#1
Hey everyone,
So I was playing on my Vox AD30VT last night pretty loud, with no issues. This morning I turned my amp on and starting playing something clean and the amp was crackling really bad. Like its not the normal amp hum I usually hear. It only crackles when I play something, almost like if the amp is "clipping".

I've tried several guitars, several amp cables, several power cables, and nothing changed. I took the amp apart, dusted it, and looked inside but don't see anything out of the ordinary. I put my hand on the back of the speaker when a friend was playing and adding pressure in different spots either reduced or increased the crackling.

I was wondering if my speaker is toast becuase the sound changes when I touch it, or if it is an electrical problem. I know there's like a tube in the unit too, I don't know if that makes a difference, I'm just not sure what to do and any help would be appreciated. If it's a speaker then no big deal, I'll just buy a new nicer one and solder it in. If it is the electronics would anyone know how I should go about fixing it? Has anyone had a crackling amp problem? Thanks!
#2
Tubes, dirty tube sockets, or bad solder joints at the sockets.
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#3
8Len8 so it's more likely to be the tube than the speaker?

How would I go about fixing it?
#4
mhillips

Buy a replacement 12ax7. Unplug amp. Open amp up. Get some DeOxit and spray down the socket. Put in new 12ax7... insert and remove it a few times before finally seating the tube into place. If the crackling persists take it to a tech. Not sure what the guts look like on that amp, but, if you haven't had any training or experience in repairing electronics, you're better off to have a professional fix it rather than break it more... or electrocute yourself.
Gear: Gibson Les Paul Studio, Gibson SG Special, Fender Stratocaster, Fender Telecaster, Fender Jazzmaster, Gretsch Pro Jet, Carvin C350, Epiphone ES-339 P90, Epiphone ES-335 Pro. Peavey 6505, Sovtek MIG-100, Vox AC30, Peavey XXX.
#5
Try sending your output to a different speaker. If that works the speaker or connections are bad. If it doesn't work you have amp problems.

Process of elimination...
"Your sound is in your hands as much as anything. It's the way you pick, and the way you hold the guitar, more than it is the amp or the guitar you use." -- Stevie Ray Vaughan

"Anybody can play. The note is only 20 percent. The attitude of the motherfucker who plays it is 80 percent." -- Miles Davis

Guthrie on tone: https://www.youtube.com/watch?v=zmohdG9lLqY
#6
Quote by mhillips
Hey everyone,
So I was playing on my Vox AD30VT last night pretty loud, with no issues. This morning I turned my amp on and starting playing something clean and the amp was crackling really bad. Like its not the normal amp hum I usually hear. It only crackles when I play something, almost like if the amp is "clipping".

I've tried several guitars, several amp cables, several power cables, and nothing changed. I took the amp apart, dusted it, and looked inside but don't see anything out of the ordinary. I put my hand on the back of the speaker when a friend was playing and adding pressure in different spots either reduced or increased the crackling.

I was wondering if my speaker is toast becuase the sound changes when I touch it, or if it is an electrical problem. I know there's like a tube in the unit too, I don't know if that makes a difference, I'm just not sure what to do and any help would be appreciated. If it's a speaker then no big deal, I'll just buy a new nicer one and solder it in. If it is the electronics would anyone know how I should go about fixing it? Has anyone had a crackling amp problem? Thanks!
Firstly, methinks that is not a smart idea because you could end up throwing the voice coils' travel out of place. Secondly, your results could mean exactly that- the voice coil is out of place and is scraping against the internals. That and/or dirt has gotten into the speaker internals and causing your problem. It is also worth trying a spare known-good tube to see if that fixes the issue.
Last edited by Will Lane at Sep 13, 2016,
#7
Well, I havnt tired a new tube yet, but I did remove the speaker and tested it in another amp. The speaker still sounds crackly and dirty in the other amp, so I'm thinking the speaker is toast.

I pulled the tube and looked at it, it doesn't look funky and the pins all looked clean, but I don't have a way to test it in another amp (my other amp I think is solid state) and I don't have a spare tube.

So....maybe just get a new speaker and hold off on the tube, or do you think maybe there's something up with the tube?

