humm/buzz from dimmer switches, knob and tube wiring, etc.....

[Jared Purdy]

I recently bought a Swart AST master, and when I plugged my LP Traditional into it I was getting a bit of buzz/humm in the neck and bridge pisition, but nothing in the middle position. I also have a Strat Deluxe, which has noisless pickups, and when I plug that guitar into the Swart, I get no buzz or humm at all.

In the pursuit of the cause of tis problem, I took the amp and the guitar to the store where I bought the guitar (Steve's Music). It is large, in an old building with a very high ceiling, and lots of florescent lights - but, all rewired. It was dead quiet there. The manager of the store, who checked the guitar, said that the humbuckers in the neck and bridge position would not cancel out the bad frequencies coming from knob and tube wiring, poor or weak grounding, or dimmer switches, but it would in the middle position as it is working off both PUs. A tech at a guitar and amp repair shop (Superfuzz Audio) said the same thing. Is tis correct? At another store very close to where I live (The Twelfth Fret) every guitar and tube amp in the store buzzes as a result of what the staff say is bad wiring (all knob and tube) and the subway that runs under the store.

In the pursuit of this issue, I took my amp and LP to my neighbours, where every room is wired with dimmer switches, and it was even worse there! The funny thing is, the LP does not buzz/humm when plugged into my 75 Fender SFPR.

Any feedback guys?

[Chuck H]

The funny thing is, the LP does not buzz/humm when plugged into my 75 Fender SFPR.

Is this with the overall gain of the SFPR the same as the Swart??? With both amps set up as tested, unplug the guitar. Does the Swart still pickup some noise by itself? Humbuckers aren't 100% efficient at cancelling hum. The more assymetrical your coils are, the more hum you'll have. So it makes some sense that your LP middle position bucks more since you have more variations in coil symmetry and inverse phase happening at the same time. As far as humbuckers not being able to block noise from knob and tube wiring, that's just hogwash. EMF is EMF and the noise is still opposed in each coil. But it is true that where there's more noise you'll get more noise. If your humbuckers can block 80% of the noise you'll still hear 20% of the noise proportionate to the EMF in any environment.

[Jared Purdy]

The Swart is totally silent when nothing is plugged into it. And actually, when nothing is plugged into the SFPR it does make some noise! And that is why I took it in for servicing yesterday as it has never been looked at in 36 years!

When the Swart is dimmed, all you hear is speaker hiss. Dead silent when the Deluxe Strat is plugged in, in all PU positions.

So are 57 PAFs more assymetrical than the Burst Buckers that are found on the Standard? Thanks.

[Chuck H]

That's a question for the guys at the pickup forum. There's still the issue of gain. If your using a higher gain setting on the Swart there will be more amplified noise too.

[GregS]

I just put Gibson 57 Classic humbuckers in an Epiphone SG and I don't have any noise issue at all, nor do I have a noise issue with Gibson Les Paul Standard which probably has very similar pickups in it.

Like Chuck says the difference in noise between the Fender and the Swart could simply be that you have pre-amp gain turned up in the Swart. I'm not familiar with that amp so I don't know if it's a high gain pre-amp type or not.

Most amps are not totally quiet in all situations at all settings. You don't know what noise is until you've heard my un-shielded Fender Jazz bass plugged into my Yorkville B200 bass amp at the rehearsal place! Your issues would probably seem like nothing at all after hearing that! It does improve though when playing out where it's not in such close proximity to a lot of other equipment.

[Jared Purdy]

Hmmmm. I have called Gibson to talk about this but have not had a reply, yet. I'll have to ask Michael Swart if it is a high gain pre-amp. It's sort of a two channel amp. It has a hard by-passable MV so as to allow you to play clean. So what you are saying is that if it is a high gain pre amp type amp, it will make more noise? That does not answer the question though as to why there was NO humm or buzz in the music store that I took it and my LP to, but it humms/buzzes in my house (and my neighbour's).

Someone suggested that I get a power conditioner. What is that?

[Chuck H]

Try this... Turn off the master on the Swart. Now turn it up until it just starts to break up. Now do the same with your PR. Is the Swart still noisier?

[GregS]

[QUOTE]So what you are saying is that if it is a high gain pre amp type amp, it will make more noise?/QUOTE]

It depends on how high you have the pre-amp gain turned up. The higher it's turned up the more noise you'll get. If your amp has 2 channels I'm guessing one is for normal/clean and the other is for lead. The lead channel (if this is what you have) will have a level control allowing you to overload following pre-amp stages to generate distortion in the pre-amp. The MV sets the level fed to the power amp. I was wondering if you had your amp on the lead channel when trying it out in these different places and that this pre-amp level control that I mentioned might have been set differently each time.

[Jared Purdy]

Thanks Greg, it hums in the normal and the MV channel . I used the words "sort of" as on the web site, Michael does not describe it as a two channel amp, and in all of the conversations that I have had with with him, those words have never come up, though in theory, it seems like it is. I'm going to buy an ART CleanBox II (made by Yorkville) tonite and see if that works. Someone I spoke with that does not carry that product doesn't think it will work. He thinks it's either an internal or external wiring issue, nothing related to knob and tube, but maybe to my neighbour's house full of dimmer switches, and something outside.

[Chuck H]

it's most certainly EMF. A power conditioner won't change anything. So at least save your $$$ on that.

[Jared Purdy]

You're right. It didn't work. Oh well, they offer a full refund, so back it goes tomorrow.

[big_teee]

I followed this from the pickup forum.
I think you guys here in amplification are right on.
Here's the deal.
I don't know how DIY you are, but if it were mine here's what I would do, I have done this several times before.
I would carefully unsolder the leads from the Jack. Both output and ground.
I would unsolder one pickup from the POT.
Probably the Bridge if the wiring is long enough to reach the jack.
I would wire that Pickup direct to the Jack.
I would connect Bridge String Ground to the Jack Sleeve.
I would control the volume with the amp and test.
If you still have this noise, your probably wasting your time trying anything else.
If its Quiet, then you have a starting place for isolating the noise.
If it is still noisey you might try the neck pickup the same way.
If both pickups are noisey, you might try to come up with another pickup to test the same way.
A lot of trouble, but sometimes you have to isolate and start elementary!
Hope this helps.
Terry

[Steve Conner]

If the guitar doesn't hum with the pickup switch in the middle position, that says to me the hum is magnetic, caused by imperfect humbucking in the asymmetrical pickups, and no amount of messing with shielding etc. will help. Only changing the pickups out for a more modern design with symmetrical coils.

I changed the pickups in my guitar for Duncan Alnico 2 Pros, and they don't really buck hum that well either compared to the old ones. Except in the middle position, which is hum-free. I gladly put up with it though, as they sound about 10x better, but I can see how someone who was picky about hum might be annoyed.

[Jared Purdy]

Hey Steve, I hear what you are saying, except, when I took the amp and the guitar to a local music store and plugged in, it didn't hum at all!! BTW, I took the back plate off last night, there is no shielding in it.

[Steve Conner]

Well, music stores tend to be large rooms, where you can stand out away from equipment and wiring. Plus, if I were a manager of a music store, and there was a problem in the building that made all the guitars buzz on the shop floor, I'd get it fixed.

Also, the hum pickup pattern can be directional. You can often find an angle you can stand relative to the source, where the hum disappears. Maybe you got lucky in the music store. You can use the guitar to track down the source of hum.