Preamp Picking Up Am Radio Signals

[mikevirok]

Hey all; it's been a while since I've stopped by this forum. I've been really busy with my repairs business and haven't had much time for recreational luthierie in a while. But I'm back!!!

Here's my dilemma. I recently purchased an Artec VR2 on-board guitar preamp (it's a variable boost that's not over-the-top). Well, before I install it into a custom build that I'm about to begin, I built a small project box to test it out...

When I engage the boost (no guitar hooked up to the cable leading in) and turn the boost up, I begin to hear it pickup AM radio transmissions (think Spinal Tap folks, it's the same issue)... I need to make this stop before I begin the routing job for its installation. If I can't make it act only as a boost and not pickup the radio frequencies, then I can't use it for this project.

Now I currently suspect the cause for this is a lack of shielding from outside frequencies. It's mounted in an old Seymour Duncan pickup box for testing purposes only. So, could a good copper-foil shield keep out the frequencies?

Virok

[Ripthorn]

Any grounded shielding will work. Just make sure that it is shielded on all sides and connected to signal ground and you won't have a problem.

[mikevirok]

Any grounded shielding will work. Just make sure that it is shielded on all sides and connected to signal ground and you won't have a problem.

I figured as much. Thanks buddy!

[Tim37]

idk what will help, i have had a few things pickup radio. 1 amp (when the gain is all the way up luckly i tend to not turn the gain all the way up) a wah pedal and a OD pedal. IDk what it is its all ways the same station ( a conservitive talk radio station.)

[Samba Pa Ti]

ive heard of this before but never seen it with my own eyes, id love to see a video of a guitar picking up AM radio just for giggles

[Paul Marossy]

You can usually get rid of RFI by adding a 47pF-100pF cap to ground on the input of the offending circuit.

[elmo7sharp9]

You can usually get rid of RFI by adding a 47pF-100pF cap to ground on the input of the offending circuit.

Threading the "hot" wire through a small ferrite bead helps, too.

[WezV]

i get it with a few pedals - generally its in french

[Tim37]

ive heard of this before but never seen it with my own eyes, id love to see a video of a guitar picking up AM radio just for giggles

mine picks up FM.

[mikevirok]

You can usually get rid of RFI by adding a 47pF-100pF cap to ground on the input of the offending circuit.

I'm most likely going to do both: shield the cavity/unit and use the cap. We'll see what occurs.

[Paul Marossy]

Shielding it will probably do the trick, but there are instances of guitar effects which are shielded picking up radio stations, so I guess also adding that cap would be a good back up measure against it.

Let us know what your results are!

[KeithHowell]

Make sure there are no "dry" solder joints. See my comment above in the "killing pots" thread.

Dry joints can have a diode effect and demodulate AM stations.

Keith

[Baazelbub]

But what if i wanted to pickup radio stations, what would i need to do for that.

[Paul Marossy]

But what if i wanted to pickup radio stations, what would i need to do for that.

Maybe you could find a way to build this into your guitar: http://sci-toys.com/scitoys/scitoys/radio/...nute_radio.html

[Baazelbub]

Maybe you could find a way to build this into your guitar: http://sci-toys.com/scitoys/scitoys/radio/...nute_radio.html

Thanks