EBS Tempest FR

gatemplin

I recently posted my frequency response graph for my DIY Tempest sub with hope that I would receive suggestions on how to improve the low end performance. Thanks to Doc, Ganzo, and Paul I realized my mistakes.
I decided to build the low Q extended bass shelf design for the Tempest. It is 340L net with two 4" flared ports tuned to 15.8 Hz. The huge sub measures 49" X 24" X 24" and weighs a ton. I finished it in oak veneer and would love to post pics but dont have a digital camera or scanner yet.

I measured the frequency response the same way as before with all the settings the same and used test tones on my computer. The SPL meter tripod mounted at listening position and the sub is corner placed, same as before.
The result is significant gains below 30 Hz where I wanted it. I have yet to demo extensively but the performance is definitely improved. I still have a 50 Hz room hump which will probably be my next project. Changing placement is not an option, I am open to any other suggestions though.

Here is the original 120L Tempest graph for reference. Thanks Paul for the spreadsheet.
[IMG]C:\Graham\Speakers\Club Polk\Tempest1.JPG[/IMG]

gatemplin

Here is the new EBS Tempest FR graph.
[IMG]C:\Graham\Speakers\Club Polk\Tempest2.JPG[/IMG]

gatemplin

Also, the performance I wanted is there. I finally heard the ring drop. At my usual sub settings (non-calibrated) and receiver volume, I hit 111dB when the ring hits the ground. sitting in the listening position ten feet away, meter weighted C fast. It could go louder but I wouldn't want to try. I guess this would qualify me for the PWC eh Doc?

Dr. Spec

Looking good - get a cheap parametric EQ like the BFD and tame that hump. You are getting excellent extension to 16 Hz, which is great news. Probably a whole new world of lows you were missing. Nice work. I'd love to see a photo of it - Mr. PWC.

Doc

gatemplin

Thanks Ed,

Yes, I cant wait to rewatch some of my dvd collection to hear what I have been missing. I will try tweaking the system to see if I can avoid the hump. If not, I may get a BFD but they look pretty intimidating. Are there any other similar, less complex substitutes for the BFD? The sub looks good IMO and I'll see if my brother has a digital camera and I'll post some pics. The sub is huge but very efficient for only 250W.

Sincerly,

Mr. PWC:D

pjdami

Graham,

Great work!! Looks like you made some huge improvements on the low end. Get a PEQ like Doc says for that hump. At least you are not getting any "nulls" that are hard to fix. Pics would be great. Gotta love those DIY people like yourself.

Enjoy. I'll be able to hear the "ring drop" in a about a month myself if all goes well with my SVS delivery estimate.

Paul

BeginnersLuck

Wow- that sonds impressive. Now i'm starting to consider building one, or two. However, I'm very happy with my dual 214L vented tempests. They are awesome. The good thing about these subwoofers is that they don't require a lot of power to get great results out of them. Maybe down the road I'll turn one of the 214L tempests into the EBS alignment. You are the first person I have read about building that EBS box. I'm glad it worked out for you...

Pic's please!

-Later,
BL

gatemplin

Thanks BL,

I dont know of anyone else building this sub either but it fits perfectly in my room. I would love to post some pics and will as soon as I get a new power cord for my camera. I agree Tempests are very efficient and I checked out your subs, nice finish. I would like to go dual EBS someday. There is absolutely no port noise and 250W is plenty.