Restoring Avance Concrete 180

Final result 1

Retro look, good sound, and bringing a great speaker to life again

Decided that we need some music in our living room. We have a separate listening room / home theater, so what we need is just to be able to play a little music from Spotify etc.

I had a small dream of doing some retro, and restoring an old classic or something, which looked cool and play ok.

A month ago I saw an add, to pick up a pair of Avance Concrete 180 speakers, for 25 Euro. They looked ok, but the foam surrounds on the woofers where completely disintegrated after some years of storage. The guy said that they played well before storing them, so I gambled that it was only a matter og changing the foam to get them to life again.

Avance Concrete 180 is a Danish speaker from around 1975, and features a heavy concrete fiber enclosure. The drivers are Danish as well, with a 3/4 inch ScanSpeak tweeter (D2008/851200) and a set of Vifa M21WO-19 and M21WO passive radiators. Not a bad starting point for a good quality speaker.

After dragging the speakers down from and 5’th floor apartment (no lift) and home, I of course tested them out immediately just hooking them up to an amp and playing something quietly through them. Both worked fine, though of course no surrounds on a woofer means no bass … but they moved at least :)   One of the speakers actually had the surround still, but with a lot of cracks and looked as it would crumble to dust if touched.

The enclosure and grill also looked to need some care to come to shine again.
I ordered new surround from …… very helpful guy ringing the shop, and was able to get factory new surrounds for all 4 woofers.

Changing the foam is not that difficult, but needs care and patience. getting the old foam off is a sticky business. The last bits can be removed with alcohol.

I decided to give the cones a very thin layer of black spray paint to make them shine again. Think that was a good idea, with a super nice result.

Knocking on the enclosure has some ringing to it (as do all enclosures) and I decided to try and dampen this some with some heavy rubber/asphalt sheets used in cars to dampen doors and other.

I had to flatten the inside, before gluing with “No more nails”, The sheets come with self adhesive, but I don’t really trust this so chose to use real glue.

The enclosures got two layers of new paint (oil based) and now look brand new.

The filters are well build and I only chose to change an old electrolytic capacitor 10uF for 3 x 3.3 uF MKT in parallel. Also changed the wiring to 2.5 mm2 using relatively cheap professional cable (I don’t believe in all the cable hype, but more copper means less loss which is of course a proven fact … so I go for more copper :) ), and I changed the terminals from plain banana plugs to proff Speakon (which is just really good and reliable connectors …. again no hype just plain science and quality), and with Speakon you’ll have a very low risk of making any unfortunate short circuit of the amp :)

Lastly I changed the fabric on the front grills.


So was it worth the trouble. For sure. I think the sound is quite good, open and well defined. There are no sharp edges with this speaker, you could say it’s a bit polite. But nothing is really missing. The bass is not really deep, but it’s there and a bit of EQ will help the lowest octave. The mid is nice and open, but not as forward as on a lot of newer speakers. I guess this is the result of having a 21 cm woofer do all the mid. But again nothing is really missing. The treble is good and detailed, and room definition is ok.

For a speaker which is almost 30 years old, I think it is a super good result, and will for sure get the music into our living room.

Also great to bring such a nice speaker back to life.