Advice needed for a wide baffle shallow box

[exurbia]

Gordon bennett, what a title.

My son wants to build a wide baffle speaker, his room won't allow too much depth for the boxes. Now here is the rub.

The box will be 385mm across, the bass driver is a Seas CA25 RE/4 DX. Working into a 63 Litre vented box. The Midrange is an Eton 4-300 and the tweeter will be either Fountek JP 3.0 NEO or Seas 29TFF/W

The question is will the tweeter and mid work well on such a wide baffle.

Any comments or ideas will be welcome

[richie00boy]

They will be fine as long as the crossover is designed appropriately. In fact I'm thinking about a kind of similar project -to wall mount some speakers. However, I will be using a fullrange speaker which does take some of the difficulties away!

Contrary to popular belief (marketing induced mostly), you can get nice sound from a wide baffle. It promotes wavelaunch.

[exurbia]

Thanks richie, I wasn't sure about the width issue. My horns are nearly five feet wide, i know the principle is different but they still image like s***

I was thinking that the wide baffle may have the same problem. After he's forked out so much for his project i'd hate to see him fail.

[Svante]

I suggest some simulations of the baffle step to find the best possible placement of the drivers.

[sreten]

Originally posted by exurbia
Gordon bennett, what a title.

My son wants to build a wide baffle speaker, his room won't allow too much depth for the boxes. Now here is the rub.

The box will be 385mm across, the bass driver is a Seas CA25 RE/4 DX. Working into a 63 Litre vented box. The Midrange is an Eton 4-300 and the tweeter will be either Fountek JP 3.0 NEO or Seas 29TFF/W

The question is will the tweeter and mid work well on such a wide baffle.

Any comments or ideas will be welcome

Hi,

It will work fine if appropriately designed.
I assume the speakers will be backed up against a wall ?

You would probably get away with little or no baffle step compensation.
(edit : note I am not disagreeing with Svante, the drivers
should still be place for the smoothest free field response,
its just the amount of overall BSC you compensate for.)

See Troels information on wide baffles here :

http://www.troelsgravesen.dk/Diy_Lou...r_Projects.htm

Also see Romans methodology here :

http://www.rjbaudio.com/Audiofiles/FRDtools.html

/sreten.

[CeramicMan]

I once built a pair of 2-ways that were approximately 35cm wide. The front was made from braced 19mm plywood and they gave a nice warm tone – no problems whatsoever. That was before I'd ever heard of "baffle steps", which was lucky.

Then I built another pair, this time only 21cm wide... and I'm definitely going back to a wide format for next time. Although the new speakers had vastly better drivers and BSC in the crossovers, they had problems with midrange resonances, which I partly attribute to early reflections and re-radiation at the edges of the smaller boxes.

IMO that "6dB step" is only part of the issue, it's the sharp parallel edges and uneven off-axis radiation that also causes problems.

[Foxx510]

Here's an idea, maybe not a great one but I'll add it anyway. How about a curved front baffle made from thin flexible sheets of mdf or ply, laminated, and formed on curved bracing made from mdf. In theory it should end up super rigid. The only pain would be routing flat areas into the baffle to mount the drivers, although you could just start the curve just at the edge of the largest driver.

[exurbia]

Thanks everyone,

We are going for a wide curved baffle, cutting the driver recess is easy. (foxx)
i will do a detailed description for those who want to know how to do it. This includes the radiused edges.
For the meantime as time is of the essence, he wants them NOW!!! I will build the large shallow wide box.
Details to follow.
TTFN,
Peter.

[exurbia]

Hi ceramic man, i see you're looking to build a 3 way. i have some pairs of Audax HP130Z2, one of the best mids ever,ever,ever. they leave the seas for dead.

[CeramicMan]

Originally posted by exurbia
Hi ceramic man, i see you're looking to build a 3 way. i have some pairs of Audax HP130Z2, one of the best mids ever,ever,ever. they leave the seas for dead.

Hi exurbia, their "z" range are the Aerogel ones, right? The Audax site didn't seem to be working properly when I tried downloading some of their driver specs the other day.

But anyway, part of my reasoning was that I'm quite familiar with paper and poly-xxx drivers from everyday life, and while they're all different, they always seem to produce the same "family" of sounds. I took a risk and forked out on Accuton drivers and was really impressed – so basically I've been looking around for something cheaper that works on the same principle.

Thanks for the heads-up though... My biggest concern ATM with the Seas' specs is the apparent "sharpness" of their resonant peaks on their FR graphs. It implies a long decay time, so even a tiny amount of midrange distortion might be easily audible if it persists after the excitation signal has decayed.