Re: USB on stereo question

tombates@xxxxxxxxxxxx wrote:

I hope this is the correct place to ask this question. I notice that
some new stereos come with a USB connection. I am trying to figure out
the purpose of it.

A relative of mine has a Philips MCM530 - a "Micro Hi-Fi System" with a USB connector on the front panel.

Here's a picture of it:
<http://www.p4c.philips.com/files/m/mcm530_22/mcm530_22_rtp_.jpg>

See here for a brochure:
<http://www.p4c.philips.com/files/m/mcm530_22/mcm530_22_pss_eng.pdf>

And here's the complete user manual:
<http://www.p4c.philips.com/files/m/mcm530_22/mcm530_22_dfu_eng.pdf>

I have visited a number of electronic stores and asked, but I keep
getting different answers.

Whatever functionality the USB connector might have on a given device is highly dependent on the manufacturer, so you could get different answers merely because of that.

Is the USB to connect a MP3 player, so you can play the songs from
your MP3 player on your stereo?

I've seen something like that on some other "Micro Hi-Fi System", but the MCM530 does not support this kind of operation. (The MCM530 has a USB "B" connector, not the USB "A" connector, so you couldn't connect MP3 players or USB sticks/keys, anyway.)

Is the USB to connect your computer to your stereo, so you can
use the speakers on your stereo for music being played on your
computer?

That's the primary use for the USB connector on MCM530. You can think of it as an external sound card - and that's how the MCM530 appears in Windows. The whole USB functionality - and apparently much of the other functionality, too - appears to be based on the Micronas UAC 355xB chip:

<http://www.esic.cn/icmanual/icmanual.asp?ic=UAC355xB&id=141312>

The "USB PC Link" is one of the program sources - the other ones being the 5-disc CD changer, the analog "line in" connectors (2xRCA), and the FM tuner. As you can see from the above picture, there's a button for selecting the "USB PC Link" mode on the front panel. There's also a similar button on the remote.

But there's more to it: the MCM530 also comes with some software - a custom version of MusicMatch Jukebox, which is a commercial subscription-based net radio/MP3 jukebox service, disguised as an MP3 player/librarian of sorts:

<http://www.musicmatch.com/>

The fancy thing here is that while the stereo is set into "USB PC Link" mode, its remote sends commands to the PC. You can control the MusicMatch application with the MCM530 remote: change tracks, start and stop playing, pause, etc. The front panel buttons also work in a similar way.

In addition to the remote control functionality, the MusicMatch application also sends the name of the artist and the name of the currently playing song to the VFD display on the front panel of your stereo - scrolling it there.

The MCM530 also comes with some drivers and software that enable various "Environment" effects. These are all created by the UAC355xB chip inside - they're some sort of DSP settings that are uploaded from the computer to the chip - but for some reason, Philips didn't make them accessible by any other way than via a computer. (There are a couple of such presets built-in that work even without a computer, but by connecting a PC to your MCM530, you'll get lots of more.) These new effects can be selected both from the PC and from the front panel buttons.

All in all, being able to control your MP3 archive (and a net radio service) with the remote, and being able to view the names of the tunes on the VFD display are pretty neat features, but the downsides are:

- The remote control functionality and the song-name-on-
the-VFD-display functionality will only work with the
MusicMatch Jukebox application. If you prefer some other
player, you won't get those features. There's no
programming information available, so other media players
can't implement any support for the same features (unless
someone reverse-engineeres the drivers and their API.)

- I havent been able to get the USB connector to work in
Linux at all. The MCM530 is recognized as a USB audio
device, but it remains silent even if you try to play back
music on it. (Maybe that's just me; I haven't been doing
any extensive testing.)

- In the end, it's only a USB connector, with the 5 meter
limitation. :( An Ethernet connector would have been much
more useful since then you could stream music to your
stereo over the home network, without needing a computer
nearby.

- Placing the USB connector on the front panel does not make
any sense since the connector (in this case) isn't intended
for removable devices. It should be relocated on the back
panel.

* * *

Other manufacturers and devices might have a completely different idea about what a USB-connector-on-a-stereo should do, so don't take this as any kind of general guideline.

--
znark

.