DIY Optimus (RCA) LX-5 Speaker mods on the cheap

Always in a quest for getting a little bit better sound out of the equipment that I have on hand – for as little money as possible – I turned to the internet looking for any advice on tweeking my speakers.

I have a pair of Radio Shack “RCA” branded Linaeum tweeter equipeed speakers. They used to be sold as “Optimus LX-5″ speakers from Radio Shack. with the name change they replaced the driver with a much better driver than the LX-5’s original driver – and thats about it.

These speakers sound pretty good, but have way too much upper bass emphasis. I found several tips online – one of which was to fill the speakers port hole with drinking straws.

I tried this, and did not notice enough of a difference to make it worthwhile.

So; I opted to add some mass to the drivers and to the speaker face to dampen unwanted resonance and also to add some poly-fil to the cabinet.

Adding polyfil to the cabinet, in laymans terms, essentialy makes the driver think that it is in a bigger box.

So, here is the speaker:


After popping off the grille you need to remove the rubber cups on the front panel and remove the four screws that hold the plastic front to the aluminum cabinet:


And, here is the inside of the cabinet as it was manufactured:


And the driver board:


First thing I did was to add some mass to the driver basket to reduce resonance.

I used Ideal brand “DuctSeal” which is available in one pound bricks, it is a non hardening putty designed to seal around air ducts, outside electrical boxes, etc.


I used it to smooth the transition between the basket and the magnet; and also on the basket itself.


then I tapped all over the driver board to listen for areas that resonated “wrong” and applied DuctSeal in the appropriate areas to eliminate the resonance.


Then I turned my attention to the cabinets themselves:


Following along with the straws inside of the port holes; I tried adding foam to the port holes as well:


But, these pieces of foam were promptly removed after the speakers were reassembled; as in my opinion it was just too much, and made the speakers sound far too “nasaly”

Having had sucess with my speakers; I turned my attention to the absolutely worthless Radio shack RCA branded subwoofer that I am using.

First off; I removed the driver:


Then to stiffen up the cone I “painted” it with “Mod Podge” – which is a sealant / glue / finish product that is available in most craft stores. One of its intended purposes is to “seal” jigsaw puzzles together after they have been assembled.


While the “Mod Podge” was drying I applied some DuctSeal to the subwoofers driver:


For the heck of it; I applied some Mod Podge to the cardboard tube in the subwoofers enclosure:


Then I also added some poly fill to the subwoofer enclosure. Typically this is not needed in subwoofers; but this subwoofer was exceptionally “honky” with an emphasis in the upper mid-bass.
My additional reasoning was that this subwoofer is only worth about $10.00; so even if I screw it up- no big deal.


And; reassembled:


The improvements gained by these modifications were nothing short of amazing.

These speakers sound like something easily costing two to three times what these speakers initially cost.
I noticed when I was working on them that I could probably notice even more of an improvement if I were to swap out the ferrite core inductor for an air core inductor and replace the caps with better quality caps.

That will probably be my final upgrade to these speakers before I ultimately upgrade to a better overall speaker.

All in all though; this took me about an hour start to finish and its like having a brand new system.
I would say that it was well worth it.

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