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5/20/2004 Thursday's News: Story DetailReturn to News Page


G5 owner reports on Optical Audio
Posted: 5/20/2004
Last Updated: 10/16/2005

I posted a reader request for feedback from G5 owners using Optical audio (I don't currently own any speakers with Optical inputs). Dozens of readers so far sent reports on their configurations (including home theater setups, DAT recorders, etc.).
If you're using Optical audio on your G5, let me know your experience and include the speaker brand/model, etc. you're using and how you like them. Thanks.

Reader Reports: (most recent first)

(added 10/16/2005)
" Current setup:
Dual G5 2GHz
1TB Lacie Raid 0 x 2
1TB Lacie Raid 0 eSata (Pci-x)
PCI ATI Radeon 9200
Nvidia FX5200

Connected to:
AudioLab 8000 DAC
Rega Brio Intergrated Amp
B&W DM601 S3

Monster TOSLink optical
Apple Airport Express with ethernet link
Gigabit Switch (Compex)

Airfoil (Rogue Amoeba) - All audio hijacked

Apple iTunes
Media Central

Everything works like a charm here. All digital signals decoded by the DAC.
Rgds, David "

(added 9/27/2005)
" here is my experience using optical audio with a G5 dual 2.5 with 10.4.2. For output I use a JBL ESC333 and it sounds great with DVD as well as with iTunes. Nevertheless I have encountered a strange behavior: when I connect a source to optical audio in, I cannot output 5.1 with DVD player. In this case, even only the carrier beam is present on optical in, 5.1 is unavailable. My analysis is that digital in (stereo) is redirected to digital out plus the output of DVDplayer (5.1). In this situation the ESC333 cannot decode the signal. If I turn DVDplayer to use system output (stereo) it's OK as well as if I disconnect digital in.
Best regards, Jean-luc E."

(added 9/27/2005)
" We have a G5 2.0. We use Klipsch GMX D 5-1.
We too have experienced the hum noise
Klipsch has exchanged the subwoofer and control box. I have swapped the optical cable. The hum noise still exists
We also are experiencing the sleep issue Our system resets to "internal speakers" also. (on wake from sleep - see report from yesterday below)
-Don "

Other owners have also reported noise with the Klipsch GMX speaker systems (older reports below).

(added 9/26/2005)
" I have the optical out on my Dual 2GHz G5 connected to a Benchmark DAC-1 (www.benchmarkmedia.com), a professional-quality digital to analog audio converter. I usually listen with Sennheiser HD650 monitors plugged into the built-in headphone amplifier.

I used to have a Headroom USB DAC and amp before, and since I switched, I am also noticing the sound prefs reset to Internal speakers after waking up from sleep (on 10.4.2). I have file a Radar bug #4272362 with Apple on this issue.

I use Rogue Amoeba's excellent freeware SoundSource to rapidly switch between audio input/output devices, but I am looking at using AppleScript or equivalent to reset the default output device after a wakeup event.
-Fazal M."

(added 8/30/2005)
" I'm using a dual G5, 2 GHZ system and I'm using the Klipsch Promedia GMX D-5.1 system. I've been using them for about a year and a half. They started off sounding great with no issues. Within the last month, however, I have noticed a significant hum in the system. Like some of the other users in he forum, I've played with cables, alternate inputs and have squarely narrowed it down to the Klipsch system. Did anyone ever find a solution to the problem from Klipsch?

Not that I know of - from the past reports on the GMX model it's inherent in the design as far as I know.

(added 7/18/2005)
Hi Mike,
I just recently bought a new 2.0 DP G5 and I hooked it up to my Creative DTT3500 DIGITAL set, via the optical port. There is NO hiss what so ever and the sound is awesome. I hooked the mac to the set via the included optical cable. It worked without a glitch.
I'm running OS 10.4.2. Cheers, Pascal"

(added 2/22/2005)
"Hi Mike, XLR8yourmac is my favorite web site, always check out this site with my first cup of coffee in the morning. I have learned so much about Mac and have solved many problems by picking up tips from here, thank you.

Here's my experience with Mac's optical audio and 5.1 surround sound speakers. I have hooked up the Logitech Z-680s to my Dual 2.0 GHz G5 via the optical audio port for over a month now, incredible sound consider speaker sizes but the best part is no HISS what so ever as other G5 owners have reported on your site. I have watched DVD movies, listened to iTune, played music CD and iPod so far and absolutely no hiss no hum.

I used the Monster Cable's optical cable between Mac and the Logitech controller. I did not use the Logitech supplied speaker wires (I can not believe they supplied such thin speaker wires for such powerful speakers) but used the Monster Cable Bi-Wire speaker wire (left over from my home audio/video system) which is a heavier gage and insulated speaker wire (maybe that's why I am not picking up any hissing noise?). Anyway, I am a happy camper with my Mac and Logitech Z-680 set up.
Albert C."

(late posting some of these - trying to catch up on past mail on the subject)

(added 2/22/2005 from 1/11 mail)
"Hello Mike,
We're have a dual 2.0 G5 hooked up via the optical out to a set of Edirol MA-10D monitors (these are inexpensive 2-way near-field audio monitors with built in amplification and both analog and digital inputs; a great value for those on a budget and limited space, though a bit weak in the bass area). Just using a generic TOSlink cable bought from B&H for under 10 bucks. The digital audio is very clean with no annoying hiss. I even tried it with a set of Sennheiser HD-25 headphones via the front jack of the Edirol and the sound is crystal clear, no significant hiss.

There is some background hiss via the analog input connected to the G5, which is no surprise, but still quite decent for these non-audiophile ears.
Jee H. L. "

(added 2/22/2005 from 1/11 mail)
"I have a G5 2.5Ghz with the Logitech Z680 6.1 speakers. They do produce a barely noticeable hiss when no sound is playing. When playing a .VOB file in VLC 0.8.1 it does produce a really loud clicking. Does anyone else have problems playing .VOB files over Optical output?
(no name given) "

I don't own any optical input speakers but if anyone else notices this let me know. (Also suggested he check for an update to VLC to see if that matters.)

(added 1/11/2005)
"I have the PowerMac G5 dual 2 ghz and the Klipsch 5.1 speaker setup, connected with a Monster Cable Toslink optical cable, available from the Apple Store. At first, in March 2004, when I got the machine and speakers, there was no problem, but since I have developed the hiss and sometimes a pop when switching channels on the Klipsch amp (I also have my PC hooked up to it on the digital coax channel).
My problem is identical to several of the other posters--I have a barely audible hum most of the time, really small, totally tolerable, and that's fine, but when I do anything on the Mac to get an alert, or if I start playing an mp3, I immediately get a huge hum that disappears a couple seconds after the alert stops, but which lasts as long as there is any audio output. It's terrible, and it's only gotten worse! I don't know how to fix the problem! Of course I get even worse hum with my PC digital coax connection.
Amiri "

(added 1/11/2005)
"I'm using the logitech z-680s on my iMac G5 20inch and they sound incredible but for that awful hiss. It's not there when u first turn the control pod on but once ya start playing audio it comes on and after that ya can mute the audio, or even turn off the whole computer and unplug it and ya still get the same surround sound hiss. Music and movies overpower it for the most part and the incredible dts surround sound makes up for it most of the time but when a quiet part comes in a movie or song ya can hear the hiss over it and it's def annoying. I'd settle for a less powerful system with an optical out if i could lose the hiss, i don't use half this things power anyway.
i had cambridge soundworks fps 1000's on my old powermac g4 and those were always great with no hiss. But alas low end systems don't have optical outs as i found out the hard way by ordering another logitech 5.1 system that was only $50 b5 getting this one. I got this one for $185 through Amazon tho which isn't bad considering what some people paid. If I paid $400 and i had this hiss i'd be going nuts cus who wants to ship back something so huge.
Jay M. "

(added 12/7/2004)
" I'm using the optical in from a Sony DAT deck to dump audio DAT to my hard drive. These are typically 16-bit 48khz files. I've found two issues.

