Resolved Help me keep my iMac quiet (boot sound)

[exploradorgt]

Hi, I have this 2009 late 27" iMac, works great. After replacing the GPU to a non supported model I'm permanently running Windows, and that's fine because lots of reasons (I'm not planning to go back any time soon to MacOS on this iMac).

The problem is the LOUD boot sound, and I can't turn it off.

• Tried headphones, but the sounds keeps coming out from the main speakers, I perfectly understand this is by design (post behavior)
• I know via dosdude1 tutorial this could be modified dumping the chip "bios", modify it and upload it again, but this can't be done directly on the machine, because THIS model in specific requires a chip programmer connected directly to the chip, I don't have that and I don't plan to do this because of it's complexity (dosdude1 explains the differences for specific models)
• Yes, I found information on how to modify the boot volume via LINUX, but... I also found warnings, explaining doing this via Linux could break your machine, and also found reports of people saying after doing this the machine behaved erratically and so they regret it.

Yes, I tried booting to High Sierra placing a proper hard drive with it inside (a fully working High Sierra boot disk tested on our other Mac). But only got a black screen (due to the unsupported GPU), I thought I would have access to the repair boot mode but nope... The machine remained black and after a few minutes would restart on it's own. To make matters worse, it somehow messed up my Windows boot drive (on the other disk, as I removed the DVD to place an hdd caddy instead), and this forced me to reinstall Windows, what a mess.

Is there a Windows tool to achieve what I'm looking for?
Is there an specific SAFE method for Linux that I don't know about?

I really hate turning on this machine early in the morning and hear this loud sound despite covering the speakers with my hands. So far I think the only option is hardware intervention of the speaker connections. Any help will be appreciated.

 

[Mr.Fox]

Be forewarned, the command may or may not work.
1) Open Terminal.
2) Type the command: sudo nvram SystemAudioVolume=%00
3)Press Enter and enter the administrator password.
4)Reboot the Mac.
If you decide to get this sound back or make it louder, you will again need the terminal and a similar command:

sudo nvram SystemAudioVolume=%80

The command differs only in the last value, %80, which indicates the volume level of the audio greeting.
If you want to revert everything back, without knowing the volume level, the default command is this:
sudo nvram -d SystemAudioVolume
It may be necessary to set the volume without turning off the output signal, in which case you will have to adjust the set of settings. If you do it wrong, you will have problems with the sound through the headphones

 

[DeltaMac]

I doubt that command will work from a Windows command line.
(OP is not running macOS, only Windows)

 

[exploradorgt]

I doubt that command will work from a Windows command line.
(OP is not running macOS, only Windows)

I find very difficult to value (or take seriously) a post or lack of effort... when the poster didn't even read the explanation, it's nonsense.

Thank you DeltaMac for noticing this. I put effort on the specifics, sadly ignored above, I see.

 

[DeltaMac]

Did you download and install the Bootcamp drivers? The Apple drivers for the audio chip might provide the same features as the macOS audio drivers. That is, the boot chime is at the level of the system audio level, whatever that may be. That extends to a reboot, so if you have the speakers muted, the boot chime will also be muted. This is not perfect, as it is easy to inadvertantly reset the hardware function that stores the audio level after a variety of actions. But, in normal operation, the boot chime is at a level equivalent to the system volume setting.
If you are not sure about bootcamp installs, the Brigadier app will probably help you. https://github.com/timsutton/brigadier

 

[exploradorgt]

Did you download and install the Bootcamp drivers? The Apple drivers for the audio chip might provide the same features as the macOS audio drivers. That is, the boot chime is at the level of the system audio level, whatever that may be. That extends to a reboot, so if you have the speakers muted, the boot chime will also be muted. This is not perfect, as it is easy to inadvertantly reset the hardware function that stores the audio level after a variety of actions. But, in normal operation, the boot chime is at a level equivalent to the system volume setting.
If you are not sure about bootcamp installs, the Brigadier app will probably help you. https://github.com/timsutton/brigadier

Yes, I have the specific Bootcamp drivers for this iMac, however changing any volume setting within Windows has no effect. Due to how macs are made, quite often there is more than 1 sound output (digital, hdmi, headphones, speakers, 8f (or something like that), but none of those show any effect.

My GPU upgrade brought several benefits (speed, more processing power, way less heating, more video memory, etc.), but unfortunately I can't boot MacOSX anymore, and trying ended up bringing what I described above.

Seems like a hardware mod is the way to go.

 

[Nguyen Duc Hieu]

Yes, I have the specific Bootcamp drivers for this iMac, however changing any volume setting within Windows has no effect. Due to how macs are made, quite often there is more than 1 sound output (digital, hdmi, headphones, speakers, 8f (or something like that), but none of those show any effect.

My GPU upgrade brought several benefits (speed, more processing power, way less heating, more video memory, etc.), but unfortunately I can't boot MacOSX anymore, and trying ended up bringing what I described above.

Seems like a hardware mod is the way to go.

We prefer the sudo -VRAM command over other more complicated options. The value will stay in the NVRAM until you clear it with NVRAM/PRAM reset method.

