Thanks for the info guys, even though it's over my old head. I questioned the cabinet guy about voids in the plywood and he told me they only use a grade with no voids so hopefully I won't have that problem.
Going to rear mount the woofs.
Frames with the stiffening ribs on the back side of the mounting flange are normally rear mounted, while the later frames with no ribs can be front or rear mounted. Of course you can front mount the ribbed frames, but either a very thick, squishy gasket or individual reliefs cut into the baffle is required to get a good seal.Originally Posted by nikki1
Due to the narrow mounting surface the bevel leaves for good sealing, I personally wouldn't front mount a large, low tuned driver to one, especially in a sealed or typical vented alignment, but never having tried it can't say for sure if it's 'much ado about nothing' on my part. At least originally, ribs were required due to cast frames not being all that strong at that point in manufacturing history plus the American attitude (at the time) to build everything as big/durable as tanks just because we had the raw material wealth to do so.
'Sound is round', making the diameter of a sound 'bubble' ~13,560"/pi, so a 13.25" cutout represents a ~326 Hz WL in size and since WLs increase exponentially with decreasing frequency there's no way beveling it will have any measured or even perceived impact on its performance until the baffle is thick, large enough enough to make a round over with a radius equal to one WL of the desired frequency, i.e. bass horn size in area, thickness.
When you see speakers with rounded over edges then, they are only affecting its BW well up into the HF, so strictly cosmetic since the tweeter is beaming this high up and even a 2 ft diameter ball as shown in Harry Olson's measurements below only smoothly diffracts down into the mids.
GM
edit: Hmm, these are .gifs, but for some reason they are being converted to .jpegs even though .gifs are listed as acceptable, so I assume this is why they won't display large enough to clearly read when clicked on. I tried uploading them as .jpegs, but that didn't work either.
Anybody got a clue what's going on beyond the usual Hostboard quirks?
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
Thanks for the info guys, even though it's over my old head. I questioned the cabinet guy about voids in the plywood and he told me they only use a grade with no voids so hopefully I won't have that problem.
Going to rear mount the woofs.
Hey GM, I guess it's my turn to help you !Whenever you use the attachments with hostboard the automatic re-sizer turns them to crap thumbnails,or tiny hard to read pics.
You have to link into them from Photobucket Flickr,Image shack,etc.. I tried to clean up the image but resolution is bad due to the small resizing.So I didn't repost them.
.
Happy Holidaze and all that jive!
When did it change? It doesn't seem that long ago I posted some pictures off my computer without any problems. Speaking of which, I just tried to add them as attachments in the body of the message and they wouldn't even display except as [attach]......[/attach]. Hope Todd got a discount for the options reduction.
Regardless, I'll add them to Flickr as time permits since they seem to have disappeared from the net except on a forum folks have to join to access them.
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
You're welcome!
Hmm, can't imagine why since it's considerably more expensive (1.5-2x in my locale) and a total waste of $$$ for cabinet construction except where it's required in an aircraft app.
I'm curious what they actually used though since the only void free plywood AFAIK is an all Baltic Birch lamination plywood (AKA Appleply) which don't include any of the furniture/cabinet grades, aircraft mil spec plywood and some marine grades, though these are no longer guaranteed void free as it was back when I was an active woodworker. There use to be a void free plywood for tropical apps made to British Standard Specification BS 1088, but I haven't seen it since the early '90s around here and a quick Google search didn't turn up any, so not sure about it.
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
One of the pair. It's a 612 bass cabinet with the sides extended to make a horn enclosure. Screwed and glued. 3/4 ply with cherry veneer where it shows and maple where it doesn't. Edge banded (still have to band the back edges). Also have to install the interior bracing, put some damping material in and finish them.
Can't say about the plywood. All I know is that I asked him if it had voids before I got it and he said no. These cabs are not for getting every last hz but rather a compromise between nothing at all and something which will perform adequately and hopefully give a fairly decent bass response. Also size and appearance. I have a wife who very tolerant and understanding but she has her limits and told me no "frieght cars" in the room. We'll see.
Going to make grill cloth frames which will fit into the top and bottom openings leaving a 3/4 strip showing in between. Also my wife's request. Any one give any advice as to cloth material and source? Whatever does the least damage to the sound in either black or brown.
Yes there is a gentleman over at LH who took over from the Zilch Cloth Emporium and Spa.Who is now the purveyor of JBL Blue & Black grill cloth named Rick his moniker is (Saeman). Be patient as he is real busy building JBL monitors with Kendrick Sound of Japan. I bought some to repair the grilles on my 612's very nice stuff ! Looks like original diamond Jbl cloth.Just go over to Lansing Heritage send a PM to (Saeman). I think the increments are still 2,3,and 5 yard pk g's $15 a yard. Your project Looks Great Good Luck with it ! :2thumbsup:
hey.. nice shop vac, and i cant see the bike... from what i can see from the end cuts in the plywood, is no voids. if you look at the end grain in most plywood you will see all kinds of voids, at least some, but i dont see them on yours
"those sounds to which no definite pitch can be assigned are usually classified as noise"<br />harvey fletcher-1928
Glad you like the vac. Had it for years and still sucks up eveything.
Ditto on the voids. I looked at the edges when I picked up the panels and there aren't any so I assume the guy's telling the truth.
Here's an anal question. Look at the front view of the cab. The upper opening has two vertical cleats to support the grill. When putting in the horn mounts I noted that the cleats are in the way of the outer edges of the horn flairs. If air were coming out of the horns it would create turbulence from the cleats. Don't know if they will effect sound waves and reflect them back or not. Be easy enough to put the cleats horzontal and out of the way. What d'ya think boys?
I'd still like to know what it is exactly.
I typically used expanded double knit from the local cloth Emporium which comes in myriad colors to match, or at least complement, most room decors and best of all, cheap, with less SPL loss than traditional grill cloth materials. Not as distinctive/decorative, but then the goal was normally to blend in as much as practical to reduce the sense of size.
It works best if stretched over a flat surface, so this supra baffle can be used to ~flush mount drivers if desired and if a 3D grill is desired, it needs to be stretched over shaped, rigid foam bonded to it.
Pet screen works well to protect against the claws, teeth, fingers of all small 'pets', but requires a bit of EQ due to its fairly high resistance.
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
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