New acquisition- Bizarre jvc magneplanar speakers

[VA50]

I made a post some years back about a set of JVC fs-100 speakers some family members of mine had me help drag out of storage and set up for them. They have always been under the impression that they were electrostatic speakers since thats what the salesmen told them back when they purchased them sometime around 1982-84. They were identified in my last thread as a magneplanar style design, Jvc refers to them as dyna-flat drivers.   They are currently in the process of packing up and moving interstate and the speakers were offered to me, i gladly accepted the offer and picked them up. They found the original owners manual while packing which is a bonus.

 

They are going to need some work. The veneer is peeling, cloth grills are ragged and the crossovers no doubt at this age could do with a freshen up, all things i will treat them to. Last time i heard them they were being powered by a very poorly sherwood amplifier. I've only given them a brief listen since picking them up, driving them with my marantz 2270. Very interesting sound, clear and highly detailed floaty highs and a fat midrange. The bipolar design gives them an incredible sound stage that is very 3 dimensional, directionality is almost non existent. They make acoustic guitars sit forward in the mix with a  live sound to them, almost as if they are being played in the room with you. There isn't much bass present which i expected, will be interesting to hear how they pair up with a subwoofer.

 

Now that is have them i've been able to pull the front grills off and get a look, very interesting bit of tech that i imagine would have cost a lot in their day.  

Edited February 19, 2019 by VA50

[andyr]

As you say, VA50 ... a very interesting - and rare - piece of kit. 

 

Whether they are a 'magneplanar design' or something different ... I can't tell from the pics.  But no way are they a 'Magnepan design (the mfr normally associated with 'magneplanar design').

 

The 'Specifications' heading says there are:

• 8x woofers
• 4x mids, and
• 1x tweeter.

Your 1st pic shows that:

• the top 4, 8x12 drivers make up the mid driver,
• the below 8, 8x12 drivers make up the woofer,
• and then there is a tweeter at the top.

If you can work out what the XO schematic is (from following all the wires), I should be able to sim this and tell you what the XO points are, between bass & mid, and mid & tweeter.  This will help you rebuild the XO with some decent quality parts - also, I suggest, it would be worth replacing the wiring. 

 

Andy

 

 

 

[VA50]

I agree about them being nothing like magnapans. The design is odd, i have no experience with electrostatic and magnapan speakers period. From the photos i've seen on planar speaker designs these are again different but seem to employ the same sort of concept. Each driver consists of 10 suspended rectangle magnets, the diaphragm is molded so it floats around these magnets then on the outside (frontside) of the diaphragm is a coil that wraps around each of the molded sections on the diaphragm. The whole plastic diaphragm is then suspended by a woven fabric surround. To me they're like a hybrid between a planar and a conventional speaker. 

 

As for the crossovers they are a really basic. The first step will be replacing the capacitors, they currently have a pair of old electrolytic bipolars in them. Ideally id like to upgrade them to film caps but the issue will be fitting them as there is not a lot of room.  

 

 

Edited February 19, 2019 by VA50

[Guest Muon N']

If you made an oversized cover that  is extended outwards you could give yourself more space.

 

That's if it has a cover.

 

Edit: I see now it would mean modifying the grill.

Edited February 19, 2019 by Muon N'

[VA50]

Fortunately they're only 6.8uf, there are some reasonably small film caps in that size that i may be able to make fit.

[frednork]

some more info here