Recent Projects

added April 2010

 

 

SONICS AS 331 1968

I picked up this pair of SONICS loudspeakers at an OP shop in Nambour (13th March 2009). I hadn't heard of this brand and the speakers looked very tired.

From the back it was clear that the cabinets were constructed from ply and they were stamped "Made in Japan"

I really was expecting to find a 3 way with perhaps some working drivers.

My feelings picked up noticing 5 ALNICO drivers in each box. Three tweeters a sealed mid and a 12in bass.

AND THEY ALL WORKED PERFECTLY

They sound incredibly sweet and detailed. VERY ALNICO. The bass is warm, tonal and nicely controlled. The mid and top are very musical and definitely have the ability to surprise

12in Bass shown above

horn supertweeter bottom left

The Walnut veneer has dramatically improved using Gilly Stephenson's Restoration wax

My Sonics speakers seem to be the AS-331s, they date back to 1968 ( I did think early 70's) There is actually quite a lot of info on the web.
The internal drivers are likely to be Coral.

http://www.audiokarma.org/forums/sho...d.php?t=142262

This link shows a US version with the grille off.

They really do sound very good indeed and they are very efficient

Pictures taken from this page show the front driver view

Added April 2010

Mine are actually quite different. Both bass and mid range have light brown coloured cones (concentric pattern on mid) The tweeter pair have black cones and square frames. The horn supertweeter appears to be the same as above

APRIL 2010

I have decided to rebuild my AS 331s. The veneer on one was pretty dry and a large piece has been missing since March 2009. The plan is simple.

I have opened them up, carefully removed all 10 drivers. Remove the glass fibre wadding, removed the front baffle, remove grille cloth and remaining veneer. Sand back repair defects, stain and treat with Danish oil.

Problems?

The front baffles are very difficult to remove. Half of the fixing screws were quite rusty, particularly the ones in hard to reach spots. I used WD40 which was really effective. The front cloths are held on with about 100 staples and many of these are quite corroded. On one speaker the twin tweeters appeared to be stuck in place and this took some time removing.

The veneer peeled off very quickly on all except the last surface. Here it appeared to be very fimly glued onto the ply. On one box the veneer had covered a dent filled with fibre glass. On the other one surface had quite bad cracking in the ply. It all required a lot of sanding.

I am still thinking about the final look but at the time of writing I am considering painting the front baffle a deep earth red soil tone to compliment the sandy coloured main drivers. Copper metal might look good. The main box will be stained and oiled to keep a more natural timber look. One side has a brilliant pattern which should look great.

With so many large paper cone drivers

I am thinking of making a protecting cover using a clear or smoky plastic. On when not in use and off for listening (with the idea that you can still see the drivers while they are protected)

sonics 12in bass superb deep dish

step one "after and before"

Note other alnico speakers in background

Working with the parts?

The front baffles were very dry. It is very difficult sanding the area around the tweeters because parts of the ply kept lifting. Working mainly by hand and going slowly obviously helps. At the start the various marks cuts and dents did not inspire much confidence. Things improve dramatically once you start using wood stain

I used a Wattyl "Nordic Pine" stain ( about 50:50 with mineral turps) The stain was rubbed in using steel wool. Colour uptake is dramatic, All the blemishes really add to the old world feel.

I really like the way the cabinets responded. Notice the chair rubber is a perfect way to protect one of the 4 tweeters during painting

This improved dramatically again once I used a single coat of Danish Oil.

The beading around the front has been replaced. These sections have been panel pinned onto PVA glue.

I loaded one of the baffles today (8th April 2010)

Wiring and fitting to the cabinets tomorrow

 

KEF C95 UniQ

I love finding old bits of stereo in junk and charity shops. I picked up a pair of very ordinary looking Technics speakers (labelled SB 55) at Lifeline ($4)

It was fairly difficult getting inside, 20+ rusty wood screws securing the back panel.

Each speaker contained an unusual looking 200mm single full range driver. (8 ohms 15W)

Somebody obviously went to some effort designing these!

The cones and surrounds are as new since the original speaker had a sealed front.

They are a genuine full range which simply sparkle with my 300B Single ended triodes.

The drivers now live in much stronger boxes. 35mm thick MDF with ply front baffle The fronts have metal guards (JAYCAR)

I love the dual concentric look