My DIY Tempest (1 Viewer)

[Mark Fitzsimmons]

I finished my Tempest sub last night. It is 122L sealed. Took me like two days to build, but 8 days waiting for the Tempest to get here from Adire; they shipped it on time, but it took UPS that long to get it to Ohio.
I haven't had that much time to listen to it. I watched the Lord of the Rings last night with it and was blown away. This is the first time I experienced bass I can feel in a Home Theater environment; I like it For movies this thing rocks.
Then I listened to a little music. The bass is really tight and accurate, not boomy what-so-ever. But I am not just getting the thump I want. I assume the solution is to mod the amp for some bass boost in the 30hz or so range, but I don't want to do this and comprimise movie fidelity. Is there anything else I can do? For music I already maxed out the level knob on the amp, when it was at a little less than half for my movie calibration: speakers at 75db, sub at 79.
Well here are the pics.
www.markfitzsimmons.com/sub/
Notice I flushmounted the sub, its hard for the pics to reflect it but it looks amazing. Definitly worth the extra time. It's really easy to do, because the height of the Tempest is .75" so get a sheet of MDF this thick and you're in business.
I still need to beautify the sub, which I'll probably get done in the next few days, but for now I was just itching to hear it so it's naked
A special thanks goes out to Dustin B who answered nearly all my questions for this project. It probably wouldn't have happened without his help.

 

[Patrick Sun]

Can anyone else see Mark's webpage with the sub pix?

 

[Brian Bunge]

Pat,

I saw them!

Brian

 

[Mark Fitzsimmons]

Another note, whats the best way to set the phase?

 

[Rick Guynn]

The easiest answer to your question is to get a BFD. You can EQ your sub for HT and store it on one preset, then EQ for music (adding whatever boost in the desired frequency range) and store it on another preset. Heck, there are 10 presets to choose from, so go nuts!

Just remember that any boost removes headroom from your amp.

RG

 

[Rick Guynn]

An easy way to set the phase is to run a sine wave through your receiver at the crossover frequency, read the SPL with a meter, and adjust the phase until the SPL is maxed.
Alternately, is you happen to have a O-Scope, you can hook the oscope to a mic and actually watch the signal as you adjust it ( I tried this, it's neat)
RG

 

[jeff lam]

Rick,
That's exactly what I do with my BFD. I have two presets, one for movies and one for music. It helps out a lot.

 

[Chris Tsutsui]

I am beginning to wonder on your placement of the subwoofer because I have the gain set to half way on my 250w amp and the receiver level to 3/4.

Is it in a corner of the room so as to activate all the bass modes?

Phase didn't affect my subwoofer all that much, maybe about 3 db when I changed it 180 degrees. The thing about adjusting phase is when you change it at one test tone, it affects another so you may have to find a comprimise in the phase adjustment.

What I hate about bass is when it begins to sound boomy like my ear is in a high pressure zone. This is where room placement in relationship to the listener and speakers can have an impact.

The tempest CAN sound boomy if placed wrong, I figured that one out...

 

[Mark Fitzsimmons]

It is in a corner.
http://www.markfitzsimmons.com/sub/DSCF0041.JPG
I just recalibrated using the Fight Club THX tones. The level on the sub amp is around one third, and on the reciever side.
Left main: +6
Center: +1
Right main: +5
Surround right: +0
Surround left: +0
Subwoofer: -7
The crossover is at 160 on the amp, but my reciever is crossed at 80hz on the subwoofer output.
Will someone make me an 80hz sine wave tone so I can set my phase?

 

[Patrick Sun]

Ah, Mark's using port 8000, and I'm sure our company's firewall doesn't allow traffic through that port anymore.

 

[Mark Fitzsimmons]

Yeah, my ISP blocks port 80, but there's always a work around

 

[Pete Mazz]

I would try facing it in a different direction. It looks like it fires right into the big stuffed sofa. Try pointing it up or even into the corner and see what you think.

Pete

 

[Mark Fitzsimmons]

Unfortunatly, I can not mount it firing up because the amp is on the panel opposite the sub driver... :frowning: but I'll try pointing it in other directions.

 

[Bryan Michael]

after breaking it in it will be alot louder when i first got my sub i turned it up and it barley had any bass and now it is broken in it hits hard

 

[Mark Fitzsimmons]

Its not that its not loud enough. Its just that in order to get acceptable levels of bass for music I have to turn it up alot. I leave the level fixed on the amp, but turn the reciever from -7 to +3 for music. At this level, it sounds good to me.
I wanted to see what levels the sub was capable of pushing. So I unhooked my mains and played just the sub on Pink Floyd's "One of These Days" and measured 118 db at the listening position. It was really loud, much louder than I'd regularly listen at.

 

[Patrick Sun]

Okay, finally got to see the pix. So, now do you know why people go the DIY route when building subwoofers? The performance/price ratio is mighty high once you get a good plan/design in place.

 

[Mark Fitzsimmons]

Yeah, cost me under $300 so far, and sounds great!

I had people over at 8:30 to watch Shrek tonight, everyone was so impressed with my system I spent the rest of the night (its just past 12 now and everyone just left) demoing my system.

I'm begining to love DIY. I'm going to get a projector soon and will make a DIY screen, and probably a flexy rack that will fit below my screen to hold my components and function as a center channel stand.

 

[John Parris]

Looking good, man
You've definately given me more hopes about my own Tempest project.

 

[Jason Hammerly]

I was going to do the same design. Trying to decide if I want to do a front firing or bottom firing. any opinions?

 

[Mark Fitzsimmons]

Jason, when I was planning my sub, I was faced with the same decision. I was told that whether I went front or down firing the sound would be the same either way. I chose to go with front firing because it would make the sub a little lower profile and whats the point in having a big 15" driver if you can't look at it
Either way, you can't miss.