Flatter speaker frequency response

[pnoboy]

For some reason, Rhodes pianos seem more sensitive than guitars to uneven frequency response.  Closed-box cabinets can suffer from various resonances unless they are stuffed.  Ordinary polyester fiber fill is an excellent stuffing material, and it is cheap and easily available.  A stuffing ratio of about 1 lb of fiberfill to 1 cubic foot of cabinet volume is a good place to start.  I have been having some difficulty adjusting my Rhodes for optimum sound, even with the use of an equalizer.  Playing the piano through headphones showed that the issues were not the piano, but the speaker.  I already was using a good quality 12" speaker, so I opened the cabinet, and found it had little stuffing.  For a princely sum of $6.99, I bought 24 ounces of fiber fill at a local fabric store, distributed it carefully in the cabinet, and voila, problem solved. 

Polyester fiber fill does two good things in a speaker cabinet.  At low, i.e., bass, frequencies it makes the cabinet look bigger to the speaker by slowing down the speed of sound.  Given that many manufacturers like to make the cabinet smaller than it should for both cost and sales appeal, this effect is usually desirable.  At higher frequencies, i.e., midrange and treble, the fiber fill acts as damping, and prevents standing waves from occurring in the cabinet.  If you're dissatisfied with the sound of your amp, before spending lots of money on new equipment, stuffing a closed-box speaker cabinet is a cheap and quick experiment to try.

[pianotuner steveo]

Is it better than old fashioned fiberglass insulation or just cheaper and easier to use? (no itch factor)

[The Real MC]

It depends on the R value of the insulation.  The lower the value, the less dense it is.

[rhodesjuzz]

Thanks for the tip!  I have similar issues with my cabinet when cranking up the volume.

--Roy

[pnoboy]

Is it better than old fashioned fiberglass insulation or just cheaper and easier to use? (no itch factor)

Fiberglass is just as good, but I hate to use it because of its itchiness, and because its fibers can break and get into the air and down into the lungs.

[pianotuner steveo]

Good to know. I never thought of this.