've looked at) all add up to make me repeat: it's a different design. Being off just a little bit on phase integration is the difference between a design that sings and one that just never quite seems right. And chances are trying this swap without a proper redesign would leave you more than a few degrees off on phase integration.

[Jim Holtz]

"Stick with the designated driver. If you change the driver you will need to redesign the crossover for the speaker, and then it is no longer a Statement."

While I appreciate the response, adding a little more displacement and lower F3 can't be a bad thing can it?
The electrical parameters and the response chart look very close for the RS225-8 and the RS270-8. The Statements woofer xover looks to be a simple 2nd order with no contour network or traps so I assume it should work fine. Both drivers exhibit a broad peak around 6k

If I build the sealed statements using the 2-10" drivers in the sealed boxes as currently drawn up (about 60 liters) the F3 should be around 46 and if I use the 2-8" and reduce the volume to 40 liter the F3 would be around 55hz
I like the idea of crossing to my sub as low as possible.
Mind you I am just using the manufacturers specs and some free box software.

What your free box software isn't showing is that the RS270 requires a VERY large cabinet. Check out CJD's MTMWW design to get an idea. Also, RS270's and RS225's both have a F/3 of around 50 Hz. if you can find the originals.

The advice you received was sound. If you alter a design with driver changes, it does in fact mean you need to remeasure and adjust the crossover. You can do whatever you want but there is no guarantee the end result will sound anything like the original design.

Try Unibox for accurate modeling results.

Jim

[WaterMark]

" Also, RS270's and RS225's both have a F/3 of around 50 Hz. if you can find the originals. "

I was using PE's specs for the new unshielded drivers and this site for basic sealed response.

http://www.mh-audio.nl/CBC.asp

No I don't want to mess up a vey good design and I appreciate the response. Just was wondering if the newer un-shielded driver specs might allow moving to the 10's in the closed box Statement as they are currently drawn up, it appeared that way to the casual reader = me ops: