overpower or underpower, a hypothetical..

[Bob Lee (QSC)]

Add me to the list. It helps clear up/tighten up the sound as another benefit.

Okay, you're on the list. I'll forward the dues information.

Plus, you qualify as one "whose knowledge I respect."

 

[johans]

When you say "monobridge into one" are you asking whether you'd be able to monobridge into the 410 that only handles 400-450W?

yes... or should i go stereo?

im leaning probably more into 1602 .. since it has higher stereo output

 

[hillbillyfunk]

I read through this thread with quite a bit of interest because I blew a eminence kappa pro 15 (rated at about 500w rms) with a 180 watt tube head (fender studio bass) at my last gig.
I was pushing the 15 pretty solidly (master on 10, gain on 4-5) for a 2 hour set and the speaker stopped working during the last song. Removing the grill and pressing in the speaker, the voice coil was rubbing a lot. I'm sure the tube head is distorting a bit at that volume (that's WHY I have a tube head). I also sealed the port on the Avatar because I like the sound better (would this cause overheating?). The speaker is under warrenty, but Dave at Avatar emailed me this:

"there is a small chance it was defective but eminence will check it out and let us know....but it is possible to overheat even a large capacity speaker like the kappa with small amp...you can get a gradual heat build up and if done for a long enough time, it will overheat and ruin the speaker.....if you had your amp on 10, I already know what eminence is going to tell me ...the general rule is that if you have your amp up past halfway, then you should get a bigger amp because small amps distort when up too high and thats what frys the speakers...I seriously doubt Eminence will warranty the speaker....we will see how this plays out with eminence but even more important is to not repeat the mishap again. .......dave"

So what do you guys think?

Thanks!

 

[pepsican]

Well, if you converted the cab from a ported to a sealed design, then you changed the overall design and probably the power handling of the cabinet. Also, tube amps usually are underrated from my experience, and put out a bit more than stated at reasonable THD %'s. Say your head actually does around 250 watts RMS. When driven incredibly hard at the right frequency it could easily double the output, putting you right at 500 watts for short periods. Couple that with changing from a ported to a sealed design that the driver may not be suited for, and I could easily see the speaker frying.

Also, I dont really agree with his statement about a small amp blowing a "large capacity speaker" at least not a driver meant for low frequencies. You could clip an amp rated at 100 watts RMS all day long into a speaker rated for 500 watts. Even at full tilt an amp rarely can do more than double its RMS for short periods of time. Youre not going to blow the speaker unless A. the amp is underrated and produces much more than 100 watts, or B. the speaker is overrated and and can not handle 500 watts. Obviously your situation is a little trickier since you are playing around right in the danger zone of power handling and clipping.

 

[Passinwind]

Also, tube amps usually are underrated from my experience, and put out a bit more than stated at reasonable THD %'s. Say your head actually does around 250 watts RMS. When driven incredibly hard at the right frequency it could easily double the output, putting you right at 500 watts for short periods.

I actually bench tested Hillbillyfunk's amp a few weeks ago. The 180 watt figure is real (180 watts RMS/~5% THD/1KHz), and like many Fenders it's actually a little bit lower than the factory rating. I also ran Win ISD to model what sealing the port on the Avatar cab would do -- and it looks ugly. That amp also has an unusual EQ scheme, which could be a suspect factor as well.

I think the bottom line is that a single 15 cab just isn't enough for what you're trying to do. We can run some tests to see what went wrong when you get the replacement driver in, but I'm betting you'll be happier with a different cab solution.

 

[hillbillyfunk]

Thanks for your responses. I'm looking at an ampeg svt 410he. It's a sealed 4x10 rated at 500 watts rms. I can pick one up at a low price, but my 1x15 was rated at 500 rms as well. Do I need to be looking at an even more powerful cab? Or will the 4 10" drivers disperse the load better?

 

[Mark Reccord]

Well, if you converted the cab from a ported to a sealed design, then you changed the overall design and probably the power handling of the cabinet. Also, tube amps usually are underrated from my experience, and put out a bit more than stated at reasonable THD %'s. Say your head actually does around 250 watts RMS. When driven incredibly hard at the right frequency it could easily double the output, putting you right at 500 watts for short periods. Couple that with changing from a ported to a sealed design that the driver may not be suited for, and I could easily see the speaker frying.

Also, I dont really agree with his statement about a small amp blowing a "large capacity speaker" at least not a driver meant for low frequencies. You could clip an amp rated at 100 watts RMS all day long into a speaker rated for 500 watts. Even at full tilt an amp rarely can do more than double its RMS for short periods of time. Youre not going to blow the speaker unless A. the amp is underrated and produces much more than 100 watts, or B. the speaker is overrated and and can not handle 500 watts. Obviously your situation is a little trickier since you are playing around right in the danger zone of power handling and clipping.

Yep. Another thing to consider is if there are large cone excursions involved due to excessive low frequency energy and part of the coil is spending time outside the gap, that significantly derates the power handling of the driver. Also, limiting excursion can have a negative affect on the amount of power a driver can handle. Consider the tuning frequency of a vented cabinet where the air pressure retards cone movement almost entirely. You don't need anywhere near the 'rated' power of the driver to cause thermal damage to the coil/former assembly at that frequency.

