New Builder, amp questions

[JBanksAVL]

Whats up.
I figure I'de introduce myself and tell yall a little about my project so far
and maybe get some help me picking an amp.

Im a Drum and Bass / Dubstep DJ,
Until today ive been rockin 2 cerwin vega sl36's on their own xti1000
Sold the CV's today to finnish building the tubas.
Right now my plan is to build 4 tuba 30s
but I want to get a new amp to run the tuba's
and use the amps i have for my tops.


Here are a few pictures of the first tuba 30.
http://a3.sphotos.ak.fbcdn.net/hphotos- ... 7612_n.jpg
http://a8.sphotos.ak.fbcdn.net/hphotos- ... 3646_n.jpg

Here are the drivers im putting in them.
http://www.mcmelectronics.com/product/55-2982

and Here is where im going to have to ask for help.

*Picking out the amp*
I know i want to stick with the Crown XTI's,
the subs are 350W/700W RMS/Peak
I want to hook 4 cabs up parallel off one amp bridged mono.
The more i read on here about impedance and voltage with the tubas
the less comfortable i feel about how im going to hook them up.

my question ..
with 4 of those drivers im looking at 1400 watts but @ what impedance ?
and can someone point me to a good thread to explain how the voltage works ...

hope i dont sound like a total noob. lol
I really wanta understand this.

Thanks !

[Bruce Weldy]

Your cabs look good, nice job.

Not sure I understand why after building such nice cabinets and all the time and effort spent to do it - that you want to put a cheap driver in it.

In comparing that speaker to a 3012LF, some of the parameters are more than 10% different. Before jumping in, be sure you get one of the more qualified guys on here to tell you if that speaker will work.

You might want to post a "will this speaker work" thread and give the link.

[JBanksAVL]

Your probably right ..
I should have posted something about my driver choice.

Hopefully i didn't make a mistake in getting them.
Eventually i want to upgrade to the Eighteen Sound 12NLW9300
I just dont have a grand to drop on speakers after building the boxes and buying amps to power them.
besides .. I got four of these for $150, it might suck but its not a Huge loss if they dont work out.
I just need them to tide me over until the winter when i will be able to invest in some good drivers.

so back to my question ...
The horn adds 2 ohms so..
4, 8 ohm speakers wired parallel in tuba30's = 2.5 ohms ?
===> so basically 2 ohms ?
right ?

The other thing is they dont list what the XTI's are @ 2 ohms bridged mono.
Ide hate to assume ..
http://www.crownaudio.com/pdf/amps/139472-3.pdf

lets see if we can get some feedback here if not ill post this somewhere else.

[Bruce Weldy]

Your probably right ..
I should have posted something about my driver choice.

Hopefully i didn't make a mistake in getting them.
Eventually i want to upgrade to the Eighteen Sound 12NLW9300
I just dont have a grand to drop on speakers after building the boxes and buying amps to power them.
besides .. I got four of these for $150, it might suck but its not a Huge loss if they dont work out.
I just need them to tide me over until the winter when i will be able to invest in some good drivers.

so back to my question ...
The horn adds 2 ohms so..
4, 8 ohm speakers wired parallel in tuba30's = 2.5 ohms ?
===> so basically 2 ohms ?
right ?

The other thing is they dont list what the XTI's are @ 2 ohms bridged mono.
Ide hate to assume ..
http://www.crownaudio.com/pdf/amps/139472-3.pdf

lets see if we can get some feedback here if not ill post this somewhere else.

They don't list a 2 ohm bridge because you can't bridge 'em to 2 ohms. When two individual channels will go down to 2 ohms each - bridging is limited to 4 ohms. No reason you can't run using both sides and not bridge. Pick an amp that will give you the power you need at 4 ohms per side. Which by the way won't be the full 350 for those speakers. I'm guessing that if a 3012lf is limited to 50 volts in a T30, your speakers will be somewhat less.

Don't get too hung up on the impedance that the cab adds. Just run two 8 ohm speaker per side of the amp. You will have more than enough for those speakers if you give 'em 700 watts at 4 ohms....that's probably more than they can take - be careful.

[Bill Fitzmaurice]

Never bridge to less than an 8 ohm load, there's no advantage to doing so and lots of disadvantages, the main one being the doubled likelihood of blowing your drivers.

[Mikey]

You might want to post a "will this speaker work" thread and give the link.

It's already been done, twice ...

http://billfitzmaurice.info/forum/viewt ... =1&t=14882

http://billfitzmaurice.info/forum/viewt ... 13&t=15099

If you read the second link above, you'll see that adequate testing was done, comparing this driver with the 3012LF...

For a given voltage, the MCM lags by 5-6 db.

28v: 124db / 36.5v: 124db / 47v: 126db ... SO, even though the MCM will "handle" respectable power, there's little to be gained with it. If you limit at 28v, you'll get decent output without heavily stressing the driver. V-plating will get you 3db, which will more than make-up for the 2db you "lose" by being stingy with the voltage. Hopefully, being conservative with power will allow these drivers to work reliably until you can afford the 3012LFs.

The testing was done on T39s, so the output of your T30s will be less, since they're less sensitive than T39s.

An XTi 1000 would be adequate to run a pair of these T30s with the MCM drivers per side, since you only need 28v.