here are my questions:

what cabs are u running that are 4 ohm single 15 and single 10's?

how are you crossing these over

why are you running 4 tops and a single sub?


THE SHORT ANSWER: No. you'll have like a .5 ohm load. which, if it even fires up, will blow up your amp. get another amp, rent one. even a small one... bridge it into the sub, shoot for about 1000-1200 watts. and run the tops off your current amp.

the 10's are Kustom KSC10 ( www.8thstreet.com )

The 15's are BullFrog DT115 ( www.us-musical.com ). All four speakers have a woofer and horn in them and all 4 are actually 8ohm not 4 ohm.


crossover on the amp


this is a 'frankenstein' system pieced together from my personal equipment and a buddy's stuff.


so if the speakers are 8ohm, would 3 of them run at a 2ohm load (which the amp will handle)?

first off... running a 2 ohm load is stupid- although the PLX is the amp to do it with, it's generally not recommended for long periods of time, the amp will be strained and it will get extremely hot.

more importantly though... you would be running 2 15's and 1 10 or vice versa. will sound all kinds of funky.

run the 15's full range and the sub if you're worried about bass and forget the 10's.

honestly, again, the best way to run this shit is to track down another amp- rent it or something... run the tops off one in stereo, 4 ohms per side, and bridge the amp into the other.

thanks for your advice dj_elite

you really should consider 1 more amp, buy a cheaper one that you can run bridged mono and use it just for the sub, the you can dedicate the 2502 to just the top cabinets. Doing it the other way will kill the amp fast, it may be able to handle it but it will not last you long, it will burn up quick on 1 side

Yeah, I'd MAYBE trust a macrotech VZ at 2 ohm for a while, but I wouldn't expect anything else to handle it for long. Actually one place I worked ran a pair of EV CA18s at 2.6 ohm and they lasted years and years, but in general I'd be cautious.

thanks for the tips. i just ended up running the 15's on one channel (mono) and the sub on the other. It was more than enough to handle the sweet 16 party last night. i'm gonna look into picking up a dedicated amp for that sub because i think it can handle more power.

so what happens if you run an 8ohm speaker @ 4ohm? i'm just thinking about the amp to get for the sub and i figure if i bridge it @ 4ohm it will push more power than @ 8ohm (right?)?

you can't... the impedance the SPEAKER sees is the same, but the AMP has to run at different impedance to provide that power.

so you can't FORCE the amp to run at 4ohms to "get more power." when you plug it in, it will sense according to the speaker and adjust to the proper impedance. if you want to run at 4ohms, you need two 8ohm speakers... either two single 18" subs (and jump one from the other) or ONE double 18" sub cabinet.

in essence though, you wont gain anything doing it this way powerwise. in a perfect world, at half the resistance, you should get twice the power. but you don't. for example, one of the QSC amps on that site gets 325 wpc @ 8 ohms, but 550 wpc @ 4 ohms, so if you're running it into two speakers, thats 275 per speaker. inefficiency, heat, etc.

bridging is a good way to get more power in mono for a sub. think of it like this... a regular amp is actually two smaller amps- one for each channel. when you run an amp bridge mono, you BRIDGE the two parts together... instead of each amp running the +/- on one channel, the left channel only runs the +, and the right channel only runs the -. they add up to one channel of big power.