Ampeg 410 speakers lighting up

Supa Scoopa · #1 03-09-2011, 10:11 PM

Hi, I'm running a 100w JCM800 into my Ampeg SVT410, and the speakers are literally lighting up at high volumes. Is this normal? I dont think this ever happened with my SVT810...

Supa Scoopa · #2 03-09-2011, 10:13 PM

I have the tweeter turned off aswell.

kranahan · #3 03-09-2011, 10:18 PM

Please use the search function.

Supa Scoopa · #4 03-09-2011, 10:21 PM

I did. Why dont you just answer me if you know whats up?

ptolemny · #5 03-09-2011, 10:25 PM

I don't have all the technical terms at hand, but there is a light inside of your cab that is activated when you are stressing the speakers; I'd back off the master volume or cut the lows back - or both.

Supa Scoopa · #6 03-09-2011, 10:28 PM

Oh that makes sense, thanks. Strange, everythings at 12'oclock except the master volume that is at 11. Marshall power?

ezstep · #7 03-09-2011, 11:05 PM

Marshall power???

No. Square waves entering the cab which could be direct current (DC) and fry something, usually the tweeter first. It usually happens when one's amp is turned to 11 because it isn't loud enough at 10. Small amps tend to fry speakers moreso than bigger amps. Less headroom.

Supa Scoopa · #8 03-09-2011, 11:12 PM

Right. Well where I live, we run on 220/240v... it fluctuates. I have it set to 240v, maybe 220v would solve the issue? Kinda scared of blowing something up.

christw · #9 03-09-2011, 11:44 PM

You're fine. The alternating wall current is rectified to DC with a plenty capable capacitor supply very early after entering the amp.

That stuff about smaller amps burning up speakers when overdriven (otherwise known as underpowering) has been dispelled. Check the links at the top of the forum about under/over powering speakers.

96tbird · #10 03-09-2011, 11:45 PM

Friend, your 240 v means nothing, fluctuations are normal with power supplies. If you are set up to run at 240 your supply might even hit 260 for short periods, but you are protected by the main fuse in the amp. Your problem is that your amp is "clipping" which means the shape of the wave of electricity that is your signal to the cab is squared off instead of round and smooth. This will blow speakers! The cab has a clipping warning light, back off on your output or you'll fry a driver. You have reached the limit of that amp.

Look at the wave like this, a saw blade. rounded teeth won't cut well, but sharp edged square teeth are sharp and cut better. Your waves are squared off and "sawing" at your speaker coils. The sharp "teeth" on the wave manifests as heat in the copper voice coils, they overheat and they will burn through their enamel insulation, short out and the speaker will be done for..

JimmyM · #11 03-09-2011, 11:47 PM

Quote:

Originally Posted by ezstep

Marshall power???

No. Square waves entering the cab which could be direct current (DC) and fry something, usually the tweeter first. It usually happens when one's amp is turned to 11 because it isn't loud enough at 10. Small amps tend to fry speakers moreso than bigger amps. Less headroom.

sorry, no. square waves don't cause dc to go to your cabs. if you have dc going to your cabs, you have a broken amp. and small amps don't fry speakers unless they're overpowering them. mere clipping alone doesn't fry cabs.

however, it is possible to fry the tweeter with clipping at too high a level, so the light bulb is there to act as a fuse and to dissipate excess power to the tweeter to help prevent it from blowing.

Supa Scoopa · #12 03-09-2011, 11:54 PM

Quote:

Originally Posted by 96tbird

Friend, your 240 v means nothing, fluctuations are normal with power supplies. If you are set up to run at 240 your supply might even hit 260 for short periods, but you are protected by the main fuse in the amp. Your problem is that your amp is "clipping" which means the shape of the wave of electricity that is your signal to the cab is squared off instead of round and smooth. This will blow speakers! The cab has a clipping warning light, back off on your output or you'll fry a driver. You have reached the limit of that amp.

Look at the wave like this, a saw blade. rounded teeth won't cut well, but sharp edged square teeth are sharp and cut better. Your waves are squared off and "sawing" at your speaker coils. The sharp "teeth" on the wave manifests as heat in the copper voice coils, they overheat and they will burn through their enamel insulation, short out and the speaker will be done for..

Thanks for the info! Hmm, its a little disapointing to find this out. I must be pushing the hell out of this little cab, I never blew any speakers in my 810 with this kind of amp...

