EP4000 or QSC RMX1450

[weng]

hi,

i'm a noob who's been reading the kappa sub box design of avaserfi and is eager to build my first diy sub. at the moment i only have a used kappa 12d vq (dual 4). i will be buying an amp but still undecided which one to get. the 2 amps i am having trouble choosing are, a used QSC RMX1450 being sold in my place (philippines) at $390 or a brand new Behringer EP4000 at $540.

i plan to wire the VC of the kappa 12d vq in parallel to make it 2 ohms and use only 1 channel of the amp for the time being. if i get the RMX1450, it can pump 700 watts (QSC spec) in 2-ohms stereo while on the other hand the EP4000 can pump 820 watts (measured) in 2-ohms stereo. in this case the EP4000 has the advantage-hands down. but i am also negotiating to get a used JL12w7 sub which will be housed in a kappa box and powered by the other channel of the amp. will there be an issue running the amp with a 2-ohm load on channel 1 and a 3-ohm (w7) load on channel 2? which of the 2 amps will be reliable in powering these loads?

oh by the way, will i benefit having 2 subs but with different make?

thanks in advance

 

[lsiberian]

I'd go with the QSC myself. Yamaha, Crown and QSC are all a bit higher quality than behringer. Typically Behringer amps are much cheaper though.

 

[jvgillow]

I would also go with the QSC one, since the power difference is not going to be substantial enough to warrant the extra cost.

2 ohms on one channel and 3 ohms on the other channel should be fine as long as you don't decrease the airflow through the amplifier. The stock fan can be pretty noisy if you have the amp sitting in your living room.

 

[BigSkreen]

I have the EP4000 in my set up and I can attest to its loudness. Once I have completed the initial set up I'm probably going to move it to another room due to the noise. I have considered replacing the fan but I'm afraid I'll end up burning up the amp.

 

[weng]

thanks guys on the feedback.

looks like QSC is the amp of choice between this comparo. the amp is used and i have no idea of its history. if for instance the amp has undergone repairs, do you guys think it can still power a 2-ohm load in stereo? any tips on what to check when buying a used amp?

 

[lsiberian]

thanks guys on the feedback.

looks like QSC is the amp of choice between this comparo. the amp is used and i have no idea of its history. if for instance the amp has undergone repairs, do you guys think it can still power a 2-ohm load in stereo? any tips on what to check when buying a used amp?

QSC amps are pretty much standard in many pro setups in my area so usually they come from a defunct band/club/organization. They aren't the Yamaha amps, but they are still very good quality.

 

[jvgillow]

any tips on what to check when buying a used amp?

Well the best way to buy a used amp is to verify that it operates properly with speakers playing music, before you hand over the cash. If that's not possible, see if you can plug it in and make sure the green status light comes on and the fan runs without making any odd noises. If that's not possible either, at least check to make sure all the knobs and connection terminals are in good condition and that the air intake/outlet are not completely caked with dirt/dust. If they are there is a good chance the amp did not have sufficient cooling.

 

[26oz]

Have had a QSC RMX2450 for many years. I love it, cant match price/power with any other.

 

[mike c]

oh by the way, will i benefit having 2 subs but with different make?

thanks in advance

no you won't gnew

 

[weng]

no you won't gnew

thanks mike

well, i better stick with the single kappa sub i have right now. i also saw another used QSC RMX850 for only $190. should have enough juice to power the kappa 12d vq at 600 watts in 8-ohm bridge.

 

[weng]

Well the best way to buy a used amp is to verify that it operates properly with speakers playing music, before you hand over the cash. If that's not possible, see if you can plug it in and make sure the green status light comes on and the fan runs without making any odd noises. If that's not possible either, at least check to make sure all the knobs and connection terminals are in good condition and that the air intake/outlet are not completely caked with dirt/dust. If they are there is a good chance the amp did not have sufficient cooling.

jeremy,

suggestions noted.

thanks

 

[mike c]

you don't need much power with the simple kappa build. in fact, i don't think it can handle more power than what was recommended

of course, you need to follow the enclosure size and port area instructions to the letter.

 

[weng]

ok, i will build the kappa box as per design. what i've seen in most of the kappa builds here are powered in stereo by an ep2500. that's 650 watts in 4-ohms (12vq). hence, the 600 watts bridge in 8 ohms of an rmx850 is already sufficient to pound the 12d vq.

but what if i need a 2nd sub. i don't have any more headroom and could not find a 12d vq. i will get stuck with a single sub if having another sub of different make will not be beneficial.

 

[mike c]

ok, i will build the kappa box as per design. what i've seen in most of the kappa builds here are powered in stereo by an ep2500. that's 650 watts in 4-ohms (12vq). hence, the 600 watts bridge in 8 ohms of an rmx850 is already sufficient to pound the 12d vq.

but what if i need a 2nd sub. i don't have any more headroom and could not find a 12d vq. i will get stuck with a single sub if having another sub of different make will not be beneficial.

looking at the numbers posted, i think the simple kappa is already pretty loud, so headroom is no problem.

you lose only the prospect of duals for a flatter frequency response.

 

[WmAx]

The Behringer is substantially more powerful than the RMX1450. EP2500/4000 outputs almost 2000 clean watts bridged, 20Hz on up, as measured by credible 3rd parties. Only the RMX2450 is comparable to the EP2500/4000. Also, build quality is near identical between them. Don't think Behringer is making substandard junk ; in fact their EP amps are of extremely high quality - superior to many 'audiophile' amps. The EP uses only high quality parts through out and uses mil-spec glass epoxy redundant PCBs(two identical PCB traces, each component soldered to each one; as to provide an entire 2nd circuit system in case damage occurs to a single solder point or trace is damaged on one PCB - there is a backup PCB). There is nothing to indicate any shortcuts were taken in the EP amp. The best anyone could come up so far, is to say the wire connectors inside the EP were a little bit not as impressive looking as the ones used in the RMX amps.

-Chris

 

[weng]

thanks chris.

what i am trying to find out now which of the 2 amps can take 2-ohms load in stereo all day (not literally though) used in HT at reasonable listening level. the ep2500/4000 has been proven to power in stereo by some who uses a 12vq (4-ohms). but in my case i will be using a 12d vq (dual 4) or possibly a w6v2 which is also dual 4 ohms. wiring the sub in parallel (8 ohms) will only take 450 watts out of the ep4000 which i have no idea if it is already fairly loud.

 

[WmAx]

thanks chris.

what i am trying to find out now which of the 2 amps can take 2-ohms load in stereo all day (not literally though) used in HT at reasonable listening level. the ep2500/4000 has been proven to power in stereo by some who uses a 12vq (4-ohms). but in my case i will be using a 12d vq (dual 4) or possibly a w6v2 which is also dual 4 ohms. wiring the sub in parallel (8 ohms) will only take 450 watts out of the ep4000 which i have no idea if it is already fairly loud.

Yes, especially for home application, the EP2500 will work in 2 ohms all day in stereo, where it will output over 1000 clean watts per channel, assuming you have a dedicated circuit for the amp with a short run to the breaker box.

The box will also work superbly for the W7. In fact, I recommend the W7 if you are going for 'reference' system. The W7 12" will match good quality conventional 18s. It does need at least 1000 clean watts per driver, however. Consider the cost of retail products. You can use W7s and pay what you would for entry level retail, but get world class performance. You should add additional two layers of ply on front of cabinet to compensate for added depth of W7. Even the 10W7 will perform at least a well as high quality conventional 15s. The 10W7 works in the same cabinet with same port. I recommend minimum 750 clean watts to the 10W7.

-Chris