Just grabbed a Yamaha FS800 and noticed something I can’t stop thinking about: I can “tilt” the bass response by slightly shifting the body’s air resonance with totally non-destructive tweaks. Using a phone spectrum app and a gentle tap on the bridge, I get a clear air mode around G#/A. If I lightly stuff a microfiber cloth in the lower bout or tape a tiny removable weight to the back (outside, near the lower bout), the peak nudges a few Hz and the low E and DADGAD drones feel noticeably fuller and less “boxy.” It’s subtle but repeatable.
Has anyone here systematically “tuned” an FS800’s air mode for recording or alternate tunings without opening the guitar up? I’m trying to figure out safe, reversible ways to coax a hair more bass from this small body while keeping the top happy.
What I’ve tried so far
- Stock lights (12-53), standard E and DADGAD. Humidity 45%.
- Phone FFT and a fingertip tap near the bridge to spot the air peak.
- Removable Blu Tack on the exterior back (pea-sized) near the lower bout: tiny downward shift in the back plate mode, perceived smoother low end.
- Microfiber cloth loosely inside the lower bout: slight upward shift of the air mode, midrange tightens, bass focus changes.
Questions for FS800 owners and tinkerers
- Where do you place small, removable mass on the outside back or sides to get the most predictable change without killing volume? Lower bout vs waist vs upper bout?
- Has anyone tried a soundhole plug on a concert body like the FS800 purely for air-mode control (not just feedback)? What size/fit affected the “air note” most?
- Do bridge pin swaps (heavy brass vs plastic) measurably shift the same response on this model, or do they mostly change attack/brightness?
- For alternate tunings like Open C or DADGAD, which custom light/medium gauges kept tension similar to standard E on the FS800’s 634 mm scale while maintaining top responsiveness?
- If you’ve done A/B recordings, did bone vs Tusq saddles change the perceived balance enough to make the mass tweaks unnecessary?
- Anyone mapped the FS800’s typical air mode and top modes with tap tests? I’d love ballpark frequencies to compare.
I’m aiming for reversible, zero-risk tweaks for home recording-no drilling, no internal weights. If you’ve got placements, putty amounts, or string sets that worked specifically on the FS800, please share settings, tunings, and even rough spectrum screenshots. If this pans out, I’ll compile everyone’s findings into a “FS800 small-body voicing cheat sheet.”