Do you use BSC on desktop speaker builds?

mayhem13

Member
2008-09-22 4:37 am
I'm working with a small midwoofer from 3khz on down in a two way and in its current test enclosure where the driver is 4" from its intended desktop location, without BSC it sounds just right although close miked its about 3db down at 100hz from 1khz. Anechoic F3 models to 45hz with the current tuning and measures more closely like F6. Any thoughts on a BSC rule of thumb for desktop speakers?
 

dumptruck

Member
2010-05-04 5:02 pm
MN
Are you sure you aren't modeling the bass extension in half space, like most programs do? Anyway, "baffle step" effects are pretty high in frequency for a tiny speaker, so it doesn't have anything to do with the bass. Look at farfield measurements (you can still get pretty close to a tiny speaker, say 0.5m or so), pseudo-freefield, or pointing up from the floor out in a large room.
 

IG81

Member
2008-02-22 1:21 pm
Assuming a desk with a wall to its back and the user sitting at said desk, one is thus in quasi quarter-space and BSC may not be needed assuming the driver has a fairly flat midrange/HF when measured on a very large baffle. I even favour somewhat of a slopping response below 150Hz or so in order to counter the mid/upper-bass gain afforded by the location.

IG
 

mayhem13

Member
2008-09-22 4:37 am
That's pretty much what I'm measuring right now.....a nice tilt that sound just right in the midbass. I don't think there's any good way to get any more bottom on a desktop.....a sub underneath is the much better option. I designed the box baffles with a 20 degree tilt so at the listening position, the listener is on the vertical axis which works with the poor vertical response of the Fountek ribbon. I may push the xo a bit higher though as I'm getting a little false detail in the crossover range probobly from highish 3rd order HD and the woofers breakup mode. I may have to notch that if i do.