Dumb question about wattage....

TimBosby · #1 05-29-2005, 11:26 AM

Hi everyone,

I just purchased an Ampeg SVT III-Pro from a very nice Talkbass member. My cabinet set up consists of 2 Aguilar GS112s (great powerful little cabs.) They are rated at 300 watts RMS each. 8 ohm cabs so together they have a 4 ohm load. The SVT III-Pro puts out 450 watts at 4 ohms. Since the cabs are 300 watts RMS, is the 450 watts put out by the SVT III-Pro going to be too much. My instinct is no, they should probably be fine as long as I never turn the SVT III-Pro up too high. But I'm having a paranoia attack. My current head that I would like to sell is an Eden WT 330 (330 watts at 4 ohms.)

I am probably going to get some new cabs at some point but I love my GS112s. I take both to full band gigs and one to drummerless gigs.

Thanks
-TimBosby

Munjibunga · #2 05-29-2005, 11:30 AM

You have 600 watts of speaker, and 450 watts of amp. You'll be a little underpowered, but it's not a big problem. Just don't drive your amp into clipping and you'll be fine. Those speakers (combined) need about 1,000 watts for optimum headroom.

TimBosby · #3 05-29-2005, 11:32 AM

Well by that equation then previously with my Eden I had 330 watts of power and 600 watts of speaker

So I should be better off now?

Mudbass · #4 05-29-2005, 11:55 AM

Quote:

Originally Posted by TimBosby

Well by that equation then previously with my Eden I had 330 watts of power and 600 watts of speaker

So I should be better off now?

Maybe yes, maybe no. Is 450 watts is louder than 330? All other things being equal, yes, but Eden is known for being fairly conservative with their power ratings so the SVT III may or may not be louder. The only way to know will be to try it out.

DubDubs · #5 05-29-2005, 12:19 PM

You'll be fine becuase

a) Speakers can usually handle about twice their RMS rating relativly safely

b) With your setup each cab is only getting about 225w.

kilgoja · #6 05-29-2005, 10:26 PM

i wouldn't put a 1000w through those speakers...that would probably blow them....it's always best to have higher speaker wattage than amp wattage....

BurningSkies · #7 05-29-2005, 10:32 PM

Quote:

Originally Posted by kilgoja

i wouldn't put a 1000w through those speakers...that would probably blow them....it's always best to have higher speaker wattage than amp wattage....

Only if you're not gonna push the amp. If you are, then you're better off with a stronger amp, and lesser speakers. This is especially true with solid state amps...Clipping in the amp can cause as much or more damage than overpowering a speaker. Square wave distortion is not your friend, nor is it your speakers' friend.

TimBosby · #8 05-29-2005, 10:32 PM

OK I have to admit, I tried it and am rather disappointed. It is not particularly loud though I love the tone. I think maybe I should get an Eden World Tour 800. I want a hybrid amp... would 800 watts (400 into each 300 RMS cab) be a good thing to try? Any help appreciated.

BurningSkies · #9 05-29-2005, 10:40 PM

You'd be doing ok with that rig.

It's no surprise that the SVT III was underpowered...they're kinda known for that.

I wouldn't be so hung up on matching your wattage to your cabs...As long as you're not going to push the amp to extremes, and you're not gonna blast those cabs, you'll be ok.

Lots of people around here use very high power amps with lower powered cabs...they can get more clean headroom that way without pushing the volume. Just because you have the power, doesn't mean you have to use it.

On the other hand...

Right now I have a (sub)300 watt amp (Mesa 400+), and I'm using with with a cab rated at 1000w and a cab rated at 500w. No problems, but then I'm not pushing the amp that hard, so no foul.

Munjibunga · #10 05-29-2005, 10:45 PM

Quote:

Originally Posted by kilgoja

....it's always best to have higher speaker wattage than amp wattage....

