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AM Stereo Tuner
Meduci AMX2000 Tuner Review
Since I
wrote that semi-scathing
review, others have contacted me and said similar things about the
Meduci business. I've been asked not to reproduce those things, or name
the people who complained, so I won't. I really do not
have it in for Mr. Deck or his business, but he's got to do a better
job building his product and standing behind it.
So
far, he hasn't. I doubt that I will live to see the day that he does.
He seems far more content to make silly
comments about this-n-that
instead of making a better product or fixing mine. From the very
moment he started giving me crap about returning the tuner, I should
have simply turned it over to PayPal.
(By
the way...I can respond to some of those points he made.
1) Yes, I'm "new" to AM stereo. I first saw it in action over
ten years ago. 2) If I got a dead Denon tuner at the time, I'm sure
that Denon would have made it right the moment I called them--or I
could have always returned the product. Mr. Deck hasn't done the former
and wouldn't allow the latter. 3) Age is largely irrelevant when it
comes to a properly designed electronic product. 4) Top end for the
Denon is proven
to be more than 10kHz in wide-band mode. Oh, and it was commissioned to
be built by an organization
that might know something about excellence in radio broadcasting, not
to mention that it was built by a company in the business of building
premier quality audio components. 5) Aggressive stereo blending? That
would be the kind employed in the Meduci, where you are either
receiving a stereo broadcast...or you're not? 6) The Delco UX-1 (more
correctly, UX1, per its GM RPO code) was a defining example of high
fidelity AM broadcast reception. It was available in vehicles from the
S-10 (seem two of 'em) all the way up to the Cadillac. Try again. 7)
It's worth mentioning that a TM-152 worked when it was sold, could have
been returned if it didn't (see a pattern here?), and can be repaired
if need be. 8) Thanks, I'd have much rather had the TM-152. 9) Any of
the AM stereo tuners I've tried are worlds quieter and more stable than
the Meduci. 10) The MCS 3050 can be modified to increase its audio
frequency response. Oh, the microcontroller fails and can't be
replaced? Boooooooogus!
Oh yeah--the Meduci tuners technically would appear not to
meet the qualifications to wear the AMAX badge for various reasons.)
By the way...anyone at Meduci should not think that coming along and trying to get this page censored will work. The Internet treats censorship as damage, and routes around it.
The
AMX2000 tuner
loaned to me has a serial number in the 40s, indicating that
production thus far has been greater than the PRO1K.
This
is the previous generation
tuner from Meduci. It is known as the AMX2000 tuner and lacks the
frequency counter display as well as the 8-to-1 reduction drive that
are provided on the PRO1K. I never had an opportunity to buy into the
AMX2000 (frankly, that is just as well) but Scott Atkinson did.
I met Mr. Atkinson by way of Audiokarma
and he offered to let me
borrow his AMX2000 tuner for an evaluation.
It's
taken me
several months to get this done, and I'm pretty sure that Scott would
like his tuner back. At least I know that if I were him, I would want
my tuner back.
So
I'm going to
have to simply get this written.
As
already
mentioned, the AMX2000 tuner lacks the frequency counter display and
8-to-1 reduction drive found on the newer PRO1K. Yet it has another
difference and that might make a difference in the audio quality. The
AMX2000 tuner utilizes a Sanyo LA1247 electronic tuner integrated
circuit instead of the later LA1245. Sanyo's datasheets tell us that
the difference between the two is in signal-to-noise ratio
performance. Yet those same datasheets also show no difference in the
published signal-to-noise ratio figures between the parts.
I
can't say as I found either tuner to sound different. Now I didn't go
and do a proper blinded test, but I don't think I have to. I hadn't
primed myself for a difference between the two tuners. Instead, I
went into this with the intention of just listening
without having thoughts one way or the other. My conclusion is that
both the PRO1K and AMX2000 tuners have basically the same high audio
output quality.
Unfortunately,
the AMX2000 tuner has the same “touchy tuning” disease as the
PRO1K after it and then some. The lack of reduction drive on the
tuning capacitor means that tuning is really, really
touchy. I also noticed that the tuning dial did not seem very
accurate.
You
see, in the time that passed between these two reviews, I built an AM
stereo transmitter kit offered by Chris Cuff.
It mostly worked when I
built it, and what didn't was soon fixed when Mr. Cuff kindly offered
to look at it. The Cuff Kit (as it seems to be “officially”
called) is a high quality low power AM stereo transmitter kit. It was
designed for high audio quality and features a quartz-oscillator
based frequency generation circuit. From my experiences, this circuit
is very stable and performs quite well. I've been very pleased with
the whole experience. Mr. Cuff also stands behind his
product.
I
was transmitting
on 1250 kHz with the kit, yet the tuning dial on the AMX2000
indicated that I was closer to 1400 kHz. Hmmm. My other tuners, most
of which are digitally tuned, also indicated 1250 kHz as the received
frequency.
Building
this kit served to confirm that the audio quality of the Meduci
tuners are basically in a league all their own. None of my other AM
stereo tuners could match it, yet my “split stereo” tube-type
Knight/Allied Radio tuner¹
came very close to doing so. Maybe if I ever get my hands on a Denon
TU-680NAB²
tuner, I will see how it compares in person. I've already seen it in
videos.
(Note that this part of the review is obsolete. I now have a TU-680NAB
and can confirm that it compares extremely favorably to the AMX2000 or
PRO1K. It leaves them both behind in terms of stability to boot.)
I
also noticed that
“images” of the transmission coming from the Cuff Kit were
present in a few places on the AMX2000 tuner's dial. To me, this
again indicates a sloppy design in the Meduci tuner. No other tuner I
have—whether solid state or tube type—has demonstrated such
behavior. (This behavior would be normal from a TRF (tuned regenerative
frequency set) but I don't think either of the Meduci tuners are TRF
designs.)
I wish I could say the previous generation Meduci tuner was better than the newer one, but I'd be lying if I did. That's too bad, because fans of AM stereo broadcasting deserve something better than this.
Final
Rating: 10%
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Copyright © 2011
William
R. Walsh.
All Rights Reserved. Permission is granted to reproduce this material
or to use any part of it in other creations, so long as the following
terms are met: attribution to this page and its author must be
supplied, no part of this page may be displayed along advertising
content of any sort, no fee may be assessed to provide access to this
information (except as reasonably necessary to cover connection time or
printing supply expenses) and no part of this material may be used in
creations that are illegal, dangerous or derogatory. Created
04/06/2011, edited and posted 05/14/2011.
1) For a brief period of time in the 1950s, stereo broadcasting was done using a "split" tuning system. This worked by using both the AM and FM tuners in a receiver. Audio from each tuning band would play through different speakers--FM might play on the left and AM would play on the right. While this worked, it required that any receiver be able to receive AM and FM broadcasts simultaneously. (Most receivers share circuitry between the AM and FM tuning subystems and cannot tune both bands at the same time.) This approach had problems for both station owners and listeners alike. For station owners, there was the overhead of running two radio transmitters and only receiving advertising revenue from one while operating in "stereo" mode. For listeners, audio quality differences between the AM and FM broadcasts were easily noted. Tuner and receiver manufacturers tried to compensate for this by designing their AM reception circuits to be of very high quality.
2) Denon's TU-680NAB is widely considered to be one of the best AM stereo tuners ever built, if not the best.. Its construction was commissioned by the National Association of Broadcasters (NAB) in the early 90s. Although I did not own one when I wrote this review, I have since acquired one and found it to be an exceptional tuner on both the AM and FM bands.