Help with noise, Vox AC30CC1

[tulk1]

My Vox AC30CC1 is probably my favorite amp. Everything! sounds good thru it. It's just too heavy to lug around. It's become my bedroom amp. Lately it's been buzzing. Like a line noise gone crazy. I've tried moving where it's plugged in; adding one of my gigging conditioners; plugging directly into the wall; using a UPS; changing to another room; changing the power cord; changing guitars plugged in; probably more. The noise comes on, then disappears as quickly as it comes on. Can't use it to record, since I never know when the noise will come back. 

I've made a recording of the noise. Uh .... didn't even think about the TV being on. So, there's commercials and The Chase going on in the vid. But you can hear the noise, and how quickly it just stops. And, if I unplug the cable from the input it goes away, as well. Just thought I'd toss this in here, just in case our local amp gurus might chime in before I take in for repair. It's just my bedroom amp, but it's got to work. Ya know?

 

[mars_hall]

Tell us about the TV (vintage and proximity).  Does it change with the brightness of the screen content?  Is it there with the guitar unplugged?

Kinda boils down to whether the noise is coming through the wall connection or being radiated through the air by a nearby appliance (tv/monitor/PC/LED on the clock radio)

[tulk1]

Shot the vid in the living room, 4 feet from the flat screen. Amp normally resides in a bedroom.  10 feet from the computer and router. Amp does it in both rooms. Are you suggesting its tech interference?  It's going to be nice today. Maybe I should take it outside, away from the wireless, etc, see if it still does it?

[mars_hall]

I have an amp near my desk/TV that will generate more noise when the screen brightness changes or during loads of certain webpages.  This would be radiated through the air.  LEDs make a lot of noise on appliances, dependent on the technology used.

If a heat pump or fridge or water pump cycle kicks in, probably through the wall and you may be on a shared circuit of one of these.

Narrow it down to radiated or the wall.

[Spectrum13]

Tried swapping tubes?

[Gitfiddler]

50 minutes ago, Spectrum13 said:

Tried swapping tubes?

That was my first thought also.  Tap your tubes with a pencil or chopstick and listen for any noise.

[tulk1]

Swapped pre's. No spare EL84s in the house to try. Thought i had a duet but haven't found them yet. May have to hit the dreaded GC.

[pressure]

I have also had this problem. It led to a bad intermittent tube. Very hard to track down. I also had an expensive cable (Klotz) with a break adding to the noise.

[tulk1]

Well, I've about exhausted my patience and what little knowledge I have about tubes and amps. Found my quartet of EL84s. Did the one-at-a-time swappers. Each time it seemed like that would be the one and ......... then .......... argh!! I've swapped cables again. Think I already mentioned doing that. And the other amp sitting right next to it doesn't buzz a peep. Guess the next stop is the repair guy. Dang it!

[rockabilly69]

Did you float the ground to see if that had any effect? (3 prong to 2 prong). And did you unplug the TV, computers, and router, and try the same test? In my opinion that is not a microphonic tube issue, it's sounds like something coming up the ground, or a faulty cable (power or guitar cord).

[Spectrum13]

12ax7 and the ef86 would be more pron than power tubes me thinks...

[tulk1]

12 hours ago, Spectrum13 said:

12ax7 and the ef86 would be more pron than power tubes me thinks...

Pretty sure it's the Top Boost channel. However, in the Bogner designed (think it was Bogner) ACXXCC line they didn't use an EF86.  Still gets that Vox self-induced OD, tho'. It's magic! Well, it was until it went south. 

15 hours ago, rockabilly69 said:

Did you float the ground to see if that had any effect? (3 prong to 2 prong). And did you unplug the TV, computers, and router, and try the same test? In my opinion that is not a microphonic tube issue, it's sounds like something coming up the ground, or a faulty cable (power or guitar cord).

I can't find 2 prong adapters (sensing a pattern here). If I find them today I'll try that. 

[tulk1]

Interesting development. The tech (a guy I trust) called and told me it was the blah blah blah some tech stuff I completely don't understand. $200 to fix, including time, parts, material, it being a VOX and his arms hurting from trying to lift it. 

Or ... he'd buy it from me for $450 because he's always wanted one. And fix it in his own time.

What would you do? 

[Steiner]

That's a small price to retain the sound you admitted you enjoyed. 

[Spectrum13]

1 hour ago, Steiner said:

That's a small price to retain the sound you admitted you enjoyed. 

That or $650 towards another Vox voiced amp or anything else you may have your ears on.

[JeffB]

1 hour ago, Steiner said:

That's a small price to retain the sound you admitted you enjoyed. 

 

9 minutes ago, Spectrum13 said:

That or $650 towards another Vox voiced amp or anything else you may have your ears on.

Both these options seem good.

 

I tend to keep and repair stuff I really like but have been rewarded by "letting go" and trying different stuff.....having said that, I dont have much of the different stuff anymore and still have my old stuff that I cant let go of.

 

[rockabilly69]

$200 is worth it if you get the amp back to where you liked it, $650 ain't buying nothing that sounds as good as an AC30. I wish you could relay what he actually said so I can tell if the repair is a $200 job.

[tulk1]

Well, I'm leaning towards selling. I really like Vox, but kinda like Fender, too. Thinking a PRRI, or DRRI. Something I can actually lift and carry without popping an arm out it's joint. Not that this is my gigging amp. But lordy, it weighs a ton. Thinking of moving the old Lone Star 1x12 now, too. Same thing ... just too darned heavy! When other amps sound as good. Thinking ..... 

[rockabilly69]

21 hours ago, tulk1 said:

Well, I'm leaning towards selling. I really like Vox, but kinda like Fender, too. Thinking a PRRI, or DRRI. Something I can actually lift and carry without popping an arm out it's joint. Not that this is my gigging amp. But lordy, it weighs a ton. Thinking of moving the old Lone Star 1x12 now, too. Same thing ... just too darned heavy! When other amps sound as good. Thinking ..... 

I know about the weight thing, my AC15 weighs a TON for the low wattage amp that it is.

[ElNumero]

Is this a reissue AC30?

[ElNumero]

23 hours ago, tulk1 said:

Well, I'm leaning towards selling. I really like Vox, but kinda like Fender, too. Thinking a PRRI, or DRRI. Something I can actually lift and carry without popping an arm out it's joint. Not that this is my gigging amp. But lordy, it weighs a ton. Thinking of moving the old Lone Star 1x12 now, too. Same thing ... just too darned heavy! When other amps sound as good. Thinking ..... 

My PV Delta Blues has the same tube layout, and for a far less price. It sounds very similar to an AC30

[Kuz]

2 hours ago, ElNumero said:

Is this a reissue AC30?

No, it's an original vintage 1963 Vox AC30 that he is contemplating selling for $450...... 

[tbonesullivan]

I'd say get it fixed. If it's a common problem, chances are if you get another one, it might have the same thing happen. You like the sound, so keep it.

[silverbeard]

I just ran across this post and thought I would put my two cents in.  Have you checked to see if there are any lap top battery chargers plugged in to a laptop in your home.  I had an incident where a cheap charger made the same type of noise in my amps.  The noise would start and stop depending on the state of charge of the laptop battery.  I finally found the trouble and replaced the charger.  

The other thought I had is to tighten all the tube socket mounting hardware and any terminal strip mounting hardware.  There might be corrosion between the chassis and the parts.   This might cause the buzz sound.

For what it's worth!  

[TalismanRich]

There's only one thing to do with a recalcitrant Vox amp!