Omni 15 sub

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Blackadder · #1 Post by **Blackadder** » Sat Dec 29, 2007 12:12 pm

I built an Omni 15 as a sub only unit and I’m about to build a second. Is the dampening material necessary when there’s no other drivers in the unit?

Thanks.

WB · #2 Post by WB » Sat Dec 29, 2007 1:51 pm

From what I understand, damping material is never used in subs. The wave length is too long to even see it. The damping is required more for the mid frequencies.

You may be the first to actually have built these for sub only use, though there has been a lot of talk about it. Interested in your impressions when your're done.

#3 Post by **Bill Fitzmaurice** » Sat Dec 29, 2007 3:22 pm

It depends on the cab configuration. Not necessary with folded horns, necessary with all else, so line it.

Mikey · #4 Post by **Mikey** » Sat Dec 29, 2007 4:35 pm

Are you using the 3015LF driver in them? Are you using the "classic" design, the TallBoy, or an alternate size/shape? I'm anxious to hear how they perform.

Harley · #5 Post by **Harley** » Sat Dec 29, 2007 8:56 pm

Mikey wrote:Are you using the 3015LF driver in them? Are you using the "classic" design, the TallBoy, or an alternate size/shape? I'm anxious to hear how they perform.

Why don't you break into the "bold barrier" and do one up yourself

Nothing like advice from an owner/builder.

Mikey · #6 Post by **Mikey** » Sat Dec 29, 2007 10:12 pm

Harley, when my buddy is finished restoring his Javelin, he'll let me use his garage for a while, to build some cabs. The O15 is fourth on my list.

Blackadder · #7 Post by **Blackadder** » Tue Jan 01, 2008 11:46 am

WB wrote:You may be the first to actually have built these for sub only use, though there has been a lot of talk about it. Interested in your impressions when your're done.
Are you using the 3015LF driver in them? Are you using the "classic" design, the TallBoy, or an alternate size/shape? I'm anxious to hear how they perform.

The deciding factor to go with this cab was that I had a couple of Carvin PS15 speakers already looking for a home.

(Fs 36.3, Vas 9.515, Qts 0.434, Qms 5.77, Qes 0.469 SPL db/w 96.3 RMS 500W)

The only thing that I changed was to center the driver, and use two horn braces - one each side of the speaker opening.

I built the standard one because the tall boy was physically too big for my needs. I've finished the first one - but for the fittings - that I'm waiting to arrive from parts express. I can't give you any objective feedback as I don't have a way to measure it. I've fired it up full range with a bass guitar played through it - and my subjective reaction was very good. Part of my parts express order is an active cross-over – so I can check it out and give you better feedback if you like to hear this stuff. I’ll be driving two of them with a 1.2KW Stewart World AMP and they’ll be used for live rock music. At some point I'll probably get an equalizer/analyzer and I'll take some readings and let you know.

WB · #8 Post by WB » Tue Jan 01, 2008 12:20 pm

Blackadder wrote:I've fired it up full range with a bass guitar played through it - and my subjective reaction was very good. Part of my parts express order is an active cross-over – so I can check it out and give you better feedback if you like to hear this stuff.

Just curious what you will eventually use for tops, and what crossover frequency you plan on using? I'm assuming this is for electric bass amplification for a rock band. Glad to hear you like it so far.

#9 Post by **Bill Fitzmaurice** » Tue Jan 01, 2008 1:32 pm

I don't think those PS15s have a lot of xmax, so go easy on the power, and high-pass them no lower than 45 Hz.

Blackadder · #10 Post by **Blackadder** » Tue Jan 01, 2008 2:36 pm

Bill Fitzmaurice wrote:I don't think those PS15s have a lot of xmax, so go easy on the power, and high-pass them no lower than 45 Hz.

It's only 1.8mm.

I was thinking of using the crossover's built in 25hz high pass - but if that's too low - I'll have to build one into the cab.

Blackadder · #11 Post by **Blackadder** » Tue Jan 01, 2008 2:41 pm

WB wrote:Just curious what you will eventually use for tops, and what crossover frequency you plan on using? I'm assuming this is for electric bass amplification for a rock band. Glad to hear you like it so far.

It's for the band's PA. We mic the Kit. The existing PA is twin 15's and a horn on each side. I was going to try the x-over at between 75 and 100 and see how it goes.

Tue Jan 01, 2008 3:40 pm

Blackadder wrote:
It's only 1.8mm.

Ouch. 1.8mm limits you to about 20 watts input through much of the cabs range. I'd dump those suckers yesterday, if not the day before.

Blackadder · #13 Post by **Blackadder** » Thu Jan 03, 2008 3:11 pm

Bill Fitzmaurice wrote:
Blackadder wrote:
It's only 1.8mm.
Ouch. 1.8mm limits you to about 20 watts input through much of the cabs range. I'd dump those suckers yesterday, if not the day before.

OK - I've ordered a couple of 3015LF's.

As this is a sub only unit - should I have the opening at the top or the bottom? Does it make any difference?

Thu Jan 03, 2008 3:55 pm

Blackadder wrote:
Bill Fitzmaurice wrote:
Blackadder wrote:
It's only 1.8mm.
Ouch. 1.8mm limits you to about 20 watts input through much of the cabs range. I'd dump those suckers yesterday, if not the day before.
OK - I've ordered a couple of 3015LF's.

As this is a sub only unit - should I have the opening at the top or the bottom? Does it make any difference?

It won't make much difference, but the bottom should be just a bit better, especially in the upper end of the bandwidth.