Speaker Question

[nssd70m2]

My next step in my MTH SD70M-2 sound installation is the speaker, only I am unsure of what my best option is. I can either install two 28mm round speakers in the fuel tank cutouts provided, which would probably be the loudest option, or I could fit a small rectangular high-bass speaker underneath the radiator section. I really love the sound of the high-bass speakers, I just don't know how the smaller ones would sound. I was thinking something along the lines of this bad boy... www.ebay.com/itm/Railmaster-DS1436-8-Bass-Reflex-Speaker-DS1436-8-YANKEEDABBLER-/310549094502?pt=Model_RR_Trains&hash=item484e2b2066

[diesellou]

I'd go with one round speaker in the fuel tank, and the other rectangular high-bass speaker within the shell. That will give the sound you would like.

[Mark R.]

Regardless of all the hype, a round speaker is much more efficient than a rectangular speaker. Two 16mm round seakers are ten times more efficient than a single 16mm X 32mm speaker.

A round speaker has equal cone length from the coil to the frame. A rectangular speaker has very little cone surface between the coil and the sides in comparison to the ends. Therefore the coil is trying to move a cone with unequal tensions. It's efficiency is going to be restricted by the narrowest distance between the coil and the frame - which is the width. So really, the 16mm X 32mm isn't going to be much more efficient than a single 16mm round speaker.

High bass .... bass reflex .... tuned port - in a speaker you can hide in your hand ? Being somewhat of an audiophile, I always chuckle whenever I see those terms used for a speaker that can't even begin to attempt to reproduce bass frequencies. Look at the specifications of any of the small speakers. Those "high bass" might generate one octive lower frequency in the mid-range band than another, but I challenge you to actually hear the difference.

What makes the speaker sound richer is the enclosure it is in - not so much the speaker itself. The two biggest problems are the fact the enclosures (sealed airtight) are never big enough. By the time you cram the speaker in that little box, there's almost no air space inside. On average, an enclosure needs to be twice the size we are given. The second problem is the fact we are dealing with plastic - which picks up an awful resonance from sound waves - then to make matters worse, we put the speaker in a plastic box ! How do you think your home stereo speakers would sound if you mounted them in a plastic tote box ?

I've done some experimenting using wood and sheet lead for enclosures, and the results are very promising. As for the size of the enclosure, instead of trying to cram the largest mis-shapen speaker in the shell you can with a way too small enclosure, I've found a smaller round speaker with a larger enclosure made from a non-resonant material to give much superior results. Yes, bigger is better - but the design is just as important.

I recently installed a single 16mm round speaker in a switcher for a customer and mounted it to a 5/8" deep sealed enclosure. He was blown away by the sound (I was actually quite surprised myself). Varying the depth of the enclosure will greatly vary the sound. Lots of experimentation will yield the optimum enclosure size.


Mark.

[nssd70m2]

Hmm. Interesting. Looks like I'll go with the fuel tank option and see what I can do to seal up the enclosure. Thanks!