Supa Scoopa · #13 03-09-2011, 11:56 PM

Quote:

Originally Posted by JimmyM

sorry, no. square waves don't cause dc to go to your cabs. if you have dc going to your cabs, you have a broken amp. and small amps don't fry speakers unless they're overpowering them. mere clipping alone doesn't fry cabs.

however, it is possible to fry the tweeter with clipping at too high a level, so the light bulb is there to act as a fuse and to dissipate excess power to the tweeter to help prevent it from blowing.

Well Jim, I have the tweeter switched off because I know I'll blow it. Maybe its just the tweeter light going off? Even though its switched off, if this is the limits of my cab with an overdriven Marshall, I'm kinda disappointed.

96tbird · #14 03-09-2011, 11:57 PM

Quote:

Originally Posted by christw

You're fine. The alternating wall current is rectified to DC with a plenty capable capacitor supply very early after entering the amp.

That stuff about smaller amps burning up speakers when overdriven (otherwise known as underpowering) has been dispelled. Check the links at the top of the forum about under/over powering speakers.

underpowering is okay as long as the amp isn't clipping. clipping frying speakers is not a myth.

overpowering is OK too. But it is no myth that too much wattage in a signal (master vol too high) can exceed the physical limit of travel of any particular driver and tearing the paper can and does happen.

I think you have misunderstood the concept you stated. It is true you can do either as long as you don't exceed the examples I have stated. They are facts of the physics involved and cannot be disputed.

JimmyM · #15 03-10-2011, 12:13 AM

Quote:

Originally Posted by 96tbird

underpowering is okay as long as the amp isn't clipping. clipping frying speakers is not a myth.

only tweeters.

Quote:

overpowering is OK too.

no it's not. overpowering is what blows speakers every time.

Quote:

But it is no myth that too much wattage in a signal (master vol too high) can exceed the physical limit of travel of any particular driver and tearing the paper can and does happen.

ok, that one is right.

Quote:

I think you have misunderstood the concept you stated. It is true you can do either as long as you don't exceed the examples I have stated. They are facts of the physics involved and cannot be disputed.

one out of three is a fact of physics.

Implosion · #16 03-10-2011, 01:44 AM

Quote:

Originally Posted by JimmyM

only tweeters.

I would think that clipping is not what causes tweeter-frying, but it's our old friend "too much power" because tweeters can't handle much power. In my 4x10 the thermal RMS rating for a single speaker is 150 W, but the tweeter is only rated at 30 W. So it's quite easy to fry a tweeter with a high frequency boost because you can't throw a lot of power at it. But if I send a signal that is clipped but has got only 0.01 watts of power in it, the tweeter will be fine. So it's not the clipped waveform that kills the tweeter. It all depends on the amount of power on the signal. Or am I totally wrong with this? Someone with more experience could chime in on this (but not preferably one of the DC guys

)

Arjank · #17 03-10-2011, 01:54 AM

Very simplified you can see it like this.
When your amp starts clipping and you push it further the amp will start to send more power to higher frequencies(the amp will add harmonic content by itself, even those you might not hear). This is what fries your tweeter (even a woofer with a low rms can be fried this way)

Implosion · #18 03-10-2011, 02:07 AM

But isn't it so that the harmonic content in it self is not the culprit, but the accumulated over all power it creates (that can be seen as the increased area of the waveform) which can be too much for some components. It is possible to have too much harmonic content even without clipping (too much low end for instance?). So basically over-excursion/over-heating caused by over-powering.

Arjank · #19 03-10-2011, 02:16 AM

Wanna know more about what amp clipping can do to your speakers then read this: Too Little Power Blowing Speakers

billfitzmaurice · #20 03-10-2011, 07:04 AM

Quote:

Originally Posted by Implosion

It is possible to have too much harmonic content even without clipping .

No. Clipping is what causes enhanced harmonic content. It's how devices like overdrive pedals, fuzztones, aural exciters and for that matter a screaming Plexi work.

Quote:

Look at the wave like this, a saw blade. rounded teeth won't cut well, but sharp edged square teeth are sharp and cut better. Your waves are squared off and "sawing" at your speaker coils. The sharp "teeth" on the wave manifests as heat in the copper voice coils, they overheat and they will burn through their enamel insulation, short out and the speaker will be done for..

That's a nice analogy, but it's 100% incorrect. Read link in the post above.