Question on Gio's bipole sealed box - will this work?

[pwan]

Hi,

I am new to speaker building and look for floor-standing sealed speaker for a 15 sq.m room (3.5 x 4m so too small to bipole I think) for both music and AV. I wonder if the box plan below will work fine in case:

http://diyaudioprojects.com/Speakers.../FE127E_SB.htm

Case 1: Use dual FE127e per ch but both drivers are on the front panel.

Case 2: Use only one FE127e (i.e. completely ignore the back one).


Many thanks!

[Scottmoose]

Don't try putting two FR drivers on the front baffle or horrible things will happen to the response due to severe comb-filter effects. A single driver is perfectly feasable though. Use 0.5lbs ft^3 of damping material uniform. Don't expect much LF performance though!

If you want compact, personally I'd do this: http://www.planet10-hifi.com/tom-zHorn.html I know it's more complicated, but trust me, if I can build a pair of double horns in my leaking garage, with a 30 year old hand saw and very little else, you should be able to manage it.

[gmilitano]

The driver on the rear compensates for the baffle step. As Scott mentioned, two drivers on the front will be problematic.

One driver will work, but you will likely find that you will need to compensate for the baffle step.

You will want to couple a sealed design with a subwoofer or two.

Also, look at this thread for a number of designs with the FE127E:

diyAudio Full Range Reference Project

[pwan]

Thanks for your comment.

Considering two FR drivers on the same panel, at least I saw two commencial ones doing so and they claim it works. One is Oemga/TS33 .


www.6moons.com/audioreviews/omega5/33.html

[gmilitano]

Originally posted by pwan
Considering two FR drivers on the same panel, at least I saw two commencial ones doing so and they claim it works. One is Oemga/TS33

www.6moons.com/audioreviews/omega5/33.html

I suspect that is a 1.5 way. Oddly enough, there is no information for that product on the manufacturers site.

[pwan]

Probably, it's one of their obsoloete product -- similar to TS1, TS2, and TS3.

Here are some in-depth info (2 pages) from the owner/designed (Louis).

http://www.audiocircle.com/circles/i...?topic=10671.0

[Scottmoose]

That's the only effective way to do it.

Sadly, you can't get around the laws of physics. When you put two identical drivers, run full-range on the same baffle, nasty things happen. For it to work, the centre-to-centre spacing needs to be less than 1wavelength of the highest frequency to be reproduced apart. If they're further apart, the end result is a massive increase in ripple in the high frequencies (comb-filter effect), while the response additionally rapidly drops away.

[pwan]

Thanks Scottmoose.

I guess I can imagin what the "comb-filter effect" is now. Per the picture, the distance between centers is around 10 cm, what frequency will it be?

[peterbrorsson]

Hi!
Maybe a dumb question but is it not possible to put the second driver at back of the top, aimed upward at 45 degree's . It will be a higher sound stage in this way. Is it Castle speakers that use this configuration? Can't remember which model.
I imagine one could have speakers closer to walls by this solution.

Just a guess....

Cheers/Peter

[Scottmoose]

Originally posted by pwan
Thanks Scottmoose.

I guess I can imagin what the "comb-filter effect" is now. Per the picture, the distance between centers is around 10 cm, what frequency will it be?

About 4Khz, give or take.

Peter -no, it's not a dumb question: the BD pipe has exactly that. http://www.t-linespeakers.org/FALL/bd-pipes.html

Castle have the second driver firing vertically upward. It's a good layout -one I like anyway. Harlech S2 and Howard S3 are the two models which have this configuration.