Power Amp Question

[aaronhutson]

Okay so im looking to run a sansamp rbi and power amp to my cabs, skipping the head.

I use 2 behringer BA410 cabs, both wired at 4 ohms. I use a behringer 450w head with a max load of 4 ohms. So im already over pushing it with a 2 ohm load.

I was considering getting a 1000w amp to run to both cabs. But i talked to a behringer tech and he said to run a 2000w, which i think will blow my cabs. The head im running already pushes both cabs almost to thier max. So i think that may be overkill.

My question is should i get a 1000w amp or could I use a 400w to power them since my 450w head pushes them without much effort. Im switching over for tone reasons and when im fully switched it will actually make my rig alot simpler.





Edit:

What about a behringer europower ep2000? I know i use alot of behringer but i always use thier amps in my pa's and i can get one pretty cheap. Would that be too much power? Im fine with the power i have now as far as volume. And really my tone is good too. Im just simplifying my rig by taking out the head and adding these. Would that amp risk blowing my speakers? or would a 1000 do? Let me know. Thanks!

Let me know what you think. Thanks!

[bongomania]

First thing to know is the wattage output ratings of an amp, and the wattage handling ratings of a speaker cab, are just "rough guidelines". The actual wattage abilities on both ends will vary drastically depending on what signal you feed the amp.

That said, what is the wattage rating given for each of the cabs?

[aaronhutson]

Originally Posted by bongomania

First thing to know is the wattage output ratings of an amp, and the wattage handling ratings of a speaker cab, are just "rough guidelines". The actual wattage abilities on both ends will vary drastically depending on what signal you feed the amp.

That said, what is the wattage rating given for each of the cabs?

The cabs are 1000w max handling. But i run my 450w head with output on half and it pushes them about to what they can handle.

[Matthew_84]

Originally Posted by aaronhutson

The cabs are 1000w max handling. But i run my 450w head with output on half and it pushes them about to what they can handle.

Yeah, but now the load is 2 Ohms

[bongomania]

The thing is, there is no "half output" setting on your amp. You probably mean you have the volume knob turned halfway, but that actually has zip to do with the wattage coming out of the amp. If you feed a hot enough signal in, you can get the full maximum wattage out even with the volume knob turned lower than halfway.

I'm curious--what cues are you seeing/hearing that make you think you've pushed those cabs to their limit?

[uhdinator]

an amp that has a minimum 4 ohm load and two 4 ohm cabs plugged into it is giving the amp a 2 ohm load. If you do that you will let the smoke out of your amp if ran that way for very long.

The BA410 is rated 1000w @ 4 ohm RMS so peak power is prob 2000w. Thats why the behringer guy recommend a 2 channel amp that is rated @2000w (1000 per channel @ 4 ohms)

If your tone is a little thin? its prob because the little 450 amp is giving ONE 410 cab half its rated average power or less. With 2-4 ohm 410's that amp is prob putting out more than 450 watts or trying too but it will cook it at some point.

The BVT4500H says its PEAK power is 450 @4 ohms prob less average power.
The BX4500H says its 450 w @4 ohm (does not say peak or RMS) its prob less that 450 average.
I suspect the realistic average power of either of these amps is prob in the 200-250w range at 4 ohms. So just using one 410 cab is underpowered with it getting 1/4 or maybe 1/3 its rated power handling. The speaker specs could be somewhat hyped also. Why Behringer makes a bass amp cab that can use so much power but no bass amp to match it I'll never understand.

When you match cabs to amps you want to match RMS (average) power handling of the cab to the RMS power rating of the amp at the given ohms rating for best performance of the system
or match the Peak power to peak power. Under powering speakers can toast them as much as over powering can.

[Matthew_84]

Originally Posted by bongomania

If you feed a hot enough signal in, you can get the full maximum wattage out even with the volume knob turned lower than halfway.

Bongo you got me thinking about something (and sorry for hijacking the thread). In a week or so I will be running a VT Bass Deluxe through an ART TubeMP into a Crown XLS1000, which surely has the potential to send out a hot enough signal to do what you had mentioned above. If the input singal was too powerful though, wouldn't the clipping light in the power amp turn on? It would be the same as simply turning up the gain too high wouldn't it? Sorry, new to this stuff.

[bongomania]

Originally Posted by uhdinator

Under powering speakers can toast them as much as over powering can.

Myth. Please read the FAQ, and search on the word "underpowering" to learn the facts.

