I blew a speaker last night

I suppose it was inevitable with my tone and playing style, not to mention how far down we tune. The right speaker in my 2x15 for my low/clean channel started buzzing about halfway through practice last night, and knowing it was done for, I soldiered through since I already knew I would have to replace it. Three songs later, it fried completely, which shut down the whole cabinet. Quite the bummer. But it's not the first time I've fried gear, so I reckon I ought to be used to it by now. So now I'm looking to replace both of the stock speakers, and I will probably go with Carvins since they are awesome and tough while being really affordable.

The band all tried to cheer me up to no avail after it happened.

I should just build me a 4x18 cabinet.

I been beating on my ne-15's for almost a year now and they keep producing ... clean tone, distortion, synth, drop octave, everything I throw at em.

That SA 2x15 cab may need some adjustment on the ports to handle the increaced output of the carbons. Ill run the figures thru WIN sd and see what I get.

4x18? who's gonna haul it to the gigs? Reminds me of the crazys who brought a 8x10 in on a dolly when the wheels weren't on the cab and then after their set, the dolly they borrowed was gone and they bitched up a storm carrying the thing out to the van they brought it in....

MIke, I wasn't really serious about the 4x18!

MadMike, the SA 2x15 does not have ports. It is a sealed cabinet. I wanted to add ports, but Seismic Audio told me that:

1. They did not know what the correct size and placement would be, and:

2. Putting in the incorrect size and type could end up ruining the frequency response of the cabinet.

If someone could tell me the correct size and type, I would do so.

allright eric. i crunched the numbers for you.

first of all ... hang in there with me. i didnt understand a lot of this sci fi gibberish when i started doing this and theres still a bit i dont understand ... but i can make any decent cabinet sound decent with decent speakers, ported correctly.

second ... i'm operating on some assumptions here.

1)seismic audio still states that their 2X15 has 2 ports in the front and you say it doesnt. i believe you because your not burdened with the responsibility of maintaining a website; you just look at it and tell me that it doesnt. i'm just gonna assume that the dimensions and thickness of ply are what they state on the website. 36"L x 18"H x 14"D made out of 5/8" ply / mdf.

2)i'm assuming that the wattage rating they provide with the frequency response is correct. this cabinet is tuned to those specs (if correct) so if you drop speakers with different frequency response and power ratings in there ... ittl be incorrect. this is what were trying to get correct. 30Hz - 5000Hz ... the low roll off is our concern with a sub cabinet like this ... i'm gonna shoot for 34Hz (30Hz isnt realistic).

3)i'm assuming that you want this to remain a 4 ohm cabinet.

4)i'm assuming that you are going to buy (2) carvin ps15-8 drivers for replacements. these are 400W drivers rated @ 8ohms. parallel wired would make this cabinet 800W @ 4ohms.

i know you blew one speaker. i recommend you replace both with the carvins. heres why. these speakers are rated at different outputs and are moving different volumes. if you use them together one speaker will be working against the other at certian frequencies (and more at the lower frequencies) killing anything like a decent sound you might be getting ... not to mention looking at cooking another speaker sooner (from over working it). if your looking to just replace one, i recommend you go with the SA replacement 15" driver and match the one thats in there ... you have what you had. i would encourage you to go with the 2 carvin ps15-8's. better quality speaker. will last longer. can handle more wattage. will sound better.

from the win - isd, so here we go ............

a cabinet 36x18x14 - 5/8" with (2) carvin ps15-8's achieving a frequency of 34Hz @ vol 30ft3 requires 2 ports, round, 4.25 at 4" long to maintain a vent mach of .12. two 4" diameter ports makes the vent mach increase to .14. anything smaller than that makes the vent mach go above .15 (you'll get vent whistling). an ideal vent mach is .1. you dont want 2 ports at 5.75" and no length ... you'll loose bass tightness ... floppy speakers.

so ... 2 ports 4.25" diameter and 4" length.

make sense?

remember ... these ports can go anywhere on the cabinet; they dont have to go on the front. its a pressure thing ... not a sound projection thing. may i suggest the bottom side rear corners.

god, why does everything have to be so scientific?

my 2x12 car cab had no thought about anything more than measure the width of the hatchback and build something that took up the whole space so it wouldn't move.

the ports are on the top of that goofy thing and it is 2 sealed sections within the cab. I could not even begin to wonder what the low end of the total freq response is but it sure gets bassy with the EQ and 3-400 watts cranking into it...lol
and since you got me thinking, I just went and measured the thing's ohmage since I never ever did..the ohmmeeter dont like ohms close to a short, but it is between 8.3 and 8.7 ( 2 4ohm car speakers in series )

s.o.m.e.d.a.y, I will purchase a scientific cabinet and hear what I've been missing all this time

Absolutely phenomenal, MadMike! Bravo!

