Mr. Foxen

I've also had amps in oscillation not blow speakers, it just makes a annoying repetitive noise. Bit like people insisting clipping kills drivers.

[quote name='Wiggybass' timestamp='1362934062' post='2006388'] Er...no...in this case the iPod would be the preamp. I can make a horrible noise by using an iPod in that way but it would only pose a threat to the PA if the power amp driving that was driven into distortion or oscillation. Look at all the bedroom guitarists who thrash their preamps to get massive distortion and never ever blow a speaker, nor are ever likely to - the pre and power amps are completely different. The preamp exists only to bring the incoming signal from the instrument up to a level where it can drive the input of the power amp. [/quote] Nope, headphones, passive, powered by ipod, make sound. You can indeed make a horrible clipped sound with an ipod, and that is it distorting, and it won't break a PA speaker. And yes, those bedroom guitarists, and gigging guitarists do get massive distortion and never blow a speaker, because distortion doesn't blow speakers.

How about asking a speaker engineer? Oh wait, one has posted on the subject a whole load of times on this forum, and another has already been linked in this thread.

[quote name='Wiggybass' timestamp='1362933678' post='2006378'] Crank what up? The iPod or the speaker? [/quote] Ipods have a power amp, its easy to clip, its how they drive the speakers in headphones.

[quote name='Wiggybass' timestamp='1362933632' post='2006376'] I don't doubt it for a moment - but I say again, ask anyone who recones drivers (and I mean professionally) and every single one will tell you that almost all damage to cone transducers is the result of being continuously driven by power amps producing unintentionally distorted signals for extended periods. There's no mistaking the difference in the damage between this type of damage and that caused by over-excursion. [/quote] If your reconer says that, you'd be better off finding a reconer who knows what they are talking about.

[quote name='Wiggybass' timestamp='1362932171' post='2006358'] Clipped waveforms might be technically the same but the massive difference in amplitude is what's relevant concerning potential speaker damage. The miniscule voltages in the preamp could never be enough to damage a driver, whereas a power amp driven into clip and / or oscillation will definitely damage transducers if left for long enough (and that may not be very long if it's a low-powered driver). Ask anyone who does recones, they'll tell you what kills drivers. [/quote] Clipping and amplitude are entirely unrelated. Clipping limits amplitude if anything. Overpowering damages speakers, waveform bears no relevance.

[quote name='Wiggybass' timestamp='1362911648' post='2005993'] Sorry, don't follow the reference - which bit of the guitar amp is / was being driven into clip - pre amp or power amp? Or both? And why can't amps put square waves into cabs? [/quote] Any of it, doesn't matter, clipped waveform is the same. Square waves require infinite bandwidth, and perfect cab behaviour (impedance, inductance etc.) and both amp and cab limit that. The limitations act to round off the square, limit enough and you bring it back to a perfect sine.

Twice now I've thrown my super 15 at people, I mostly play gigs because they are funny, and there isn't much funnier than the look on someone's face when they offer to help you shift your 2x15 bass cab and you go 'Sure, catch.'. It survived fine.

[quote name='KingBollock' timestamp='1362872092' post='2005775'] [media]http://www.youtube.com/watch?v=4wRTxBhqNuY[/media] [/quote] Ha, this one did cross my mind.

If both all lined correctly it should sound the same. If the original cab isn't, then the internal reflections and such are part of the sound, so a different shaped inside won't sound the same.

[quote name='xilddx' timestamp='1362766370' post='2004590'] I have a half eaten tub of Philadelphia Light in the fridge that's heavier than this [/quote] Way to wreck a dude's buzz and give them the munchies.

[quote name='Wiggybass' timestamp='1362757376' post='2004376'] You'll endanger your cab(s) far more by trying to drive them with an amp that isn't powerful enough than one which is (according to the bare specs) too powerful. Most speaker damage is the result of square-wave distortion which is what amps produce when they're pushed at or beyond their limits. If your amp is producing the volume you need whilst working well within its capabilities then happy days - technically you might be able to push the drivers beyond their excursion limits but with a good brand like a Berg I think you'll reach your desired volume long before that happens. [/quote] All this is not true. Again, 50w guitar head into 300w 4x12, driven far into clipping. Also amplifiers can't put out square waves into cabs.

When you say 'local luthier' do you mean 'local guitar tech'? Totally different things, I kept being called a luthier because I do setups, I've never made a lute in my life. At the pretty bodger end of guitar tech too.

[media]http://www.youtube.com/watch?v=k2KBIs__91s[/media] [media]http://www.youtube.com/watch?v=fmdmnnv2NkY[/media]

Some cabs have a lightbulb in the tweeter circuit, which dissipates the extra power.

[quote name='owen' timestamp='1362695791' post='2003664'] Sorry, would clipping be a better word to use than distortion? [/quote] same thing. Distortion is what happens to a waveform when its clipped. When you overdrive things, they are clipping. You get other sorts of distortion too tough.

Dig the bridge.

[quote name='owen' timestamp='1362694470' post='2003632'] It is not too many watts that does nasty things to cabs, it is too few being driven into distortion. I used to drive an NV610 with an 800w amp for many happy hours. [/quote] No it isn't. Otherwise valve amps would kill cabs all the time.

Ask Ampeg would be a start I reckon.

Super 12 will do that fine. Watts is down to how loud you want to go. It can take them, but it doesn't need them.

[quote name='BassTractor' timestamp='1362679135' post='2003305'] 2) the DI button is not switching between ground and lift (whatever those might be if they even exist) but is a ground lift switch [/quote] Think its switching between grounded, and having the ground connection lifted (so not on the ground any more).

SM<PS is switch mode power supply, pretty unrelated to the output. You can make a valve amp with SMPS, think Peavey did one.