Screening an ES335

jaymenon

Actually a Yamaha SA2200.

I really don't like the high frequency inductive buzz you get when you take your hands off of the strings / metal parts.

On a Strat or a Les Paul its easy: apply foil / graphite paint to the cavities / rear of the pickguard and create a conductive 'Faraday Cage' around the electrics, then no more buzz (it of course has no effect whatsoever on 50Hz hum, which is a totally different thing).

But how do you screen an ES335?

And if you have 4 conductor wiring and push-pull pots for series/parallel switching - with those 4 little wires floating around, does that make it even more difficult?

jaymenon

I’m slowly getting somewhere…

I figured all I need is to connect the ground to some part of my body. So as an experiment, I used a Jack-Jack extension coupler to use two guitar leads in series from my guitar to the amp.

30cm Jack lead - coupler - 2m Jack lead to amp

If I lay the coupler on my bare skin, voila...! Nicely screened, no inductive buzz (pic below)

https://i.imgur.com/j7SE46P.jpg

I could use one of these devices, but there is nowhere on a 335 to safely attach it without scratching. It would work beautifully on a Stratocaster or telecaster though...

https://i.imgur.com/SlA5uf4.jpg

jaymenon

For the ultimate in shielding I could wear one of these, but it would probably scratch the instrument…

https://i.imgur.com/TIH9cHP.jpg

Winny_Pooh

A 335 with braided metal sleeve wiring is already screened, as are the humbuckers, sitting in a fully metal case. Fenders need screening because they use fiber pickup bases, single coils and cloth covered wire. If things are quiet when you touch the strings that is correct as the human body is a big antenna for noise and passes it onto the guitar. In effect you are grounding yourself when you touch the strings. 

ICBM

Winny_Pooh said:

A 335 with braided metal sleeve wiring is already screened, as are the humbuckers, sitting in a fully metal case. Fenders need screening because they use fiber pickup bases, single coils and cloth covered wire. If things are quiet when you touch the strings that is correct as the human body is a big antenna for noise and passes it onto the guitar. In effect you are grounding yourself when you touch the strings. 

The problem in 335s is that the control wiring isn't shielded - and it's especially bad in this Yamaha because it has coil-splits with push-pull pots and associated bare wiring.

In the 60s and 70s Gibson used to put metal shielding cans on the pots, with all the unshielded wiring and the tone caps inside, but they're a massive pain if you ever need to work on the wiring. The Gibson-size ones wouldn't fit switched pots either.

Worse, I've also seen some guitars which have splittable humbuckers where the split wire is an extra, unshielded wire *outside* the braided cable to the pickup - I don't think it's Yamaha though.

Proper shielding isn't rocket science - it's a bit surprising that guitar companies still can't get it right after 70 years...

It would probably be possible to spray shielding paint into the cavity, but it's a big job as it would need the whole wiring loom taking out and the front of the guitar masking to stop any accidental leakage - the sort of thing that's easier done when the guitar is made than afterwards.

jaymenon

https://i.imgur.com/D0zfkRn.jpg

That’s sloppy wiring, I have a feeling somebody has rewired this...

Jimbro66

jaymenon said:

https://i.imgur.com/D0zfkRn.jpg

That’s sloppy wiring, I have a feeling somebody has rewired this...

That’s exactly what I thought when I saw the photo in your second post.

The harness I took out of my ‘82 Gibson 335 was all screened cable and none of the unscreened connections of cloth-covered core were longer than 15mm, most were shorter. The only longer unscreened ‘wires’ were the legs of the two ceramic tone caps.

The replacement harness was made similarly but with better components so there were no unscreened cables to cause any noise.

If your push/pull pots were wired competently the small extra unshielded connections shouldn’t be an issue but it looks like you have some fairly long unshielded wires in there.

BTW, seeing how some of the other wiring looks, have you checked that the bridge is properly grounded?

Funkfingers

ICBM said: 

splittable humbuckers where the split wire is an extra, unshielded wire *outside* the braided cable to the pickup - I don't think it's Yamaha though.

PRS McCarty humbuckers are like that. The intention is that the split is always made to leave the “outside” screw coils operational.

Obviously, in a circuit with partial/“tuned” coil splittage - as often now practiced by PRS themselves - this method is probably introducing some noise unnecessarily. 

jaymenon

So how would I solder the series connection (the middle two wires on the humbucker), whilst simultaneously ensuring that the 'wires/joint complex' is screened please?

Like in this Seymour Duncan diagram below, 'solder the red and white wires'. They're still unscreened right? Okay in a well screened Les Paul, not so much in a 335...

And so even in full humbucker mode, the signal is passing through the series connection, and is prone to picking up 'interference'? 

Anything I can do besides keeping the wires as short as possible?

Or is a braided two conductor wire fundamentally superior?

[Imgur](https://i.imgur.com/m9sKqJR.jpg)

Jimbro66

The diagram you show refers to push/pull pots but doesn't show any in the circuit! The SD circuit diagram for series/parallel using push/pull pots would be this one:


For clarity they are not showing all the screening but, for example, the wires from the pickups would be screened right up to as close as possible to the p/p switch connections. Likewise, the wires from the pots to the sector switch and from that switch to the output jack would all be screened. It's all about good harness design whereas the SD diagrams are simplified. If those wires were not screened you would pick up a lot of noise and, as you have found, screening any sort of hollow body electric is more than a challenge so that is why screened cables are a must.