 

[Southpaw5]

For car audio, here's a sight with some expanation what's going on.
http://www.bcae1.com/2ltlpwr.htm

It summarizes:
" * If your speakers are capable of handling significantly more than your amplifier can produce, driving them with a clipped signal will not likely hurt them.
* If the speakers can handle 3 or 4 times the power that your amplifier can produce, there's virtually no way to damage your speakers (no matter how clipped the signal is).
* If your speakers are rated for the same power handling as your amplifier is capable of producing cleanly, driving them with a clipped signal for extended periods of time may cause speaker damage and/or premature failure.
* If your speakers are rated for the same power handling as your amplifier is capable of producing cleanly, driving them with a square wave signal for extended periods of time will likely cause speaker damage. "

Looks like good solid advice even for bass amps/cabinets.

What if your speakers are rated for lower wattage than you amp can produce? clean or clipped? thanks

 

[bongomania]

That's easy--you have the potential to blow your speakers, regardless of clean or clipped. Just listen for signs of speaker distortion, and if you hear any then turn your amp down (or play with less dynamic spikes).

 

[BassmanPaul]

Yet another Zombie thread!! Is there a full moon this week or what?????

Paul

 

[Jaco who?]

The best way to fry drivers is to send square wave from an overdriven, underpowered amp ( though 1000 watts is hardly underpowered, you could blow those speakers pretty well with a 300 watt amp if you are going to push it to distortion, though). Go for the 1500 watts, my friend.

That's right, let's get five more pages of this drivel.

 

[Joey3313]

The best way to fry drivers is to send square wave from an overdriven, underpowered amp ( though 1000 watts is hardly underpowered, you could blow those speakers pretty well with a 300 watt amp if you are going to push it to distortion, though). Go for the 1500 watts, my friend.

Considering this thread is 4 years old, I think this "advice" may be entirely pointless.


I mean, if he's STILL having trouble deciding, there are larger issues.

 

[anonymous101511]

excellent point, I just saw the last few posts that were more 'current"

 

[billfitzmaurice]

excellent point, I just saw the last few posts that were more 'current"

And in the ensuing four years we've gotten to the point where 'square wave cooking speakers' is finally accepted as myth. Resurrecting that old wives tale is non-productive to say the least.

 

[Bob Lee (QSC)]

The best way to fry drivers is to send square wave from an overdriven, underpowered amp ( though 1000 watts is hardly underpowered, you could blow those speakers pretty well with a 300 watt amp if you are going to push it to distortion, though). Go for the 1500 watts, my friend.

Uh, wrong.

 

[bongomania]

I hope you're joking.

 

[Growly Lytes]

How is it possible to blow a woofer rated for 300 watts when I'm only using a 100 watt amp to push it?

Underpowering a speaker is likely to damage the voice coil due to the excess heat created by distortion. This distortion, called clipping, is created when the amp is not able to supply the power demand when the volume is turned up. If you turn the volume up very high without the power to back it up, you'll end up clipping the signal coming out of the amp. The speaker will try to reproduce this clipped signal, and if played under these circumstances for any length of time, the speaker will not last very long.

There is a mis-conception that if you're not giving the speaker as much power as it can handle you won't blow it, but that simply is not the case. The only way to really address this problem is to replace your speaker for one with a lower power rating, and a higher SPL rating, or replace your amp with one that better matches the speaker's power handling capability. An alternative to replacing the equipment is to simply keep your volume turned down!

Make certain that power and ground wiring for the amplifier is sufficient to deliver adequate current to the amp. Proper wire gauge and clean connections are critical for strong performance

 

[Ric5]

If you had
an Avater 2x12 cab rated for 1200 watts rms, and the choice of two power amps (I already have a good pre).

Would you take the amp rated for 1000 watts or the amp rated for 1500 watts?

Thanks

I am currently running an ampeg b3 150 watts into a 2x10 and a 1x18 for a 4 ohm load. I set the gain about 2 or 3 and the master volume at 3 or 4 and it is very loud. I run 1/10 the watts of the 1500 watt head and I get all the volume I need. When I rehearse I have to turn my bass down a little to keep from being too loud. When I gig I run an xlr into a pa with subs.

I have 2 ampeg b2r heads that are rated 350 watts. If I really need power then I can daisy chain them together and have 2 amps both running 2 cabs each at 350 watts of power each. But I have never needed that much power.

I run basses with preamps and effects that boost the signal so the signal is hot running into the amp which makes the amp louder.

I don't have the overhead that the 1500 watt head has but I go for more of a retro dirty sound.

 

[B-string]

uh...nevermind

 

[bongomania]

Underpowering a speaker is likely to damage the voice coil due to the excess heat created by distortion.

Please stop repeating lies. Please read the FAQ. Please read the posts by professional amp and speaker engineers such as Bob Lee, Jerrold Tiers, Bill Fitzmaurice, Agedhorse, Hasbeen, Mark Reccord, etc. etc.