Balanced vs. Digital

[comabereni]

Background:
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So far I've run over 1/2-mile of CAT-5e (3 cables containing 4 twisted pairs each, unshielded but safely distanced from power wires) to every room on the first-level of my home exclusively for music. This is in addition to CAT5e intended for my home network, and I'm planning runs to the 2nd and 3rd floors soon. Everything terminates to a central media center location where I plan to install PC-based "music servers" running 24/7 playing a CD collection ripped to hard drives as well as Internet radio stations (thank you Foobar).

My electronics engineer brother-in-law (non-audiophile) visited yesterday to assess my plan and wondered why I would choose to go with a balanced system instead of all-digital with DAC's to decode at each listening station/terminal. Granted, while he understands what balanced means in a general sense, I don't think he understands much if at all the sonic benefits of going balanced. And I confess I do not either.

His points about the pro's of digital included:

- PC-source is already digital and can apparently be output bit-perfect through the optical S/PDIF jack on cards like the my Chaintech AV710, and perhaps bit-perfect via coaxial S/PDIF with other cards (eliminating the need for optical-to-copper conversion)

- Optical S/PDIF can be readily converted to coaxial and then to CAT5e (or to CAT5e directly) using devices like this (though I have no idea what kind of signal degradation might occur using such devices):

S/PDIF Coaxial / Toslink Optical Bi-Directional Converter

- To be remotely located at each listening station, DAC-Amps are readily available/easily made, and relatively affordable compared with balanced equipment.

- If necessary, the digital signal could easily be boosted for my longer runs such as to the 3rd floor library or 2nd floor master bedroom suite.

- And finally, I would have several more channels available by going digital vs. balanced

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By going balanced instead, here are the pro's that I can see:

- Sound cards like the EMU-1212m have balanced output jacks already, so the card is ready out-of-the-box to do professional level output and *only* requires balanced amplification at the listening terminals/stations.

(Note: This sounds easier than it probably is--the one balanced headphone amp I've seen, the Headroom Blockhead, is a stunning $3,300 to $3,800, and I need several

. Also, there seems to be little DIY history making them, though I did receive some ideas on making a balanced-to-unbalanced circuit a few weeks ago (thank you to all who replied). In addition, balanced loudspeaker amps are also very expensive should I choose to plug loudspeakers into one of the terminals. Nothing insurmountable I suppose, but I get the sense I'd be brewing things up from scratch and might finally have it all soldered up by 2008.)

- Sound quality from balanced systems must be absolutely first rate and ideal for long cabling runs or I wouldn't be reading and hearing so many great things about it.

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So my biggest questions are:

1) Are "balanced" systems/circuits inherently higher in quality over digital systems/circuits from an electrical/physical standpoint?

2) What limitations exist in transmitting digital (boosting signal as necessary) and decoding at the listening terminals with DACs compared with going fully balanced (or balanced-->unbalanced-->amplified) at the terminal ends?

(Note: My longest run is estimated to only be around 75-feet even going from 1st to 3rd floor due to a fortuitously located media center in a nice, central spot in our home.)

3) If I do a fully balanced system-- starting with 1212m's and going all the way through the headphone(s), are there any plans/projects I could draw upon to build high quality amps like the Blockhead? (Or anyone here up to the task to give me some direction if I need it?

)

(I realize I'd be rewiring my headphones if I went with this last option).

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Thanks in advance for anyone willing/able to tackle my questions...

Paul

EDIT: Yes, I realize that for less money and hassle, I could pick up a couple handfuls of iPods to roam around with, but I'm also patching into televisions and want Internet radio available to the family.

I also considered multiple micro-ATX workstations at the listening terminals connected to the network, but there are six of us and numerous listening stations planned, so that's not really a feasible option. Well, it might be after I hear the recommendations

. I suppose I could build panels with mini/micro-PCs w/sound cards into my walls and connect them to one surface-mounted LCD panel at each location with a VGA switch so you could dial in your preferred music that way--might be kind of cool actually...)

