[vilacr]

I decided to go with the eD 19Ov.2 b/c they gave me a deal of the driver and the eq2 for $300. I was dead set on going sealed but now I am reconsidering. I modeled in winisd (I have enclosure already built at 4.26ft^3) and came up with some funky numbers. The A7s 450 is in a similar enclosure and is pretty good for a sealed enclosure. I then modeled a ported enclosure and came up with a 4 in. diameter and 6.76 in long. Is this correct? I can easily cut a 4in circle and order a 17 in port. What do you guys think ?
I would prefer a sealed enclosure but the model isn't working to well.





I have a behringer ep1500 amp if anyone models the designs. (please someone do as I got some strange numbers when trying for sealed)

 

[vilacr]

Anyone?

 

[evilskillit]

Here is something. SPL Modeled with 1000 watts input power. Sub had plenty of excursion left sealed and would probably play with with a bit of EQ on the low end in a sealed box, anyways here are 2 boxes, 1 sealed, 1 ported with spl showing.

 

[vilacr]

I found this for sealed enclosures. If true then the .707 isn't always best.


Qtc Response Peak Sound Quality and Characteristics


0.5 0 Critically damped, lowered SPL, huge enclosure.



0.577 0 Optimal driver damping, lowered SPL, best transient response, huge enclosure.


0.707 0 Usually considered the "optimum" alignment by most designers, gives excellent transient response, low bass performance and power handling, and flattest response curve before F3. Enclosure may be fairly large.


0.85 + 0.69 dB Good alignment if optimum is to large an enclosure, generally very good performance with only slightly accentuated (non-flat) bass, good low bass response. Medium sized enclosure.


1.0 +1.25 dB Best compromise enclosure. Much smaller box than optimum, fair transient response and low bass performance, more noticeable midbass peak. Medium-smaller sized enclosure.


1.1 +1.83 dB Maximum power handling and efficiency, smaller sized enclosure, more pronounced midbass peak. Smaller enclosure.


1.3 +3 dB Driver may sound noticeably boomy, especially smaller drivers with higher Fs and Qts. Fair (or worse) transient response and compromised low bass response. Pronounced mid-bass peak makes the enclosure louder but less accurate. Small enclosure.


2.0 +6 dB Very boomy and muddy, poor transient response and low bass performance. Very small enclosure.

 

[Mike P.]

If this is for music then go with a Q of .707.

 

[evilskillit]

As you can see the sealed enclosure I posted is close to 7.07, 6.5 is not so far off. Either way you can see how the closed version compares to the ported version, EQ would help it out noticably.

 

[vilacr]

This is strictly for HT use. In your graph the box sizes are different. In my graph both boxes are modeled in a 4.25ft^3 box. In this box they model close to equal. I am afraid of port noise with the ported enclosure.

 

[Mike P.]

If this is for HT then forget sealed. Port noise is not an issue with the proper sized port. How big of a cabinet is acceptable and what amplifier will be powering the sub?

 

[vilacr]

If this is for HT then forget sealed. Port noise is not an issue with the proper sized port. How big of a cabinet is acceptable and what amplifier will be powering the sub?

I have built a 4.25ft^3 enclosure (similar to the A7 450)and am powering it with a behringer ep1500 amp. Winisd says I need a 4in diameter and 17.1in length port tuned to 20hz.

 

[evilskillit]

Yeah see that is your problem modeling the sub in a ported box that small. You can use it but if you want as much low end extension as possible you'll need a much bigger box. The ported box I modeled is much larger than the sealed box, you will however notice that even if you make the sealed box 20 cubic feet the bass won't go nearly as deep as the ported box. But if you make the ported box very small, as small as your 4.7 cu ft sealed box the low end extension will suffer.

Btw sorry that I missed earlier that you already had a box. However buying a sub and then stuffing it into an existing box is usually the least efficient way to do things and other than being able to choose between sealed, ported and passive radiators if the box is already made then you get what you get and can't really do much about it. If you want low bass I would sugguest either building a bigger ported box or look into putting passive radiators into the box that you have because that is usually the only way to get really deep loud bass out of a really small box.

In your current box a 4" diameter port needs to be approx 17" long. However port air speed will be off the chart when you're up around 1000 watts and you'll be hooting like a horn below about 50hz. If you want your port to not make any bad noises down below 50hz when playing really loud you'll need a port bigger than 5" really. You'll need to either make a slot port or buy a 6" tube, and that will need to be around 34"-40" long depending on the cross sectional area.

