[....]
Here is the paper:
http://www.kongsfjord.no/dl/Audio/ELPAFs.pdf
[....]
Then look at that filter. I mean serious, discrete LCR with
questionable source and load impedance?
Wow, he is putting a large capacitor across the audio amplifier
output. That should sound *interesting*
I know. He should have used the dual of the circuit. Series L rather
than parallel C. Even then, the source impedance isn't known.
A simple buffer amplifier would make the impedance known. If I was
betting on what it is, I'd bet under and Ohm for the impedance of even
a modest amplifier.
I never
bothered to see if the component values are correct.
I stopped at the first part I saw.
The whole
implementation is stupid enough that I didn't believe checking the
design was worth the effort.
I have little faith in Mr. Lankford's theories, but at least it keeps
him off the streets. Granted, it sounds like he did use some cheap
synchronous demod radios since he complained about the growl. As I
said, sync is hard to do well in practice. Drake wouldn't have made
the B rev if the sync in the older model didn't suck. The AR7030
probably had the best off the shelf synchro for a consumer radio, but
even the designer complained about it.
See the bottom of this page:
http://www.aoruk.com/archive/pdf/sync.pdf
Some other interesting reading about the design:
http://www.aoruk.com/archive/comments.htmhttp://www.aoruk.com/archive...
I never own a Sherwood sync demod, so I can't comment on the quality.
In fact, I never met anyone that owned one. However, Sherwood does
test a lot of radios and is considered well in the industry.