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Meduci AMX2000 Tuner Review



Rating: One half of one star

I'm going to go out on a limb here and guess that I'm not one of Jeff Deck's favorite people in the whole wide world. For those just tuning in (please, excuse the pun), I bought into his Meduci PRO1K tuner and found its tuning circuit design to be unfortunately—if not fatally—flawed. Make no mistake, it sounded great. Yet I cannot recommend it to anyone because of its flaws and the seemingly absolute unwillingness for its maker to stand behind it.

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 tuner came very close to doing so. Maybe if I ever get my hands on a Denon TU-680NAB 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.


So, Mr. Deck, can you deliver or not? That is the only question you need to answer. Until or if you do, I can't say anything good about your product or business.

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.

Footnotes:

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.