1) If I turn the DAT deck off, the next time I turn it on, I have to reset the Audio/MIDI app to set itself to the external clock. One could use the internal clock that it defaults to, but it will actually resample on the fly, so it's best to use external clock.

2) BIAS-Peak sucks. I pulled my hair out getting a clean audio signal in via Peak. I would get distortion during recording, seemingly random.
I could cure it by plugging in a set of headphones to the front of the G5. upon doing that, I'd get a clean signal for a period of time, then distortion would return (DAT deck running the whole time). No other audio app had this issue. I used, with success: Audio Recorder, Sound Studio, Garageband, Soundtrack. Peak, versions 3 and 4, failed to record cleanly. I've just bought a new DP 2.5GHz G5, so I'll try the same test on there to see how things perform.
(I asked David for details on his previous system used (2003 model G5? 10.3.6 or 10.3.7? latest peak updates?)-Mike)
(What was the previous system?)
Dual 2GHz purchased in Oct. 2003

(what OS version used?)

(There was some peak updates in the last few weeks I think - were you using them?)
Yup, no changes. "

(added 12/7/2004)
"Mike, I read your site so often I feel like I know you ;)
I was having complete loss of audio and posted this over at the MacNN forums under a topic about complete loss of sound, and I mean everything, headphones, optical and analog outs:

"I have a dual 2.0 G5, rev A., Elgato EyeTV 500 HDTV tuner, Logitech Z-5500 sound system using optical out from my G5 running 10.3.6. The problem was occurring sometime after start-up because I would hear the start-up "gong" but after the menubar appeared I would hear an audible "pop" and all sound would go out. It was not a hardware fault because when I booted my back-up drive with another version of 10.3.6 it would work fine. I finally took a risk and used Carbon Copy Cloner to transfer over some system files from my back-up to see if it was a corrupted core audio file somewhere and that did the trick. The sound all came back but then after a few hours of usage the sound was lost again. There seemed to be no rhyme nor reason why - something seemed to be corrupting core audio or taking over sound in some insidious way.

After a few days of pulling my hair out, I finally figured out what the root cause of my total loss of sound on my G5, internal - external - headphones & optical outs - the whole shebang. I noticed the "pop" was when my menu extras were loading - I use, and love, Menu Meters so I uninstalled it and rebooted and nothing happened. One by one I eliminated everything in my menubar as a precaution and the last thing I thought would affect sound was my Contour Shuttle software. When I remove the Shuttle software, ver. 2.0.2 btw, the sound problem goes away!

Somehow there must have been some kind of problem with the contour's USB driver with sound. I realize my set-up may have been fairly uncommon with some oddball hardware like the eye-tv 500 and probably not too many people are using the optical outs on their G5 Powermacs and iMacs but the moral of the story is that USB drivers and devices can do some surprising things, so make sure to uninstall the USB drivers when trouble-shooting. I never would have guessed that something like that would have happened."

Since that post I have had the feeling that the culprit may be more than just Contour's software, I believe it to be a system level issue with USB drivers/devices. The optical out seems to be a bit flaky as well - sometimes it comes right on and sometimes it seems to take the Z-5500 decoder to receive the digital data from the G5. After sleep the system seems to occasionally switch back to the internal speakers or headphones. I have not had any kp's with EyeTV and the DVD player as some have reported though.

As to the Z-5500's, they are almost completely noise/hiss free with the optical connection. The analog connections are pretty quiet as well but not near the noiselessness of the optical connection. A tip for anyone who has hiss with the Z-5500's is that the control center's connection to the sub, looks like a trusty old 9-Pin D-SUB connecter like on old joysticks, can be a bit loose even when the thumb screws are tightened all the way. I had no hiss until I moved the sub then I heard a really annoying buzz coming from all the front channels. Not very loud but noticeably worse than even the analog connections. I then isolated it to the controller's connector on the sub. It doesn't appear to be broken or anything, just that the connector allows for some play. If the cable is pulling the connector too much with a little force perpendicular to the port it seems to mess the digital optical's sound quality. After taking the stress off the port from the cable the hiss went away. I was playing some music on very low sound levels and can reproduce the annoying buzz/hiss at will and haven't had the hiss since I identified it.
Overall I am very happy with the quality sound, construction and appearance of the speakers. They are almost impossible to beat for the price IMHO.
-Jerry C. "

(added 12/7/2004)
" Dear Mike,
Just a quick follow up from my original e-mail (Dec. 2nd report below). I recently installed Security update 2004-12-02 and restarted to find that my alert sounds had returned. Unfortunately this was short lived as after playing a DVD in Apple's DVD player they had stopped playing again. I found a restart would bring them back but using DVD player always caused them to no longer be heard.

My understanding and as has been pointed out by others is that DVD player will take over the optical out entirely when sending an encoded surround soundtrack. I guess for whatever reason it is not telling the OS it can play the sounds when it is quit. All other sounds like iTunes, Quicktime movies and games will play fine after DVD player however.

The bug causing a reset of the sound output in System preferences following sleep also remains. I guess one option would be to always turn off the computer but with Mac OS X I prefer to just use sleep. For the record my Mac is a Dual 2.5GHz running Mac OS X 10.3.6 with the latest 5.1.8f7 firmware, the only additions to the standard specifications are an additional 2GB of RAM (4 x 512MB Kingston) and a Maxtor 300GB SATA drive (16MB Cache), plus the Z-5500 speakers of course.
Regards, Matthew "

Another report on Kernel Panics w/some apps: (2nd report of this)

(added 12/6/2004)
"Hi Mike,
I have the second generation 1.8 DP G5 with radeon 9600 connected to a Denon AVR3600 receiver and B&W 603 speakers, sounds great. However I am also experiencing some issue with kernel panics with eyetv, dvd player and vlc. (see an earlier report on kernel panics in eyetv and DVD player.) However I cannot say that this is limited to the digital audio, I've been having trouble with frequent kernel panics prior to setting up the digital audio. Though I have caused it to panic while playing with the audio settings. Any hardware tests I've run don't show any problems and the recent firmware update didn't help. -Jason
(I asked if he had any 3rd party RAM (i.e. ram other than what shipped in the G5.) I don't own any optical audio speakers, etc. and use 3rd party RAM OK in my G5 but it's one thing that comes up with problems like KP's (although there can be other causes, including some software/extensions).-Mike)
Thanks for the follow up queations. I don't have any third party RAM installed, just the apple supplied 512 MB. The software is fine, I have tested it extensively running the same things (w/o digital audio and the radeon 9600) and it will run reliably indefinitely. The Kernel panics usually occur after running the machine for 24 to 48 hours straight. About 95 percent of them have occurred while watching eyetv, but the panic log gives a different reason every time (ata, pci controller, graphics card, usb, memory...) The machine just spent just under 2 weeks at the local apple store and they tested it for 3 days without kernel panics using their external HD. Currently I am starting to wonder if one of the problems is related to the serial ata controller or the hd. I have been using an external firewire hd as the eyetv scratch disk for the past 2.5 days and haven't had any Kernel panics, though I haven't tried any dvds or playing with the digital audio settings.

