03-09-2009, 05:12 AM

Hi

Can anyone give me any advice please? I have an imac G5 Power PC and have just relocated it in my house next to my stereo system. I have connected it to my Yamaha Amp via the speaker out cable on the mac. I am using a 3.5mm lead into the mac which connects with two (red and white) leads at the back of the amp aux sockets.

All I get when I try to play music from the mac is a loud buzzing noise through the amp. Am I connecting it up wrong or maybe this is not possible to do with my current set up?

Any advice would be greatly appreciated! Thank you

03-09-2009, 05:29 AM

Are you sure that the 3.5" to RCA cable is in good shape? Sounds like a grounding issue. Do you have the 3.5 plug all the way in the jack? Are you plugging into the Line Out of the Line In?

I have my iMac G5 hooked up that way and it works great. No hum. VERY quiet.

03-09-2009, 07:02 AM

Hi

Yes - it's a brand new lead - just bought it yesterday. Lead all the way in and the red and white connectors at the other end go to the aux in points in the amp. Is it definitely the speaker oulet I use on the mac? Doesn't even play any sound through the amp - just the hum. Tried the jack in the headphone socket of the mac and still get the hum but can hear quiet, low quality music through the amp.

Thanks

03-09-2009, 08:31 AM

Try going to System Preferences>Sound and click on the Output tab. What does it say there? That's the only other thing I can think of. Are you sure you have the proper source selected on your amplifier?

03-09-2009, 09:00 AM

Yes, def have "aux" selected on the amp but as soon as I switch to this output, the buzzing starts! Will try system preferences on the mac and see what it says there. Could it be possible that the amp is just not compatable?

Will post again when checked system prefs - Thanks

03-09-2009, 02:19 PM

Hi - have checked system preferences>sound>output and it is set to Internal speakers - Port: Internal Audio. Do I need to change this? It doesn't seem to let me change anything here.

03-09-2009, 04:49 PM

There are 2 jacks for audio on the iMac G5. One is a Line Input and the other is an Headphone/Optical Digital Output. I am wondering if the jack has gotten dirty and therefor no ground connection. Try turning the 3.5" plug around in the jack and see if the hum changes. It should not say Internal Speakers when a plug is plugged into the Headphone jack.

I have the last version of the iMac G5 - The iSight one and it says Line Out with my cable plugged in. The older iMac G5s say Headphone according to what I read.

03-09-2009, 06:56 PM

I have the imac G5 with the inbuilt isight - it was the first model with the integrated isight though. My audio points are labelled with the speaker out symbol and then the other is labelled with the headphones symbol but says (optical output) next to it.

Just to update - have tried my ipod with the current set up and it works perfectly. Have also tried my work PC (Sony Vaio) and it also works perfectly.

Headphones into my mac output also sound fine.

It's so frustrating as it should work in theory!! Could it be that the mac just won't work with my amp?

03-09-2009, 07:27 PM

There is only one iMac G5 with the iSight. It was out a very short time and was replaced with the first Intel iMac. I have that same machine. The one you think is a Speaker is an Line Input. Trust me, I have used it many times. The one with the Headphone Symbol and that also says Optical Output on the very left (Last Jack In the Row) is the one you want. It's both a audio out and Optical TosLink out. If it hums there did you try turning the plug in the jack and see if it crackles or changes?

ANY amp will work with that jack. There is something wrong with the ground. Maybe your iMac does not like that plug on the end of your cable. Could you take a pic of the plug and post it here?

03-10-2009, 04:55 AM

Hi - thanks for the info. Apologies for any confusion - I am using the output on the very left (optical output) with the headphone symbol. I think it may be the plug that the mac doesn't like - strange though as all my other plugs i.e. headphones etc. work ok and they appear to have the same plug. My ipod sounds great through the amp using same connections and also my laptop PC. Do I need to buy a better cable - digital output or something?

It starts to hum as soon as I even touch the jack near the optical output socket on the mac. Could it be something to do with system prefs on the mac?

03-10-2009, 05:37 AM

The Digital cable is for an Amp with TosLink Digital Inputs so no, you do not need that.

I also agree it's strange your iPod and Windows Laptop work fine. The Jack on the iMac since it does double duty as both Analog and Digital out seems more picky to me with some 3.5" jacks. Can you try another cable and see if you get the same hum?

Are you saying it hums only when you touch or move it? Does it ever get sound?

03-10-2009, 04:37 PM

Hi - I went and bought another new cable today! Recommended by a mac retailer. Same cable as before with 3.5mm plug on one end and red and white connectors to the amp on the other - this time gold connectors though so better quality!! STILL the same problem! All set up fine then as soon as I plug the cable into the mac audio output socket the hum starts! It is really loud with the jack halfway in and then half as loud when fully in. Can play music fine and it all goes through the amp and speakers ok but still with the annoying hum in the background. Tried plugging my ipod into the end of the jack and no hum at all and sounds great. As soon as the jack is fully in the ipod the hum stops and it is silent as it should be.

What I also discovered by accident is that when I take the jack out of the mac when it's still connected to the amp, if I touch the jack it gives out the same hum! It just seems that the mac doesn't like the connection to the amp via the jack and there is some kind of interference getting in.

Think I'm just going to use my ipod to play my music through the amp as can't see a way to fix the problem??