[bongomania]

Originally Posted by Matthew_84

Bongo you got me thinking about something (and sorry for hijacking the thread). In a week or so I will be running a VT Bass Deluxe through an ART TubeMP into a Crown XLS1000, which surely has the potential to send out a hot enough signal to do what you had mentioned above. If the input singal was too powerful though, wouldn't the clipping light in the power amp turn on? It would be the same as simply turning up the gain too high wouldn't it? Sorry, new to this stuff.

Weeellll.... Complicated. For one thing, clip lights on power amps do not all mean the same thing. Some mean the input stage is being clipped; some mean the output stage is being clipped; some indicate that clipping may happen soon but not yet; and beyond all that, whether any part of the amp is clipping is not necessarily a problem by itself.

Bottom line in all cases is: if it sounds good, everything is fine. If the speakers sound like they are about to rip themselves apart and poop the bed, they probably are.

[Zooberwerx]

Originally Posted by aaronhutson

Okay so im looking to run a sansamp rbi and power amp to my cabs, skipping the head...

Without getting too technical, I'd recommend a "2400" amp like the QSC RMX 2450 or equivalent. Sidenote: in a handful of cases, the product # designation reflects output in bridged mono / 4 ohms. The 2450 will push ~650 watts per side (per cab) which should be more than adequate for a Behringer 4 X 10. Lots of attractive, inexpensive, lightweight options (Crown DriveCore, Peavey IPR) which will fit your needs without draining your savings. Check the websites for spec's.

Good call on the RBI! I use an RPM.

Riis

[aaronhutson]

Originally Posted by bongomania

I'm curious--what cues are you seeing/hearing that make you think you've pushed those cabs to their limit?

Well its way loud for one. and i can see the subs kicking and they are kicking so hard that i see it and i worry im gonna blow one. ha. I mean in theory it could be that the head is working harder than it looks to push both cabs. But even with one cab, it can only take about to the 10 or 11 oclock position.

[bongomania]

If the cones are moving a lot and sounding good, then they are doing their job and you should stop worrying. If the movement is accompanied by a farting, buzzing, ugly noise, then the cones are at risk.

I'm betting you are worrying for nothing.

[aaronhutson]

Originally Posted by bongomania

If the cones are moving a lot and sounding good, then they are doing their job and you should stop worrying. If the movement is accompanied by a farting, buzzing, ugly noise, then the cones are at risk.

I'm betting you are worrying for nothing.

I wouldnt doubt that. They sound good. They just kick really hard. But I am probably worrying for no reason. I guess I should just borrow some amps and try them out and see which sounds best.

[Bob Lee (QSC)]

Originally Posted by uhdinator

Under powering speakers can toast them as much as over powering can.

Never turn off your amp and don't even stop playing, ever. You wouldn't want to underpower your loudspeakers.

Hey, there's no such thing as "underpowering" a loudspeaker.

[Bob Lee (QSC)]

Originally Posted by bongomania

Weeellll.... Complicated. For one thing, clip lights on power amps do not all mean the same thing. Some mean the input stage is being clipped; some mean the output stage is being clipped; some indicate that clipping may happen soon but not yet; and beyond all that, whether any part of the amp is clipping is not necessarily a problem by itself.

Bottom line in all cases is: if it sounds good, everything is fine. If the speakers sound like they are about to rip themselves apart and poop the bed, they probably are.

If an amp has clip LEDs, they're there to indicate clipping in the output section. There might be some that also have clip indication for the input section, but I've never seen one. A design engineer who would put in a clip LED for the input circuitry but not the output would have an awfully strange set of priorities.

I'd guess that most amps' clip LEDs indicate actual clipping, though some are more sensitive than others.

[uhdinator]

I understand its not the power rating that kills speakers,
Its thermal, or mechanical failure

[bongomania]

Same thing. None of those have anything to do with the myth of underpowering.

[walterw]

with two 4Ω cabs and a sansamp, a regular power amp makes perfect sense. even a 4-500 watt per side amp will be way more powerful than what you have now, so you can run it all lower, not stress any components, and still kick ass with it. try a real amp, like a QSC (hey, bob!)

[steveksux]

Originally Posted by bongomania

Same thing. None of those have anything to do with the myth of underpowering.

Yup. Hard to generate too much thermal and mechanical stress by using LESS power...

Where does the energy come from that produces the thermal and mechanical stress if not from the power amp? More power=more stress. Less power=less stress.

Randy

[TimmyP]

If you play through good PAs, your bass rig does not need to be that big. That's what the PA and monitors are for.

However if I wanted a big amp, my choices would likely be a K1 (1100 bridged into 8, 1500 bridged into 4) or a PL236 (lighter, more powerful, more expensive). I've never A-B'd the two, but these amps have always beat the amps to which I've been able to compare them.