Amplifier Buzz

Factual Questions
1

I’m soliciting opinions from musicians, electricians and anybody else with an opinion.

Here’s the situation. I have a 50 watt Marshall Amp. I bought it new about a year ago. I also have a First Class Delia guitar that I bought used about 6 months ago. The only other equipment I use is the foot-pedal that came with the amp (to switch between clean and buit-in effects). I usually play with the gain up to about a third, and enough volume to be heard – just crunchy enough.

The problem is a nasty buzz that occasionally shows up, almost at random. And sometimes goes away at random as well.

The first time it happened, I was at my band’s studio and the amp was on, the guitar plugged in, but at the time we were taking a break, so the volume on the guitar was down. Out of nowhere … bzzzzzzzzzz. We futzed around with all the settings and did some control experiments – swapping out cords, plugging it into different outlets, swapping out guitars – no luck.

That night I took both the amp and the guitar home. I plugged it in in my living room and could not recreate the buzz. I couldn’t play it at volume in my condo, but I could put all the settings the same as in the studio. I even let it sit there for an hour, amp on, guitar volume down, still no buzz. So I decided against bringing it into the shop for them to fix something that I couldn’t prove was broken.

Since then, I’ve been playing it in the studio again and every so often it comes back. And every so often it goes away.

Key points. It sounds like some sort of ground buzz. When I touch the strings the buzz lessens, but not so much that it doesn’t still sound like shit.

The studio – it was built by the boys in the band and crew, most of whom are carpenters by trade. It’s in the back of our bass player’s garage/barn and I’m not sure what all the specs are behind how it’s wired.
The only thing I can think of, though, is that it has to be the wiring. I’ve guessed that someone turned on the TeeVee in the house or something and this is causing the interference. Most of the guys (who know a lot more about electricity than I do) have shot me down on that guess and insist it must be something with my equipment.

I’m lost. I love my amp and I love my guitar. I don’t want them to be defective (and I don’t think they are).

Anybody got any ideas?

2

IANAElectronics guy, so not much help beyond saying Yeah, it is probably something you can hunt down and kill.

  • is thisyour guitar? if so, it has humbuckers; otherwise, if it had single coil pickups your probably might be standard RF hum

  • shielding your guitar - First Acts aren’t high-end; one of the first compromises on a lower-priced guitar is less shielding and lower-quality components. Have your guitar checked by a tech for ground/shielding issues and considering getting it improved. Google guitar shielding - lots of online stuff…

  • Your amp may not be grounded in some way relative to the studio…

3

I sometimes get a buzz or whine with beats (rapid and intermittent) if I have my iPhone on near my setup, especially if it’s in my breast pocket. When I switch it off (not power-off) and put it in my front pants pocket it usually goes away. I think it’ll happen with any cell phone.

4

If it only happens in the studio, I suspect that there is a problem with the safety ground in the studio wiring. Remember that when you touch the strings your hands are electrically connected to the building safety ground. If it is screwed up, the worst that can happen is you can die a horribly painful death. In other words, this is quite possibly a VERY BIG DEAL.

It is also possible that someone is running something nearby (like a fluorescent light or a blender or who knows what, might even be the TV that you were guessing) that is causing a lot of electrical noise, which is getting either picked up by the amplifier through the air, or it is coming in through the amplifier’s electrical power connection. Generally, a power transformer will feed 2 or 3 houses, so the interference may even be coming from your neighbor.

It could also be a bad connection of some sort inside your amp, that only goes wonky when it gets too hot. You would never notice it if you play at low volume.

Considering that guys in the band with some carpentry skills probably don’t know a whole lot about grounding, I’m guessing that the bad ground is the most likely. This can kill people, burn down the barn, etc. so it is something that definitely needs to be evaluated by a competent electrician.

(I’m an electrical engineer with over 20 years of experience by the way)

5

That is indeed like my guitar. I think I wrote “First Class”, but I meant “First Act.” I think mine is a slightly different model. Mine is blue/wood grain with different inlays, but yes, it does have two meaty humbuckers.

