Isetta build

[Castlesteve1]

I’m looking at building a Paul Carmody isetta project for my sister in law. Problem is however that the fountek fe85 appears to be no longer available. Has anyone got a work around for this?

[Wolf]

Use the TB W3-593SF, and use one of these filters:


Since it's for a pair in parallel in a bipole, you may have to fiddle with the resistance value. The W3-871S = W3-593SF as far as drivers go. It's the same cone and surround, just a different frame.

Have fun!
Wolf

[Wolf]

Of course, it won't be an Isetta anymore. Call it the KR200.
Wolf

[Castlesteve1]

Of course, it won't be an Isetta anymore. Call it the KR200.
Wolf

Thanks Wolf. Should I put the fullrange drivers in separate chambers? I’m just not familiar with bipole designs. Also, why KR200?

[Castlesteve1]

Thanks Wolf. Should I put the fullrange drivers in separate chambers? I’m just not familiar with bipole designs. Also, why KR200?

I guess it’s to do with the Messerschmitt kr200

[Wolf]

Name: Just another dinky car model. Yes, Messerschmitt KR200.

You don't have to make them in Bipolar arrangements. I would use the network as it stands, and maybe place an L-pad in the resistor spot like a rheostat, and rotate until they sound right. I would use the larger of the 2 coil values, and if you feel it enacts suppression too low, then just take a couple/three windings off and retry. It will be some trial and see kind of thing. DEFINITELY place them in separate volumes, just like the Isetta does to keep the woofer from moving their cones at higher excursions.

I couldn't find the image I had of the contour network, so I did not post that, but it fit on a plate attached to the binding post plate.

Have fun!
Wolf

[Wolf]

One more thing, please keep the 100uF cap as in Paul's original design. It will limit the xmax the 3" drivers have to handle.
Wolf

[Wolf]

Another option is my Dragon Foals with the HiVi M3N. Just use the double notch in place of the single on the KR200 or Isetta.
Wolf

[cspirou]

I have seen the FE86 listed as a replacement for the FE85. Would that work as a drop-in alternative?

[buggers]

It may be a replacement, but not a drop in one. They do not have the same specifications.

[981CS]

Or, build the Sprite. I'm actually quite impressed with the low end those little drivers have. Enough so that I'm building a set of satellite speakers based on that design.