My amplifier is a Fender Rumble 25 and my bass is a Squier Fender Jazz Bass, both bought in last june.
The amplifier has always made some buzz when turned on and there´s clearly buzz coming from a ground loop, but, at least in usual volumes, the overall buzz is barely noticeable, despite if the sound is going out through the speakers or through one of my very cheap headphones (connected in the amplifier phones output) (a Philips SHPS2500, a Sony MDR-XB550, both over-ear, and the in-ear that came with my smartphone).
In other words, in my ordinary playing, listening through the speakers or the cheap headphones, the buzz has no significance.
There are some intriguing facts about this buzz:
1) The relation between the volumes of the pickups has a huge influence the intensity of the buzz: if both volumes are similar, the buzz hits its minimum, but, in opposite way, if I turn the volume of one pickup to the maximum and the volume of the other to the minimum, the buzz reaches it´s maximum, becoming really loud.
2) Despite the ground loop question, if I touches the strings, the buzz stays virtuallly the same.
3) If I walk with my bass away from the amplifier or if I rotate whily I´m playing, the buzz vary considerably (some eletromagnetic field interference?)
Today I bought a Audio Technica ATH-M50x, and it sounds really great, both for listening music or playing bass, but the problem is that the buzz becomes much louder, reaching a level that makes impossible to play the bass.
In US this is an average headphone, but you have no idea of how much it costs here in Brazil (something about 1/3 or 1/4 of the month pay of the regular middle class guy), so the decision of refunding it or not is very important (please, Josh, never call the Squier Jazz Bass a cheap bass again hahahaha ).
This new buzz situation too has some intriguing facts:
1) The overall volume of the amplifier has influence over the buzz, but what really matters for the buzz is the level of the treble (the mid and bass makes virtually no difference) and the overdrive (if on or off).
2) If I turn off both the volume of the pickups of the bass and the volume of the amplifier, the buzz is still there, easily noticeable. Both these volume changes makes no great difference in the buzz, which is strange for me.
3) There´s little difference in the buzz level if the amplifier has no cable connected or if is connected on the bass (strange too, no?).
That being said:
Someone has any idea why with my old and cheap headphones connected in the amplifier or through it´s speakers the buzz isn´t disturbing but with my new headphones connected in this same amplifier the buzz becomes really loud, making it impossible to play the bass?
Thanks for the help!