I think I sold the studio constructors a little short. The main builders were my brother-in-law/drummer and Steve the bass player, who build luxury homes from the ground up, so they know what they are doing. On the other hand, this studio was built about a decade ago, so I don’t put it past them to have put in some funky wiring here and there.

I really don’t think it’s the guitar, but I take note of the advice and I’ll probably bring it into my local shop to get a once over. It just really sucks, because when the buzz isn’t there, that amp sounds like Heaven cumming over Eden while giving Nirvana a hand-job. With the buzz it even makes my punk-at-heart sensibilities want to smash things all over the place.

6

I would supect a grounding problem. Either in the building or your equipment.

When you are getting the buzz are your amp and guitar plugged into the same out let?

7

The number one suspect in these cases is ground loops.
Make sure that your guitar is grounded to the Amp in one, and only one place, and that all the other equipment is grounded is a similar fashion. Make sure all electronics are plugged into the same outlet.

8

beowulff’s advice is very good. You should try that first.

In my home studio, the 60 cycle hum was caused by the TV cable box plugged into the same power supply as the mixer. The solution was this. If you have a TV cable box in the studio completely unhook it and see if it helps. It can cause a hum even if it’s not on.

9

Aha. You maybe onto something. We do indeed have a TeeVee complete with cable box up in the corner of the room … for Red Sox games (we provide soundtrack for need rallies) and the occasional porn.

What? Steve got and introductory offer on the Playboy channel. It’s purely a feduciary decision on his part.

10

Even the most highly skilled professional electricians are usually unfamiliar with the special requirements of studio wiring. In my experience, if you wire a studio exactly the same as a home, you will have grounding problems.

A studio needs a grounding system much like that used in a hospital. This means:

[ul]
[li]One grounding point for the entire system[/li][li]Isolated neutrals and grounds[/li][li]“Hospital” outlets with isolated grounds[/li][/ul]
I’ve wired two recording studios, a radio station and uncountable performance venues, and isolated grounds are the only way I’ve found to totally eliminate ground loops.

In addition, you need to ensure that all the sound generating and processing equipment is on the same phase. That means, if the power coming into the building is something like a single 100 amp, 220 volt breaker panel, all the sound must be on either the even or odd numbered breakers. In a panel, the breaker locations alternate from one side of the 220 to the other, so a dual breaker can can cover both 110 phases and deliver 220 volts.

11

I’m an amateur electronics guy and a former amateur musician (I gave away all the electrical stuff, and only kept a Fender acoustic guitar). If the sound is a “hum”, then I would say “ground loop” is most likely, but if it’s a “buzz” as you described, I would go looking for loose screws in the amp, or maybe tears in the speaker. Hums are sine waves, like a ground loop, or a power supply filter capacitor going bad or developing a loose connection. Buzzes are square, triangle, or sawtooth waves, like a loose part acting as a “positive feedback”. All are sometimes used intentionally in electronic music, by using mechanical or electronic circuits to reproduce the effect, but if it’s accidental, then “hum” or “buzz” is the best way for me to track it down. But I’d have to hear it. If you live near me, I’d be happy to go take a listen and look (for a price, of course, since I make most of my money these days as a “handyman”). Otherwise, that’s all I can say in a text-only forum. Although I can think of things that can go wrong that are much more expensive (as in cheaper to replace the bad equipment) to fix, though not actually dangerous.

ETA: What gaffa said about grounding. I was an unpaid roadie (unless you count the free beer) for a couple of bar-bands and DJs, and the grounding was always an issue. If it’s actually a “hum” rather than “buzz”, look for grounding problems.

12

Is that what kids are calling it these days?

13

Just in case anyone (besides me) is interested …

… regularly scheduled band practice / jam night was on Tuesday.

No buzz whatsoever. Go figure.

14

I just came in to say that I had no idea First Act made instruments beyond the “my first guitar” lines I see in the toy stores - I’d always dismissed them as a budget also-ran brand.

After checking their site and seeing some of the instruments (and prices) I’m quite surprised - they seem like quality axes.

15

I knew nothing about them when I got it. I saw it in my local music store, in the used rack. It was affordable, and it played like a dream so … merry christmas to me.