Also, to clean the tube ports, should I just compressed air products, like endust?
#8
Quote by mhillips
Well, I havnt tired a new tube yet, but I did remove the speaker and tested it in another amp. The speaker still sounds crackly and dirty in the other amp, so I'm thinking the speaker is toast.

I pulled the tube and looked at it, it doesn't look funky and the pins all looked clean, but I don't have a way to test it in another amp (my other amp I think is solid state) and I don't have a spare tube.

So....maybe just get a new speaker and hold off on the tube, or do you think maybe there's something up with the tube?

Also, to clean the tube ports, should I just compressed air products, like endust?
If the speaker sounded bad in another amp, then yes I would say it is the speaker and not worry about the tube. Given the modelling nature of the AD30VT, I doubt the speaker is "guitar-voiced" in frequency response in comparison to a FRFR speaker, which is what I guess is more like what is in your amp. I would presume all the "magic" of the AD30VT is done in the circuitry of the amp and the speaker just produces the sound as cleanly as possible- whereas a normal guitar amp uses a speaker with a drastically altered frequency response curve to shape the sound. But I do not know that for sure about your amp, I cannot find much info on the speaker.

I think you would have an easier time finding another AD30VT. They are not too expensive on the used market. If you can dig up the info on the speaker and order the same model, that would be fine too. Or maybe this could be your excuse to just get a new amp altogether...

Use only contact cleaner (CAIG Deoxit D5 is what I use) for cleaning electrical contacts. I spray just a bit on the pins of the tube, not directly into the socket.
Last edited by Will Lane at Sep 13, 2016,
#9
Thanks for all the info Will Lane. I was also curious, if I were to change the speaker, would I have to find one thats a 30 watt? Like the amp is a 30 watt amp, so would I be able to put in a 35w speaker? Or should I just try to match the factory specs?

I was curious because I found a great deal on a speaker, but it is rated for 35 watts and wasn't sure if I should go for it.
#10
The wattage rating is the most the speaker can handle, not the required wattage for that speaker. With a 30 watt amp you could run a 100 watt rated speaker with no problems, that just means it can handle a maximum of 100 watts. Same for the 35 watt one you're looking at. 30 watts will work fine. You could run a 25 watt speaker, but you would have to be careful about playing it maxed out, that would blow the speaker.

Don't bash me, I've done it, just go easy on the volume/power and it will work. I knew it so I never ran it past about 1/3 volume. Worked great, just made sure I never cranked it.

Another speaker test. Once it's out of the cabinet, gently push the cone back and forth and listen. If it sounds scratchy, it has a blown voice coil.

One thing about speakers most people don't think about. When transporting, always load it face down or face up. That way the speaker cone travels in the same direction it does when working if you hit a bump. Hit a bump with the amp or speaker cabinet standing up, the voice coil moves horizontally, and can slam against the housing. That can result in a scratched voice coil, and blown speaker. That may be why you blew a speaker, drive over a few bumpy roads with a speaker standing vertically, the voice coil can be damaged. I'm almost positive that's what blew one of our PA speakers before a gig last year. At practice it worked perfect, got to a gig 3 days later and it was blown. Only thing that happened was hauling it to the gig in a trailer, standing up. Not moved any other time, bass player kept it in place for practice at home all the time. Plug n play.

I never transport an amp or speaker cabinet standing vertically, always face down or face up. My 1967 Kustom 212 cabinet has the same Emminence speakers I installed in 1990, I've played it freakin LOUD a couple of hundred times through a 130 watt Peavey MX. Loud enough in a few cases to play clean leads with a maxed Marshall stack doing rhythm parts...Still working perfect after years of that kind of abuse. Band I was with when I used it played clubs and played loud, 130 watt amp at 7 on the volume knob, never blew a speaker. Trust me that's freakin LOUD...ear damage loud...always carried it laying down, still working perfect...
Hmmm...I wonder what this button does...
#11
Thanks for the info Paleo Pete I appreciate it!
Yeah, I havnt moved the amp lately, but I was playing it loud, maxed out last time before I noticed it sounded funky. I usually transport it upright and from now on I'll transfer all my speakers on their side to prevent damage.

