Why did my speakers blow?

[Old Garage-Bander]

I routinely run an amp rated at more power than the rating of the cab. I have never blown or even creased a speaker. The way it works is you don't crank the amp past what the cabs can handle. Once the cabs start complaining, you have to turn it down.

Now getting down to the OP's predicament, I would bet the EQ was set bass heavy. Those little 6-inch speakers can't begin to handle the amp's full output if it has a lot of bass content. Correct me if I'm wrong about the EQ.

Thanks for checking in. You bring wisdom to the conversation. It seems that many of those who profess to use overly high power amps with significantly underrated cabs, either fail to know they have to keep them turned down, or fail to pass that information along to others. Sure it can be done, but with great caution. If someone "accidentally" cranks your 500 watt amp up to 11 without your knowledge, your 200 watt cab will suffer. Then someone reads that high power amps with low power cabs is OK. But if they do not understand the caveats, then trouble is afoot. I'm glad you finally brought some sense to that whole conversation.

 

[BassmanPaul]

Perhaps only one cabinet was actually connected.

I mentioned that in post#2 Jim.

 

[AMJBASS]

Thanks for checking in. You bring wisdom to the conversation. It seems that many of those who profess to use overly high power amps with significantly underrated cabs, either fail to know they have to keep them turned down, or fail to pass that information along to others. Sure it can be done, but with great caution. If someone "accidentally" cranks your 500 watt amp up to 11 without your knowledge, your 200 watt cab will suffer. Then someone reads that high power amps with low power cabs is OK. But if they do not understand the caveats, then trouble is afoot. I'm glad you finally brought some sense to that whole conversation.

I don't know about great caution. You just use common sense. I have also frequently used amplifiers with much higher wattage rating into cabinets rated at less. You just have to realize that your amp isn't putting out a continuous amount of power at its rating.

 

[Mugre]

Did you try Orange County Speaker?

Indeed, a quality outfit but sadly they are closing or may already be closed. We have a commercial account with them and will be sad to not have this valuable asset. Some of the workers are talking about opening a smaller re-coning business but we haven't heard anything concrete yet.

Mugre

 

[ajschnitzelbank]

Oh, crud :-(

Indeed, a quality outfit but sadly they are closing or may already be closed. We have a commercial account with them and will be sad to not have this valuable asset. Some of the workers are talking about opening a smaller re-coning business but we haven't heard anything concrete yet.

Mugre

Thanks for the heads up.

 

[T_Bone_TL]

The OP is (assuming profile up to date) from Ra-cha-cha, so closer to home might try:

Link Removed

Sound Source • Rochester NY's Top Music Store • Offering Instrument Sales, Instrument Rentals, Instrument Repair, Pro Audio, Recording, DJ, Music Accessories, Music Books, Keyboards, Guitars, Drums, and More • (585) 271-5370

There's also a place listed under at least 3 names with a bad website link (or several) - ""The Speaker Place", "Newfoam" and "Speaker parts" - given the bad web links, could be defunct.

A bit further away to the East is: [Invalid or Expired Link Removed] in Troy.

 

[BogeyBass]

I think it's a case of typical manufacturer or industry wattage
ratings.

just cause its rated at 600watts
don't mean it won't go bye bye
way way before that.

in reality taking a guess the cab probably does 150/ 170 watts
and 200 to 250 would probably damage it.

most manufacturers rate the speaker at the thermal rating.
thermal rating being rated how much heat the voicecoil and the glue will
take before meltdown.

otherwise mechanical damage can happen way lower than the thermal rating.

 

[BurningSkies]

Lets take a moment here. You've said that it was blown and that it happened with your usual gain and volume. How did you have your EQ set? And those filters on the MB amp? Also, if you have an active EQ on your bass, how was that set? Have you recently changed your bass?

 

[JimmyM]

They needed the money.

HA!

This is why you go by your ears and your common sense and not by the numbers. Numbers are often misleading and almost never tell the whole story.

 

[marmadaddy]

Perhaps only one cabinet was actually connected.

I suppose it's possible, but I remember breaking down that night and no speakon connectors came away too easily. I've also confirmed that both cables work.

 

[marmadaddy]

Hmm... Looks like the MarkBass Little Mark III is "old school" HPFless tech - blech. If you had the amp's bass EQ up past noon it's possible that it did overexcursion the cab - especially if only one was actually plugged in. Personally I'd not run an amp rated at more that 1/4 the rating of a ported cab without a HPF, especially if using an OD either separate or built into the amp. OTOH 300w of amp with a decent HPF into a well designed 600w cab shouldn't be a problem...

