ERR Speakers for RS Commander Kits

John, did you mean to say the ERR 8 ohm speakers are louder instead of 4 ohm?

Pete

gunrunnerjohn posted:

I recently did a test of the old ERR 8 ohm speaker and enclosure against the new 3rd Rail ERR 16 ohm speaker and enclosure, and the results are in.

I'm not too surprised that the 4 ohm speaker has about 6db higher output from the same conditions.  I think it might be wise to go to the 4 ohm speakers for the new ERR stuff, many times the volume is somewhat marginal, it would be nice to maximize the potential.

I use a phone dB Meter app, and the phone and the speaker under test were placed about 6" apart in exactly the same orientation for each test.  The measurement was most noticeable with the whistle, I was using the small steam sound board in the tests.

Yes Norton is right. You first stated 8 ohm then 16 ohm and out of left field comes 4 ohm. 

So 4 ohms and how many watts?

Don’t worry about Watts first worry about the output impedance of the railsounds boards.  What were the boards designed for?   4, 8, 16?  I’m betting the 3rdrail 16 ohm ones are meant for two in parellel.  

Mismatching speaker impedance with the amps output impedance can cause damage.  Granted we are not talking a lot of watts here like a stereo but for the best sound that’s not distorted go with what the boards are designed to handle

Yes, I did mean 8 ohms, I was working on an MTH engine and had 4 ohms in my head.

I don't think the 16 ohm speaker is doing any damage, but 8 ohms would be a better choice, at least IMO.  You can always turn the volume down, but when you're at max, it's hard to turn it up!

In this thread from last week, Scott Mann explained the use of the 16 ohm speakers in the new kits.

https://ogrforum.com/...mmander-kit-received

Right Rich, note that I was a participant in that thread.  That doesn't remove the fact that you'll get maximum power transfer if you match the rated impedance of the amplifier to the speaker.  The audio board uses the LM4861M amplifier.  All the documentation suggests 8 ohms for the speaker.  A peek at the spec sheet tells you why that is.

At a load impedance of 8 ohms it will deliver 1.1W to the load.  At 16 ohms, that drops to around .7 watts.  Regardless of how you tweak the sound file, you aren't capable of delivering the same amount of power to the load as you aren't ideally impedance matched to the specifications of the part used.

Here's a link to the whole spec sheet: LM4861 Specification Sheet.

Thanks for the information and the explanation, John. So if 3rd Rail is going to be supplying 16 ohm speakers with their kits, is there a source for 8 ohm speakers that will fit in the enclosure?

A question worth exploring.   I suspect the same brand of speaker that's in the kit is available in 8 ohms as well.

Here you go: 40mm 8 ohm 3W Speaker, $5.61 for two.

FWIW, the old ERR RS Commander speaker is the same size, just 8 ohms instead of 16 ohms.

OK  So I am getting two ERR kits from 3rd Rail at the end of this month. I have the PRR Gp30 coal train and the Dummy unit. I wanted to have sound come out of the Dummy unit as well as the powered unit. I believe I read on this forum that I can swap out the 8 ohm speaker for the two 16 ohm speakers to have sound from one railsound unit come out of two speakers.

Bottom line question from the discussion above. IS it wise to spend for the two 8 ohm speakers and install in my Weaver models E8's [Each getting the ERR kit] and using the two 16 Ohm speakers for the GP30 Powered/dummy set?

You can indeed do that, just run a tether between the two units.  Make sure the speakers are in phase and they have baffles.  In this scenario, the speakers are in parallel to yield 8 ohm impedance.  A nice tether for stuff like this is the Minatronics stuff.