EDIT2: Hmmm, in-wall PC-music panels... it's got me thinking (a dangerous thing sometimes). Even if all six micro-PC's were running and playing 192kbps Internet music, it would only consume about 1/2 my available broadband connection. If playing local music ripped to disk, then even less bandwidth issues. Would only need to ensure they were turned off before firing up more at other locations, or I could always get a second broadband subscription if needed, I suppose...

Of course I'm looking at this thing and thinking to myself that it's just N-U-T-S, but it bypasses playlists/channels limitations since you'd have every playlist and radio station to choose from remotely, and addresses the fact that I understand PC's a lot better than balanced systems, remote DACs, etc. I could have several of these things wired up in a fraction of the time (plus they would look kind of cool .
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Still hoping for answers to my earlier questions on balanced vs. digital...

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[morgan jones]

First, either analogue or digital signals can be transmitted balanced or unbalanced. Second, to get the advantages of balanced operation when sent over reasonable runs of twisted pair, the source and destination equipment need to be designed for the job. It is highly unlikely that a "balanced" output on a soundcard is good enough.

Your best option is to use that CAT5 cable for its intended use, and send balanced digital (AES3). Note that you cannot daisy chain digital audio. The cable must run between source and destination without any bits hanging over the end, or spurs along the way. Thus, it is unsuitable for a ring main.

Conversely, if you had decent line send or ring main amplifiers, analogue can be sent round a ring main quite cheerfully with spurs and a multitude of loads applied.

 

[tangent]

Go digital...but not the way you were thinking!

There are several devices out there that connect to your network and will pull music from Internet radio and from any Windows file server (including Samba on Linux and Mac OS X). They have RCA and headphone outputs, usually, though these are consumer quality. They also have digital outputs, so you can add your own DAC.

The advantage of this over going straight PC-digital-DAC is that you get local control in each room. Where's the convenience factor if you have to troop downstairs, wiggle the mouse on the PC, wait for the monitor to wake up, and find the Winamp icon....all just to change the radio station? Your family'll say "screw that", and plug in a real radio.

The one I have is the Turtle Beach Audiotron, but you'll definitely want a DAC with it in rooms with discriminating listeners.

Less long in the tooth is the Slim Devices Squeezebox. I have no idea how it sounds.

There are still others that I know even less about than the Squeezebox.

 

[jefemeister]

Quote:

Originally Posted by comabereni So my biggest questions are: 1) Are "balanced" systems/circuits inherently higher in quality over digital systems/circuits from an electrical/physical standpoint? 2) What limitations exist in transmitting digital (boosting signal as necessary) and decoding at the listening terminals with DACs compared with going fully balanced (or balanced-->unbalanced-->amplified) at the terminal ends? (Note: My longest run is estimated to only be around 75-feet even going from 1st to 3rd floor due to a fortuitously located media center in a nice, central spot in our home.) [/B]

1) Your brother is right. The signal will be dramatically better if you do a D/A conversion at every node. Digital works best when the signal is kept in the digital domain for as long as possible. Balanced analog connections are much better than single-ended ones over long distances such as your's, but digital is even better since there is minimal loss and the signal is not subject to radiation, etc as much. That is if you are using fiber optic (toslink, ST glass, etc). Another option would be to run balanced AES/EBU digital connections, but this is probably not likely with your soundcard/DAC setup unless you use professional type equipment. Coax digital will be subject to everything that a normal analog connection would.

2) If you go with ST Glass, no boosting will be necessary. Those fibers can transmit for 1000s of feet "unattenuated." Toslink can be lossy, but you can always run into a repeater if necessary. If you're handy with the DIY, a optical repeater is pretty simple to make.

This sounds like a sweet project. I want to see some pictures once you get it going!

 

[comabereni]

I seem to always come away enlightened after posting my questions here...

Okay, from the replies I've received so far:

1) Digital makes the most sense, especially since I ran CAT5e.

2) Connecting devices to my LAN at each node will ensure control over channels at the points where family members listen (BTW, this was always the plan--the panel schematic I shared above was a sample listening node/station, not the source rack. Even when I was considering balanced analog, I planned to have 3 or 4 channels at each listening node to switch between).

