Blowing new speakers (newer amp content)

[åron]

So the other day I picked up a Deliverance 4x12 off to go with my Sig X. If you ever get chance to play one of these at full volume, don't pass it up. Too much fun. I played all day yesterday; didn't stop to eat, answer the phone or anything else. Where my previous rigs seemed to frustrate me with their limitations, this amp spoils me with seemingly endless tonal variations.

Anyway, I just couldn't turn the damn thing off and leave the studio. Just as I was about to call it a day, the whole thing cuts out. It turns out the left 2 drivers are fried. It's a 16ohm mono or 8 stereo cab. I'm thinking the previous owner mistakenly hit the switch and wore out the left side drivers with an unacceptable mismatch. I guess I finished the job. That should teach me to buy second hand speakers no matter how "new" they supposedly are. Hopefully I can get some replacement p-50s next week.


VHT head runs the show with the help of the Lexicon G2. Power comes from 2 KT88's running a closed 4x12 and 2 KT77's driving an open 4x10. Yes, the Mesa is now little bitch. I'm liking the new arrangement.

[Rsmacker]

You sure the drivers are toast? If they were on the way out before you started caning it, you would have known it, the thing would have sounded shite. For 2 drivers to burn out just like that is very unusual unless they have had a good fucking beforehand, and you would hear them farting the moment you plugged in.

Not trying to humour you, so if you are of a technical bent, I'm sorry, but in case anyone else is interested.....

Take the drivers out and gently press them in, not too far, using pretty even pressure across the cone round the dust cover. They should move easily, and return when you release. If they bind, or scrape, that's a good indication of a burned out voice coil. As I say, when they are thraped, but not totally cheesed, you should hear this anyway straight away. Well-thrashed drivers sometimes even stink of burning down at the voice coil.

Then, if you put a AA battery across the terminals of the speaker you should hear it crackle and see the cone move if the driver is OK. A burned out cone will just give you nothing.

You will also get nothing out of a driver with fucked leads into the coil. The cone will move freely, no binding, no burning ming, but the little delicate platinum leads from the coil that go through the paper to the terminals on the basket might be fucked. Cheaper drivers are bastards for this, but with a good soldering iron, and a light touch, you should be able to dab them back on. Usually things like pulling jacks out of guitars with amp still on full whack does this - the fucking great bang forces the driver to the edge of its travel and if there isn't enough slack on the lead-outs, you end up with silence.

I have to say I would be surprised if you managed to toast both drivers on one side of a stereo cab at once, just like that. In fact I'd go so far as to say I've never encountered anyone burn out 2 drivers in one session unless there was a fault with their amp, certainly not through just caning the drivers to death! I have to confess ignorance of your amp, is it a stereo amp? Did the amp get really fucking hot? Are your valves OK? (Or valve, just one side?)
I suppose you could burn them out if you were deaf or ignored the sound of the drivers croaking their last and pleading for mercy, but that is usually the realm of tosser DJs with banging dance music ignoring the nasty sound of a clipping amplifier, turning it up even when it distorting to hell, but they still think they want it louder. They don't realise it will sound better quieter, but without the distortion, that things only go so loud and turning up just increases the fizz and clipping, not the volume and quality. Kids eh?!!!

Distorted guitar is a definite sought after clip, and drivers are made to tolerate the boundaries of this kind of use. If you were using an amp which was rated below the RMS value of the drivers on that channel, I can't really see how you'd fuck these without knowing you were doing it! Kinda like driving a car absolutely flat out down one of your interstate highways, very difficult to fuck up the engine by just doing that, even at mental speeds, other factors do the damage (no oil for example), and you would be well aware that the thing was reaching crisis point before everything stopped.

Anyway, don't mean to sound too patronising, maybe I've typed this and you knew about this stuff anyway!!

If they are burned out, cut the cone out, pull the coil out of the magnet and take a pic, showing the burned coil! (You will be able to tell if the coil has bottomed out too, but this is usually a bass driver thing).
I'd suggest reconing them if they were decent drivers, but if they were Eminence......well......umm, they make great door-stops, and are probably cheaper to replace with new ones anyway!!!

[åron]

The amp is 100 watts mono. The two problem drivers show up as an infinite load with the multimeter. The right side meters out at 7.3 ohms and works fine. I will try the battery trick and check again for any of the symptoms you mention. It doesn't make any sound when I flex the coil, perhaps it is the leads. Thanks!

[Robert Burns]

I got to play with your SigX at NAMM...and man, was it a brute!
Your right...in 45 minutes, i dont think i tried 1/2 of the tonal
variations.. Awesome amp. Congrats.. (and P-50's will have
you back in business!