Monday, 25 February 2013

MEASUREMENTS: What 'lo-fi' looks like (SONY CFD-S05).

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<Originally posted on Squeezebox Forum Feruary 13, 2013>

I realized over the weekend that it has been at least 10 years since I actually played any cassette tapes! My dad was interested in getting some old cassettes transferred and I discovered both my cassette players at home didn't work.

So, off to the local Wal-Mart-like big block store and I came home with this beauty :-)

The Sony CFD-S05 does a lot for $60. It's a smallish boombox CD player, cassette player, AM/FM radio... Even has a little phono plug input up front for iPod's and the like. Since the cassettes I wanted to transfer were mostly >30 years old, I certainly did not need a Nakamichi. As a "utility" audio player for the kids, although this unit isn't $20 like the absolute cheapest in the store, I suspect this is the kind of lowest end "quality" most of us would be willing to have around the house. Therefore, I figure it might be interesting to measure this unit as a "point of reference" as context to the other measurements and consider what $60 buys.

Set-up: SONY headphone out (MegaBass off) --> 0404USB, shielded phono to RCA RadioShack cables. Test signals burned on Fujifilm CD-R at 24x (no fancy media here or extra-slow 1x burning).

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As you see, I've added the SB Radio, Boom, and Touch as comparisons. Note that the Radio and Boom were also measured from headphone out while Touch was with the standard RCA line out. Clearly, the Sony was outmatched by all the others. The Sony's dynamic range is about 12-bits due to high noise floor.

The most obvious anomaly is the frequency response - very nasty:
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Here's the THD graph:
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Again, quite poor. The elevated noise floor is clearly an issue.

Jitter, anyone?
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Well, it's not good but... At ~90dB between the 11kHz signal and the tallest sideband, I'd say this is actually not terrible either! I'd be much more concerned about the other results and especially that horrifying frequency response than care about the jitter.

Conclusion?
Not unexpectedly, this is clearly not "hi-fi" (no kiddin'!). Subjectively when I plug in headphones, it's the frequency response that most noticeably makes it sound poor (gutless bass and accentuated treble, no wonder Sony included the "MegaBass" button); plus the noise level is audible with volume up a bit. I suspect that the frequency response curve was purposely "tuned" to make it sound better with the small built-in speakers (single driver) rather than achieve flat response which should be trivial with any modern DAC. Rolling off the low bass to remove rattling & midrange distortions and boosting the treble to compensate for the lack of a true tweeter. To not turn off this compensation when using the headphones is a sign of "cheapness"

Having said the above, also consider that some high-priced gear have really bad measurements yet get praised during subjective evaluation (I'm not going to name names here but look through some of Stereophile's measurements on-line).

Of interest is that the jitter test was the least concerning result even in such an inexpensive unit spinning physical media.

Now you know what a cheap lo-fi mass market boombox measures like in 2013 :-)

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