Metropoulos Forum

I had a customer send me a clip of his Metro-Plex making a terrible noise when he played notes on the G string of his Strat. This set me off to diagnose the issue and come up with a fix... Oh the slippery slope.

I grabbed my Nash Strat and easily recreated the harsh, white noise issue on G string notes, especially using the neck pickup in 4 or 5 position.
For the next several days I obsessed over this scrutinized every section and component of the MP circuit looking for the culprit. I couldn't make the issue happen with my signal generator, which should have been an early clue. Yet, for days I reworked, swapped parts, added filtering, changed tubes, listened to individual gain stages....you name it. No stone left un-turned.

After a solid week I started asking other respected techs if they were familiar with this and what they do to fix it. Many knew exactly what I was talking about immediately. None could offer a sure fix.

Eventually, I took the Nash and started playing through vintage amps here in the shop. ALL amps had the issue at some level. OK, so I'm not completely crazy and the MP design is not total garbage! Progress!

I'm convinced that the initial transient on open G notes has a high peak and modulates the HT voltage in tube gain stages. I also think there is a physical/mechanical noise happening on the Strat that get amplified.

One certainty here: I CAN NOT EVER UN-HEAR THIS NOW! I'm haunted by it for the rest of my time.

Watch this clip at your own risk, you have been warned. LOL I'm sure many of you have already heard this phenomenon and have likely tried to deal with it in many ways. If you have had any success I'd love to hear how.




george

isn't that just fret rattle and buzz? The G and Low E are problematic strings because of the low tension. The G string being thin and unwound causes the most grief.

AFAIK raising the action is basically all you can do. If you find that this is some kind of weird sympathetic oscillation I'll be taking notes .

It's also been my observation that my frets typically wear the most on the g string where the typical blues bends occur. Low frets in commonly used locations just exacerbates the issue.

There is a fret buzz aspect, no question. But you can also hear the white noise attached to the note, the harsh power supply sound that lasts about 50-100mS at the start of the note.

Seems the transient peak at the start of the note may be highest with single coils and notes on the unwound G string.

george

ok I know what you mean now, I gave up worrying about that ages ago. IIRC My Marshall style amp has always done it more than my old PTP Gibson. I always assumed it was some kind of reverberant oscillation inherent in guitar amps that just gets aggravated by all the usual suspects, lead dress, filtering, tired iron, worn out tubes, poor solder joints etc...

I used to think that was what people meant by ghosting.

I'll be watching this thread.

I CERTAINLY have heard that. Always that it was just peculiar to particular guitars and thought it occurred on all of mine becuase of (my) lousy setup skills.

Can we be sure it's not just what happens to fret buzz when you overdrive it?

Isn't there a dirty little trade secret or is it an old wives tail about the "G' especially on older Les Pauls not playing in tune when tuned to "correct" pitch. You have to tune it sharp or something? Something about some Les Pauls having the bridge in the wrong position? or ??

I can definitely hear it with the strat, not so much with the Les Paul. With the strat I guess there are two things working together: First, the G string has the lowest tension and - at least on a vintage 7 1/4 fretboard radius - is most of the time closest to the fretboard, unless you compensate for the radius and find the high E string note out on blues bends. Second, with vintage style pickups the magnet stagger has the highest pole under the G string to compensate for the then popular string sets with a wound G string. So I think it's a combination of the fret buzz and the attack being amplified on the G string the most.

Cheers Stephan

A few of my guitars used to do the dredded G string buzz which is getting amplified, I put the guitar on the Erlewine Neck Jig and get out the radius beams and lightly do a fret dress and the buzz is gone!

When was the last time your guitars had a good setup done?

I think that may be your culprit!

Sounds like a string rattling against a fret to me. One reason I get taller frets installed is to not have that kind of noise. I can't say I've ever heard that noise before outside of string rattle. I have heard it with the neck relief being too tight, so you might need a little more relief in those areas on the neck.

Of course low frets will need to be replaced, or leveled/dressed.

I use 9-42 strings and I think they are easier to finger behind the frets and cause more lift of the string when pressed.

Past that, I don't profess to know how to solve an amp circuit issue like this one. All I know about building amps is what I've learned from your 100 & 50w instructions, and that short time I had my single ended amps being built from 2002-2005.

I decided it was a guitar (string, fret) issue once and for all when I heard the exact same sound playing through a Pod. Oddly enough, the British model settings did it far worse than the Fender and others! AC30 was the worst of all. Something in the high emphasis in those circuits seems to really bring out the noise.

For the Metro-Plex, I went back to the drawing board. Started at the input jacks and redesigned each stage while testing and listening for this sound. Eventually, I got the tone and frequency response I was looking for while exacerbating this issue as little as possible. I was able to make the tone clean up better with the guitar volume in the process. So the agonizing over this at least resulted in a positive development.

It's always an a adventure...

george

I have been battling a string issue for years. Acoustically, I get this high pitched ping aftertone type sound, especially on the G string It never really came through the amp, very much that is. Mainly just irritating playing with out an amp. I thought it had to do with, as Chief says, my lousy set up skills. BUT, went I went to a small local shop here and played several different guitars that he had set up nearly all of them had the issue irrespective of Fender 6 hole trem, Floyd Rose, hard tail, or through body. I asked him about it. He mentioned the G string has all sorts of issues and potential issues.

So, I am glad that I am not the only one to have issue and that possibly my tech skills aren't that lousy.

this is partially why some prefer wound G strings. I think a light .015 G string ala EC & Hendrix does help (although I'm using .017 on my jazz box)

Guitars lacking a proper setup generally have this issue.
With partsocasters & frankenstrat builds that sport a licensed Floyd Rose bridge, piecing the body & neck - neck & bridge;
and in some cases, bridge to nut, can get a bit involved going through trial & error. Locking nut shims & micro shims that fit under each individual saddle to get your radius contour just right. A nice finishing touch when trying to marry everything together.
Gets a little difficult to see these phantom things, or to pinpoint where it's coming from or what's causing it exactly.
If you're using an aluminum ABR bridge type, check to see if it has flattened. This would cause the middle two strings or D & G to bottom out on the fret(s) and rattle; not following the fretboards' radius. In that case, best to put that original piece'o in the case and purchase a quality replacement of the same neck radius, that is made of steel.

Roe wrote:this is partially why some prefer wound G strings. I think a light .015 G string ala EC & Hendrix does help (although I'm using .017 on my jazz box)

I just read a whole bunch about the plain "G" being a problem and a lot of guys solved it going to a wound G. I'm gonna give that a shot. It seems to be much more prominent on Gibson scale instruments.