On non-beta releases of OS X I've had roughly half a dozen kernel panics over the past 4 years on various machines prior to this tower which has had about 15 within the first month and a half of ownership. I've always had a pretty easy time figuring out what caused the kernel panics. But I'm stumped with this machine. (Check the logs to see if they have any info.)
The tech at the apple store must not know how to interpret the panic logs since he was unwilling to look at them and ask apple corporate if they had any ideas. I'm going to see if this continues to run reliably using an external scratch disk before contacting apple corporate for a follow up. "

(added 12/6/2004)
"Hi Mike, This is creepy, I was reading the article and I too just also hooked up my 2.5 ghz G5 to a Yamaha a/v (HTR-5630) to the digital optical with two Kenwood Bookshelf speakers (KVS 220) and a Yamaha Bass Sub (VST MSW10).
Sound is great, I have a small apt and it fills the room nicely. Though when I turn the receiver off, the Prefs stay on the D.O. I also have no hiss what so ever. When i switched the Audio out to analog the sound was louder but hissy (if that is a word). The D.O. Sounds much warmer.
Mike H. "

Ideally (with no amplifier issues) the optical audio should be cleaner and the hiss reported in the past by some was usually due to the speaker system's amplifier.

(added 12/6/2004)
"Hey Mike. I'm not using the G5's optical out port; I'm using my Revolution 7.1's Coax out. (there's a previous page here with Revolution 7.1 owner reports) (RCA cables are cheaper and more readily available. ;)). But I have a set of Logitech z680's, and I too get the noise from the speakers while they're powered on. I can live with it easily enough, but some people have been reporting really obnoxious levels of noise.

In my experience, VLC can be a culprit of worse-than-normal levels of noise coming from the speakers. The symptoms are readily audible white noise coming from the speakers and music or sounds being literally overwhelmed by it.

VLC, when outputting audio through an optical out, loads its own drivers, and this can sometimes cause problems. Even restarting your machine won't help. The fix, I've found, is to open up VLC again, start playing an audio file (or video file with an audio track), switch the output to your digital out and then quit VLC. Basically, you have to mess around with VLC's audio output a little.
Maybe this will help those with noise problems.
-- Damien S.
Macintosh Developer "

Thanks, but I don't think VLC is a factor in most of the noise reports (i.e. hiss from some speaker system's amplifiers - known issues in some cases, see older reports below.)

(added 12/6/2004)
"Regarding this: (from a previous reader report below)
"The last issue is DVD playback related. When a DVD is playing no other audio can be heard as DVD player takes over, (with analogue speakers you could hear iChat sounds for example whilst watching a DVD) I believe this is normal behaviour?:

This is a limitation of any computer outputting the Dolby Digital or DTS bitstream. The DD/DTS bitstream is a lossy compressed 5.1 channel discreet sound stream, and no computer DVD player has been designed with the capability to decompress the soundstream, mix in a beep or other computer sound, and then re-compress the bitstream for digital output, even on Windows PCs - the bitstream is just dumped straight out the digital out as an unmodified (and un-mixed) 5.1 signal. When playing a DVD through the analog outputs, the DVD player is outputting a two-channel analog signal derived from the digital sound bitstream off the DVD which is then easily mixed with any system sounds.
- Nate "

(added 12/3/2004)
"Hi Mike...
I've got a G5 1.8SP (2nd gen), with OSX 10.3.6. The digital out is connected to a Yamaha A/V receiver with 2 floor standing speakers. The sound quality is excellent. As one would expect, it is no different than my Toshiba DVD player connected digitally to the A/V receiver (as in both cases, it is the receiver doing the digital to analog conversion). No hiss, noise or other sonic issues.

I do note that if the receiver is turned off while the computer is on, the Sound Preference will switch immediately to the internal speakers (or headphones, if attached). I notice others having this experience too. Also, if I plug in headphones to the computer it will automatically switch to that output.
Cheers, Harmer "

(added 12/3/2004)
"Hi Mike,
I'm using a G5 dual 2Gig system running 10.3.6 with a set of Logitech Z680 speakers using the optical connector.

I would agree with some of the other posts regarding the hiss from the Z680 speakers - it is definatly the speakers but I find it more like a digital 'hiss' rather than noisy amps - Logitech are aware of the situation and there is a revised firmware for the controller that reduces the problem, although as I discovered does not eliminate it - as when checking with Logitech support in the UK I already had the latest revision! :)

I have no problems with the system sounds, for example when using itunes. System sounds, or any other sound streams, will not be available when AC3 or DTS are being used. I have also noticed the click when AC3/DTS playback begins or resumes - believe me. using an Audigy on a PC is far, far worse ;-) the mac is fantastic in comparison. I do get a delay in starting audio playback on DVD but the decoder on the Logitech speakers just seems to take a while to settle down.

I have had the problem Matthew mentions about the sound control panel (prev. report below) - it seems to have a mind of its own! - it's ok most of the time but occaisionally gets really confused & I have to reset it. Don't understand why the volume control doesn't work though - surely can't be that hard for apple to implement it in the OS, after all itunes can do it!

Overall I like the Logitech setup and I can't fault the audio on the G5. The noise from the 9800pro however. . . but that's another story. . . . ;-)
Regards, Adam "

I too had a OEM 9800 Pro with a 'dentist drill' frequency fan, which I replaced last December with a very quiet (but outrageously expensive) Verax HS/Fan cooler. (See the video topics page, graphics card section for links to that install guide/article and one for a much lower-cost alternative (VGA silencer).

Kernel Panics w/EyeTV and DVD Player:

(added 12/3/2004)
" Just wondering if you had any other reports from readers getting kernel panics when using the g5 optical audio out for dolby digital audio....
it happens frequently both with EyeTV and DVD player... I had my motherboard replaced a while ago so it may be an incompatibility with the mobo and the optical audio module. I don't know if the optical audio on the g5 is directly on its board or not.
-kenton "

I don't remember any reports on KP's like that (other than those from users of 3rd party audio drivers - like many past reports on the M-audio Transit device.)

