Hi folks. I did a comparison of the Knowles Dumbo speaker in various configurations plus a 16 x 30mm oval in a sealed enclosure. Video here: [video=youtube;p49RflBHfBE]http://www.youtube.com/watch?feature=player_detailpage&v=p49RflBHfBE[/video] The video should be self-explanatory, but for the record, the first segment is the Dumbo without a sealed enclosure (I built the sides, but left the back off); the second is a sealed enclosure that is 6mm deep, leaving an air chamber of 1.5mm behind the speaker; the third is a sealed enclosure where I built the enclosure 25mm wide, and offset the speaker to one side. This gives a much larger air chamber, and I think you will see it significantly improves the sound. The final segment is a 16 x 30mm oval in a sealed enclosure that is 8mm deep. My own view is that the Dumbo with the expanded air chamber is the best sounding of all, and even with the expanded enclosure, the overall dimensions are 15mm wide X 27mm long by 6.5mm high. Both enclosures are made mostly from .040 styrene; the "enlarged" enclosure uses 1/32 lead sheet (instead of styrene) for a bottom and the same lead sheet to seal off the top side of the enclosure (I did this to keep the overall depth down). But even the Dumbo with the smallest enclosure just surrounding the speaker with 6mm depth (overall depth is a bit over 7.5mm because the .040 base of the enclosure adds a bit under another 1.5 mm) sounds pretty good. The speakers are driven by a completely stock Tsunami TSU-750 heavy steam with all factory defaults - I haven't played around with any of the sound levels or the EQ. The Dumbo will almost certainly by my sound speaker of choice for future installs; I'll be putting them in my EM-1s, but my design probably will still require removing the circuit board because of the overall depth. John C.
Hi John, and thank you for taking the time to post your experiment. "Sounds" like the Dumbo with a proper enclosure blows the 1630 out of the water (and it's waterproof, too... I ordered several from Digikey over the weekend, so they should be here in a couple of days. Can't wait to try them. Can't beat the price, either... Regards, Otto K.
John, Great video showing the difference in enclosures. I really like the expanded chamber idea. Great work. Doug
Nice test, thank for sharing. May I ask what you use to glue the enclosure together and also to the speaker?
John, I have looked and listened to this video several times, but not until today when my order of speakers arrived did I realize how small these are. It looks to me that besides the EM-1s tender that they could be used in the Kato GS-4 tenders. These might even be small enough if one wished to add sound to a boxcar that it could be added there with a sound only decoder.
Roger, I have a question for you. Who is currently making an N scale sound only decoder? I have two old Soundtraxx DSX decoders that are pretty good. But I don't believe they make them anymore and the ones I have do not have a lot of sound options. I think I read, at some point, that Digitrax is making sound only decoders. Don't know for sure and would question the quality. Any insight would be appreciated, Carl
Digitrax makes a sound only decoder SFX004. Referred to as soundbug. I cant answer about quality as I have never used one, there SDN144PS is a sound and motor function decoder. not to bad for the buck. Biggest drawback is lack of back emf at least to me. Doug
Carl, I think you meant this question for John Colombo since I do not see any other "Rogers" participating in this discussion. To paraphrase the TV house hunting show, I am a Sound Decoder Virgin.
OK. Here is the EM-1 with a Tsunami Heavy Steam decoder and one of the Dumbo speakers in my "elongated" enclosure. [video=youtube;8aZ7d-KlxKc]http://www.youtube.com/watch?feature=player_detailpage&v=8aZ7d-KlxKc[/video] John C.
The EM-1 has an opening in the bottom of the tender. I think that is what you are asking, so I am not trying to pre-empted the answer from John. I am posting a comment because I have two of the locomotive also and in off line discuss I learned some people think that Bachmann put a hole in the bottom of the tender as preparation for further release of the locomotive.
I drilled about 30 holes in the coal load with a #70 drill bit. There is a hole in the bottom of the tender for a 15mm round speaker, but mine is mounted below the coal load, so I used holes in the load for sound egress. John C.
Thanks for posting the videos, great comparison and a plug for enclosures. I will have to try one of these in my next Soundlok install. About the Digitrax SDN144PS- I used one on a MP 4-6-2 Pacific in a Bachmann tender and it's an easy install. The sound files they come loaded with are their weak point for me. I think the unit is capable of better sound than it currently has available. Maybe some work by a good sound guy to get new files?
For those interested. I had an e-mail from Digi Key today stating that the Knowles Dumbo speaker is going away. No more production. That chews. Carl
