Bass horn ideas again. A possible build. Need criticism.

[mas]

Hi! ...thought I would give my 2 cents as I have been lurking for quite awhile and have a 'little ' experience with this.

Regarding the Baltic Plywood vs. MDF issue:

With all due respects to both the high quality Baltic plywood camp (which I must profess to prefer in most cases simply due to its being more resilient to handling and moisture ) and to the high quality MDF camp (which does have superior density - and thus it is heavier - and lower resonant qualities and the ability to be tooled to very high tolerances), you would do fine with the MDF. If you aren't planning on using them for SR use and carrying them around and banging them up, and you don't have to worry about the wear and tear (not to mention shooting Polane!!), the MDF will actually present you with some superior qualities compared to plywood as you have already mentioned. And it accepts veneer very well.

Also, I am sure from previous discussions that you are intimate with the differences in joinery required by the different materials.

One additional note, MDF is hard on bits and blades! Whether it is the binder, the density, or a combination of all that, it results in greater heating of the bits and blades, not to mention the nasty dust (please wear a respirator! - although regular hard/softwood dust is not safe either!).

Bottomline, for internal stationary use and if you are prepared for the dust and tool wear and heed the required joinery techniques appropriate for MDF, you would do well to use MDF.

Good Luck!!

[taphorny]

Has anyone given thought about overlay of T.D.'s "tapped horn" concept onto existing heritage schemes?

[homemadeheresy]

Hey guys,

Just found this post and was curious as to how the progress was coming. I had a bass bin design that never materialized, but am anxious to hear some data from what you are constructing.

Good luck,

Sam

[jwc]

Ah. Yes. This thread is not forgotten. I have a pile of panels cut for one jubilee clone. I also have the drivers. Stay tuned. Step by step stuff coming.

jc

[Daddy Dee]

Alright! This will be great!

[jwc]

I am a little intimidated. Just lacking the bottom and top which is an easy cut.

Shouldn't be as back breaking as the dbb construction. I did those by a Jigsaw only. Bunch of sanding. That won't be needed as much here.

It will be hard for me to focus on my Prostate Cancer presentation tomorrow. I have a pile of wood on my mind.

Does anyone have photos of a T-nut installation and a simple explanation how they did it. This will be the first time for me to use em.

jc

[djk]

" T-nut installation "

Make sure the threads on the T-nut are OK before installing it.

Drill the correct size hole, slightly undersized. It will not be in most common drill bit sets. Take a t-nut to the store with you when you buy it. Press the T-nut in with a C-clamp and a scrap of wood to protect the work.

[mas]

You can easily make a T-Nut press with a bolt (small enough in diameter to fit through the T-nut center), 2 fender washers, and a nut (preferably one that fits onto the bolt ;-).

A nut driver or socket wrench will tighten the nut and press the washer, thus seating the T-nut quickly, easily and precisely.

[D-MAN]

Go, JC, Go!

I would glue the T-nut in so it won't break loose from the wood when overly tightened.

This is just a precautionary measure, though.

Dana

[jwc]

Ok guys. Now I won't ask this many questions during this whole process but I have never used T-nuts.

Now I have driver "plates" made to remove and replace drivers. I did this in case I may use different drivers in the future besides these.

The Plates are 17" tall and 12.5" wide. The slot is 5 x 9. I made marking of the center in both directions to line up the driver.

Now.....how many holes would you use in the plate???? 4 or more????

jc

[jwc]

Check this out.

Now Tom Mobley sent me some T-nuts for a different project. These are 1/4" x 5/16". I assume taking a 1/4" screw and hole for the t-nut 5/16".

Notice on this picture that the screw isn't long enough. This driver has a "tall" mounting rim....much thicker than a K33. Also much heavier than a K33. That is quite a long distance. Does this look right?

jc

[djk]

1/4-20 is not a good size for most woofers, and not a plain head.

Klipsch uses 10-32.

[gaspr]

Hi JW

Just a few thoughts here. If the plate is going to be

removable, why not just use 1/4" carriage bolts to attach the

speakers with nuts and lock washers on the speaker side. You

would have to recess the hole for the head of the bolt slightly to

allow the plate to mount tightly to the front of the dog house.

It seems to me that where t-nuts would be required is for the bolts

that would attach the plate to the dog house, as these would be

more inaccessible.

Garth

[D-MAN]

I've wondered about this myself. As you know I'm a fan of the removable motor board.

However, the confinement imposed in the Jubilee back chamber is such that I question whether a board-mounted driver could fit through the access cutout, being that, in the stock version, the access is recessed flush with the top and therefore requires an inside lip.

Hence, I don't know if there's room enough to fit through the available "hole".

I would therefore go with the more-likely approach of a direct-driver mount to the baffle using t-nuts embedded in the baffle in the mounting pattern of the driver.

Correct me if I'm wrong, guys...

DM

[jwc]

I have had concerns of the space issue. If mount straight to baffle, I could get away with 12, 3, 6, 9 positions. The other positions will probably be right where the flares/ramps are on the other side.

I'm not sure I followed the idea of carraige bolts.

jc

[gaspr]

I guess what I was trying to say was that if you can remove the

plate, then it really doesn't matter how you attach the speakers

to it, as long as the front of the plate remains flush ( no bolt

heads protuding). The problem of how to attach the plate securely

to the inside of the dog house remains.

If a mounting lip was attached to the outside of the dog house,

then perhaps a larger access hole could be used? Access

holes top and bottom might be considered as well. This

would make it much easier to remove the speaker/plate assemblies.

[gaspr]

One more thought. If you decide to mount directly to the

baffle, you could use t-nuts for any or all of the holes, as long

as the t-nuts are in place before the ramps are attached.

[jwc]

Thanks for the advice. I think I may ditch the mounting plate for the moment. What I think I will do is layout where the ramps will go. I know I could have the base of a t-nut under a ramps but I would prefer not.

I Already plan on a top and bottom access to the inner chamber.

I will try and run to Home Depot this weekend to see if they have the t-nuts that djk was mentioning. Mine are too short for use with this woofer.

jc

[DrWho]

You can use any machined screw with the T-Nut...you don't have to take what you can get in the "kits". 1/4-20 just specifies how wide the bolt needs to be and how close the threads are. So just get some 1/4-20 bolts that are the length you need.

Or if you go with 10-32 (I'll ditto that recommendation), then you'll need to find 10-32 bolts that are the length you need.

Keep in mind that you should favor on the short side for the bolt - so that you don't have to worry about tightening causing the bolt to shoot out the other side.

When installing T-Nuts I usually put the bolt through the hole first and then attach it to the T-Nut before pounding it in. This is to ensure that the bolt and t-nut both end up travelling perpendicular to the surface. There have been times when pounding in the T-Nut without a bolt present that the T-Nut twists a bit making it immensly difficult to get the bolt to thread properly. I think that made sense?

[CONVERGENCE]

The folded horn cabinet still being produced today

in large quantities .

Here is a picture of an earlier model from 1975.