Edit: I have not checked that SD diagram and, as @Funkfingers has sometimes mentioned, they are not always accurate!

jaymenon

Thanks Jimbro66...

Looking at the diagram doesn't the screening for the pickup cable stop where the black bit ends?

After that aren't they merely bare red, black, white and green wires with insulation but not screening?

Jimbro66

jaymenon said:

Thanks Jimbro66...

Looking at the diagram doesn't the screening for the pickup cable stop where the black bit ends?

After that aren't they merely bare red, black, white and green wires with insulation but not screening?

No. As I said, the SD diagrams are simplified for clarity and do not show the extent of screened cables. As you said in an earlier post, the control cavity of a Les Paul for example can be screened with tape or paint but in a hollow or semi-solid guitar all wiring should be screened right up to the final connections, i.e. probably no more that 10-15mm of unscreened wire showing.

I’m posting from mobile at present but when I am back at the pc I’ll post a photo of the RS Guitarworks harness that’s in my 335 so you can see how thoroughly it is screened.

jaymenon

I'm not sure I'm understanding this...

Till now, I've been under the impression that for a wire to be screened, it needs to be 'coaxial' (i.e. enclosed within a conductive screen, which is connected to ground)

Since none of the four coloured wires any longer have that screen (beyond the point marked by the arrows in the pic below) I would imagine that they are not screened...? 

Happy to be corrected...

[Imgur](https://i.imgur.com/PgOYhss.jpg)

Jimbro66

You are understanding correctly. What is confusing you is that the unscreened wires are shown much longer in that drawing than they would actually be.

In the morning I'll post a screened harness photo so that you can see that the unscreened wires are so short as not to contribute any significant noise. If SD drew them that short it might be difficult to see which wires are connected to what.

ICBM

As Jimbro66 said - make the bare wires as short as possible. You should be able to connect the shield to the tab on the end of the pull-switch casing and leave only 5-10mm of bare wire to the switch terminals if you’re really neat. The connections to the other pots and switch should also be shielded cable and not the bare wires shown.

Funkfingers said:

PRS McCarty humbuckers are like that. The intention is that the split is always made to leave the “outside” screw coils operational.

Obviously, in a circuit with partial/“tuned” coil splittage - as often now practiced by PRS themselves - this method is probably introducing some noise unnecessarily. 

I thought it was PRS. It’s a really stupid way to do it and certainly introduces at lot of noise - the split wire is basically an aerial connected to the coil junction.

They also used about 8” of plain wire between the controls in my Hollowbody - it buzzed like a wasps nest until I redid it properly with shielded cable...

Jimbro66

OK @jaymenon, here is a photo of the harness I installed in my Gibson ES-335:

Hopefully you can now see what I was trying to explain, that all wiring is screened and where the inner cores are unscreened at the soldered connections their length is kept to the absolute minimum -  probably 10mm or less. The same would be true if the guitar had push/pull switches integral with the pots. That length of unscreened wire is too short to introduce any noticeable noise. In fact, despite the hookup wires of the two capacitors being unscreened (I saw your other thread) my 335 is quiet even at high levels of amplification, regardless of whether I am touching the strings or not! At those volume levels feedback becomes the greater issue.

When I saw the photo in your second post I immediately noticed that you have unscreened wires crossing the f-hole which shouldn't happen if the harness has been properly constructed. I have no idea what their purpose is but the Yamaha guitars I've worked on in the past have been fairly tidily wired so, like you, I wonder whether someone has been fiddling with yours? I certainly wouldn't expect the issues you are having in a guitar of that quality.

BTW you probably already know this but beware of dimmer switches. They introduce a lot of noise in unscreened guitar circuits. Our dining room has one and is immediately below the spare room I practice in so well screened guitars are essential.

ICBM

Also notice that in that loom, the caps are installed with the outer foil at the ground end. It makes less difference when they're between the pots since when the tone pots are turned up there is a resistance between the outer foil and ground, but it's still better that way than having it at the signal end.

Jimbro66

Just coincidentally a SA2200 has been posted for sale here

https://www.thefretboard.co.uk/discussion/186419/yamaha-sa2200-violin-burst-in-excellent-conditon-with-hiscox-pro-ii-gs-case-1000#latest

No wires visible in the f-hole.

ICBM

Jimbro66 said:

Just coincidentally a SA2200 has been posted for sale here

No wires visible in the f-hole.

There aren't in the one in Strung Out Guitars either.

I'm very sure jaymenon's one has been messed about with, but I'm not totally certain it's the cause (or the only cause) of the buzz.

Jimbro66

ICBM said:

Jimbro66 said:

Just coincidentally a SA2200 has been posted for sale here

No wires visible in the f-hole.

There aren't in the one in Strung Out Guitars either.

I'm very sure jaymenon's one has been messed about with, but I'm not totally certain it's the cause (or the only cause) of the buzz.

Interesting ICBM.

Another thing I've noted is that @jaymenon refers to series/parallel switching with push/pull pots whereas Yamaha says the guitar has coil taps via push/push tone pots. A change in specification perhaps? Or did someone rewire the guitar?

jaymenon

Please don’t quote me on that. I have no idea what the exact mechanism is. I know that it involves a single coil simulation...

But they are very much push-pull pots (not push-push, which I much prefer)