Thank you for clearing up what so many others couldn't!

Your assumptions on all points are correct, and even your guesswork seems to be almost spot-on.

1. I do see where the SA website says their 2x15 has two ports in the middle, but I can't seem to find them on the photos. Also, they made some changes to their cabinets after I bought mine, so it is possible they are now porting them. That all being said, I can absolutely conform that mine does not have ports.

2. I think you are hitting it more than close enough to work properly as far as frequency response goes. 34hz is perfect for what we playing now.

3. Yes. I still want it to be 4 ohms.

4. Again, correct. I have flirted with going with the Carvin Neo's, but they cost $99 as opposed to the PS15-8's at $69. Not a huge difference, but that $60 is a factor at the moment. Right now, I still have to make the money go as far as possible since I only just got back to working full-time two weeks ago. And besides, I have used the Carvin PS15-8's a few times in the past, and not once did I ever have any problems or complaints with them. So with the cabinet pushed up to an 800-watt rating, that is more than enough for me.

To clarify a point about the cost factor, I even looked at the SA replacement drivers which range from $50 to $80, and I have complete confidence that the Carvins are vastly superior. Since I have already blown one SA speaker, this is one area where I have to compromise being frugal just a little bit, as I don't want to spend the absolute lowest price I can find of $100 for a pair of SA's....only to have them blow again. This is why I am justifying $69 for a Carvin instead of buying a $50 SA.

By your suggestion of the bottom-side rear corners, do you mean along the very bottom on the back of the cabinet? Would there be any reason not to have them in the middle on the front?

amimbari wrote:

god, why does everything have to be so scientific?

my 2x12 car cab had no thought about anything more than measure the width of the hatchback and build something that took up the whole space so it wouldn't move.

the ports are on the top of that goofy thing and it is 2 sealed sections within the cab. I could not even begin to wonder what the low end of the total freq response is but it sure gets bassy with the EQ and 3-400 watts cranking into it...lol
and since you got me thinking, I just went and measured the thing's ohmage since I never ever did..the ohmmeeter dont like ohms close to a short, but it is between 8.3 and 8.7 ( 2 4ohm car speakers in series )

s.o.m.e.d.a.y, I will purchase a scientific cabinet and hear what I've been missing all this time

I understand what you are saying Mike, but the web is awash with horror stories of improperly-ported bass cabinets killed their tonality and output. This is also something I have heard first-hand from guys who built their own cabs, only to render them useless with the wrong size and type of ports. Given all of this, I'm not wishing to gamble on it.

I keep running thru it in my head. Two 4" ports seem like a bit much to me. I don't want you to end up with your speakers flopping around.

Example ... my 215 is modeled after the discontinued markbass cab. Same dimensions ... about 14" cubed bigger than yours with 100 less watts. I have two 3.5" ports. Live, I have them open to hit the 38hz ... studio, I plug up one port to tighten up the low end.

That's what the software gave me and it worked great.

Perhaps where my perception is skewed is that its two powerful speakers with such a low rf in a relatively small cab. The bigger the cabinet, the more precise the numbers that come out of the software are.

Its gonna be a while before you get your speakers, so ill run the numbers a few more times to see what I get and let you know.

I was thinking the port holes on the bottom, as all my big cabs are up on casters ... but you can put them anywhere on the cabinet as long as the port tube is clear.

considering your using this cab as a main speaker, yes to just throw some stuff together would be a dangerous thing if it turned out to not produce the sound and SPL you need from your existing amps.

Part of me is wondering if maybe I ought to hold off on the porting, and instead upgrade my low/clean cabinet to something like two 4x10's. Then I would use the 2x15 for my distortion channel. But for now, I have to do something, otherwise there won't be any band practice until I do. So I'm kind of committed to getting that speaker replaced, and I might just hunker down and change both of them now so they will be matched.

If only I would get that letter from Ed McMahon telling me I've won the big prize....

I would assume that uncle sam is gonna end up owing you some loot.

incometax refund?...ya I get one also but not nearly enough for me to say "hmm, there's a 1000.00 item, my tax check will pay for it"..hehehe

I usually get around 300-400 each year.

Considering that I was unemployed for nearly all of 2010, I'm hoping to get back something. Whatever it is, I will probably throw it at my rig.