 

[vilacr]

10.5 cu ft is entirely to big as WAF didn't want to accept the 4.25 cu ft enclosure. Thats why I found the eD 19Ov.2 searching for a driver to fit those specs. I figured if the A7 450 uses that enclosure so can I. What is the smallest enclosure I can use to get deep bass down to about 20hz?I may be able to talk her into maybe 6ft cu ft. at most.

 

[evilskillit]

Well let me look at what you could do with that 4.25 with some passive radiators. That would of course require that you spend more money. You could even use the enclosure you have now but it has an F3 of 45hz and a fairly steep rolloff after that which would be fine for music but for HT will probably not make you happy at all. But you could do that and see where it takes you.

Edit* Ehh, the passive radiators don't really seem to be helping much either other than adding another $100-$200 to the cost of the project. Tho actually looking at the SPL of that sub at high wattage its still pretty loud down around 20hz and room gain would be helping out so you might try it tuned to 20hz in that 4.5 cu with a slot port or something and see how it works.

One thing I just thought of and tried in WinISD is that if you have any way of adding EQ to the signal if you can boost around 4 or 5db around 22-24hz then you can get a nice gentle slope down to about 20hz. You are however going to need a high pass filter around 15-18hz tho otherwise the thing will start bottoming out pretty hard if you play loud material that goes below 20hz. So the question is, do you have any way to EQ the signal and add a high pass filter? If so try it out in the box you have right now ported to 20hz and it should work ok.

 

[vilacr]

Well let me look at what you could do with that 4.25 with some passive radiators. That would of course require that you spend more money. You could even use the enclosure you have now but it has an F3 of 45hz and a fairly steep rolloff after that which would be fine for music but for HT will probably not make you happy at all. But you could do that and see where it takes you.

Edit* Ehh, the passive radiators don't really seem to be helping much either other than adding another $100-$200 to the cost of the project. Tho actually looking at the SPL of that sub at high wattage its still pretty loud down around 20hz and room gain would be helping out so you might try it tuned to 20hz in that 4.5 cu with a slot port or something and see how it works.

One thing I just thought of and tried in WinISD is that if you have any way of adding EQ to the signal if you can boost around 4 or 5db around 22-24hz then you can get a nice gentle slope down to about 20hz. You are however going to need a high pass filter around 15-18hz tho otherwise the thing will start bottoming out pretty hard if you play loud material that goes below 20hz. So the question is, do you have any way to EQ the signal and add a high pass filter? If so try it out in the box you have right now ported to 20hz and it should work ok.

I have the eD eq.2 that came with the 19Ov.2. Which port are you referring to? The 4in diameter and 17 in long port?

 

[brandonnash]

To get as deep as you want you will need a larger enclosure and a lower tune. A 4" port is way too small. I use an 8" port on mine and I've never heard a peep out of it even when playing at loud levels close to port tuning. What would the wife say about a port on the outside of the box? You can make it longer that way allowing a larger port and you'd save some of your enclosure volume.

 

[vilacr]

I guess an outer port will be ok. How will that work?

 

[evilskillit]

Either that or you have to make a slot port in the box. You'll need a port with as much area as a 6" tube. So either use a 6" tube or something like a 3.5"x10" slot port. The exact length will depend on what size tube you use. Ideally at this point you should be using WinISD yourself so you can fiddle around with this stuff and find the exact numbers that work within parameters you are allowed.

And yes the eQ.2 will do everything you need. Except for the adjustable low pass out to cut the high frequencies out of the sub. Its a bit odd that it doesn't have that but I guess most HT receivers do that today anyways on the LFE out.

 

[vilacr]

I have done a little modeling with winisd and came up with this. Let me know if it will work. An enclosure 9.6cu ft. with a port 6 inches in diameter and 13.5 inches long. Will that cut down on the port noise?

 

[evilskillit]

Should work great. Port air velocity might be a bit high at 1000 watts but at that point the sound will be so loud anyways I don't think you'd be able to tell. At any sane listening levels the port air speed will be well within acceptable levels. Especially if you flare the ends of the port a bit.

Congradulations on conning the wife into accepting a 9.6 cubic foot box If she likes movies she'll agree it was well worth it when she hears it.

 

[vilacr]

She loves movies. I conned her talking up her teacher friends coming over on Fridays for movie night :bigsmile: I will start tomorrow. Thank you.

 

[evilskillit]

Awesome, post pics. And measurements if you ever get any :R