earthing loop problems with electric guitar

Hi folks. Not sure if you can help. I use a 500 watt inverter and when using the electric guitar / amp off it there is awful buzz. Is it safe and could it help to earth the inverter via the negative lead to the vehicle chassis. Rather than the negative battery terminal? Any other suggestions. Big thank you for your time. Warm greetings from Brighton UK.


  • mcgivormcgivor Solar Expert Posts: 3,424 ✭✭✭✭✭
    Tell us more about your inverter, is it a modified or pure sine wave, it is not uncommon to get interference from cheaper units, something designed for telecom usage would probably be more appropriate for the application.
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  • BB.BB. Super Moderators, Administrators Posts: 30,625 admin
    Be very careful about ground bonding... In general, grounding the battery bank negative lead to your chassis is fine.

    However, the output of the AC inverter--As McGivor says, that depends on the brand/type/model of AC inverter.

    In general, you cannot ground either output of a MSW (modified square/sine wave inverter) AC output (ground bonded neutral in the USA) as this will create a short circuit through the AC inverter between the battery negative ground bond and the AC "neutral" bond.

    And, again in general, you usually can ground bond one of the AC output leads of a PSW/TSW (Pure/True sine wave) AC inverter as the AC output is fully transformer isolated. (check the manuals--there are exceptions).

    MSW inverters tend to be very electrically noisy and are not usually a good match to audio electronics.

    An isolation transformer (AC isolation transformer from inverter to amplifier) can help. Also, there are audio isolation transformers that can help resolve ground loop issues.

    Note that there can be safety issues with old amplifier designs (typically tube type guitar, radio, etc.):
    Quite a few old amplifiers (and radios) back in the day drew power by directly rectifying the household "mains" wiring. This is an inherently unsafe practice.

    Given that you are in the UK--Your AC mains may have different conventions for "Neutral Bonding" than the US (or may not have any neutral bonding at all).

    Need to understand your exact configuration/hardware before attempting and grounding solutions (isolation transformers are usually a "safe" thing to play with--However you can end up with mains voltage on one side and "safe" signals on the other side of the transformer--Be very careful).

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • PhotowhitPhotowhit Solar Expert Posts: 5,200 ✭✭✭✭
    Bill can peak and see that you are in the UK, in the US I would check small inverters for their UL status, if they are UL458 (for mobile use) they are likely to have internal grounding (even pure sine wave) Some may be able to disconnect, like ExelTech and some may have automatic disconnect like Outback, nice when connecting to outside energy sources.

    If they carry UL1741 They very like don't have internal grounding.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do
  • BB.BB. Super Moderators, Administrators Posts: 30,625 admin

    This time, I had another clue:
    Warm greetings from Brighton UK.

    Sometimes I do notice the details in a post....

    -Bill :o
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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