Found this Discussion and resources:
http://www.cowanaudio.com/th.html

http://www.diyaudio.com/forums/wild-...eld-coils.html

I had hoped that this might happen some day.
I will be watching this

This looked Interesting.

http://www.diyaudio.com/forums/multi...ml#post1033586

I'll have to research that.

I got into audio my freshman year of collage in 1973. While I hated the "West coast sound",
The JBL L100 looked great, and had a great woofer. It is also higher efficiency than most.
HTGuide did a Thread on redesigning the XO and made a very appealing speaker.
I looked up the woofer and its 88 db efficient. So much for perception of efficiency.

My thought was to design a 3 way speaker that is ultra low distortion, 50Hz F6, and 93db efficiency. Borrowing the L100 concept, Driver compliment 12" woofer, 4" mid-range and OS compression driver.

There are at least 3 drivers in the 4" class with 93db Audax HM100Z0 4" Aerogel Mid-range ,
Fostex FE126En 4" Full Range
I already have and love MP14RCY/P in ob, but they are only 90db sensitivity.

The B&C 3/4" or 1/2" CD look like they might be a perfect match. Sure beats a 2" paper tweeter.
Even a B&C...

http://www.diyaudio.com/forums/parts...ml#post2330818

This speaks for itself:
http://www.diyaudio.com/forums/multi...ml#post2318365

Nelson has created a storm of interest with the Zen I/V.

I have a DAC that I can use this with, a K&K RAKK DAC Mk1.

Currently, it has a passive supply and a switchable shunt resistor.

So I am brainstorming on what it would take for an active Zen I/V with a shunt volume control, and both SE and Balanced outputs.

Basics: PCM1794 has differential outputs with 8 ma current output.
http://focus.ti.com/lit/ds/symlink/pcm1794.pdf
So I need 2 Zen I/V per channel.
At present, I am running a DCX2496 Digital crossover, so balanced outputs are a plus.

I am considering using the buffer from this post.
Since bipolar supplies are required for the I/V section, a buffer that does not require additional caps seems prudent.

For the volume control, either http://www.kandkaudio.com/linestage.html Shunt Stepped attenuator or a single LDR replacing the K&K unit.

Finally,...

http://www.diyaudio.com/forums/analo...ml#post2258073

This looks cool.

http://www.diyaudio.com/forums/parts...-resistor.html

Motorola used one on their first cell phone.

Chauser eleptical low pass with nulls at 4.5k and 9k iirc.

Now I am wondering if I could create a "passive line level" with this, avoiding inductors.

Here is a link to a design article:
http://electronicdesign.com/article/...sband6366.aspx

Here is a circuit I like.
Not excessive voltage drop, no absolute expectations on voltage or current.

http://aquinaudio.webspace.virginmed...act_choke.html

A link to the discussion in the Tube Forum

http://www.diyaudio.com/forums/tubes...ml#post2173626