3) Doing the D/A conversion at every node ensures the signal stays clean and digital until converted at the farthest points--where you listen.

Putting it all together and also adding some additional research along the lines of network music devices, I decided it would make sense to go with mini-itx formfactor PC's (chassis-less M/B's) at the listening nodes, mounted behind panels in the walls per my drawing above and with each connected to a central music server (no local HDD's necessary) and to the Internet for Internet radio. Mini-ITX M/B's only draw around 25w according to my research, so 2 or 3 of them could even share one silent fanless power supply unit.

Add to that, DataPro makes control switches capable of operating from 2 to 8 PC's from a single console station (one LCD monitor, USB mouse, USB keyboard). Perfect for running all these mini-PC's behind panels in the wall to select playlists or even browse out on to the web for some video music.

I read a review that strongly praised these Mini-ITX M/B's as being almost ideal platforms for PC-based Hi-Fi. This was referred to here--an interesting read if you haven't seen it yet.

To finalize each station, I would only need to add amplification, and for critical listening nodes, an external DAC. Also, I'm (still) considering mobile amps that run on DC power more or less permanently connected to each headphone cord so that I needn't repeat amplification circuits all over the house.

Balanced (analog) makes a lot less sense given my wiring, chosen sources, reasonable length runs, etc. I'm not sure if Ethernet is balanced or not. If not, perhaps balanced digital is still something I should be considering... I'm game if it keeps everything clean.

If not this network mini-ITX nodes solution, then unbalanced-distribution amplification would probably work too, only not with as much versatility. Still would be able to switch between several channels at the listening nodes, but less playlist options (and no browsing from the terminals).

Finally, I could still do balanced-analog as I made sure to make separate parallel runs to each node from the central server location.

Thoughts?

Thanks!!

 

[Archeopteryx]

If I understand correctly, there will be a pc at every listening station. Why not tranmit the digital audio via ethernet (ie, the servers only serve, each listening station must decode the audio format).

 

[tangent]

Quote:

I decided it would make sense to go with mini-itx formfactor PC's

If you want a PC, use a PC. If you want a piece of consumer electronics, use a piece of consumer electronics. Trying to turn one into the other is suboptimal.

Think for a minute how you're going to use it. How long does it take to change radio stations or playlists with a PC, and how long with some dedicated device? If the latter is designed correctly, it should be a whole lot faster. That is, unless you add a lot of specialty hardware to the PC, in which case it isn't a PC anymore.

You don't need a 1GHz i386 clone to play music. You don't need a PCI bus to play music. You need a little 50MHz bittybox with a built-in DSP MP3 decoding chip.

Quote:

I'm not sure if Ethernet is balanced or not.

It is. It's good for 100 meters.

 

[aos]

Quote:

You don't need a 1GHz i386 clone to play music. You don't need a PCI bus to play music. You need a little 50MHz bittybox with a built-in DSP MP3 decoding chip.

That's going to be rather problematic. For plaback of mp3's, a slow box like that with a hw decoder will work great. But for playing uncompressed formats, you're in trouble. And I doubt anyone here wants to only play mp3's.

With very small full-blown PC all-in-one motherboards like Via Epia series, one can make a mini-ITX size system that is specifically designed to be a media center, that is even totally or nearly totally silent (except for hard drive). They even come with TV video outs and coaxial digital outs (though unfortunately Epia shares the same jack for composite out and for coax digital out).

You can also consider using Apple's Airport Express to stream digital audio. You are limited at the moment to using iTunes (I'm sure there are much worse fates than that) but it's likely there will be plugins for Windows or Linux players in the future now that the stream's encryption key has been found.

 

[tangent]

Quote:

But for playing uncompressed formats, you're in trouble

Squeezebox plays Apple Lossless, FLAC and uncompressed WAV and AIFF. Audiotron supports WAV.

 

[aos]

Quote:

Squeezebox plays Apple Lossless, FLAC and uncompressed WAV and AIFF. Audiotron supports WAV.

