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I was asked if I could come up with activity for our young men youth group to teach them about sound/speakers. To hopefully peak their interest in sound and an interest in building something.

I was thinking of building an SLA with this driver: https://www.parts-express.com/fountek-f ... m--299-022
But I wanted to set up some toggle switches to show them the coupling effect of 1 to 2 speakers, 2 to 4, and 3 to 6 speakers increase Db output.

I am not sure how I can wire it to have the switches turn on the desired speakers if they are wired in series/parallel.

I am open to suggestions or alternate/less expensive drivers. We have about 15 young men in our group, I hope to peak their interest enough to have them want to build a pair of powered bookshelf speakers for their computers or have a portable powered boom box.

I don't know if Bill has a Student Discount on SLA plans if a few want to build a pair full 6 speaker SLA's

Thanks in advance,

Oscar

Since the group would not be building them for commercial purposes you'd only need to buy one set of plans for all of them. With the series/parallel wiring it would be pretty complicated to switch all those drivers, and you wouldn't get an accurate result anyway, as any unused drivers would act as passive radiators, messing up the result.

But, if funds permit, you could build several different models, in the various permutations, and compare the results that way. If you have a half dozen students, each could build their own. Just an idea.

Thanks Bill,

If I were to isolate each driver with a divider and run them in parallel, would the increase in Db be noticeable? Would that be a more accurate way to show results of coupling? I know SQ wise it won't be great, I just want to let them hear how coupling drivers increases loudness with the same power. This would just be for show and teaching example.

We are going to also show them a lunch box boombox.

Thanks again Bill

If you divide them the whole is equal to the sum of the parts, so that would work, except for the parallel part, assuming you don't have a 1 ohm capable amp.

Would it work to stack absorbing foam blocks in font of each driver you want to "turn off" so they stay in the electrical load as wired but you acoustically "turn them on" by removing each block ?

Bill Fitzmaurice wrote:If you divide them the whole is equal to the sum of the parts, so that would work, except for the parallel part, assuming you don't have a 1 ohm capable amp.

Maybe I will just run 3 and 6 speakers and keep it simple.

dswpro wrote:Would it work to stack absorbing foam blocks in font of each driver you want to "turn off" so they stay in the electrical load as wired but you acoustically "turn them on" by removing each block ?

That is an interesting idea. I will look into that

Thanks

Foam blocks would only stop sound if they were solid, not porous.

Just a thought... you could build one of them bringing each set of speaker wires to the outside of the cab on a terminal strip or banana plugs, or something similar. That would let you demonstrate the various wiring outside the cab to "experiment" With different configurations, and then just change out the backplate for a standard one when you're done.

Bill Fitzmaurice wrote:Since the group would not be building them for commercial purposes you'd only need to buy one set of plans for all of them. With the series/parallel wiring it would be pretty complicated to switch all those drivers, and you wouldn't get an accurate result anyway, as any unused drivers would act as passive radiators, messing up the result.

Perhaps a switching arrangement with a multi pole switch so when the speaker is switched off, it also applies a dead short across the voice coil. This would considerably limit the ability for the driver to act as a passive radiator.

*pique


I like the idea of teaching the young men something about speakers.