Question about doubling front baffle...

[CADman_ks]

The parts have been ordered for my Stentorians.

In the build notes, Curt states that it would be better to at least add 1/2" to the front baffle. That makes some sense.

However, I'm going to need to buy an extra 1/2 sheet of MDF, and I was going to get 3/4". If I double the baffle to 3/4" is there anything special that I need to do the rest of the cabinet? Change the size?

I've read on other posts that you have to chamfer the back side, and that makes sense, but how much do you need to chamfer them.

CADman_ks

[cjd]

3/4 is fine. I'll have to find pics (or someone else) of good chamfer work on the back side.

[fjhuerta]

Many people around here would tell you 3/4" is too thin

Considering the amount of holes (and bass) the Stentorians have, I'd probably use 1.5" or more! (no kidding).

[CADman_ks]

You mean double 3/4" for 1 1/2", and then chamfer the back?

Or were you saying single 3/4" front would be fine?

Just making sure ...

CADman_ks

[CADman_ks]

Many people around here would tell you 3/4" is too thin

Considering the amount of holes (and bass) the Stentorians have, I'd probably use 1.5" or more! (no kidding).

You guys are scaring me. LOL!!!

CADman_ks

[NPF]

Yea, I would go thicker over thinner. Do note though that these happen to be fairly narrow (only 7 inches inside dim) so that will help out a bunch, but on the other hand with this number of drivers in close proximity the front has been turned into swiss cheese. Ultimately, this comes down to personal preference and experience. Curt used 3/4 ply for his front and mentions going thicker... I used 3/4 mdf plus 1/2in ply to get 1-1/4 thick. As you get thicker you do want to chamfer the back side to help the drivers breath better. The easiest would be to use a half in chamfer bit - this would take the edge of the chamfer to the side wall. If you look at my pictures I do not have a chamfer on the back simply because I screwed up and glued the front on instead of the back when I assembled it - duh! So, I kind of shot myself in the foot there. Not really a huge deal though. Your talking about loosing that tiny bit of perfection in the end...If these were reference speakers I would worry about this more, but they are just shop speakers for me.

Yes, you do need to take into account the extra thickness. Keep the internal volume the same - i.e. the cabinet will grow deeper by the amount you add to the thickness of the front baffle.

Nate

[---k---]

I used 2 layers of 3/4 for 1.5" thick on my Khanspires. That is fairly common. Overkill? I guess it depends on how big of a perfectionist you are. You'll find lots of different solutions to trying to stiffen the front baffle, from everything to thick plywood to marble. 3/4"+1/2" is probably good. You could consider 3/4"ply + 1/4 hardboard. Or whatever.

Here is a good photo of why and how to chamfer the back side:

https://www.htguide.com/forum/showthread.php?t=26309&page=4&pp=35

Looking at that photo now, I'm thinking I should have opened the back side up even more , but it is probably good enough.

One thing, the shielded RS drivers had a big magnet and shielding blocking the backside. This made chamfering the back side very important. The Aura woofers that you have in the Stens have a small neo motor and open frame. So you probably don't have to worry too much about this, if at all. But it can't hurt. It only takes a few minutes to do. I did it with all my ND140 builds, which is a very similar driver.

[fjhuerta]

You guys are scaring me. LOL!!!

CADman_ks

No joke! I actually use 1.5" baffles for my speakers.

[CADman_ks]

...

One thing, the shielded RS drivers had a big magnet and shielding blocking the backside. This made chamfering the back side very important. The Aura woofers that you have in the Stens have a small neo motor and open frame. So you probably don't have to worry too much about this, if at all. But it can't hurt. It only takes a few minutes to do. I did it with all my ND140 builds, which is a very similar driver.

That's kind of what I figured. I don't know how big of a chamfer bit I have, so I see what I have and go from there.

I have another question about the inner "stuffing". I was planning on using fiberglass insulation there, since I know where I can get some, and that will save me some money. The plans call for 1 lb per cavity. I noticed in your speaker build that you used something that looked like 2" fiberglass.

Do I need to do something like the panel, or will putting bat insulation in there be the equivalent of the stuffing.

If I can use regular bat insulation, do I need 1 lb per cavity as well with that, or should I use less? I realize that this is somewhat a personal taste as well for how they are tuned, but I'm sure that I'm going to want to put some in there. I just to makes sure that 1 lb of fiberglass equals 1 lb of Acustastuff.

CADman_ks

[---k---]

I've used R13 fiberglass and just peel it apart to the thickness I want. I've also used rigid OC703 on the walls. There are different opinions on how best to do it. I typically line the walls with some type of foam (PE Sonic barrier), rigidi fiberglass, batt fiberglass (2" of R13", or wool (Thomas has used this on lots of projects, but it is expensive) and then stuff with filler to taste. I just do what looks right to me. I'm then on the lucky end in that CJD designs the rest of the speaker around the box I give him. I've only ever spent an hour here and and hour there experimenting. Nothing extensive.

Fiberglass insulation, pillow stuffing, or Acustastuff will all work for the stuffing. They will be very slightly different. You may or may not need to adjust the amount to account for the differences in properties and differences in voicing taste. Vance Dickenson shows measurements in his book Loudspeaker Design Cookbook. IIRC, the differences were very very small. I would start with 1lb of fiberglass insulation and go from there.

FWIW, I've seen people make much bigger changes than the type of stuffing and been extremely happy with the speakers. Others agonize over more minor changes and spend more time experimenting than actually listening. It all depends on how golden your ears are.

I would build them as close as possible to the original designer OR plan on possibly doing a little experimentation.

[mattsk8]

Here's another pic of a way to chamfer the edges. This is a 1 1/4" baffle for some Statements. I've seen it done w/ a 45 degree bevel bit, and seen it done w/ a dado bit. In this pic, the woofers were done w/ the bevel bit (you can just see the edges of the woofers in the pic) and the mids were done w/ a dado bit. The bevel bit gives you a sturdier mount on the baffle.

[CADman_ks]

I actually think that I'm going to do mine with the 45deg bit on the router. I've laid it out, and I should be able to get a 1/2" chamfer on there. Now, I might not have a bit that big, so I'll go to whatever it is that I have that's the biggest.

Like ---k--- said, the magnets on the Auras are really small, so if I don't get to the total 1/2" chamfer, some will be better than none. The speakers in the holes should be fairly open to the back...

CADman_ks