Author Topic: Audio Issues on 1.5GHz Mac Mini G4  (Read 528 times)

Offline lukesnyder01

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Audio Issues on 1.5GHz Mac Mini G4
« on: May 23, 2020, 07:50:35 AM »
Hi all! This is my first post on your lovely forum, so please let me know if I'm posting in the right place or breaking any rules. I've searched around for some solution, but have yet to find a real answer.

I just got my Mac Mini G4 with OS 9.2.2 installed. It boots nicely, the startup sound plays nice and loud, and then... no audio. When I go to the control panel to adjust the main volume, the slider is stuck all the way to the left. I can grab it and drag it, but it always snaps back to the lowest position. I've connected speakers to the headphone jack and stuck them right up to my ear, and I can confirm that there's some sound coming out, but it's suuuuuper quiet.

Anyone have any solutions or suggestions before I start buying stuff to try (like an interface, or getting larger speakers with better amplification)?

Offline Bolkonskij

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Re: Audio Issues on 1.5GHz Mac Mini G4
« Reply #1 on: May 23, 2020, 01:42:19 PM »
Welcome to the forums, Luke!

IIRC Sound does currently not work on a Mac Mini with OS9 except for the headphone jack. So plug in some external speakers. You'll want some with a volume control so you can adjust it to your needs.
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Offline lukesnyder01

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Re: Audio Issues on 1.5GHz Mac Mini G4
« Reply #2 on: May 23, 2020, 05:30:21 PM »
Welcome to the forums, Luke!

IIRC Sound does currently not work on a Mac Mini with OS9 except for the headphone jack. So plug in some external speakers. You'll want some with a volume control so you can adjust it to your needs.

Thanks!

Yeah, that seems like what other people have experienced. So odd, since the startup chime plays fine. I guess I'll be looking for some speakers. I only tested it out with a little 4 W speaker, and it was barely audible.

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Re: Audio Issues on 1.5GHz Mac Mini G4
« Reply #3 on: May 23, 2020, 11:28:39 PM »
the built-in speaker is also barely audible. when it comes to that, it is not a loss. :)
« Last Edit: May 24, 2020, 09:14:34 AM by IIO »
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Offline lukesnyder01

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Re: Audio Issues on 1.5GHz Mac Mini G4
« Reply #4 on: May 24, 2020, 08:14:15 AM »
the built-in speaker als also barely audible. when it comes to that, it is not a loss. :)

Good to know, that makes me feel a bit better. It's curious to me that the audio coming out the headphone jack is so quiet too though. I haven't measured it, but it almost seems like mic level audio, like I'd want to pre-amp it. Either way, I purchased some cheap 4" 24W RMS active bookshelf speakers, and that should be get the output high enough in a single gain stage.

I'm curious to see if it'll be noisy or not. Not that I really care too much about the audio quality, since I'm honestly mostly interested in going back and playing all the games from my childhood. Not like I'm doing anything where the audio quality actually matters!

Offline lukesnyder01

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Re: Audio Issues on 1.5GHz Mac Mini G4
« Reply #5 on: May 27, 2020, 08:52:39 PM »
An update: the new speakers I got, despite being plenty loud in general, simply cannot provide enough gain. Cranked all the way up, you practically have to sit right in front of them for output to be audible. I decided to change gears, and try something else. I thought I'd try a phono preamp, because the signal out of the headphone jack is about at that level. I grabbed a cheap one (Depusheng PP500) off Amazon that had some volume control knobs. I'm running a stereo 3.5mm to RCA splitter into the preamp, then taking the 6.35mm out into my desktop speakers. Finally, I have enough gain! However, there's a ton of noise, mostly because I have to figure out how to ground it to the Mac Mini.

At this point, I'm out of my depth, I think. Anyone know where I can ground to the Mini?

Offline GaryN

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Re: Audio Issues on 1.5GHz Mac Mini G4
« Reply #6 on: May 27, 2020, 10:10:57 PM »
By now, you should have realized you're fighting a losing battle. The teeny-tiny signal at the jack is probably crosstalk from another part of the audio circuit. The amplifier that's supposed to be providing signal is OFF. It's controlled by software and that's just not happening there.

As you add more and more gain after the fact - as you have with a phono preamp (!) you unavoidably amplify ALL of the random noises, hum, buzzes etc.
YOU, my friend, have discovered the REAL meaning of the term "signal-to-noise ratio"… and especially what it sounds like when that ratio sucks.
Your assumption that grounding the pre like you would a turntable will fix the noise is mistaken. You can't amplify a signal that isn't there to begin with.

If you MUST try, anywhere a screw hits metal like where you screw the end of a PCI card into the chassis…oops, that's right, it's a Mini - it doesn't have any PCI slots. Who knows? Pop the case open and try touching the ground wire to various places on the metal chassis until you're convinced that it won't work.

Somewhere, someone must have a software fix for the Mini. With all of the Mac geniuses around here, I'm surprised it hasn't already been done and documented.

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Re: Audio Issues on 1.5GHz Mac Mini G4
« Reply #7 on: May 27, 2020, 11:15:00 PM »
we generally recommend to use a firewire or usb audio interface. for pro audio people this is the normal way to get audio anyway, for other users the idea might a bit strange. anything with explicite macos9 drivers for some $15 will do.
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Offline Jacques

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Re: Audio Issues on 1.5GHz Mac Mini G4
« Reply #8 on: May 28, 2020, 03:19:01 AM »
Audio on the mini is an issue. However, as suggested above, I don't think grounding will help as the noise or chatter seems to come from the sound circuit...it was a cheap entry level machine and I don't think they would have spent loads on circuit isolation.

The DVI thumb turn screws go to ground on the mini though if you want to try it.