(added 12/2/2004)
"Dear Mike,
I recently purchased the new Logitech Z-5500 5.1 surround system to replace my analogue 2.1 speakers. The new system is connected to my G5 with an optical cable. The sound quality is excellent especially with DTS encoded material and I don't notice any hiss.
When set to digital out the system volume and keyboard volume keys are disabled. This is normal but takes a bit of getting used to. I have come across a few issues, the first is that the system alerts no longer play no matter what volume they are set to. I am hoping this is a temporary bug in Mac OS X as I find them useful when receiving e-mail or pressing the wrong key and don't really want to connect a second set of speakers. If anyone can confirm this It would be useful there is hope for a fix.

Another issue is that on waking from sleep the sound output is set back to internal speakers and needs to be manually be changed back to optical in system preferences to be fair from what I have read on the web this may be a known issue and I still get audio even when it is set incorrectly this way.

The last issue is DVD playback related. When a DVD is playing no other audio can be heard as DVD player takes over, (with analogue speakers you could hear iChat sounds for example whilst watching a DVD) I believe this is normal behaviour? When DVD player is launched or quit however there is a pop from the speakers and usually a delay before the audio starts. I have found this means that if you are skipping through a DVD you have to start playback a few seconds before the bit you want otherwise you will miss the audio. In a few instances if the audio starts immediately it may not be possible to get the first second.
Regards, Matthew"

(BTW - just for the record please include system and OS details in reports. thanks) I don't own any Optical audio speakers personally but a later reader report above commented on the volume keys issue.

(added 10/17/2004)
"Hi Mike, I was reading all of the posts on the site about the G5 and optical audio out hiss problems. (with some speaker/amplifiers)
My specs: Logitech Z680 5.1's

I am *thankfully* happy to report no hiss. And the Z680's are pretty incredible. I've had a lot of computer speaker systems and these are by far the best in terms of sound quality and not distorting at high volumes.

I have a couple of questions and after searching your site could not find any answers. I am a newbie to optical audio so please bear with me...

Q: By using the optical out on the G5 with a toslink cable, is there any added CPU cycles being used for the digital processing? Am I sucking CPU cycles by going optical. (not that I know of)

Q: Since the optical technology in the G5 is really just stereo, what am I gaining by going with optical to my Z680's? (I'm no audio expert, but in theory optical audio should have lower noise, better immunity from interference, etc.)

(added 9/15/2004)
"Mike, My setup includes a brand new G5 dual 2.5 GHz tower (which shipped 2 weeks before the date quoted by the Apple Store), an Apple Cinema 20 inch display, and the Klipsch GMX 5.1 speakers. Almost forgot, I am using the Monster Cable optical cable to connect to the Klipsch unit. As Klipsch states, analog output from the computer has hiss. Big deal.
Digital output (i.e. DVD sound) is very quiet. Sometimes, I need to turn down the volume to save my eardrums and keep from aggravating my neighbors. The auto-mute feature (mutes the sound after a few seconds of no sound output) has advantages and disadvantages. It can be a pain when changing DVD chapters. On the other hand, it is nice not to have to listen to hiss all of the time. On the whole, I am extremely satisfied with the sound. My previous system included a Klipsch analog Promedia 2.1 system. I have been very pleased with the Klipsch products.
Thanks, Steve
P.S. The 20 inch Cinema display is great for watching DVDs! "

Previous GMX system owners mentioned hiss/noise using optical audio inputs also (see many previous reports below - unless they've fixed that).

(added 9/15/2004)
"I also have G5 connected via a TOSLink optical cable to a Logitech Z-680 that hisses. When I first turn on the Z-680 it remains quiet until the first sound from the G5, then the hissing starts. It is a constant sound from all speakers and seems unaffected by the Logitech volume control. As long as I'm listening to music, it isn't a problem, but as soon as the music stops, I again become aware of the hissing. Since the Z-680 controller sits on my desktop just to the side of my display, I can simply turn it off when not in use and rely instead on the internal speaker for beeps and similar sounds, e.g., announcements. It's a disappointment to spend this much on a set of speakers and to have them hissing, but it's hardly worth the time and trouble to repack all the speakers and wires for a complete system return. I would be interested if Logitech could isolate the problem to just one part of their system and replace only that, e.g., if it is in the desktop controller, arrange for a swap. Of course, if the problem is the optical interface to the G5, Logitech isn't to blame, but Apple is!
Peter C."

Again from the previous reports from pro DAT users (below) it's not the G5's optical out. (If there was a common noise problem then every user would be reporting it - especially the pro audio users.) These consumer grade speakers (from what I gather) once they detect an output from the G5, their amplifier has the hiss, not the G5's output. If it was the G5 - the pro audio guys would be screaming about it - look at the DAT reports here - not one reported any hiss or noise that I remember.
I've seen many flaws in apple's products (many times over the years) and the G5 has other flaws like low firewire performance but I don't think noise on the optical out is one of them. Granted any mass-produced product can have problems that are not common with every sample.

(added 9/15/2004)
" Hi Mike, Just hooked up a pair of Z-680's (ebuyer.com, $225 delivered to CA) on a June04 Dual 2GHz/2GB/10.3.5 G5, and immediately (compared to the analog 2.1 setup that was on there) I could hear noticeable hiss. The volume control on the control module does not affect it; it's a constant level. Now, clearly, many sound systems have a 'noise' when they are turned on, and it becomes irrelevant when you crank it up. But the hiss is louder than the G5... :)

Dropping in Call of Duty, cranking it up; it goes away (well, can't be heard, anyway; and the surround is awesome). Music on DVD designed for 5.1 sounds great, too (try Tubular Bells 2003...).

Seems like it's a gain thing, prolly from the amplifier(s) (6 of 'em for a 5.1 setup) like several have stated in your G5/Optical Audio section. (see reports below - can be worse with some speaker system amplifiers. Note the pro DAT audio users reported no noise/hiss on the G5's optical out.-Mike)
Sound controls are basically grayed out in Sound preferences once you select Digital Audio Out, shouldn't there be a gain control of some type? Being able to get it down to 75% or so wouldn't hurt, so when you wanted quiet, you had it. Then again, turn off the unit with the remote and the hiss stops... ;)
Best, Gunnar "

(added 8/10/2004)
"Hi, Mike. I have a G5 2.5GHz and Logitech Z-680 speakers which is connected via the optical SPIF cable. I have the Monster THX optical cable.
The latest G5 has no problems, as far as I have tested. I run FCP 4HD and play various sounds from iTunes and Soundtrack application. So far I do not hear any popping or clicking noise being emitted from the G5.

When I stick my ear to the speakers, I hear a slight hissing noise which is obviously coming from the amplifier of the Z-680. When I turn the volume of the Logitech all the way to its max setting the hiss does not increase. It is a constant hissing sound all through out. I switch between inputs from the 6-channel analog connected to my Pioneer DVD DTS/Dolby Digital player, then to the Coaxial (connected to nothing), and to the digital optical connected to my G5 - no change in hiss pattern or addition of sound from any source.