You are incorrect, sir. EAW recommends 1.5 to 2 times the rated speaker power for amps. Just don't crank them up. For instance, I'm running a PLX 2402 bridged into each one of my EAW SBX-220 subs, which are rated at 1,400 watts. They can run all day at that power. Every once in a while though, there will be a transient input that will need an extra 1,000 watts. The speakers can handle this, but the amp needs to have the headroom to play it without distortion. That's where the extra power comes in.

If you take a 1,000-watt cabinet and power it with a 300-watt amp, it'll be just fine ... until you turn up the amp too far, and it clips trying to give the speaker all it will take. The key is to be careful. If you know you're underpowered, don't try to get more power out of the amp than it can give. If you have lots of extra headroom, don't try to give the speaker more power than it can take.

TimBosby · #11 05-29-2005, 10:46 PM

With my two Aguilar GS112s and my Eden WT 330 I always had to keep the volume and gain at least half when our drummer was around.

I thought this problem would be solved with the SVT III pro but it doesn't seem to be the case.

Well damn. Now I have to unload what I just bought. I like Eden though. Anyone have a World Tour 800 for a good price?

BurningSkies · #12 05-29-2005, 10:51 PM

Also...Make your power amp work harder than your pre amp.

Push that power amp up to 3/4ths power at least and keep your pre lower...you're less likely to clip the pre, and maybe you'll get a bit more volume.

Munjibunga · #13 05-29-2005, 10:51 PM

Ampeg ... pfffffft!

Lowtonejoe · #14 05-30-2005, 12:55 AM

Quote:

Originally Posted by TimBosby

OK I have to admit, I tried it and am rather disappointed. It is not particularly loud though I love the tone. I think maybe I should get an Eden World Tour 800. I want a hybrid amp... would 800 watts (400 into each 300 RMS cab) be a good thing to try? Any help appreciated.

I don't know if this will help at all with your SVT-III but I read recently (in a thread here on TB) that someone was told by an Ampeg employee that the best way to run a B2R or SVT-III was to turn the master up all the way and adjust your volume with the pre-gain.

Give it a shot and tell us what you think.

Joe.

kilgoja · #15 05-30-2005, 01:04 AM

well all i know is that my svt classic and my mesa 400+ are 300watts and my ampeg 8x10 and my mesa 2x15 cabinets are both 800watts....so the speakers can hold more wattage than my amps are putting out....that way there is no way to blow the speakers even at full volume...which i never use anyway.......if i had a 1000 watt amp and turned it up all the way it would blow the speakers because they can only handle 800 watts....it may work a different way....but if that's the case then why don't ampeg and mesa make cabinets that are 300 watts to go with their amp heads

i've kinda always been confused by this rms...program...peak wattage stuff...i've heard 2 different things over the years....have less amp wattage and turn it up and have more amp wattage and don't turn it up so i don't really know i guess...all i know is i haven't had any problems so i guess my way is working...lol

BurningSkies · #16 05-30-2005, 09:04 AM

Quote:

Originally Posted by kilgoja

well all i know is that my svt classic and my mesa 400+ are 300watts and my ampeg 8x10 and my mesa 2x15 cabinets are both 800watts....so the speakers can hold more wattage than my amps are putting out....that way there is no way to blow the speakers even at full volume...

Ah, but you see, there IS. That's what clipping does, and why it's more dangerous than 'overpowering' your speakers. Do a bit of a search around here...If you push your amp into clipping, you're sending a VERY high wattage (and uncontrolled) signal to your speakers...As in well beyond what that amp lists as its peak power. And on top of that, the TYPE of signal it sends to your speakers can do grave damage too. This isn't as much of an issue with tube amps...they have 'soft clipping', but it is an issue.

Think of RMS as the 'average' running wattage of your amp. While using it, you put out signal thats both lower and higher than that. The PEAK power is roughly the wattage your amp puts out while still being under the ceiling of clipping.

With your home stereo, you can generally match your speakers...the recorded music you play has a different kind of wave signature...its been compressed (that's part of what 'mastering' is all about), and is much more 'polite' to speakers. In a live music/bass application, it's another story. Bass amps have a wide frequency range, and can produce lows that are high wattage...and generally aren't compressed into a 'polite' form for the speaker.

