My sub project

[fouchagalaga]

I'm thinking about starting my 2nd diy project: a sub. The goal with this project is not 'WOAH' sound but something that will provide some ok bass. I also didn't want it to be really expensive so that's why I'm not thinking about 500W subs. I'm thinking about this speaker here:
http://daytonaudio.com/files/specs/S..._specsheet.pdf
It's only 51$ on Parts express and it's the one that seemed the best when I used on WinISD. It will be powered by a 70W sub amp:
http://www.parts-express.com/pe/show...number=300-784
With this amp I thought of also powering my frst diy project which are 2 8ohm MTM speakers.
The enclosure will be vented with two 1,75'' ports of 3,75'' long:
http://www.parts-express.com/pe/psho...number=260-407
Enclosure will be about 70 L or 2.4 cu ft (24'' tall x 16'' wide x 14,75'' deep) which seems massive size to me but I guess that's what happens with a 12'' driver.
Can anybody give me any feedback on this project? Is it ok or is it awful idea? any ameliorations? Also, how do I fill it? Do I simply use foam on the walls or I also need to fill with polyfill? If I make braces, do I just make a cross in the middle of the enclosure?

[Glowbug]

How big of a room do you have?

It'll be a good start, but I have a single 12" with 250W and believe me, sometimes I wish I had a second for very bottom-heavy stuff.

If your budget can accommodate it, the Dayton Reference HF is a very nice driver

If I make braces, do I just make a cross in the middle of the enclosure?

Yes, you want to brace the middle of the perpendicular sides.

[fouchagalaga]

don't know the exact size of the room but it's like a medium sized room. I was looking at The HF series from Dayton but then I would need a better amp and everything. Although they are pretty impressive and I would like one. Only thing is that I am the only bass amateur in this house so if I ever turn it up I'll get yelled at. That's why thought low power sub would be good and cheap. And also, what width would be the brace?

[chris661]

Good driver choice. I used the 8" version with good effect (2 of, sealed @42L, LT to 28Hz).

Brace as much as you can (within reason), as I still get some colouration at high volumes on the 2 unbraced panels of my subs (the panel measures 15" by9", and it visibly vibrates -before- the speakers bottom out.

It might be an idea to make the box smaller (and sealed) and add a Linkwitz circuit, but that has severe limitations on maximum volumes at really low frequencies (I can get a pair of DVC speakers (60Wrms per coil) to bottom out with a 50W amp, around 30Hz, but it is still loud enough to cover the house, so it might be worth a look for you.

Chris

[fouchagalaga]

I'm not too much into making my own crossover since my first attempt wasn't too brilliant. Thanks for the advice Chris. Maybe I should take a look at the same speaker but in 10'' version. I don't know why I started out with the idea of 12'' but perhaps 10'' will allow me to go smaller and have about the same sound. 12'' Fs= 26Hz and Fs 10'' = 30Hz... Anyway, anyone have advice on the filling?

[AdamThorne]

Hooray for modest sub builds! Many people go so big, I think there's a lot of quality that can be had from less titanic efforts.

I don't know if you have looked at MCM's sub amps, but I kinda like them over the PE choices for budget setups.
http://www.mcmelectronics.com/browse...odules/3831187

Also, I just got a F-1 from CSS and I'm loving it. Great for taking the low-end load off the mains, with higher fidelity than your average plate amp XO.
http://www.creativesound.ca/details.php?model=F-1

My understanding is that you don't need to sweat the stuffing too much, as the sub will only be reproducing sounds that wouldn't be absorbed much by stuffing anyway. I threw a package of fluff from my local hobby shop into mine just for the heck of it.

Did you say in your first post that you intend to power your main speakers off the sub amp? I don't think the plate amp works that way...

[Glowbug]

Also, I just got a F-1 from CSS and I'm loving it. Great for taking the low-end load off the mains, with higher fidelity than your average plate amp XO.
http://www.creativesound.ca/details.php?model=F-1

I've been thinking about getting one of those. Really don't want the Fostexes stressed too much, they don't have a lot of "give" before Xmech, that's for sure It sounds OK?

And yeah, for a ported enclosure I wouldn't worry about polyfill too much...

[fouchagalaga]

Originally posted by AdamThorne
I don't think the plate amp works that way...

Well if you look at the amps image there's a 'TO Speakers' output... What does that do? and thanks a lot for the post!the only problem is : since I live in Canada And that in Canada there aren't many places that sell stuff I need that's why I'm ordering from the states. Ordering everything from one spot and sending it to the P.O. Box costs less since I only pay shipping once. But still that amp is really interesting for 70$!
How do you guys think this sub will sound?

[AdamThorne]

I believe that the "To Speakers" section is for the speaker level input.

If you don't have an RCA out that you can feed into the "low level" input, you have to run your speaker wire into the "From Amplifier" input. Then you need to get the speaker level feed back out so that you can run it to your actual speakers.

The plate amp looks like a high impedence in the bass frequencies to your amplifier, so the plate amp is really doing the work there. At higher frequencies the cross over in the plate amp just sends the signal along to the main speakers.

[fouchagalaga]

Hmmm.. I ddn't really get that.... Are you saying it can be done?