I had the amp up loud because my drummer plays super loud. If I got another 30w speaker and cranked it all the way would I risk blowing the it again? Would the 35w be a better choice to give me a little bit more leeway?

I read online somewhere else just now that a lot of guys get higher wattage heads to drive their cabs....something about headroom. This doesn't make sense to be, but would that matter becuase I have a combo amp? I'm sure they arnt cracking their amps up to 11 though.
Last edited by mhillips at Sep 14, 2016,
#12
Will Lane +1

I would look for a new amp.

another thought: It would be cool if you could turn your current amp into a head, easy and quick and may come in handy down the line.
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#13
Quote by Paleo Pete
One thing about speakers most people don't think about. When transporting, always load it face down or face up. That way the speaker cone travels in the same direction it does when working if you hit a bump. Hit a bump with the amp or speaker cabinet standing up, the voice coil moves horizontally, and can slam against the housing. That can result in a scratched voice coil, and blown speaker.
How do our amp's speakers survive shipping?
Quote by mhillips
Thanks for the info Paleo PeteI had the amp up loud because my drummer plays super loud. If I got another 30w speaker and cranked it all the way would I risk blowing the it again? Would the 35w be a better choice to give me a little bit more leeway?

I read online somewhere else just now that a lot of guys get higher wattage heads to drive their cabs....something about headroom. This doesn't make sense to be, but would that matter becuase I have a combo amp? I'm sure they arnt cracking their amps up to 11 though.
Good practice is to have the speaker rated at a higher wattage than the amp can put out. So if the amp is 30w, 35w+ handling from the speaker is good. Just in case the amp's wattage rating is a bit conservative, or the speaker's rating is too generous. I would use 10w+ personally though. But many people run amps with speakers rated at the exact same wattage or in some cases even lower. But to be safe, have more wattage capable from the speaker. Also make sure you match impedance (ohms) exactly.

Higher wattage heads are used to be louder with more headroom, which headroom is (roughly) how loud the amp can be before it starts breaking up. Wattage does not exactly specify headroom or volume though, more like a suggestion. With higher wattage heads, you need higher wattage speakers to take their power.
Last edited by Will Lane at Sep 14, 2016,
#14
Thanks Will Lane!

So I tested the speaker by pushing the cone and its toast. It sounds super scratchy and crackly. I took a bass amp speaker and tried the same thing and it doesn't make a peep.

So I then put the amp back together, but I wired the bass speaker, which is a 25w, to the amp. It's a lot quieter than my old speaker and I had it at 25% volume, but it sounds way better. Like I couldn't believe how much more sustain I had.

So I need either a new speaker or a whole new amp, but I don't have the cash right now for a whole new setup. I think a nice speaker would probably save the amp. Thanks everyone for all the ideas and advice!
Last edited by mhillips at Sep 14, 2016,
#15
Just need a speaker.
As far as modelling amps go, the Vox VT series are pretty good.
Even take most pedals fairly well.
I had the same model as you and stuck an Eminence Ragin Cajun in it. Made a world of difference. YMMV.
#16
i would be tempted to look for a eminence legend. they play pretty nice with most amps.

i did have one a very long time ago that i used with a modeler (line 6 duoverb), they worked really well together.
WTLT 2014 GG&A

Quote by andersondb7
alright "king of the guitar forum"


Quote by trashedlostfdup
nope i am "GOD of the guitar forum" i think that fits me better.


Quote by andersondb7
youre just being a jerk man.



****** NEW NEW NEW!
2017-07-07 2017-07-07 Update and a Chat On Noise Constraints *** NEW FRIDAY 7/7
2017-04-13 RUN AWAY from COMPUTERS!!! TCE? RANT ALERT!!!
2017-03-02 - Guitar Philosophy 1001- Be Prepared For the Situation (Thursday 2017-03-02)
2017-02-21 How to Hot-Rod the Hell of your Stratocaster for $50! (Tuesday 2017-2-21)
Resentments and Rambling from a Guitar Junkie
---> http://trashedengineering.blogspot.com/