Building sleds for Altec multicell horns

**Elitopus1** · September 10th, 2017, 11:17 PM

I want to build some adjustable sleds for my 805 horns. I have looked at pics of the old Altec sleds, and many of them look to be just a piece of plywood with a couple L brackets for the front, and an adjustable L bracket for the back.

I was thinking about using some 3/4 BB plywood and L brackets like what I have seen in the pictures. The thing I want to change is the distance from the horn to the top of the cab. The pics I have seen raise the horns up like 6" from the top of the cab. I want mine closer.

My questions are...

Should I use something thicker than 3/4" ply? Maybe double it up

How can I isolate the sled from the top of the cabinet? Rubber or felt spacers?

I figure if I support the horn on the fronts and also on the rear mount, I shouldn't need an extra brace for the 288 driver right?

Right now my idea is a 29"x16" piece of ply. It matches the width pretty close (my 828 cabs are 29.5" wide), and the 16" length will give me room to slide the sled around front to back on the cab to align the VC's.

Any ideas or advice of how I can make these better for HiFi? Thanks

**norelco** · September 10th, 2017, 11:29 PM

Try the rubber vibration pad.

Vibration pad with Cork

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**Elitopus1** · September 11th, 2017, 02:53 PM

I'm guessing the rubber/cork pad can only be found online? Looks like it would be great for between the cabinet and sled.

I was reading some old threads and found a thread about a sled for a 1005 horn. The poster said it was 20"x30" and had multiple mounting holes to fit different horns. Maybe I'll stick with this size so it will be true to an original sled.

**gdmoore28** · September 11th, 2017, 03:37 PM

Originally Posted by norelco

Try the rubber vibration pad.

Vibration pad with Cork

Sent from my iPhone using Tapatalk

Ohhhh . . . that's some nice looking rubber material. Where can you buy that stuff? I'm going to need something along that line to apply to the bottom of the super tweeter cabinet I'm going to build shortly. I'm building it from very, very heavy material, but having that type of rubber on the bottom would stop them from migrating across the cabinets.

Eli, I've no idea on the size of the sleds (as usual), but I would build them from the heaviest material at hand. 3/4" MDF would probably be fine. Once you reach the size you are talking about, that's putting on the weight. And the rubber sheets shown should make positioning a breeze. Of course, you can either veneer or paint the sled to match the cab.

As for the L-brackets, I go to Lowes or Home Depot. They have a large selection of L-brackets that should fit any configuration you have. If not, it's an easy project to custom-bend your own from either steel or aluminum flat stock and drill your holes as needed.

GeeDeeEmm

**norelco** · September 11th, 2017, 07:44 PM

Try in some local hardware shop, you can buy it separately, rubber vibration pad, cork and rubber adhesive glue and DIY[emoji106]

Or order it online - Anti-Vibration Pads for Machines from Super Soundprooofing[emoji769]Co.

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GM · September 11th, 2017, 08:41 PM

FWIW, horns, pipes, etc., have a terminus [mouth] end correction, so ideally the horn spacing to the cab/whatever should take this into consideration to maintain its polar response, hence Altec's rather high spacing on its bigger horns.

GM

**Elitopus1** · September 12th, 2017, 07:17 AM

Originally Posted by GM

FWIW, horns, pipes, etc., have a terminus [mouth] end correction, so ideally the horn spacing to the cab/whatever should take this into consideration to maintain its polar response, hence Altec's rather high spacing on its bigger horns.

GM

I have heard about a terminus in reference to a pipe. I never did understand what exactly it was though.

How can I determine the proper distance from the bottom of the 805 to the top of the 828?

I figured there was a reason Altec raised the multicells up so much. I like the idea of having the horns low, like Phil's are. With the parts I have right now, the horns will be about 2.5-3" above the 828 cabs. Do I need to raise this more?