I'd be careful before believing those claims. I got Prismiq box last year - which does everything and is a pretty nice little box running embedded linux - and even though it was technically capable of playing uncompressed audio, the software support was not there, so in fact it was encoding anything other than mp3 into an mpeg - compatible audio format. So yes, it played wav, but what was coming on the other side was a lossy compressed audio. While the infrastructure was impressive (with a bit of hacking, you could control the streaming to the unit via its tomcat web browser, allowing you to provide any kind of support on your own), the developer's team was your typical one, too many features to add and too little time, and the features you want near the bottom of their list. Eventually I found that every single box on the market either didn't have real wav support, or was missing another key feature (like video, or digital out, etc.). Things might've improved since then but I'm not holding my breath. I AM happy with the new Airport Express I got, though.

 

[comabereni]

Quote:

Originally Posted by tangent Squeezebox plays Apple Lossless, FLAC and uncompressed WAV and AIFF. Audiotron supports WAV.

Hi Tangent, AOS, Archeo...,

Thanks to your earlier posts, I essentially came off the fence in favor of a solution that utilizes the CAT5e for its intended use instead of trying to rig it to a topography for which it was not designed (I had like 2 miles of the stuff, so I used it). Early on, I almost bought and ran coaxial instead. But since all my music and sources in the PC format, it ultimately makes sense to do it that way.

As for these new network music boxes, I agree with you that they probably have an improved interface when it comes to switching channels readily and quickly, and I am definitely staying open to the option. The rub comes when you consider the form-factor for installation purposes, and the fact that there are literally six of us that I want to provide headphone listening to at several of the stations. Imagine, if you will, a stack of Squeezeboxes hanging on the wall, numbering anywhere from six down to two, in seven locations throughout my home. For mounting in a rack of audio equipment, or perhaps even on a bookshelf on either side of the bed, it would look and work great. But hanging on the wall behind our large sectional? Next to the breakfast bar? Not so elegant. Still, it would be quick and painless to install and has a less clunky interface.

My EE brother-in-law designs PC-based components and discussed the possibility of LCD displays (one per headphone jack) and simple up/down selector buttons to cycle through preset playlists (channels), either on the master panel or even on pads connected by cables to the master panel that you plug your headphones into (that could also house the amps and/or DACs). Of course he also said it would take him weeks to design and put together in his limited spare time and told me I was largely on my own

.

I'm thinking instead that it would be quite simple to program keystrokes into a keyboard encoder such as those utilized by arcade cabinet and flight simulator builders and use panel-mounted buttons to select "next playlist", "replay mode", "play", "pause", etc. in Foobar. Only problem I see--I'm not sure there is a keystroke to select different/next playlists, but that's a surmountable problem I think. These buttons would automatically activate when switching between mini-ITX M/B's (channels)--one M/B per jack. IOW, stand up, push the button on the DataPro switch to select the PC playing your music, then press the appropriate buttons to change playlists, pause, play, fast forward, etc. Maybe the keyboard encoder buttons could be in the remote pad, but then you're back to the display challenge...

Anyway, that's where I am on this currently. Still lots of room to change my mind...

 

[13405]

You can be 100% sure you are taking the right route by going digital.

However - when it comes to each node, it is a very unelegant and overly complex solution by using a full blown pc. I do myself own a fanless P4 based mini-itx system, but can you imagine ever having to boot them up? you could leave them on 24/7, but you still have an issue of reliability and control over the system. Tangent offered very good advice.

You could always consider re-housing an existing solution.

If you do end up sticking with your mini-itx idea, I advise you look into a standard called PC/104. It is essentially formed around low power systems in a rugged and small form factor (i mean really small).
I also advise you look into matrix orbital/other serial/RS-232 LCD displays and existing software (There is lots available on most platforms). Some of the matrix orbital displays have buttons which are programmable with the correct software.
I would recommend against using anything windows based and research other media centre/player prjects based on linux. (such as car mp3 'libraries' etc.)

If you research each of these properly you should come up with plenty of new ideas which will hopefully get your idea closer to your ideal.

