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gotbass
New
Username: gotbass

Post Number: 1
Registered: 9-2004
Posted on Monday, September 27, 2004 - 10:33 pm:   Edit Post

i have a 300 watt RMS Behringer BX3000T bass amp head. i use this with two speaker cabinets. one cabinet can hold two 10 inch speakers, the second holds a single 15 inch speaker. the manual says that the amp has a minimum load of 4 OHMS. 300 watt RMS output power into 1 by 4 OHMS or 2 by 8 OHMS. im looking into getting new speakers.. i have no clue what the wattage was on the previous speakers. what speaker wattage would give me the most volume. like would i use two 300 watt 10 inch speakers and a 300 watt 15 inch speaker to get the most volume from this amp or what.... just wondering if anyone could please help me out. it would be much appreciated.
-Angel
bsee
Advanced Member
Username: bsee

Post Number: 297
Registered: 3-2004
Posted on Monday, September 27, 2004 - 11:31 pm:   Edit Post

If you have two cabs, then both cabs will be 8-ohm. That means each cabinet will be 8-ohms and handle 150 watts RMS. The 1x15 is easy - those are the specs for the speaker. Common wisdom these days says that you don't want a speaker that has too much extra capacity. I would look for something with a max of 125-175 watt capacity.

The 2x10 is a bit tougher to get the 8-ohms. You either need a pair of 4-ohm speakers in series, or a pair of 16-ohm speakers in parallel. These speakers will split the other 150 watts, so they will want to handle something like 60-100 watts each.

In reality, 300 watts is very little power to drive a good bass signal through that many speakers. 300 watts per cabinet makes a lot more sense, so you might want to build your speaker cabinets for this eventuality. You will have an easier time doing so, since this is a more typical power-handling range for bass speakers.

If you go this route, I would consider the Eminence Beta series. I would go for the Beta-15A and a pair of Beta-10Bs.
poor_nigel
Advanced Member
Username: poor_nigel

Post Number: 226
Registered: 7-2003
Posted on Tuesday, September 28, 2004 - 3:22 am:   Edit Post

It is not wattage that will determine the volume obtained per speaker, but its efficiency (sensitivity) rating. Since you have chosen an economy head (I mean nothing negative by this), it is assumed you want speakers that are economical, too. Therefore, I agree with everything Bob posted above. The speakers Bob listed can be had for less than $200 for all three, not including shipping, and seem very well matched for your head and existing cabinets. They are all 98db at 1 watt at 1 meter sound pressure level. For the price, these are very good speakers.
davehouck
Senior Member
Username: davehouck

Post Number: 887
Registered: 5-2002
Posted on Tuesday, September 28, 2004 - 5:32 am:   Edit Post

Angel; welcome to the group. Bakersfield, birthplace of the Bakersfield sound!
bsee
Advanced Member
Username: bsee

Post Number: 299
Registered: 3-2004
Posted on Tuesday, September 28, 2004 - 9:39 am:   Edit Post

I probably should also have mentioned that I bought an original SWR baby blue several months ago and it arrived with blown speakers. I did a bunch of checking and ended up with the Eminence Alpha series as right for this amp. Sounds great. I would have tried for OEM, but both of the original brands of speakers that shipped in this amp over the years are since discontinued.
gotbass
New
Username: gotbass

Post Number: 2
Registered: 9-2004
Posted on Tuesday, September 28, 2004 - 10:25 pm:   Edit Post

ok so for the dual 10s, whatis the difference between series and parallel... is it the wiring inside the cabinet... im just trying to match something specifically to the head that i have... just got it...plan to have it for some time... but thanks for the suggestions.
bsee
Advanced Member
Username: bsee

Post Number: 304
Registered: 3-2004
Posted on Tuesday, September 28, 2004 - 10:52 pm:   Edit Post

Series means the circuit runs through one speaker and then the other in succession. That means there is a wire from one connector on the jack to the + side of one speaker, then a wire from the - side of that speaker to the + side of the other speaker, and then the other connector on the jack. The cabinet in this case will have twice the ohm rating of the speakers, so 4-ohm speakers give you an 8-ohm cab.

Parallel involves two wires coming from each connector on the jack, one set going to the + on each speaker, and the pair on the other side going to the - on each speaker. The cabinet in this case will have 1/2 the ohm rating of the speakers, so 16-ohm speakers give you an 8-ohm cab.

I am not sure what the standard is for plug/ring on the connector as far as which is supposed to go to the positive side. You'll have to make sure that you wire both cabinets the same way, though, or the phase will be reversed and it will sound like crap. I would expect that a web search should find you all the info you need on speaker cabinet wiring.

-Bob
poor_nigel
Advanced Member
Username: poor_nigel

Post Number: 231
Registered: 7-2003
Posted on Wednesday, September 29, 2004 - 1:15 am:   Edit Post

For quarter inch plugs and jacks, the center tip of the plug and center contact of the jack are always positive and the body/shaft of the plug and outer ring of the jack are always negative. When color is involved, red is positive and black is negative. There are volumes and volumes of these basics on the Internet. The more you learn of these basics, the less you need to go to professionals when minor things go wrong.
Note: The above can be reversed, but usually only on DC power supplies, and they almost always list which is positive and negative on the item. But we was talking speakers here.

I just typed out a long post explaining wiring speakers as water running through a series of pipes, as that is how I learned basic electricity. However, let's simplify this with pictures. Go to the link below and click on the link at the bottom, left of your screen entitled Speaker Wiring. Why they could not have used two speakers diagram in the basic parallel picture, I don't know. Just cut half the picture out for what you want to do.

http://www.usspeaker.com/homepage.htm

Note: Getting a speaker out of phase literally has one speaker fighting the other(s). When one goes out on the cycle, the other is moving inward, instead of both pushing and pulling air in unison. This is a hack explanation, but the basic idea is there.

BTW – Welcome Angel!
gotbass
New
Username: gotbass

Post Number: 3
Registered: 9-2004
Posted on Wednesday, September 29, 2004 - 4:56 pm:   Edit Post

thanks everyone. all of your comments will help me out a great deal... funny thing... i was looking at the speakers off of the US speaker.com.

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