LS3/5A DIY Challenge Part 2

I choose brass screws and nuts (#10 for HF units/crossover stands/cabinet faceplate. #9 for LF unit) since they are non-magnetic and cause less problem when you assemble the cabinet where the very strong magnets are nearby. It doesn't mean it will sound better and indeed the golden colour of the screws are very match with the cabinet.

Original design of LS3/5A uses rubber gasket to seal the LF unit with the faceplate and the faceplate to the cabinet. I choose to use the cork sheet to serve these purposes.  I stick 1mm cork sheet to the back of the faceplate and it's not only seal all the air gaps but also reduce the reflection of the sound wave from the faceplate.

Work in progress

The most difficult part in making the cabinet is the countersink of the faceplate.  I need to tailor-make a circle guide for my router so I can make a perfect circle.

For the sake of convenience, I choose to use Pink Fiberglas Insulation as the acoustic material in cabinet.  It also doesn't mean it sounds better ether.  However, many people say, and fiberglass insulation is better. If you have the LS3/5A, you can try by yourself. May be one day I can find the wool insulation in Canada and try it out. It is the premium stuff for heritage house and were used in some old loudspeakers during 1940s.

Assembling the units are very straight forward and easy except your metal tools may always stick to the big magnets. Just one suggestion, using tape to cover the spider of the LF unit before soldering the wire.  The hot solder will jump into the spider and melt the cone. Be careful.

First thing to do after the assembling is check the resistance of the output and make sure there is no short circuit.  Before any further measurement, I connect the LS3/5A to my Roberts amp (aka Akai M7) and listen to my favourite music. What a surprise!  The 7W little amp can actually handle the LS3/5A very very well. ...................

The soundtrack was a live recording and recorded by Tascam IM2 in my listening room.

The below is the measurement of the frequency responses between two speakers see if they are well matched.

 

And here is the comparison between Celestion SL6s and the DIY LS35A.  The peak in the graph is caused by the source (the test disc) and I may use my signal generator to test the speaker again in later time.