 

[comabereni]

Quote:

Originally Posted by Oli You can be 100% sure you are taking the right route by going digital. However - when it comes to each node, it is a very unelegant and overly complex solution by using a full blown pc. I do myself own a fanless P4 based mini-itx system, but can you imagine ever having to boot them up? you could leave them on 24/7, but you still have an issue of reliability and control over the system. Tangent offered very good advice. You could always consider re-housing an existing solution. If you do end up sticking with your mini-itx idea, I advise you look into a standard called PC/104. It is essentially formed around low power systems in a rugged and small form factor (i mean really small). I also advise you look into matrix orbital/other serial/RS-232 LCD displays and existing software (There is lots available on most platforms). Some of the matrix orbital displays have buttons which are programmable with the correct software. I would recommend against using anything windows based and research other media centre/player prjects based on linux. (such as car mp3 'libraries' etc.) If you research each of these properly you should come up with plenty of new ideas which will hopefully get your idea closer to your ideal.

Oli,

Yes, Tangent's advice is good--these look like decent, reasonably compact, non-overblown devices and I'm certainly capable of making new enclosures (and I may do exactly this, at least for some stations).

But if I do mini/micro-ITX, I get the capability of IDE HDD per listening station, browser capability, remote email

, control over hardware selection (and the recent generation of sound cards are apparently of very high quality). And they are inexpensively replaced when time comes to upgrade. Finally, I *really* love Foobar--it's a quality piece of software and I'm afraid there may be no non-Windows equivalent, but I sure wish there was and I'll be looking into it, as recommended, so I can try to avoid booting a full WinXP session per each node each time someone wants to listen (though I suspect most of these would remain on most of the time--being set to logoff the network automatically after a certain period has passed, or manually from the server that would probably sit next to my primary workstation).

I look forward to more reviews on high-end systems built around mini/micro-ITX, but this one caught my attention. It's worth reading I think:

"The One Has Arrived"

In the review, the author says: "My suspicion is that the overall electrical and RF noise floor of this tiny, low watt M10000/Aria package is muc lower than that of the big AMD computer... and is now my reference transport in the Sunfire/MBL system..." He also says, "The 9632 put out a digital signal so clean, so tight, so jitter free... normally reserved for $3000 and up high-end CD transports."

Anyway, I may not use the HDSP 9632, but mini-PCs as a platform for music are worth experimenting with, especially given that the combined price of components is in the range with the network music boxes Tangent recommends. Still, as I mentioned, there are places in my home where the music boxes might work really nicely. Lastly, I will certainly look into PC/104 as well as Matrix Orbital displays. Thank you.

 

[comabereni]

I just discovered all the cool keyboard shortcuts available in Foobar--the ability to cycle through playlists and set the playback order using hotkeys means I can ditch the keyboard and mouse and use a pad of buttons on the panel at each listening station, operating a keyboard encoder behind the panel to trigger Foobar's keyboard shortcuts.

This should make using Foobar and dedicated mini-ITX music PCs almost as easy as Tangent's recommended commercial network music boxes.

It would go like this:

Press a button to change to the PC playing your music and activate the buttons/LCD panel --> the 10" LCD display shows the Foobar application playing your music --> use the button pad to cycle playlists --> press play on the button pad --> listen

In addition, buttons would let you browse the playlist, play in random order, repeat order, etc. I would probably only need a dozen buttons or so, all shared by all the PCs behind the panel. The DataPro switch makes this all possible by allowing all PCs behind the panel to share a single pad and LCD display.

External keyboard and mouse ports on the panel would permit programming Foobar with new playlists, configurations, etc. Unplug the kb and mouse when finished and reboot. Foobar can also be set to automatically play upon bootup.

Okay, now to build it. Need to finish lots of other stuff first...

 

[Frenchman]

I realize this thread is a bit old but I think I might be able to suggest something neat thing for you. Your setup sounds exactly like what I'd do with one exception. There is no need for a local keyboard and mouse ever after the install. Simply install VNC or use XP Pros remote desktop. That will make things much easier for admin after the boxes are installed. This also means you don't have to reboot.

Also, if you don't mind getting less MB for your buck but value the silence, grab some compact flash cards to install instead of hard drives. Part of their standard is operating at ATA devices so you can boot right off of them.