DIY Round 4.1..
5.25" speaker adapters.
In the last post we spoke about some available options that could be readily purchased. This post concentrates only on DIY options and some tips.
1 - Modify the Stern stock speaker plates. All you have to do is remove the plates, cut off the 2 studs that held the 4" speaker on. Then drill new holes for the 5.25" mounting. Install some 6-32 machine screws, reinstall the plates and you are ready to mount up some flush mount speakers. You'll need a dremmel, drill and some drill bits.
Tips: You will need a 9/64 drill bit to drill the holes for the 6-32 screws. Once you drill the holes in the plate install the 4 screws and run a nylock nuts down to the plate to lock them in(you will not need washers). You do not need to worry about the bolt heads on the front of the plate as they will push into the speaker foam. Use black machine screws if you can find them, if not use a sharpie on the bolt heads so you will not see them through the foam.
If you really want to be precise, then make a small 1 to 1 drill template that you can print out and align using the current two studs before cutting them off.
2 - You can design and make your own adapters. This will take way more time than it maybe worth. But if you want to tinker and have the skills then it's not so bad. You can 3D print it, make it out of wood, machine it out of aluminum, use foam core like shown in a previous post. How you make it depends on the methods you have access to and feel comfortable using.
Tips: Try to use 6-32 machine screws in your design. This will keep everything consistent with everything else on the machine and be easily servicable by the same size nut driver used on everything else.
3 - If you have a 3D printer you can print your own using 1 of the 2 designs on Thingiverse. Which design may depend on the speakers you want to use.
Tips: Be ready to drill out the bolt holes with a 9/64 drill bit for 6-32 screws. Every printer prints a little different and odds are high the holes will be undersized. Make a trip to the hardware store after you print the adapters not before. This will save you from having to go to the hardware store twice(like I did). Have some silicone handy or even hot glue to close up air gaps. (see below)
I started by printing one of the adapters on thingiverse as I thought it would be the most common choice. However; it didn't take long to see there was a fundemental flaw with the design. Then with some googling and looking at other vendors selling adapters and full.speaker kits, I was like holy crap they are all making the most basic design errors.
Let me explain - speakers make noise by creating air pressure waves. As the speaker cone moves forward the air infront of the cone creates a high pressure zone, while the air behind the cone creates a low pressure zone. When those two zones are allowed to mix the result is noise cancelation. This is why a speaker sounds so much different when it's in an enclosure versus just sitting commando on a desk. You lose almost all low end, it becomes very muffled and you lose tons of sound volume/decibals too. In order to get the most out of your speakers you don't want these two air pressure zones mixing with each other.
All the adapters I have seen, all have big gaps allowing the front and back air pressure zones to mingle and create noise cancelation.(See Pictures) To resolve this be ready to use silicone or hot glue to close up these gaps.
So what am I going to do? I don't like the idea of sealing my speakers up with goop. Mainly because it's not conducive to swapping in and out speakers for testing. Instead I'm going to bang my head against the wall and design a better adapter. One that will stop the air mixing and also be able to mount the JBL/Infinity Plus-One speaker designs.
I'll post what I come up with next.
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