The Logitech Z-680 isn't the greatest speaker set in the world. For less than USD300 you get a DTS/Dolby amplified speaker that allows you to connect from various inputs. That's a great feature. For the price you pay, the sound quality is terrific. The trade-off, of course, is the high gain in amplification. You aren't paying a lot for great components in its amplifier so it isn't surprising this hiss is evident.
Regards, Rodney O.
www.oneframeoff.com "

Another Klipsch GMX owner noting hiss:

(added 8/9/2004)
"I just received a Klipsch GMX D-5.1 speaker setup on August 5th, and it does hiss. I have tried the analog and optical inputs from my G5 as well as the analog inputs driven by a PC. The same annoying hiss under all circumstances. The 10 year old powered Sony speakers I was previously using with my G5 never had this problem.
Jeff. "

Farther down is a section with many more GMX owner reports on this (amp noise).

(added 8/5/2004)
I have a G5 dual 2.0 that I got in late June, I'm using Logitech x680s and I don't have a problem with hiss or white noise. When there is nothing going on you can hear a very faint hiss from the center channel, but during music, game or movie playback there's nothing noticeable.

(added 8/5/2004)
"I have a dual 1.8 G5, just got the Logitech z680's and the white noise is horrible, just thought i'd let you know.
Daniel "

See below for reports on hiss from Klipsch GMX owners also, which is due to the amplifier. (if it was a design flaw in the G5's optical out, then the pro audio users with DAT would be reporting it also, but their reports below noted no noise.)

This Z-680 system owner didn't note any noise (not all 680 user's did).

(added 8/5/2004)
"I'm using Logitech Z-680 6.1 surround sound speakers. Have had no problems. Surround sound DVDs sound great. Sound from iTunes also sounds fantastic.
(I asked if he heard any noise, since some 680 owners noted white noise, perhaps from the ampl. as did many GMX owners)
No, no noise coming through to speakers. I would think that he might have a bad optical cable (maybe a kink somewhere) as optical is pretty impervious to noise caused by induction of electricity and RF signals.
-Nate P. "

(added 8/5/2004)
"Hi Mike. I use my Dual G5 as an additional source in a home theater connected via optical to a Meridian 568.2 surround sound processor: http://www.meridian-audio.com/p_568.htm.
Works great. Dolby Digital or DTS audio (which the G5 w/Apple's DVD Player can't handle itself) is successfully transmitted to the Meridian equipment where music and soundtracks are then upsampled to give very crisp & clean 96kHz/24bit resolution playback within my 7.1-channel digital setup. DVD-Audio discs, however, won't play from the Mac.
-Brad B. "

A Kipsch (not GMX series) owner had previously written that he didn't hear the hiss the GMX owners mentioned (see below). I wondered if the problem was related to the GMX series amp:

(added 8/5/2004)
"You hit the nail right on the head the original klipsch GMX had problems with hiss but the new ones do not. Klipsch corrected the problem. Check the Klipsch forums here:
As for the G5 having dirty optical outs (a quote a reader mentioned as being posted from klipsch on another site) thats baloney!
I have never had an ounce of hiss from my G5 optical out.
Shawn F.
(he had previously written)
"klipsch promedia 5.1's hooked thru klipsch's dd-5.1 decoder from the optical output on my g5 dual 2.0 has no hiss at all even with my ear right next to the speakers and them turned all the way up. "

More comments on Klipsch GMX Amplifier Noise: (The GMX series at least seems to have a known issue with hiss in the amplifer even w/o any connection to the G5 - today I received many GMX owner reports noting the hiss - including some tests w/o any connection to the G5. This same amplifier hiss may be in other consumer speaker/amp sets also. Note the Pro Audio equipment users (DAT, etc.) here have mentioned no noise on the optical out.)

" Mike, I have the Klipsch GMX 5:1 Speaker system running digi-optical from my Dual 2.0 G5 and yes I do get the hiss. It is most apparent when dragging items to trash or when any system sound comes on. This hiss lasts for 1 to 2 seconds then disappears. I have heard this on other Klipsch set-ups also.
I do not get the hiss when I run optical out to my Sony Dream Machine 5:1 system. So It does appear to be a Klipsch issue. The hiss has also gotten gradually worse over time and now an actual hum audible during music and dvd playback. Sounds like the Amp has feed back when ever audio is put out although no hum when no sound is generated. I suspect my Klipsch power supply will die a fairly early death at this point :(
Sincerly; Doug (Zoraster) "

(added 7/26/2004) Mike, I too have the hiss that others have mentioned but do not find it all that distracting. The thing that does bother me is a very loud buzzing/bleeping that results whenever I get a call or text message on my Sony Ericsson T616. The volume of these bleeps is directly related to the phone's proximity to the speakers. It has been loud enough to startle my roommate when he was in the room next to mine. It was so bad that I initially thought the speakers were defective so I exchanged them the next day. The new set had the same problem.

I suspect that the control pod is poorly shielded and reacts to whatever frequency the phone is operating on. There is an upside though...it makes these noises BEFORE the phone starts ringing so it allows me to see a second or two into the future.
FYI. -Jonatan"

See previous reports below from GMX owners that noted even w/o a G5 connection there was hiss (a known issue reportedly with the amp).

(added 7/26/2004)
" I am also having a problem with my Klipsch GMX 2.1 speakers hissing and spiking (long pops) when connected to my Dual 2.0 G5, connecting directly or via FireWire through an M-Audio FireWire 410. I don't mind the hiss as much as the pops. The seem to come from electrical signal somehow leaking through, regardless of whether or not the speakers are in use or in the off position. I am strongly considering returning them.
Marc O. "

(added 7/26/2004)
" I have yet to get my DP 2.5 in to test its optical outs... but i have noticed that several readers have written in with hissing on their Klipsch ProMedia setups. (Note - most mention the GMX series) I have a ProMedia 2.1 (GMX) system that is hooked up through analog connection to my iMac. It is a previously known issue that these speakers hiss. Regardless if they are on or plugged into a source. (I assume he means they hiss as long as they are on, even if not plugged into a source but see his later comments on this.)
People have supposedly confirmed this with Klipsch. There is nothing you can do to prevent this hiss and it is inherent in the design of the speakers. It is not horrible, but is noticable if you put your ear to the speaker.
I think it is important for people to be certain that the hiss they are hearing is originating in the g5, and not the ProMedia speakers.
(he later wrote)
Believe it or not, they hiss when they are "off." The main controls for the speakers (if you are not familiar with them) are operated from a small pod which accepts inputs, controls volume, bass and has a connection with the sub. The sub, in turn, connects with the sattelites and also has an ac connection.
When the volume is turned all the way down on the control pod, it clicks off, and the little glowing status LED on the front of the unit goes from green to red showing that the unit is "off." it will not reproduce any sound... (but if the LED is red/glowing, there's still power present) it will however continue to hiss in this state. again - its not a blaring hiss, but it is audible if you put your ear to the speaker. When the main power switch on the back of the sub is turned off, then obviously speakers loose power and they no longer hiss.

