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View Full Version : best cheap speaker replacement (10") for vox AD30VT? is that what I need?



Weshunter
February 27th, 2011, 08:24 PM
I'm pretty sure I ruined the speaker in my practice amp, a vox valvetronics ad30vt. the drummer i was playing with was loud so i played it dimed + a fulldrive 2 dimed pretty much all the time. eventually it started to fade out on me, then i'd turn it off and it would come back for a little while before eventually not working at all (except through the headphone out).

so that means i need a new speaker right? what's a good replacement? eminence ragin cajun? anything better or close to just as good for cheaper?

deeaa
February 27th, 2011, 09:53 PM
Um, I could be wrong but I'd venture the power amp section is blown, not the speaker. Speakers don't usually die like that, they either develop a horrid screech, just quit, or literally burn with a bad smell...when they go, they don't go back. My guess is you blew the actual amp 'stones' I dunno what they're called in English, or a cap or two, due to overheating. Open it up and look for leaks, bulging caps or burn marks anywhere.

But, FWIW, I replaced my AD30VT speaker with a Celestion G35-10 and it became entirely different sounding an amp, getting a definite Marshall feel overall, much less ultra-highs and much more growl and bite.

The main issue with speaker change in these is that whatever a speaker you use, it'll sound very different thru that speaker and the headphone out, then, as the original speaker is much more a fullrange speaker than a guitar speaker.

Weshunter
February 27th, 2011, 10:01 PM
if it is the amp stones, is it fixable for a reasonable price? maybe i should just take it to an amp guy

deeaa
February 28th, 2011, 12:00 AM
I really don't know at all...check the speaker first in any case just to rule it out for sure and take a peek inside. If there doesn't seem to be a catastrophic failure anywhere e.g. burns in several places, there's a chance it's fixable with relative ease. But unless you know a real cheap amp guy with lotsa spares 4 cheap around, it'll likely cost at minimum something like half the amp value, and if it needs any serious work, it'll quickly start to approach the amp value. They sell for what, 150;- or so used?

Still, always worth checking things around.

Starts to bug me I don't know what those 'stones' are, are they called rectifiers? Power transistors? I hope someone will chime in. Anyway there's 3 major components to any SS amp basically; the transformer with its coil and the capacitors (the battery-shaped barrels which are usual suspects in failures) and 'them stones' screwed into heatsinks. Plus lots of small parts of course.

Most often, in my experience, caps go bad, especially in cheaper gear and old gear - they have a clear shelf life. But when it's due to either overheating or shorting the speaker cable, I understand it's often the rectifiers that blow, unless the fuse blows first, but that'd be quite abrupt a stop.

Weshunter
February 28th, 2011, 08:39 AM
thanks for the help, i'll take it apart and see what it looks like inside

duhvoodooman
February 28th, 2011, 10:19 AM
thanks for the help, i'll take it apart and see what it looks like insideI would advise against that. The AD30VT is a complex, microprocessor-based modeling amp and repairs are best left to a qualified professional. It's also a fairly large PITA to even get inside one, with all the bolts & screws that have to be removed.

I agree with Dee--doesn't sound like a speaker issue. Almost certainly something in the electronics.....

tunghaichuan
February 28th, 2011, 10:33 AM
I agree with Dee and DVM, it sounds like the electronics. Your amp has solid state devices in the power section, which do not like to be driven hard. Doing so generates a lot of heat which can damage the output transistors.

Hate to be the bearer of more bad news, but it usually isn't worth the cost of the repair to have amps like yours fixed. It could be somethings simple, but it usually isn't. Those amps were not meant to be repaired. You could take it to a tech, but you might be better off putting the money towards a new amp.

Weshunter
February 28th, 2011, 01:43 PM
i took it apart and tried the speaker on my other amp and it worked, so it's definitely not the speaker. there is no clear problem on the circuit board that my completely untrained eye can see, so i'm inclined to think that there's nothing to be done with it except pay to get it fixed which will likely not be worth it. oh well, that's sort of a bummer, i was going to use it as my backup amp. i guess i can still use the modeling stuff like a POD line out to the PA if i'm in a pinch.

thanks for the info guys, saved me money on a speaker i couldn't use and probably money on a repair that wouldn't be worth it.

deeaa
February 28th, 2011, 10:55 PM
Yeah, what I'd probably do is mainly just for fun rip the chassis apart and make a small 'recording head' out of the amp section for recording to the computer and leave it at that. The speaker isn't gonna work in most any other amp/use as it's specifically made for the amp, but maybe you could make a small 1x10" cab out of it for some use.