I run the eq flat, except for the High which I keep around 11 o'clock as it seems to add highs at the 12 o'clock position.

 

[marmadaddy]

The OP is (assuming profile up to date) from Ra-cha-cha, so closer to home might try:

Link Removed

Sound Source • Rochester NY's Top Music Store • Offering Instrument Sales, Instrument Rentals, Instrument Repair, Pro Audio, Recording, DJ, Music Accessories, Music Books, Keyboards, Guitars, Drums, and More • (585) 271-5370

There's also a place listed under at least 3 names with a bad website link (or several) - ""The Speaker Place", "Newfoam" and "Speaker parts" - given the bad web links, could be defunct.

A bit further away to the East is: [Invalid or Expired Link Removed] in Troy.

Thanks. Audio Sound Solutions doesn't repair MB speakers and Sound Source doesn't repair speakers. I'm in that store at least weekly. Nice people, I recommend it.

Lets take a moment here. You've said that it was blown and that it happened with your usual gain and volume. How did you have your EQ set? And those filters on the MB amp? Also, if you have an active EQ on your bass, how was that set? Have you recently changed your bass?

EQ was flat as usual, VLE and VPF were at their normal settings. Bass was my 81 P that's been my main instrument since I bought it new.
There was nothing different about my equipment on this gig compared to the previous fifty at least.

I'm going to replace the speakers and seriously consider this as an excuse opportunity to upgrade to something more "robust".

 

[Ewo]

Been playing a long time and used a ton of different rigs over the years. I'm not a chronic speaker-trasher, but a couple years ago I did burn a 12 driver. Was pushing a pair of Baer ML112s (8 ohms, rated at 300W each) with an Aguilar TH500 (500W into a 4 ohm load). The band was loud, and the guitarist was throwing down a lot of low end. I didn't feel like I was slotting _under_ that stuff in the mix well enough, so I dialed up some bass boost. Guess I didn't hear the speakers complaining because the mix was noisy--but I burned one of the drivers over the course of a four hour gig.

IANA tech, just a player--but I learned two things from making that mistake: (1) power ratings are no more than guides, and numbers cannot be taken as reassurance a rig is bulletproof; (2) it's wise to listen closely for even small indicators a speaker is complaining.

 

[agedhorse]

IANA tech, just a player--but I learned two things from making that mistake: (1) power ratings are no more than guides, and numbers cannot be taken as reassurance a rig is bulletproof; (2) it's wise to listen closely for even small indicators a speaker is complaining.

IMO, this are very good observations.

 

[MDBass]

I'm having a hard time understanding this.

I run a MarkBass Little Mark III into two MarkBass NYC 604 cabs.
The head is rated at 500W RMS @ 4 ohms / 300W RMS @ 8 ohms.
The cabs are 8 ohms with a published power handling capacity of 600W RMS each.

Going by the published specs, there's no way this head should have overpowered those speakers.

I played a gig two weeks ago and everything sounded fine right through the end of the night. I didn't turn Input gain or Master volume up any higher than I normally do, actually I've run it hotter. Input was a little shy of 9 o'clock, Master was at 11 o'clock. It was warm in the room but not particularly hot. Stage lights were all LED.

I brought one cab to a worship gig the next Saturday and I get the unmistakable sound of fried speakers.
Later testing showed three of the four speakers have frozen voice coils. The other cab is fine. Speaker cables test fine.

There's no recone kit for these so my only option is buying new ones. It's pricey but I haven't had to replace a speaker for my bass rig in years so I'm not that put out, but I really want to know what could have happened.

How could three of the four speakers in one cab have fried under these conditions? Any ideas?

As others have mentioned, the cabs "wattage" is actually their thermal rating; mechanical failure due to over excursion is still possible under "safe" power.

My DB750 puts out 750 watts at four ohms, but due to the lack of built in HPF I can easily blow apart any commercial cab rated for 1200+ watts (810, 412, etc.) with the gain and master both well below noon and without even boosting the bass.

I'd look into picking up an FDeck HPF or another similar hi pass filter to avoid this issue again in the future

 

[ThisBass]

IANA tech, just a player--but I learned two things from making that mistake: (1) power ratings are no more than guides, and numbers cannot be taken as reassurance a rig is bulletproof; (2) it's wise to listen closely for even small indicators a speaker is complaining.

+1
meant as supplement, excessive cone excursion that appears rather randomly is an indicator that the driver is overloaded with to much of sub content. It's a more visible indicator rather than audible thing like "crying for help" phrase which is broadly common.