Just for clarification, i'm using the "Klipsch GMX 2.1" speakers. Hope this information helps - other then the hiss - which again is very minimal, the speakers sound great!

(he later wrote in reply to my comments on the red LED indicating power was still present)
technically they are still receiving power. they are just supposed to be off - i'm assuming more of a standby state. but even in this state they hiss. when power is completely shut down - on the sub - then there is no hiss. unfortunately, climbing under my desk and fumbling for the off switch on the sub is not an ideal way to power them on and off. one would assume - as on every other computer speaker system ever made, that shuting off the remote power switch on the sattelites/control pod would kill power going to the speakers and stop sound from being produced. this is not the case.

the speakers do this when they are completely disconnected from any outside source. i actually just got off the phone with klipsch and they said that it is a problem with their gain being set too high. there is no way to solve the problem - it is inherent in the speakers. i'm considering upgrading to their THX certified speakers, which lack the visual appeal of the GMX, but also lack this hissing problem and have even better sound. i also want to again stress that its not a deafening hiss. but now that i know that its a known design flaw, i feel like i want it fixed/replaced. i probably would have kept them if not for this renewed intrest after writing with you. now, after speaking with them, i want them to fix their mistake.

you may want to advise people having a hissing problem with their G5's and klipsch speakers to see if this problem continues when they disconnect all inputs. Again, this is for the ProMedia GMX A-2.1 speakers. "

I don't own these speakers but posting this as a FYI (most previous G5/optical audio reports with other speakers didn't mention this problem). If you do have noise on any speaker, try to isolate it to the source/audio output (and not due to cables, or inherent in the speakers/amp, ground loop, etc. - and of course to rule out the Mac as the source, disconnect them from the system.) I welcome other reports on these speakers from readers.

Another Klipsch owner wrote about the hiss, but said it's not bothered him:

" I have the Klipsch Pro Media 2.1 GMX-A speakers, and yes, they do hiss even if the control pod is turned off. In the off position, you can hear the hiss from about 3 feet, and from about 2 feet and closer, the hiss is pretty noticeable.
If the computer (and other inputs) are muted, you can turn the volume all the way up and the hiss gets louder. Honestly, though, the hiss is not very noticeable when music (or other sound) is being played through them, and if the speakers are off and you're not close the the speakers, you won't hear it and it won't bother you.
Before buying these, I read a lot of reviews that say "it is noticable if you put your ear to the speaker," well, they're not headphones, and I have been very satisfied with the speakers. The sound quality is very good and the hiss has yet to bother me.
-Benn "

I've gotten many more mails on this issue - but for those that still blame the G5 for the Optical audio noise/hiss with these series of Klipsch speakers (one reader mentioned a mac fixit post saying the company had said the G5's audio outputs were "dirty"):

"Consider this report anonymous...
I can confirm the Klipsch Promedia GMX 2.1 & 5.1 speaker hiss. My wife works for Klipsch and this is a known issue. It has nothing to do with the optical in - just too much gain in the amplifier."
Here's a link to a topic in Klipsch's forums that talks about the issue.

And although this G5 user said the -analog- audio out of the G5 had some noise, like most other G5 owners on the previous page here - he noted no noise on the optical outputs (like any system or hardware, there could be samples that do have problems - but it's not common/not a design issue apparently)

" I'm using the optical outputs of Rev 1 G5 1.8 DP connected to the D/A converters of a DAT machine.

So far there have been no issues, no noise, no problems with the digital outputs, however I am only using the digital outs because of the terrible noise problems on this G5's analogue outputs.

The G5 is used in a processional home-studio environment with a dedicated earth (ground) bus, and its own dedicated (non-ring) AC supply, so ground loop hum should not be an issue (and wasn't on the QuickSilver the G5 replaces) It's the studio of a friend of mine which I set up and maintain.

Personally, I'm waiting for reports on the rev2 models before taking the plunge . . .

Another comment on the Amp:

" I own the ProMedia 4 and 4.1 amplifiers (just the amps, not the systems), and just from an audio tech perspective the noise you are hearing is the noise floor of the amp design itself. If there's hiss, the power amp is on, and because of the design of the amp, there is system noise there. ... With the volume all the way down, that leaves mainly the power amp stage as the only source for this noise. Don't get me wrong, as an audio guy I am pleased with what Klipsch crammed into the package, and it's all a matter of economics - cleaner parts and more engineering time both cost money, Klipsch had to cut something out to make the retail price point. I think (at least on the Promedia 4 and 4.1's) they made a good compromise.
Rick P. "

Clearly for those owners of speaker systems (w/amps) that hear hiss/noise with no connection to them, the G5 can't be blamed for it. I can't say that every G5 ever made has perfect optical audio out . But except for Klipsch GMX owners (which based on the above has the hiss w/o any connection to the G5) most of the reports here didn't note the problem. If it was a common problem or design flaw, then -every- G5 owner using Optical audio out would be reporting it, not just a small percentage of users (other than GMX users).
I'm not blindly defending the G5s either, there are some common issues like lower than expected Firewire drive performance. (Lower than the MDD G4 towers, or even later PowerBook G4s.)

(added 7/26/2004)
"Just to let others know I am using the pro media 5.1 klipsch speakers and have no hiss. (I asked if these were "GMX" series) I use the klipsch promedia DD-5.1 decoder hooked to the promedia 5.1 speakers. It has Optical and coaxial inputs as well as an equalizer and fully adjustable sound fields. I use the optical out on my G5 and the sound is incredible.
(he later wrote)
Oh just as an addendum to my previous post my klipsch promedia 5.1's hooked thru klipsch's dd-5.1 decoder from the optical output on my g5 dual 2.0 has no hiss at all even with my ear right next to the speakers and them turned all the way up. I don't know what is wrong with some of the setups discussed here but I have no problem with either of my klipsch 2.1s or my 5.1. (I asked if these were "GMX" models and he said no - see his later report above.) They are excellent speakers. Shawn "

(added 7/26/2004)
Currently I am using an inexpensive Surround sound unit from Wally world. (?) Due to the fact it only has audio in optical I can only attest to that portion of the system. It Works! I can't complain as the whole unit only cost $50. Speakers and all.
It was an impulse buy, but for my tone deaf ears it serves its purpose. I have to use the regular audio in from the unit to the G5. I guess I should give spec's - G-5 1.8GHz single proc W/ 1.5GB of memory running OS X 10.3.4. I am looking at a Panasonic SA-XR25S. Which has all the imputs and outputs I need. I haven't been able to find a review of the unit and that is my hold up presently. Any one have any knowledge of that unit ??
Bill J. "

If anyone has used the Panasonic SA-XR25S or knows of a review online of it - let me know.

