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Old Jun 09, 2015, 10:46 AM
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Andrew, what is the ETA for the bass transducer back in stock?
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Old Jun 09, 2015, 11:48 AM
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Nice Camel!

Been wondering about attaching the TT-25s to the inside of a fiberglass cowl as well. Same concerned about the mounting screws. So far been just too chicken to try it.
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Old Jun 12, 2015, 07:41 AM
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I will start posting my installation pics here as it seems like folks have the same questions. The Camel is unique because I will be using all three types of speakers: two MaxSPL 2", one TT-25, and one bass transducer. I need the ballast, so weight is not an issue.
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Old Jun 12, 2015, 06:00 PM
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Thanks Tony! Sorry I have been absent for a couple of days. Lots going on here.

Andrew
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Old Jun 15, 2015, 01:29 AM
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Max 2 sealed enclosure with port, 3 questions.

Quote:
Originally Posted by Dpetsel View Post
It would be hard to calculate the length of the tube to tune the port because the actual volume of the interior space of the plane is unknown.

... If you want to experiment, put the speaker in a small cardboard box that is sealed and cut a small 3/4 inch hole in the front surface about an inch away. You immediately see an increase in volume and if you put a small tube in the hole you are increasing the distance the sound wave has to travel to exit the box.

The only down side would be an interior volume too small to allow the wave to exit the space in sync with the motion of the cone, cancelling out the forward wave and decreasing volume. It's not a tremendous increase in sound but it does increase the low frequencies a bit.
I'm mounting a couple of Max2 speakers in a 1/4 scale J-3 Piper. This is a gas-electric conversion so the plane was built *extremely* solid. The fuse from the firewall to the front of the cabin is 1/4" plywood for the bottom and the sides plus sheeting on the curved top..

Even though the cubic inch area in this space is huge it's actually very inconvenient to work with. I'm cutting a hatch in the bottom to access items inside the space, but it's reeeeally hard to deal with because it's not as if I can fit my two whole hand inside it to work. Well, they might fit through the hatch opening but by then the hole is filled and I can' see inside. But it'll work.

I would like to build a -real- speaker enclosure, with a correct sized port, to get the bass sound from the speaker because with its 2" size that's it's only major limitation.

I then intend to mount that enclosure box on the hatch door itself, and mount the sound board on the back side of the speaker enclosure. Obviously this will be a pretty heavy item so I'll mount it to the fuse with about 6 #6 screws with blind nuts.

Q1: So the QUESTION is what volume in ci should I aim for for the speaker? One calculator I found online asks for the resonant frequency, the Qes, and the EBP of the speaker. (I don't even know what those acronyms mean and even if I looked them up I wouldn't know how to guesstimate appropriate values for a given random 2" speaker.)

Q2: Another Q. Is is better to make two separate enclosures, one for each speaker, and a port for each, or to put both speakers in one box with one port? As regards construction it works out almost the same way. The way I'd build two enclosures would be for them to be right next to each other with a 1/4" plywood divider between them. It's almost the same to make it a single box and leave out the divider -if- it's a good thing to do.

Q3: My ONLY concern about this whole idea is that I know that the speakers get hot. The purpose of the holes in the plastic case is to let the sound out -and- let the heat out. If I build a sealed enclosure with a port I'm -assuming- that the air moving out/in the port should bring in enough new air to not let the speakers overheat. The Q is, am I kidding myself, I can't do anything like this because the speakers -will- overheat unless they have a ton of air circulating around them?

Any clues?
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Last edited by jbarchuk; Jun 15, 2015 at 02:07 AM.
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Old Jun 15, 2015, 08:10 AM
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1/4 Scale Electric Cub Sound Install

Here are my pics of the speakers installed on the Hangar 9 1/4 scale Super Cub. Some scale-looking vents are cut on the bottom, and this provides ample sound in the air. It worked out awesome, and the speakers are just mounted with zip ties!

Note: The zip tie on the sound card IS NOT TIGHT! It is just snugged up so the card stays on velcro mounted on the back of the card.
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Old Jun 15, 2015, 10:49 AM
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Quote:
Originally Posted by tclaridge View Post
Here are my pics of the speakers installed on the Hangar 9 1/4 scale Super Cub.
Very good clues!! I hadn't thought about mounting it in the cowl because I don't -have- a cowl yet. LOL!! I bought this used and a couple of parts were missing. It's about 25 years old. For example the wing struts were wood, one was cracked, so I need to make them from scratch with CF and aluminum fairing.

I can't get a cowl easily from fiberglassspecialties because no one has been able to exactly identify the original kit manufacturer. There are about 4 cowls that are close in size and 2 that are closest but I still haven't picked one yet.

I also hesitate to mount the speakers in the cowl because of -pressure- and -vibration-. Yes fiberglass is strong but also flexible. You should keep an eye on the where the cowl mounts to the firewall. Probably screws through holes in the cowl. If a slight crack starts it'll just keep traveling. A wood box enclosure weighs a ton more but can easily stand up to the stress.
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