iPhone speakers for blasters

[themaninthesuitcase[Admin]]

An iPhone speaker? In a blaster? Madness surely? No, and you can blame model train people. I just stole it from them.

 

To an extent a speaker is a speaker is a speaker. There's a few things you need to know about. One is the impedance measured in ohms (Ω) and the other one is wattage.

 

When you drive the speaker most drivers will state what impedance they need, and how many watts they put out. So something like "4-8Ω 3W", which is what's on the driver I am using. You'll also find that most of these will put out more power, and so be louder, at the lower impedance so you want to shoot for 4 if you can. For this one it's 3W at 4ohms and only 1.8 at 8ohms.

 

So with that in mind on to the speaker. I am using a speaker for an iPhone 8 plus, but anything in the iPhone 5-8 range is all similar in size for a give phone class (e.g. normal vs the larger plus models). These came from AliExpress and are quite affordable, I got a 5 pack for £2.93 (with free postage as I made my order over £8 to qualify for choice).

 

I went with the bigger speaker as I have room, and in general bigger is better with speakers. If space is limited get a non-plus speaker and it will be around half the size but volume will probably suffer.

 

 

The specs on these online are sparse so first job is to work out what impedance these are. Using a multi meter over the 2 contacts (not photos sorry those pins are tiny and needs both hands) and I got about 8.7 ohms. This is DC resistance, which isn't the same as impedance but close enough. 8 ohm speakers.  We don't know what wattage they will take but the train people seem to drive them hard, but if yours blows up then sorry no warrantee here.

 

But we want 4ohms for maximum loud from our pew pew so how do we do that.  We use 2 speakers, and wire them in parallel. Thanks to physics 2 speakers (resistors) in parallel make a smaller one. I won't cover the maths but simply if you have 2 of the same resistance in parallel you halve the resistance. So our 8 ohm speakers will be one 4 ohm one once wired up.

 

Now on how to do it. If you've got a different speaker, you're on your own but basically join both of + sides together and both of the - sides together. None of of this is marked, so just join them "the same" on each. If you don't it will work but the speakers will be backwards to each other and sound awful and weak (they will be out of phase).

 

 

This is how I did it:

 

First the speakers have a few bits of plastic sticking out so those where trimmed with a pair of flush cutters.

 

 

This isn't 100% needed but makes the package tidier.

 

In order to parallel the speakers I decided to "piggy back them". So started by picking one speaker and bending out the contacts so they stuck straight out and so would fit over the side of the lower speaker.

 

 

I then stacked the speakers. Due to the shape I sandwiched in a bit of 1.5mm HIPS I had lying around to pack out the air gap.  With them carefully positioned so that the bent leg touched the unbent leg on the lower speaker, I applied a tiny bit of flux from a flux pen and tack soldered one side, then the same on the other side. Now things where stable I applied a little more solder to make the joint more solid. Care is needed here, these are small pins and you also don't want to cook the speaker by applying too much heat for too long.

 

 

To attach the leads I pre soldered (aka tinned) both the wire and the connections again with some flux. This means the join is just a case of holding the wire in place and re-heating which makes the whole process far easier, but was still fiddly. I did add a touch more solder but this is probably unnecessary.

 

 

At this point it's probably wise to test things. Hook it up make sure it works and sounds good. All okay, then you can move on. If not check things like you haven't created a short or melted the speaker by checking the resistance across the speaker if you have a meter, you're looking for something like 4-5 ohms of DC resistance.

 

Things work but are fragile so lets try add some strength.  First grab som 2-3mm heat shrink about 2-3cm long and slide it over the leads and slide it up close as you can whilst still being gentle.  Ideally use a heat gun to shrink this in a more controlled manor than a lighter.  Next we want to glue things in place to further strengthen things. You can use hot glue if you want, but this can be messy so I went with 8 year old E6000 as I had some left and seemed perfect for the job.

 

 

This looks messy but the E6000 self levelled quickly and looked a lot cleaner. We want to glue the contacts, and also the wire it's self so hopefully there will be no strain on the contacts.

 

Really you should now wait 12 hours or so for the glue to go off, but I am lazy and wanted it done.  The final step in adding strength is more heat shrink. I want to say this was in the region of 13mm dia but may have been more like 15mm. I just grabbed some the right size from my stash.  Cut a bit the right length to cover the whole assembly and shrink down again.

 

 

 

 

And you're all done.

 

Here is a comparison vs the typical 28mm speaker people generally use in blasters and lightsabres.

 

 

It's a a little bigger but I think the shape means it will fit inside a blaster a bit easier and be less awkward to mount. It also sounds significantly nicer.

 

 

[gmrhodes13[Staff]]

 Very nice, hadn't thought of using a mobile speaker, now who's Iphone can I procure