(added 7/26/2004)
"Mike, The white noise with the optical out that two other owners reported is exactly what I hear on my Logitech Z680 (as I reported earlier). It definitely is the G5 as when the G5 is shut down or goes to sleep the white noise reduces to about 1/4 of its intensity. (If it was a common G5 design issue, then it would not be there if the G5 was off or disconnected from them. If there's any noise at all with the G5 off or disconnected then the G5 can't be the source of it. That noise is just getting amplified when the amp is on/senses an input.-Mike) As I had mentioned early there were some reports on MacFixIt some time ago about this white noise, and Klipsh tech support stated that the optical output on the G5 Mac was dirty and that was causing the white noise.
(See the comments above about the Klipsch GMX speakers - yes, it's a known issue alright, but with the amplifier, not with the G5's outputs. If the G5's optical outputs were "dirty" (i.e. a common/design flaw) then why aren't all reports here noting the problem? And why are the Pro Audio (DAT) users not reporting any noise on the optical out of the G5?)

Maybe the reason some do not hear it is that they may be in a more noisy environment or have their speakers placed farther away than mine are.
Mike "

That's not the problem as you can see from the reports here (some noted putting their ear to the speaker) It's clearly *not* a common problem or everyone would be reporting it. If you take out the GMX speaker owners, most don't have the noise problem. (Again I'm not saying all G5's optical out is flawless, but if it were a design flaw every user - especially those with pro equipment would be reporting it.)

(added 7/26/2004)
"Hi Mike, Just wanted to write in to add to the optical audio thread. I've got a G5 DP2.0 with Klipsch Promedia 5.1 system connected via Toslink. There's an awful hiss coming from all 6 speakers. And what's more, it behaves like the Powerbook delayed mute thing. For example, if there's no signal coming from the system, there's no hiss, but if I make an alert sound, it seems to "wake up" the speakers and the hissing begins. Then if there's no signal for a few seconds, it silences itself again.
Seems somewhat rare, but there it is...
(After all the GMX series noise reports today, I asked Simon if his 5.1's were GMX's)
Indeed, the GMX D-5.1. "

(added 7/22/2004)
"I am running a g5 2.0 with the klipsch gmx 5.1 surround system. This is connected with the Monster optical audio cable. There seems to be some white noise always running in the background. This is worse with some audio and not so bad with other audio. I don't know how to turn off the NAP mode so I'm not sure how to fix the issue.
Nate "

See the above comments on GMX's hiss/noise. (Disabling NAP mode was a common tip for the problem of G5 Power Supply chirping/squealing noises based on all the GMX comments, I don't think that would have any effect on this. It requires installing Apple's CHUD Tools, then using the "Hardware" control panel in system preferences, and it resets back to enabled after a restart)
Most previous reports (below) from G5 owners didn't note hearing any optical audio noise (assuming cables are good, no external source of the interference (like the amplifier - which in the GMX's case seems to be the source), no ground loop problems, etc.)

(added 5/21/2004)
"The digital optical out on my Dual 2GHz G5 is connected to my home theater. Stereo: Onkyo TX-SR800
Speakers: Bose Acoustimass 16 + center channel for 7.1 output.
Digital audio cable: cablestogo.com: 12ft Hi-Resolution 4-in-1 RCA/S-Video Cable
S-video adapter: Apple's DVI->S-video adapter.
S-video cable: cablestogo.com: 4m Velocity LT TOSLINK Digital Optical Cable
TV: Panasonic 56" widescreen PT56-WXF95A

The audio is awesome.

I've never heard any noisyness. It's always been a clear signal.
I typically run with Highest performance processor settings... maybe noise people are hearing is the whining power supply. You might suggest that the people experiencing noise disable Nap mode. Just a thought. (only one G5 owner report here previously mentioned a "white noise" on the optical outputs, more than his analog outputs which I thought seemed very strange. (see later reports above for some other noise reports.) The G5 P.S. intermittent squealing/chirping noise is different though and usually solved by disabling NAP mode using CHUD tools.-Mike)

Now if I only could force the DVI->S-Video adapter to realize that I've got a 16:9 not a 4:3 aspect ratio, I'd have no complaints about Apple's OEM Radeon 9800.
--Steve "

(added 5/21/2004)
"yep, built-in Optical Audio works fine...
on a Dual G5 2.0 with Edirol MA-10Ds (not the best sounding near-field monitors but dirt cheap!)
No noise that I can tell, seems clean. Clean on my other G5 too.
my rig:
Dual G5 2.0, 2GB RAM
1 TB LaCie FireWire Disk Array
Radion 7200 PCI
3x VP191b 19" LCDs
-Fred T. "

(reports below were posted 5/20/2004)

"Just FYI, I'm using the optical audio output of my dual 2.0Ghz G5 system, connected to a pair of Roland studio monitor speakers. (These were originally intended for use with Roland's "V-Studio" series of stand-alone hard disk recorders/mixers - but they're a teriffic match for the G5 too.)

The only thing I noticed is that the default sound level coming from the G5 seems to be rather high. I have to have the studio monitors turned down to about 1 to 1 1/2 (out of 10 on the volume dials on the rear of them) so the sound isn't blaringly loud.
Otherwise, it sounds excellent!
Tom W. "

"I wanted to add a note somewhat disagreeing with reader Christopher M. when he said "You can only choose one sound output per machine."
This isn't entirely true; I currently have my G5 hooked up to an older RCA DD 5.1 home theater system via the optical out, to a set of 2.1 flat panel Andio computer speakers (neat little things that double as picture frames, but still sound quite good) via the rear minijack, and a pair of old Sony headphones via the front headphone port (that port was practically worth the purchase of the G5!).

At least with this setup, outside of a 5.1 soundtrack on DVDs, the G5 is constantly sending out an audio stream on all three ports. I can leave everything hooked up at the same time, and all I have to do to switch from the computer speakers to the home theater is physically turn the computer speakers off and switch the home theater to the Optical input the G5 is hooked to--instant, beautiful, crisp sound. Turn both the home theater and the computer speakers off, and I can use the headphones with no other adjustments.

The only time I have to fiddle with preferences is if I want to output the 5.1 soundtrack from a DVD via DVD Player to the optical out; doing that turns off the analog outputs from that DVD.

This is an ideal setup for me. Incidentally, so long as something is plugged into either analog out port (front or rear), the tinny internal speaker is disabled automatically.

Although I admittedly haven't done thorough tests, I haven't noticed any significant amount of white noise on the audio outputs. I have noticed a soft hiss from my analog 2.1 speakers if I listen closely and the volume is turned way up, but not outside the range of what I've heard from similar systems.

I'll make a point of checking the optical out for hiss when I get home tonight. I forgot to mention and it's worth noting, by the way, that the optical out (as people familiar with the things would probably expect) does not respond to the computer's volume control in most applications--it merely sends a raw signal for the amplifier to do with as it pleases.
--Marc M"

"Hi Mike, I seem to have a different audio experience than some of your posters. I use a G5 2.0GHz Dual and run the optical out to a Pioneer Reciever VSX-D411 digital in. I set the sound panel to select the digital out. This powers 5 speakers I have attached to the reciever in 5 channel stereo mode. I also have an old pair of Apple stereo speakers attached to the analog out of the G5. Once I installed Mac OS X 10.3 I found that when digital was selected that both my digital speakers and the analog connected speakers could play at the same time.

