I also have a Helix. Just to make sure I’m understanding, when you say volume on the Helix, do you mean the main out volume - the big knob on the middle-right of the front panel?
If so, I’m not quite understanding how that would change the sound, except for making it quieter/louder. That knob controls the final output volume of the Helix. It doesn’t change the tone in any way whatsoever. (Human ears hear differently at different volumes, of course - that might be why it sounds different. Check out “fletcher munson equal loudness contours” for more info.)
If your guitar is too quiet, but you have to turn down the Helix to 10 o’clock to balance it musically with the BeatBuddy, you have two options:
- BeatBuddy at 100% volume, Helix at 35% volume (10 o’clock), then turn up that mixer channel so that the Helix is as loud as it was at 3 o’clock before
- Use two separate mixer channels
Personally, if there are available channels to spare, I’d go with option #2.
In general, the best practice of gain staging would be:
- Use separate channels for the Helix and BeatBuddy
- Keep the output volume on the Helix and BeatBuddy boxes themselves at 100% maximum
- Adjust the input gain/trim of each mixer channel to find the ideal input level: reasonably high, but low enough so the loud parts never clip
- Use the mixer’s faders (or lower knobs in the case of a small mixer) to balance the parts musically
- Set your active speakers’ input sensitivity to 0dB (12 o’clock on my QSC K10s; may be different for you)
- Use the mixer’s master fader to adjust the overall volume of everything as needed
Of course, that’s not the only way people do it, and modern equipment is pretty forgiving of deviations from that best practice. That’s usually the most technically sound and foolproof method, though.
I hope that’s useful - thanks,