That's why having more wattage works for most people. They know that they're not really gonna turn all the way up, and any possible transient peaks are not going to trigger their amps into clipping, because the amp has lots of headroom...the signal is going to stay clean on those peaks, and not send damaging signal. Now, on the other hand, if you've got a lower powered amp and you're going to use it at as high volume as possible, then you're pushing your luck. You're much more likely to push that amp past the 'clean ceiling' and into clipping sending 'bad' signal to your amp.

Thus, if you had a 1000 watt amp and a 300 watt amp, and you played them at the same volume... you're better off playing the higher wattage one, as the lower wattage one is working harder and much closer to its 'limit' of clipping and distortion with the potential of harming your speakers. The high wattage amp is not working as hard and remains to send clean 'non-threatening' signal to your speakers.

kilgoja · #17 05-30-2005, 12:47 PM

interesting.....i've never ran any amp at full volume...i don't think that is a good idea.....i didn't know tube amps could clip out...or at least i've never seen it...but i guess it is possible...i wish they would just make things simpler and just make things match like 500w with 500w or something like that and just leave out all of the info about rms, program, peak, blah blah blah....i guess it is useful info but it confuses a lot of people..including me...lol....i've also heard from people that if you have a 1000 watt amp then it is sending out 1000 watts no matter what the volume is on.....they said the volume doesn't control the wattage....just the loudness or something like that.....do you know anything about that ...is that just crap...

GSPLBASSDC · #18 05-30-2005, 01:10 PM

Quote:

Originally Posted by kilgoja

interesting.....i've never ran any amp at full volume...i don't think that is a good idea.....i didn't know tube amps could clip out...or at least i've never seen it...but i guess it is possible...i wish they would just make things simpler and just make things match like 500w with 500w or something like that and just leave out all of the info about rms, program, peak, blah blah blah....i guess it is useful info but it confuses a lot of people..including me...lol....i've also heard from people that if you have a 1000 watt amp then it is sending out 1000 watts no matter what the volume is on.....they said the volume doesn't control the wattage....just the loudness or something like that.....do you know anything about that ...is that just crap...

The volume knob doesn't control the wattage, per se, but it has a direct effect on the spl (sound pressure level) that is sent to the speakers. It sometimes gets kinda confusing, with all the physics involved 'n all, but it's really helpful to know a little bit about headroom, clipping, spl's, wattage , and impedance (ohms)

BurningSkies · #19 05-30-2005, 01:19 PM

Amp and speaker makers give you that info because nothing is quite black and white. The figures give you a sort of range so you can figure where a amp or speaker's performance is. Mesa is particulary difficult, because they like to quote peak rather than RMS with their amps...your 400+ is really under 300 watts...a 6L6 can only give 25 watts in the best of situations...

The other thing is that tubes amps have a louder 'precieved' volume to most people. Really, a watt=a watt. But in practical live situations, it doesn't quite stack up that way.

Beyond that, different frequencies take different amounts of power to produce at the same volumes. Most loud guitar amps are 50 or 100 watts...because the frequency range that they produce takes less power. Bass amps on the other hand can be quiet at 300 watts. Those big waves at the low end of the frequency spectrum take more power.

In the real world, what this means is, if you're gonna boost your low end eq, you're using more power to do it...and you're losing headroom that will keep you away from clipping. So now you can see that clipping can be caused not only by volume, but also by your tone settings.

Munjibunga · #20 05-30-2005, 02:02 PM

Quote:

Originally Posted by kilgoja

well all i know is that my svt classic and my mesa 400+ are 300watts and my ampeg 8x10 and my mesa 2x15 cabinets are both 800watts....so the speakers can hold more wattage than my amps are putting out....that way there is no way to blow the speakers even at full volume...

This is exactly where you are wrong. If you crank up your 300-watt amp to the point where it clips (and it will, while trying hard to put out more power than it's rated for), you will cause clipping, which creates big ugly square waves, which speakers detest. Trust me, 300-watt square waves will send your 800-watt speakers out to lunch.

Can I get an amen, bretheren?