Very transparent sound!

[pqrannes]

Look at these little speakers I found at the scout's weekly garage sale last week. They are obvious homemade, not with the best finish (the veneer is coming of), but the connectors on the back gave them away. Normally average Danish speakers of the 70s and 80s came with unremovable cords.

The front came of quite easy and revealed a baffle (?) out of plexi-glass. And since the x-over visible thru the glass looked kind of well size and they didn’t sound that bad tested at the garage sale I got them for about 2.50 USD.

At home they turned out have Peerless woofer/midrange units and the thickness of the plexi-glass was about 0.30 inch. And they sounded just marvellous with small amps (both my Braun tube amp and a little Sansui QR-1500 sitting here in my office). Even better than a really nice pair of Dynaco (Scandyna) A-10 I’ve got.

The speakers measure about 38 x 24 x 18 cm (15 x 9.5 x 7 inches).

My question for you AK’s is thus: is the any sonic reason for using plexi-glass for the baffle?

Tomorrow the scout’s garage sale in on again. And this time is the first after the monthly public collection so I can hardly sleep to night. By the way here is a list (out of memory) of the more interestin stuff I’ve found at the scouts within the last 1½ year, all for less than 10 usd each:
• Pioneer RT-707 (r2r)
• Pioneer RT-909 (r2r)
• AR-6’s (speakers)
• The Fisher 800-T (receiver)
• Sansui au-101 (small amp)
• Connaisseur BD2 (TT)

Peter, Denmark

 

[ManFromPorlock]

That's interesting. I'd expect the plexiglass to flex, so when the speaker cone moved forward, the baffle would move back because the speaker body is mounted to it. That would decrease the volume behind the baffle just as the forward motion of the cone was increasing it... hmm. You'd end up with a large amplitude compression wave in front of the speaker and a smaller amplitude rarefaction wave in front of the baffle. That might just be an interesting way to minimize the speaker's rear output.

On the other hand, the guy who made it probably just wanted to look at the guts of the thing in action.

 

[outlawmws]

If it was a factory job, I'd expect that to be a floor demo unit to show the guts to potential customers.

Maybe some homeowners saw a set and wanted his own?

 

[pqrannes]

Thx.
From my non-technical point of view this plexiglass plate will not flex. It is rather thick. And the idea of it being a copy of demo model is interesting but the speakers actually had a normal tissue covered front. Strange.

I didn't find anything at the scouts tonight. A small Tandberg R2R for a friend who can't hear his old tapes since his own Tandberg doesn't work.

I left a two pairs of Beovox (B&O) 1700 bookshelf speakers behind, they looked and sounded (I checked them out) ok but there are so many speakers out there! Maybe I'll get them next time.

Peter, Denmark