Too many highs after shielding

[stratblueser]

Hi,

after shielding my strat with copper paint the noise was gone but there were too many highs present in the sound. After removing the paint from the pickup cavities (it's still in the cavity housing the electronics and on the back of the pickguard), the sound is as it should be again. How could this happen? Did I use too much of the paint?
When shielding the pickup cavities with copper foil will I have the same probs again? I've shielded 4 guitars with copperfoil before and never had a problem.....

Cheers,
Christian

[ccoleman]

could you post some mp3's of the sound ?

[stratblueser]

I've removed the copper paint from the pickup-cavities, so I can't record a mp3 with the trebbly sound any more....

[png123]

How did you shield with copper foil?
What adhesive did you use?

[stratblueser]

I've shielded this guitar with copper paint not with foil.

The other guitars have been shielded with adhesive copper foil by DiMarzio.

Christian

[png123]

Well the QBT Mod uses Copper Self Adhesive Tape but it should have same effect i think

[ccoleman]

I am not sure about what I am about to say, but I think that it is possible that the QTB mod could naturally bring out more harmonics, they were perhaps previously missing due to magnetic and electric field interference that is now blocked after the QTB mod.

But it ALSO sounds like MAYBE the addition of the shielding, which is really a low resistance ground plane faraday cage, this new shielding may have altered the shape of the magnetic field emenating from the pickups.

Hard to say without an A/B comparison mp3 and some pics.

[stratblueser]

Hello ccoleman,

I've had a Telecaster which sounded way better after shielding with copper foil, so I know how an improvement should sound.

But after the QTB mod on this guitar the other bandmates complained about the icepicky highs that were not present before. I'm sure, the shielding had an effect on the magnetic field. The question is now, if I should remove the rest of the shielding in the electronic's cavity and spend some money on copper-foil or if this is wasted time and money when the result is the same again.....

Cheers,
Christian

[ChrisK]

but there were too many highs present

What adhesive did you use?

;D

But after the QTB mod on this guitar the other bandmates complained about the icepicky highs that were not present before.

???Tone Control working

[stratblueser]

No, the highs were too aggressive to tame them with the tone-controls, warms were missing too....

The copper paint was Kontakt Chemie EMV, I could not find any Datasheet in english for this one in the net...

[JohnH]

This problem I have not heard of before. I cant think of any reason why conductive paint shielding would change the tone in a way that foil would not. I have also not heard before, of shielding in general, changing the tone significantly at all.

So one theory could be that something else was happening - maybe some splash of paint was partly connecting to the pickup circuit? With paint, it is not as conductive as foil, so little short circuits between shielding and signal could make just a change in tone or volume, whereas with a similar issue with foil, it would more likely short out totally. Hence the issue would be more subtle and harder to trace.

Paint shielding works fine, i have it on one of mine.

Now here's a different and more tenuous hypothesis, based on your symptoms:
The shielding around the pups, while not in contact with them, is close to them and forms a capacitor between the pup coils and ground. A capacitor is essentially just two conductive surfaces separated by a small gap. Check out Channelman's 'boost without active electronics' thread, to see how adding small caps, in combination with the pickup circuitry, can lead to a peak in high treble. Maybe that is what is happening here? - the capacitance from pups to shielding is in the right place electrically to cause this effect. I would not have expected this to be significant normally however. If this was the case, foil would also cause it.

In the interest of science, before you try shielding again, how about making that MP3 sample, with carefully recorded settings of your gear, so that you can make a comparison after wards?

cheers

John

[stratblueser]

Hello John,

this is what a luthier told me a couple of hours ago. He said, that he suspects that the pup's cavities are not deep enough with this guitar and so the shielding is too near to the pickups.

Anyway, I will leave it as it is now. Shielding the electronic's cavity and the back of the pickguard is better than nothing and the difference to a completely shielded guitar when the strings are touched is not so big.....

Cheers,
Christian

[JohnH]

OK - well that more evidence that my second thought might be correct. with shielding too close to the pups, the capacitance would increase.

J