I also find that VLC plays thru both outputs upon opening a movie. If I only want the digital outs to play I simply turn the analog volume down and I hear just the digital. If I want the digital off I just turn off the reciever.

In Jaguar only the digital out played when selected. I really like that panther plays audio to both digital and analog outs when the digital out is selected. It gives me a 7 speaker stereo effect that I enjoy.

I have not heard any white noise on the digital out. If you select the wrong audio out setting in VLC you can get an ear full of white noise though ;)
So turn the volume down before changing audio settings in VLC.
Hope this helps,
Michael B.

"I currently have an optical->coax converter to hookup the G5 to an old Cambridge 5.1 Soundworks System. Sound is great, considering a budget system.
I no longer have the hissing I get from the analog output.

I'd also like to note that I run a Sony Playstation 2 to my G5 (hooked up via AlchemyTV), and I have the PS2's sound going to the G5 via an optical cable. But the problem is, digital sound coming from the PS2 does not get passed through to the output. I had to manually set the sound settings in the PS2 to a non-digital format before I could hear sound. I guess OS X (or the hardware itself) does not simply pass the data through to the output.

"Been using Logitech Z680 speakers and optical audio from day 1 without problems - I'm curious as to what specifically you would like addressed.
(I asked if he'd noticed any noise, etc. - although only one person so far (below) had, saying he used the analog outputs which had less "white noise" than his G5's optical output, which sounds very strange. Also info on equipment used is useful - as some of these reports show.)
No quirks or noise, DVD player outputs Dolby Digital as far as I can tell, absolutely no problems. Speakers are fine, more than loud enough.
-Jose "

"I have the Logitech Z680 with my G5. I agree that they sound great. I wind up using the analog inputs however as there is a persistent white noise with the optical signal which is much louder that the white noise that I hear with the analog inputs. I remember reading something on Mac fixit that the G5 optical outputs were dirty and that is why they have the loud white noise. Klipsh is apparently working with Apple to fix this.
Mike "

I asked other G5 owners reporting here about noise on the optical outputs - so far none have reported this issue. I don't know what could be causing that with his system/configuration/environment.

"I don't use a speaker set with the Optical Out, but I do have a 45-foot toslink cable running from my G5 to my home theater in the living room, and the sound is incredible... I have it running into a Sony STR-DE945 home theater unit. The bass is a little heavy from the G5, but easily adjustable.

I do with that OS X has an easy switch from my Bose USB SoundSticks to the Digital Optical Out so that I didn't have to keep opening System Preferences. You can only choose one sound output per machine.
Christopher M."

"Greetings, Mike. Here are some observations on my optical audio system. I have a dual 2GHz G5 and the Logitech Z680 5.1 system. I opted for the Monster Cable THX I100 8-foot cable because, even though "digital is digital," there is still a difference in how snugly the connectors fit on either end, and the cable is better protected from bending and possible breaks.

The bass on the Z680 is not as tight as I wanted, but then, again, what can you expect from a complete system that cost about a third of what just the center channel speaker on my home theater system cost me. Let me just say that it's good enough now so that I can definitely tell the difference between MP3/AAC and uncompressed (aiff, wav, Apple lossless) audio, that I'm in the process of re-ripping my whole music library to lossless format.

Installation was straightforward, taking about a half hour to install and get up and running. As expected, you lose volume control of the system sound level, but the controls on the Z680 are easy to use. Volume levels in iTunes and Quicktime are still adjustable, but not in DVD Player. Also, there is a noticeable (about 2 seconds) lag before you get sound when you start a DVD movie, or when you stop/pause and restart. There is no loss in sound when you jump from chapter to chapter.

Being able to play Dolby 5.1 and DTS DVDs and DTS CDs is really cool! Even stereo audio, using DPL2 effects, sounds great. Definitely a couple of notches better than my HK Sound Sticks.

By the way, I have not been able to get VLC to work with it, not even the latest version (0.7.2-test3), but I may just be overlooking something.

Overall installation and use have been trouble-free, and the investment has been well worth it.
Tony A.
TLC Graphics

"i use the logitech 680 speaker system with my G5. the 5.1 sound output from DVD Player makes watching movies on it great!
-ming f. "

"I have used the optical out with my Home Cinema system (Pioner VSX-C100 connected to Audio Pro Cinema House speakers) as well to a couple of monitor type of speakers (Edirol MA-20D). No problem what so ever!
Keep up the good work with keeping xlr8yourmac one of the premium mac sites!
Best Regards
/Magnus "

"Hello! I am not using speakers with direct optical inputs, but rather feeding an old DAT recorder that does.
My G5 Dual 2 GHz tower is central to my company's digital media processing lab, with lots of ins and outs to analog equipment like SVHS, audio cassette, and so on. The optical feed to the DAT recorder provides a clean, ground loop free environment for all my audio digitizing and monitoring.

The Sony DTC-700 DAT has done very well in providing clean audio in and out to the analog patch bay without any major issues. After some system updates, or the resulting reboots, or some other strangeness, the sample rates for the optical interface on the G5 have to be reset with the Applications>Utilities>Audio Midi Setup application.
I use 48kHz sample 24 bit settings for regular applications, and 48kHz 16 bit for compatibility with Ambrosia Software's Wiretap application. To put the DAT recorder into passthrough mode, simply push the record button until DA appears in the display, while the optical input is selected.

For anyone with a DAT recorder, this is a real bonus to owning a G5, that very very common noise and ground loop issues with analog circuits inside electrically noisy computer cases are gone for good!
Thanks for such an excellent and helpful website!
John P.
Pioneer Digital Media "

"Hi Mike, I have a dual G5 and purchased the Klipsch ProMedia GMX D-5.1 with 2nd Sub-woofer. The unit sounds great with true 5:1 audio with DVD playback. You need to select the optical output in the sound control panel and doing so disables the internal speaker.
Volume control works with the applications but not the volume slider in the menu bar. If you need more specific information let me know.
Douglas G.
(he later wrote)
Mike, I have an update on the humm/hiss from my Klipsch GMX 5:1 audio. It turns out that I have had some electrical problems on my street with low voltage and fluctuation. Our Electric company fixed the problem this week and I placed all my peripherals on voltage regulators and the humm is gone.

The Klipsch system still produces a short hiss when dragging items to trash and other system sounds but music, game and DVD playback is crystal clear now.
-Douglas G. "

"Hi Mike, I'm using my G5 1.8ghz model with optical out. I've had USB speakers in the past and was never impressed. I like bookshelf speakers much more than the smaller "computer type" speakers.
Currently I have the G5 hooked up to a Sony STR-DE597 receiver through optical audio out. For now I'm only running a 2.1 setup. I've got two Sony SSMB350H bookshelf speakers, as well as a Polk audio PW202 sub. The sound is awesome, its great to be able to run a large sub like this. The setup was easy, I just plugged in the optical cable, setup my receiver for 2.1, plugged in the speakers and sub and it worked.
Dan H. "

If you're using Optical audio on your G5, let me know your experience and include the speaker brand/model, etc. you're using and how you like them. Thanks.

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