Author Topic: Speakers: Series vs. Parallel  (Read 847 times)

Michael Larson

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Speakers: Series vs. Parallel
« on: November 26, 2021, 03:19:46 PM »
Over time there has been fair amount of talk here about which way is best to wire a pair of speakers.  I think the best answer is that it is pretty much subjective; what sounds good to one may not to another.  For each of us, I think we should hear the difference for ourselves to make an informed decision.

I am not a fan of making and breaking connections of wires when I'm trying to determine which method is best, I find it slow and clumsy and it distracts me from the intended task.  I want a way that will allow me to instantly switch between the two.  Enter the DPDT toggle.  The following schematic shows how to wire a DPDT switch to allow switching between series and parallel connections:

Series-Parallel Speaker Selector.PNG

While not shown as such in the schematic, I have decided the safest choice of toggle is a center-off function.  I can theorize that a toggle is break-before-make, but in an abundance of caution I know that a center-off toggle is absolutely BBM.  If a make-before-break switch is used it will short the speaker output of the decoder, and even if it is only for a fraction of a second, we don't want that!

In the interest of making this as easy as possible to deploy, here is a PCB layout I put together.

Top:
Speaker Series-Parallel Selector Top.png

Bottom:
Speaker Series-Parallel Selector Bottom.png

I plan on building one for my workbench.  If anyone else is interested please let me know.  Bare PCB's are cheap ($2 + shipping), assembled is a bit more due to the cost of the toggle switch ($10 + shipping).  I am not making any profit on these, the quoted prices are what they cost me for parts.  If you are inclined to want to print your own boards, I have attached the Gerber files for you.

Michael
Michael Larson
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Re: Speakers: Series vs. Parallel
« Reply #1 on: November 27, 2021, 09:28:26 PM »
Nice idea for testing new speakers to get a basic idea about them before installing them.

You may want to look at expanding this idea and make the series vs parallel board part of a simple LM tester board, like this but much much neater and probably compact: https://rpug.pdc.ca/index.php/topic,549.0.html

- Tim




Michael Larson

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Re: Speakers: Series vs. Parallel
« Reply #2 on: November 27, 2021, 10:26:25 PM »
You may want to look at expanding this idea and make the series vs parallel board part of a simple LM tester board, like this but much much neater and probably compact: https://rpug.pdc.ca/index.php/topic,549.0.html

- Tim

Tim,

I appreciate the suggestion.  I had thought of that and am formulating a plan now.  I envision a board that can be used to test DCC decoders as well as RP modules, since I have both.  I've looked at the commercially available DCC testers and haven't seen one yet that looks like it could easily be adapted for an RP module.  I'm thinking about including an 8 pin NMRA (backward compatibility), a 9 pin, and a 21 pin connector with additional connectors (including 6 pin) for various other functions based on manufacturer specs.  Other suggestions are welcome.  Now to do some research...

Michael
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Re: Speakers: Series vs. Parallel
« Reply #3 on: March 20, 2022, 02:04:55 PM »
When you do your comparision, you really need to compare SPL's too.

I would suggest putting a pot in one of the positions so your comparison will be apples to apples.

Different amplifiers work different ways, and I don't know if the Ring hardware is analog or digital (the sound amp).

Normally, the parallel configuration will draw more current and thus the SPL will be "louder" in that configuration, so I would put a volume pot in that configuration, but you may have to experiment.

(also harmonic distortion should roughly double, so the "quality" should be less)

Greg
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