Combo Mystery - please help!

[Troels J]

Hi TalkBass people,
I'm new on the cyberblock, and I really hope you can help me with this one. I've just started playing again after a pause of twelve years, and just bought a new Warwick Blue Cab 15 Watt combo. When I play my new combo in the local store with my own bass and lead it sounds fine, but when I do the same at home, I start to get a lot of background buzz when the volume goes past 3. I have the tone knob all the way down to reduce the noise, but this helps only a little (The noise is only there when the bass is jacked in).
The store guy said that it might have to do with other things plugged into the same socket, but the noise is also there when I have only the combo plugged in!
Do any of you have a check-list for reducing combo noise?
Should I get a shorter lead (it is 6 meters)?
Please help!
Troels Johansen

 

[joeyl]

what kind of lighting in the house? fluorescent? are your outlets grounded, the problem is obviously your home environment

 

[Troels J]

Thanks for the quick reply! The lighting is a mixture of energy-saving bulbs and normal bulbs, one fluorescent light in the kitchen, though. But actually I think that perhaps some energy-saving bulbs work in the same way as fluorescent lamps?
I actually don't know if the outlets are grounded - the amp doesn't have three "rods" in its plug.

 

[BassmanPaul]

I would think that any amp made by Warwick would have a grounded power cord. Check if the ground pin, the round one, has been broken off. If it has have the plug replaced immediately.

As for the hum, if it is only there when you plug in your bass then either the bass or the signal cable is the culprit. Move around your room and see if the sound of the hum changes. Single coil pickups just love grab noise induced by your household wiring.

Paul

 

[Troels J]

Thanks for the input, I'll try the bass in different places tonight and see if it works.
The plug doesnt have a ground pin, only a hole looking like a ground pin could be installed there. Can grounding the combo reduce noise?
Troels

 

[T-Bird]

Hi, Troels.

First of all, Welcome to the TalkBass.

One should never use any electrical appliances that are ungrounded or doesn't have a double insulation. Really bad things can happen. Grounding is the way to go.

To Your problem, yes energy saving lamps radiate and feed back quite considerably to the surrounding area and circuit, not enough to fail in the emission and radiation tests, but quite much still.

The way to tell if the problem is bass-related or amp (power)-related is to have preferably someone else to move the bass to different locations and orientations as You listen to the amp. If You do it by Yourself the phasing issues can lead to false diagnose. If the interference stays the same it's most probably the power in the house that's causing the problems. If the interference varies from location to location the pickups or the shielding is most likely to blame.

Knowing what bass You have and what country You live in would help as some basses are more prone to picking up interference and also some countries/locations can have power issues that can have an effect to MI equipment.

If it's the dirty electricity that's causing the problems, and grounding won't help, an UPS of appropriate size (same wattage) will help.

Regards
Sam