Michael Lawson


Did you crack open your R2000 to bypass the
audio chain?? Sounds like the Rec out is pretty
much a line out.





So you replaced the caps in the audio chain within
the receiver to discover this, or did you use an external
detector at this time??

--Mike L.
-------------------------------
I have the top and bottom off both of my R2000s.
I compared the audio from the straight from the detector
diode with that at the record/line out. There is a slight
difference. The rec out doens't have too much between it and
the detector.

The HA1368R audio power output Ic was used by many companies
in the late 70's and early 80s. I have a pioneer output module that
has two of these and Ihave played with themover the years in an
attempt to improve the sound. My goal then was a super simple ,
super small stereo for my wife. She was never satisfied. Didn't like
the "grit".
Once I got to thinking about distortion, I knew that IC sucked. I re-
verifiedit by feeding audio into connector 49(AF2). Feeding a 1K
low distgrion sine wave into it, I could plainly see the notch. When I
fed BW limited clasic CD audio inpto that smae point, the audio
sounds like er crud.

Elliot sound has a design simlar to one that I use that lets you see or
hear just what an amp or fitler is doing to your audio.
http://sound.westhost.com/project57.htm


If I were gong to go to the trouble of changing the audio caps, I would
be more inlined to build anactive detecot, 2nd link in my opening post,
cut the volume and tone cotolrs loose, and build a standalone internal
MOSFET amp. The speaker sounds great even on weak and noisy
signals when powered by a better amplifier.

I now wonder how much of the better reception in Drakes and NRDs
are "simply" because of the better detectors. I now think that a lot of
the noise/distortion on real weak signals was created by the simple
detector. I had written this off as being caused by the PLL phase
noise.

On very weak signals it is like I have a new receiver. On strong voice

signals I doubt if anyone could tell the difference. But on weak voice
or
even good strong music progrmas, it is a whole new ball game.

Is this worthwhile? I really don't know. My only cost has been for the
AD607s
and the 500HZ CW crystal fitler I bought from FC. The audio is so much
better
that myu wife without me telling her what I was up to, noticed the
improvement.
Given that outside temps are 95F with 60&RH, it is almost as bad as
being
iced in. I have learned a lot and hope to learn more. Adnwhile it may
be viewed
as crazie to add a DSP I am looking into pullin ghte DSP module from my

PCR1000 and adding it to the outboard detector.

A side benft has been the Piooner MOSFET stereo units. Since I
expressed
an interest to a frineds son, he scrounged up 4 more units, three brand
new
in the box. He moonlights as an installer for a local dealer. He
mentioned to
his manager that a guy he knew had a use for those "old dogs". So I
received
4 of them with a nice note from the manager hoping that I could use
them.
Seems that if it doens't have a built in CD you can't sell auto stereos
today.
I also recieved 2 sets of Cambrdge Sound Works "Home Theater" systems.
The amp, decoder and wall wart power supply are junk. The 5 little
satellite
speakers do a wonderfull job on voice. So I use the minimus for music
and
PC audio, and switch to the tiny speakers for voice. The only problem
is my
wife wants a similar setup in her sewing room to listen to her MP3
player,
CD, FM and PC. I am going to spend $25 on another set of Minius 7s for
her
and whip up a system for her tonight.

I even installed one in my Civic an now listen to my MP3 player instead
of brain
dead radio. While I would preferr to listen to SW whole I drive,
Listening to
"Vinyl Cafe''" is an acceptable option.

The nicest thing is I now have a "real" hifi system connected to my PC
so I can
transfer vinyl to CD (home recording act of 1984)and listen with
speakers instead
of headphones headphones.

And I still have a spare 4Ch 22W stereo amp to do something else fun
with.

Terry