B20 in open baffle, help needed

[gychang]

I have the plywood cut the opening but realize the size needs to be changed, besides the Pioneer B20s, I also have piezo tweeters and L-pads laying around. Would science oriented folks here help me out to get the better sound?

Is there a reasonable size of the baffle I should shoot for? (size now is 24"x16"), I can certainly add more width.
Should I need to add electronics to my L-pad (various resistors I have laying around)

I realize the bass will suffer in open baffle, I will be driving these in a smallish room with my Pioneer Elite HT receiver.

gychang

[bigdh31]

There are two things that are going to limit the bass response of your current configuration. The baffle is a little small and the driver has a moderate QTS. If you paired these with a sub-woofer it might work well. The fun of DIY is trying different things. You might like the baffle just as it is.

Getting good ob bass usually involves larger baffles and larger drivers with QTS values approaching 1.

See MJ Kings excellent site "www.quarter-wave.com" for good info on ob design.

There are many references on connecting a pizo tweeter that you can find with google.

[Pano]

Please see this thread: Pictures -- Why Not attach Them ??
I have fixed it.

[gychang]

Originally Posted by Pano

Please see this thread: Pictures -- Why Not attach Them ??
I have fixed it.

thanks,

[GM]

Originally Posted by gychang

Is there a reasonable size of the baffle I should shoot for?

The B20 has a ~171 Hz mass corner which ignoring any near boundary gain equates to a ~36" wide baffle. Put an 8 ohm non inductive wire wound power resistor in series and it drops to ~100 Hz with a ~61" wide baffle. Of course as you move them back into corners they can be reduced in width, though at some point they start sounding a bit 'boxy' if you don't toss a big roll of insulation in the corner.

You'll need an XO for the piezo along with the 'L' pad. Godzilla has considerable experience with this combo, so check out what he's done.

GM

[Nelson Pass]

You probably should go as wide and high as you can. I've had good results
with 36"w x 72"h, but I've also been able to get away with 24w X 48h,
especially if you don't mind a little bass eq.

[gychang]

Originally Posted by Nelson Pass

You probably should go as wide and high as you can. I've had good results
with 36"w x 72"h, but I've also been able to get away with 24w X 48h,
especially if you don't mind a little bass eq.

does it have to be flat?, can the baffle be bent back a little...

[Pano]

Wings can help.

[gychang]

Originally Posted by Pano

Wings can help.

I was wondering if the size of wings can be included in the baffle size calculations.

[Pano]

Kinda, sorta. They don't count 100%, tho.