Most likely. However, did you install the pickups yourself? I've noticed that so many people have volume knob issues when they install their own pickups. Even when the person knows what they're doing, doing it themselvevs somehow brings up a slight volume knob issue. Usually it's simply a poor soldering job. I installed my own EMG on my 7-string and it sounds great. Except when i'm touching the pickup and when i adjust my volume. All it does is buzz when i touch the pickup and crackle a little when i turn the volume up. It hasn't bothered me much though, so i've left it how it is and it sounds wicked.

__________________
Mr. 7-String
My Rig:
Guitar:
Custom Ibanez 7-String AX Series (Custom design work & replaced the stock pickups With an EMG707) That's the best way to go; Buy a cheap guitar, and work the **** out of it until it goes from a total piece to a piece of art.
Amplifier:
Mesa (Because Mesa's the only way to go) Dual Rectifier.
Pedal Board:
Boss TU-2 Tuning Pedal
Boss MT-2 Distortion Pedal (Which I don't even need due to the intense Mesa Distortion)
Behringer V-Amp Multi-Effects pedal
Zoom Multi-Effects pedal (Which I rarely use because it's a piece... but it kind of sounds okay on stage)