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Post by nebrzephyr on Aug 28, 2014 12:00:34 GMT -8
So, was wondering if any forum member has added sound to the recent Athearn RTR SD45 "sound ready" chassis. The chassis has a place to mount a speaker in the rear weight, a Soundtraxx 810113 dimension wise fits perfect. But here's the question. The speaker "box" in the weight has a solid bottom so if you mount the speaker so it fits, the speaker cone is facing into the solid metal box.
Does this make sense? And you can not easily mount the speaker into the chassis with the cone facing up, it would require building an encloser. It would seem that having the speaker cone facing into the solid metal box would not provide very good sound. But I'm not an expert on sound so was looking for input from forum members more knowledgeable. Not sure what Athearn had in mind on this.
Thanks. Bob
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Post by edwardsutorik on Aug 28, 2014 13:48:48 GMT -8
Speakers have a natural oscillation frequency. That means that when any part of the sound that is being reproduced happens in that range, it is reproduced much louder than the other frequencies--distortion. A way to minimize this is with an enclosure. It damps the vibrations at the natural frequency. In the case of the Athearn mounting, the enclosure is created by the weight that the speaker is facing. You will note there is a gasket to eliminate air leakage from the enclosure space. The smaller the enclosure volume, the more damped the speaker cone.
I am enamored with the idea of clamping two speakers together, face to face. This will have the same effect, except that there will be two emitting speakers. But you don't have a normal enclosure taking up space.
Ed
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Post by bdhicks on Aug 28, 2014 17:18:03 GMT -8
A speaker will create sound off of both sides of the speaker cone, so mounting them with the front out vs the back doesn't make much of a difference. Since the back is moving in when the front is moving out and vice-versa, the sounds from the front and back will tend to cancel each other out if you hear them together, which is why it is important to use sealed enclosure to isolate one side.
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Post by nebrzephyr on Aug 29, 2014 5:22:34 GMT -8
OK. Thanks for the feedback. Here's a couple photos. I'm assuming if I mount the speaker cone down I would still need to build an enclosure for the back of the speaker that is exposed. Valid assumption??
Thanks. Bob
OK...forum error on attempting to add photos, something about forum has exceeded it allowed space.
"Error: This forum has exceeded its attachment space limit. Your file cannot be uploaded."
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Post by edwardsutorik on Aug 29, 2014 6:33:31 GMT -8
I'm assuming if I mount the speaker cone down I would still need to build an enclosure for the back of the speaker that is exposed. Valid assumption?? The speaker will make better quality sound if the natural resonance frequency is damped. An enclosure on either face of the speaker will do that. The extent of the damping will be increased by having a smaller enclosure and by making the sides of the enclosure more rigid. Athearn appears to have gone this route. Ed
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Post by nebrzephyr on Aug 30, 2014 7:06:22 GMT -8
A quick update on this. There is only .020 clearance in width between the speaker weight and the SD45 shell. Which means if you use the Soundtraxx #810113 speaker, which the frame looks to be designed for, you can not enclose the rear of the speaker with a styrene enclosure. Or at least no way I can figure out. It will be interesting to see what Athearn comes up with if they every announce their own speaker solution. Since they work with Soundtraxx on the decoder I would think they also worked with them on the speaker situation, thus the perfect fit of the #810113 in the sound "cavity". Bob
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Post by NS4122 on Aug 30, 2014 10:24:54 GMT -8
A quick update on this. There is only .020 clearance in width between the speaker weight and the SD45 shell. Which means if you use the Soundtraxx #810113 speaker, which the frame looks to be designed for, you can not enclose the rear of the speaker with a styrene enclosure. Or at least no way I can figure out. It will be interesting to see what Athearn comes up with if they every announce their own speaker solution. Since they work with Soundtraxx on the decoder I would think they also worked with them on the speaker situation, thus the perfect fit of the #810113 in the sound "cavity". Bob Are you sure you have a "sound ready" unit? It was my understanding that the newly announced Athearn SD-40 was going to be their first RTR unit to have a sound ready chassis. I have found no reference to SD-45's having those chassis. Since all of the Athearn sound installations I have ever seen use a 28mm round speaker, the use of the 810113 small oval would be a radical departure. The small oval would however be used on RTR units without a factory speaker mount. If possible could you try again to post a (low res) photo?
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Post by Donnell Wells on Aug 30, 2014 10:25:19 GMT -8
OK. Thanks for the feedback. Here's a couple photos. I'm assuming if I mount the speaker cone down I would still need to build an enclosure for the back of the speaker that is exposed. Valid assumption?? Thanks. Bob OK...forum error on attempting to add photos, something about forum has exceeded it allowed space. "Error: This forum has exceeded its attachment space limit. Your file cannot be uploaded."
Hello Bob,
I found out that each Proboards forum only gets 200 megabytes of attachment file storage space. I purchased 500MB so we should be okay to continue posting attachments. The only other way to post pictures is to upload them to a photo hosting site and then "hot link" them here.
Donnell
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Deleted
Deleted Member
Posts: 0
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Post by Deleted on Aug 30, 2014 11:14:05 GMT -8
The latest run of the RTR SD45's have the sound ready chassis. I have 2 right now on my workbench. The enclosure replaces the weight that cantilevers out over the rear truck. The whole thing unscrews and I am replacing it with Railmaster speaker/enclosure combo.
Keith Turley Monrovia, California
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Post by nebrzephyr on Aug 31, 2014 6:13:12 GMT -8
OK...here's the photos of the "Sound Ready" SD45 sound cavity in the rear weight. Again, that weight only has .020 clearance on the side between the weight and the shell. Bob
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Post by canrailfan on Sept 1, 2014 17:36:40 GMT -8
Hi Bob,
If you fasten the speaker on the weight as in your picture, you do not need to build an enclosure. You've 'enclosed' the front of the speaker which will work the same as a built-up enclosure on the back.
Run a fine bead of silicone sealant around the lip of the cavity in the weight before setting the speaker in place to make sure there is no air leakage. Also make sure the mounting holes of the speaker are closed, either by the mounting screws or with some silicone sealant.
If the speaker you have is too high and doesn't allow the shell to sit down properly, look for a thinner speaker of the same length and width. They come as thin as 4.2 mm (about 3/16"). Turn the speaker 180 degrees from the one pictured so the wires from the terminals don't have to cross over the top of the speaker.
Hope this helps.
David
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Post by ssw on Sept 1, 2014 19:06:08 GMT -8
I have one of these, an SSW one (go figure) and have been kicking around dropping a Loksound with railmaster speaker in there... Which speaker should I use to fit? I haven't cracked it open to measure yet.
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Post by grabbem88 on Sept 2, 2014 8:12:46 GMT -8
If you have the mount use a 15x35
If not you'll either have to cut weight or remove it all together if you use a railmaster 14x36-8
Or get some zimo 11x15's sugar cubes
If you go loksound get there 645e3 file way better than there early 645 file that's 4-5 yrs old
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