Need advice on sonosub

[rodsprit]

Don't remember the exact difference between the H and X. But the X was to be used in ported enclosures, while the H was supposed to be used in closed enclosures.

[Mike P.]

I modeled the SDX15 in 252 liters tuned to 15.4 hz with 1000 watts input and a Hi-Pass filter at 15 hz. Port air speed is 26.5 m/s at 14.5 hz. You'll be fine with a 6" diameter flared port.

[SteveCallas]

fredk wrote:

but for a 14Hz tune ported enclosure I was at around 290L for the SDX15 and 174L for the AV 15H

14hz tune in 174 liters means your port is going to suffer. You'd probably have to go with a 4-5" diameter port, which isn't nearly enough for a 15" driver with medium to high displacement. No matter how well the driver models, for a 15" with medium to high displacement, you're going to need to use at least ~250 liters for proper porting.

Mike wrote:

I modeled the SDX15 in 252 liters tuned to 15.4 hz with 1000 watts input and a Hi-Pass filter at 15 hz

With all due respect Mike, I'm not understanding this recent trend I'm seeing on this forum of designs with a high pass filter centered at or immediately below tune. It doesn't make sense because it is defeating a good chunk of port output and creating a lot of distortion where there should be really low distortion. With a 15hz tune, assuming that one even feels the need to use a highpass filter (which they really shouldn't, especially with two such subs), the highest I would center the frequency of a highpass would be 12hz.

[Mike P.]

With all due respect Mike, I'm not understanding this recent trend I'm seeing on this forum of designs with a high pass filter centered at or immediately below tune. It doesn't make sense because it is defeating a good chunk of port output and creating a lot of distortion where there should be really low distortion. With a 15hz tune, assuming that one even feels the need to use a highpass filter (which they really shouldn't, especially with two such subs), the highest I would center the frequency of a highpass would be 12hz.

With a 12 hz high pass what would the air speed be in 252 liters tuned to 15.4 hz with a 6" diameter port?

[fredk]

Rod, I see that AE recommends the H for small pr or sealed. Didn't see that the other day.

Steve, I know just enough about Winisd and modeling to be dangerous. Hence the "probably not optimum tunings" disclaimer.

[SteveCallas]

Mike wrote:

With a 12 hz high pass what would the air speed be in 252 liters tuned to 15.4 hz with a 6" diameter port?

At what frequency and how much power?


rodsprit, now that I model this driver, you really should use more than 250 liters with a mid teen tune. The low end rolls off a fair amount with 250 - are you sure you can't go any larger?

[rodsprit]

Thanks for the replies!

How much larger are you suggesting?

When I model in WinISD, there is an option ''series resistance'' under signal tab. Should i set this to 2.0 for a 4Ω driver?
WinISD calculates for boxes. I'm using a cylindrical shape, doesn't that change everything it calculates??

Tried modeling some and difference between 250L and 300L wasn't much in SPL with 1000W.

Behringer EP2500 can deliver 2x1200W into 2Ω. If the driver is 4Ω then it can deliver 600W into each driver. Isn't that little when on their specs it says they are supposed to be run by 1000W ?
I could buy two ep2500.. And run bridged.. but 2400W is overkill.

What exactly is a dual 2Ω driver?

[Ryan Anderson]

SteveCallas wrote:

14hz tune in 174 liters means your port is going to suffer. You'd probably have to go with a 4-5" diameter port, which isn't nearly enough for a 15" driver with medium to high displacement. No matter how well the driver models, for a 15" with medium to high displacement, you're going to need to use at least ~250 liters for proper porting.


With all due respect Mike, I'm not understanding this recent trend I'm seeing on this forum of designs with a high pass filter centered at or immediately below tune. It doesn't make sense because it is defeating a good chunk of port output and creating a lot of distortion where there should be really low distortion. With a 15hz tune, assuming that one even feels the need to use a highpass filter (which they really shouldn't, especially with two such subs), the highest I would center the frequency of a highpass would be 12hz.

I've been wondering about this myself... this is at least the second time I've seen using the HPF to decrease airspeed.... tuning to X Hz is where we're supposed to get the most.... which is why airspeed is the most... so why are we trying to cheat and get away with smaller ports to avoid compression and turbulence by effectively turning the volume way down where our efficiency and gain are supposed to be the most?

SteveCallas wrote:

At what frequency and how much power?


rodsprit, now that I model this driver, you really should use more than 250 liters with a mid teen tune. The low end rolls off a fair amount with 250 - are you sure you can't go any larger?

another thing I'm still trying to understand is unwillingness to give up space. I sure see WAF a lot. No one wants to make an enclosure large enough to maximize capabilities as well as a large enough port diameter. kinda goes hand in hand, doesn't it? Make a little more room for a bigger box which will shorten length so you can bring air speed way down for premium DIY performance. I though that was the whole point to DIY.... not getting a little 15"x15"x15" box with a little 12" so the wiffey doesn't get all upset

[Mike P.]

so why are we trying to cheat and get away with smaller ports

Simply because a larger diameter port won't fit.

[SteveCallas]

rodsprit, enter your parameters to match my attachment.

Your design ultimately needs to be decided on by you, but if it were me, I'd go with 350 liters and a 7" diameter port that is 34" long for a ~14.6hz tune with no highpass filtering for both subs. A bridged EP2500 for each sub would be ideal, but if cash is tight, a single to run both subs will still work great.

Where do you find a 7" diameter port you may ask? Check a place like Lowes or Home Depot where they sell 6" diameter conceret forms (often referred to by name brand Sonotube), and measure a handful, as they tend to range in size quite a bit. Get the largest one you can find, even if it is only 6.5". Report back what size you can find and we can advise you on the correct length.