I'm on the look out for an officially supported G4 as I'm also getting lots of OpenGL issues on the mini, not sure if it's driver related. I could also do with more than one internal drive!

Ps, try a reset PRam, my mini is stuck on max volume, not minimum.

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Re: Audio Issues on 1.5GHz Mac Mini G4
« Reply #9 on: May 28, 2020, 05:20:39 AM »
as I'm also getting lots of OpenGL issues on the mini, not sure if it's driver related.

uh. details?
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Offline lukesnyder01

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Re: Audio Issues on 1.5GHz Mac Mini G4
« Reply #10 on: May 28, 2020, 05:51:02 AM »
By now, you should have realized you're fighting a losing battle. The teeny-tiny signal at the jack is probably crosstalk from another part of the audio circuit. The amplifier that's supposed to be providing signal is OFF. It's controlled by software and that's just not happening there.

I'm fairly certain that you're right, although the only noise that I'm hearing out of the amped signal is electrical hum, which is what led me to believe theres a ground loop. Probably if I could deal with that, the noise floor will still be too high. Thanks for your input!

we generally recommend to use a firewire or usb audio interface. for pro audio people this is the normal way to get audio anyway, for other users the idea might a bit strange. anything with explicite macos9 drivers for some $15 will do.

This is probably my next step. Do you know offhand if there's curated list of reasonably cheap ones that are still available?

Audio on the mini is an issue. However, as suggested above, I don't think grounding will help as the noise or chatter seems to come from the sound circuit...it was a cheap entry level machine and I don't think they would have spent loads on circuit isolation.

The DVI thumb turn screws go to ground on the mini though if you want to try it.

I'm on the look out for an officially supported G4 as I'm also getting lots of OpenGL issues on the mini, not sure if it's driver related. I could also do with more than one internal drive!

Ps, try a reset PRam, my mini is stuck on max volume, not minimum.

I'll give the DVI screw a shot later today when I have my hands on the hardware again. Sounds like that might be the best option without opening the case. It's interesting that yours is stuck at the top, that seems to be what everyone else has experienced. I'll reset it today and report back.

Offline Jacques

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Re: Audio Issues on 1.5GHz Mac Mini G4
« Reply #11 on: May 28, 2020, 07:05:56 AM »
as I'm also getting lots of OpenGL issues on the mini, not sure if it's driver related.

uh. details?

Ghosting in ArchiCAD, almost like the sync buffers aren't clearing. Redraw issues In Vectorworks where items don't clear after a pan. It's intermittent in VW but ArchiCAD is constant in the 3D window. 

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Re: Audio Issues on 1.5GHz Mac Mini G4
« Reply #12 on: May 28, 2020, 12:37:40 PM »

This is probably my next step. Do you know offhand if there's curated list of reasonably cheap ones that are still available?
we have various such threads here but the small and cheap ones are probably missing. i can offer a few search terms such as roland / edirol / cakewalk, m-audio / midiman, behringer, motu. until ~2001 all of them should have proper dirver support for mac.
« Last Edit: May 29, 2020, 06:44:09 PM by IIO »
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Offline lukesnyder01

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Re: Audio Issues on 1.5GHz Mac Mini G4
« Reply #13 on: May 28, 2020, 12:45:27 PM »
we have various such threads here but the small and cheap ones are probably missing. i can offer a few search terms such as roland / edirol / cakewalk, m-audio / midiman, behringer, motu. until ~2001 all of them should have proper dirver support for mac.

Yeah, I was looking around at a few of the threads here. Guess it's going to be off to eBay again, haha.

Offline lukesnyder01

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Re: Audio Issues on 1.5GHz Mac Mini G4
« Reply #14 on: May 28, 2020, 03:21:44 PM »
By now, you should have realized you're fighting a losing battle. The teeny-tiny signal at the jack is probably crosstalk from another part of the audio circuit. The amplifier that's supposed to be providing signal is OFF. It's controlled by software and that's just not happening there.

As you add more and more gain after the fact - as you have with a phono preamp (!) you unavoidably amplify ALL of the random noises, hum, buzzes etc.
YOU, my friend, have discovered the REAL meaning of the term "signal-to-noise ratio"… and especially what it sounds like when that ratio sucks.
Your assumption that grounding the pre like you would a turntable will fix the noise is mistaken. You can't amplify a signal that isn't there to begin with.

If you MUST try, anywhere a screw hits metal like where you screw the end of a PCI card into the chassis…oops, that's right, it's a Mini - it doesn't have any PCI slots. Who knows? Pop the case open and try touching the ground wire to various places on the metal chassis until you're convinced that it won't work.

Somewhere, someone must have a software fix for the Mini. With all of the Mac geniuses around here, I'm surprised it hasn't already been done and documented.

Ok! So, I've come home today and done some experimenting. First off, I very carefully listened to the output from the headphone jack directly, and then again at the same level through the preamp. The sound directly out of the jack has an acceptable level of noise, no audible 60 or 120 cycle hum, and no appreciable pops, clicks, or crackling. When I go through the preamp, without adding any extra gain, there's a huge amount of electrical noise. When I ground the preamp to the mini's chassis, the 60hz hum goes away entirely (had to take the top of the case off, like you mentioned. The DVI thumbscrew sort of worked). However, there's still a higher frequency electrical hum that's almost as loud as the good signal. There's something going on with this phono preamp that I just completely don't understand, because it's definitely the source of the extra noise.

Either way, I think you're right, and I'm going to just give up with using the 3.5mm audio out. This has felt exactly like every other losing battle I've participated in, and I'm ready for digital audio out. Boy, it sure would be amazing to be able to do without additional hardware and drivers though. I do wish there was a simpler solution.