There is some easy testing method to check how robust the drivers compete with sub content. It's hard to explain cause and effect even in native language, so hopefully someone else can take it.

 

[gregbackstrom]

First, I am sorry to hear about what happened to you rig.
You didn't happen to mix average or RMS power with peak power ratings? I've seen the same speakers with very different ratings depending on how power is measured. There are different ways to state amp power output and speaker power handling. You don't want to do apples & Oranges.

Now for this...
There are a number of people on TB that claim it is OK to run an amp that is capable of generating significantly MORE power than can be handled by the combination of speakers connected to that amp. These people normally drive me crazy, and well that's my problem.

These guys were pretty adamant that it is OK to run more amp than what your speakers can handle. I'm sure they'll pop up here in droves to explain how this all really works and save you some future grief.
(p.s. if your sarcasm filter isn't on, it should be)

In the approximately 49 years that I've played bass, I have not damaged a driver. And I frequently use amps that supply MANY more watts than my speakers can handle. I avoid damaging the cabs by not overdriving them -- it's as simple as that!

One of my current rigs of choice includes a Peavey IPR2-5000 into three 350 watt cabinets. Even though this amp is capable of producing thousands more watts that my cabs can handle, I can pretty much guarantee you that I won't damage my drivers with this amp (unless the amp malfunctions, of course).

Just be careful!!! Keep the volume and EQ reasonable, and your gear should last a long, long time!

By the way, I'm not posting to drive you crazy -- that's just a side benefit!

 

[Ewo]

+1
meant as supplement, excessive cone excursion that appears rather randomly is an indicator that the driver is overloaded with to much of sub content. It's a more visible indicator rather than audible thing like "crying for help" phrase which is broadly common.

There is some easy testing method to check how robust the drivers compete with sub content. It's hard to explain cause and effect even in native language, so hopefully someone else can take it.

IANA speaker designer, either, but I have a guess at what was happening when I toasted the driver. I've read some threads about cabs, and if I'm understanding it correctly ported cabs are vulnerable to over excursion when you hit them with a lot of power at a frequency below some limit determined by the port dimensions and shape. Just spitballing this, but I betcha when I goosed the bass EQ I was exceeding that limit.

 

[Nawlins]

I routinely run an amp rated at more power than the rating of the cab. I have never blown or even creased a speaker. The way it works is you don't crank the amp past what the cabs can handle. Once the cabs start complaining, you have to turn it down.

Now getting down to the OP's predicament, I would bet the EQ was set bass heavy. Those little 6-inch speakers can't begin to handle the amp's full output if it has a lot of bass content. Correct me if I'm wrong about the EQ.

I agree with Munjibunga. What fries speakers is distortion from the power amp OR sending the speaker frequencies it can't reproduce. It's physics. The energy has to go somewhere. If energy (low frequencies from the amplifier) reach the speaker from the power amp can't be reproduced by the speaker, they turn to heat, and unfortunately that process happens in the voice coil of your speaker.

The other most common scenario is distortion from the power amp of your rig. If you push an amp past what it can reproduce, you get distortion. It doesn't matter how much power. You're more likely to blow a speaker with an underpowered rig, because you're more likely to get in situations where you push the hell out of it to keep up with your band.

 

[Rip Van Dan]

I mentioned that in post#2 Jim.

Actually, if the amp puts out 300 watts at 8 ohms and 500 at 4 ohms, hooking one 8 ohm speaker up would limit the amp to 300 watts. Since the speaker cabs are rated to handle 600 watts, hooking one up at 300 watts should be no big deal.

My guess would be that he has the bass EQ way up, which sucks power from the amp and can overextend the speakers. Aged horse explained this pretty well (as always). The OP should have heard this happening though. Your sound goes to sh*t when your speakers do that and the speakers don't live long if you continue to do it.

Another thing he might try once he gets his speakers fixed is adjusting the gain differently. Now, there are a lot of different gain structures out there, so this might not work, but give it a try. His gain is set pretty low. Turn the master down a bit so you can comfortably hear what you're playing. Then slowly turn the gain up while playing the same run each time you try it - ideally across 4 strings. If the master isn't up too high, you should be able to hear when the gain signal starts to break up (distort). Turn in back down about 1 notch and then start to turn up your master. Presuming (could easily be wrong) that this is a straightforward gain structure, you should now be giving your power section the cleanest, lowest-noise signal for it to amplify. If your gain is set too low, the signal becomes noisier and has less volume. It can make a BIG difference in the volume of your gear without causing any problems to your speakers. Since it doesn't take as much power to get the volume, the amp will also run cooler which is a plus for long-term reliability.