BillFitzmaurice.info

Great job man! Way to disguise it! Guests will be lookin at your sattelites saying "wow these have alot of bass!"

When I build my tt or at I plan on a plexiglas access cover and putting LEDs in there and wire it to the speaker so it flashes to the beat!

DJ Higgumz wrote:Great job man! Way to disguise it! Guests will be lookin at your sattelites saying "wow these have alot of bass!"

When I build my tt or at I plan on a plexiglas access cover and putting LEDs in there and wire it to the speaker so it flashes to the beat!

Thanks!

Looking forward to the finish!

Tom Smit wrote:
Looking forward to the finish!

Yeah, me too. I got sidetracked with my OTop/T39 build, so it might be 3-4 weeks before I have a chance to finish it.

In the meantime, it's been thumping away in the opposite corner of its little brother:


The cabling mess has been cleaned up since that picture. After I'm done with everything, I really need to build a wider TV stand to hold all of my components. I had to put the XBox behind the TV to fit the amp for the two subs.

Shawn,

I love the "blonde haired, blue eyed" model in that photo. Cute kid. Future BFM builder?

One question with the 21" vs the 18": you've got them separated by 1/3 to 1/2 wavelength. Doesn't that lead to cancellations between the boxes? I'd think they would be more effective if coupled, that is less than 4 feet apart. Or, separated by more than 24 feet. Maybe I'm "smoking something (too good)", but I'm just wondering.

Besides, there's one voting member who's vote "trumps all other voters", and she probably says, "the cabinet goes there!".

Chris

gzc_stageTech wrote:Shawn,

I love the "blonde haired, blue eyed" model in that photo. Cute kid. Future BFM builder?

One question with the 21" vs the 18": you've got them separated by 1/3 to 1/2 wavelength. Doesn't that lead to cancellations between the boxes? I'd think they would be more effective if coupled, that is less than 4 feet apart. Or, separated by more than 24 feet. Maybe I'm "smoking something (too good)", but I'm just wondering.

Besides, there's one voting member who's vote "trumps all other voters", and she probably says, "the cabinet goes there!".

Chris

That's a very valid question that I don't completely know the answer to. They do sound better coupled together, but It's definitely more of an aesthetics decision than anything. I did some sweeps last week with REW from my listening position (subs in same spot as above picture, mic directly in the center of the room where couch would be). I measured each sub separately, then both combined:

Purple: Single T18
Green: Dual T18
Red: Combined



I don't have an SPL meter to calibrate REW, so take the overall dB ratings with a grain of salt. The two subs together are 2dB to 3dB louder on average through most of the range compared to the dual T18 on its own, with the exception of ~54hz and ~67hz. The drop at ~67hz is completely due to the room, as it also happens when the dual T18 is running solo. If I flip the sub around in the room and measure from ~3 feet from the mouth, it looks like this:


I'm trying to learn as much as I can, but I still don't fully understand the ~67hz drop (or the other minor drops). Is it due to the dimensions of the room, or some other factor? The single T18 doesn't seem to have quite the drastic drop at 67hz from where it's sitting.

From the "ear test", it definitely sounds better with both on compared to only one. It's amazing how much louder the dual is compared to the single.

gzc_stageTech wrote:I love the "blonde haired, blue eyed" model in that photo. Cute kid. Future BFM builder?

Him and his older brother (2 and 4) both like to "help" by building their own creations from my wood scraps. My oldest has built me at least twenty "subwoofers" over the past few months.

shawn_g wrote:...but I still don't fully understand the ~67hz drop (or the other minor drops). Is it due to the dimensions of the room, or some other factor?...

From the "ear test", it definitely sounds better with both on compared to only one. It's amazing how much louder the dual is compared to the single.

Perhaps it is a "room mode" where a frequency is attenuated. What are the room dimensions: L x W x H?

shawn_g wrote:...Him and his older brother (2 and 4) both like to "help" by building their own creations from my wood scraps...

Now that you say that, I can see the other "finger and toes" by the headphones. Those guys probably enjoy "building with you". And they probably get sawdust everywhere (I'm sure mom loves that). Way to go Shawn.

Chris

gzc_stageTech wrote: Perhaps it is a "room mode" where a frequency is attenuated. What are the room dimensions: L x W x H?

We have a semi-open floorplan where the living room, dining area, and kitchen are open to one another.

Green boxes are where the subs would be:

Get them into it while theyre young! My dad got me into repairing dirtbikes and fourwheelers at like four, and now I'm doing more than he does! Hell there's only a handful of us teenagers on this forum! We have 1up on our generation from the knowledge we've gained here and the diy personality. It looks like in that room it has alot of cabin gain from 20- 40 hz. Maybe I'll make a quickie for my room!

shawn_g wrote: We have a semi-open floorplan where the living room, dining area, and kitchen are open to one another.

I think you may have a couple of room modes, especially around the 60-70 Hz range.

Here, check out this link: http://www.mcsquared.com/modecalc.htm

Still, it looks like a big dip in your plot.

Chris

gzc_stageTech wrote:

shawn_g wrote: We have a semi-open floorplan where the living room, dining area, and kitchen are open to one another.

I think you may have a couple of room modes, especially around the 60-70 Hz range.

Here, check out this link: http://www.mcsquared.com/modecalc.htm

Still, it looks like a big dip in your plot.

Chris

Interesting link. It shows an axial room mode for my room at 66.47hz and 67.26hz, which is almost spot on with the dip.

DJ Higgumz wrote:Get them into it while theyre young!
...

Completely agree!

shawn_g wrote:Him and his older brother (2 and 4) both like to "help" by building their own creations from my wood scraps. My oldest has built me at least twenty "subwoofers" over the past few months.

As a manly man I'm not afraid to say the thought of this is very very cute.

88h88 wrote:
As a manly man I'm not afraid to say the thought of this is very very cute.

I guess I'm biased being their dad and all, but they're awesome kids!



[/EndBragging]

After staring at an unfinished pine box in the corner of my room for waaay too long, I finally got around to making an enclosure for it to fit into. As you can see, I made a hollow box that the T18 (the second one I made) slides into. Let this be a lesson to future builders: don't put a functional, but unfinished sub in place until it's completely done.



It's a tight squeeze:



I believe this concludes the T18 build odyssey.

Nice work!