Just to confirm:
1. You can't get a Mac OS compatible VBIOS to flash your upgraded GPU?
2. You can get the vBIOS, but don't know/want to flash with the GRML Linux method?
3. You can't add OCLP EFI (and adjust it to match with your new GPU in iMac 2009) to your High Sierra HDD?

When you answer NO to the above question, then other solutions should be considered.

It seems a dead-end for your case with MacOS (Quadro Q1000m with no MacOS compatible VBIOS)

 

[exploradorgt]

Did you download and install the Bootcamp drivers? The Apple drivers for the audio chip might provide the same features as the macOS audio drivers. That is, the boot chime is at the level of the system audio level, whatever that may be. That extends to a reboot, so if you have the speakers muted, the boot chime will also be muted. This is not perfect, as it is easy to inadvertantly reset the hardware function that stores the audio level after a variety of actions. But, in normal operation, the boot chime is at a level equivalent to the system volume setting.
If you are not sure about bootcamp installs, the Brigadier app will probably help you. https://github.com/timsutton/brigadier

Yes, I tried, didn't work. Found other testimonials of people trying the same with no luck. The matter requires a lot of trying, as I found out diff models of macs behave and respond differently to specific changes, but in my case I had no positive results. Thanks.

 

[exploradorgt]

We prefer the sudo -VRAM command over other more complicated options. The value will stay in the NVRAM until you clear it with NVRAM/PRAM reset method.

Just to confirm:
1. You can't get a Mac OS compatible VBIOS to flash your upgraded GPU?
2. You can get the vBIOS, but don't know/want to flash with the GRML Linux method?
3. You can't add OCLP EFI (and adjust it to match with your new GPU in iMac 2009) to your High Sierra HDD?

When you answer NO to the above question, then other solutions should be considered.

It seems a dead-end for your case with MacOS (Quadro Q1000m with no MacOS compatible VBIOS)

Exactly, I ran out of options.

I couldn't find a compatible vBIOS, the Quadro 1000m is almost unheard of regarding GPU changes on the mac, mostly because most people go after keep using MacOSX, and this leads them to discard non viable options for that, my case is different, as I prefer running Windows on this imac. I can say I exhausted myself searching for this because there are bits mentioned here and there of what could possibly work, but mostly "I think this might be compatible", and lots of broken links. So nope, I couldn't get a verified compatible vBios, and I'm not daring to risk bricking anything unless someone could share a detailed experience around the same hardware (GPU). This answers #1 and #2.

About #3, I explored this, but got lost on OCLP, and how to adjust it to the new GPU. Lucky me, my wife has a MacBookPro, so yes I can install or play with MacOS Sierra installers or hard disks, but this lead to nowhere.

Yes, it seems like a dead end to me. I will make (in the future) a hardware mode to deal with the volume output during the boot process. Even if I could modify the VRAM with alternative methods, at some point I will need to reset the VRAM and repeat the process, that's something I would like to avoid, so a hardware mode sounds better to me. I already modded this imac using an Arduino for the lost but now recovered brightness control, I just have to add a temporary measure to reduce the volume during boot (or mute it). 2 relays for muting or 2 transistors for volume control should do it (or 2 channel digital pot would be better).

Thanks everyone, a hardware mode will be.

 

[Nguyen Duc Hieu]

Easy and cheap hardware mod:
2 pieces of muting foam applied to two lower corners of the iMac.
Or 1 long piece of muting foam to cover the whole length of the lower edge.

Another costly mod is to buy/borrow the stock GPU just to boot to Mac OS drive and type the sudo NVRAM command. The value you set will stay there until you reset NVRAM.

I don't know if you can do the following, just a suggestion for reference (which I would try first in case I didn't have the stock GPU)

- Boot High Sierra HDD on another Mac,
- Preset the auto login and allow remote control on High Sierra.
- Remove the Quadro Q1000m, install the High Sierra HDD on the iMac (don't need to install the useless internal display)
- Power-up the iMac with no GPU (blindly) and do NVRAM reset, then let it boot with High Sierra, it is supposed to get to High Sierra desktop (thanks to the auto-login preset),
- From another Mac computer, ssh to the iMac and type the sudo -nVRAM command.
- Reboot the iMac to confirm the system audio volume has been turned down.
- Now reassemble GPU and Windows SSD and remove High Sierra HDD.

Allow a remote computer to access your Mac

Allow remote login on your Mac so you can use SSH or SFTP to access it from another computer.

support.apple.com

 

[exploradorgt]

Easy and cheap hardware mod:
2 pieces of muting foam applied to two lower corners of the iMac.
Or 1 long piece of muting foam to cover the whole length of the lower edge.

Another costly mod is to buy/borrow the stock GPU just to boot to Mac OS drive and type the sudo NVRAM command. The value you set will stay there until you reset NVRAM.

I don't know if you can do the following, just a suggestion for reference (which I would try first in case I didn't have the stock GPU)

- Boot High Sierra HDD on another Mac,
- Preset the auto login and allow remote control on High Sierra.
- Remove the Quadro Q1000m, install the High Sierra HDD on the iMac (don't need to install the useless internal display)
- Power-up the iMac with no GPU (blindly) and do NVRAM reset, then let it boot with High Sierra, it is supposed to get to High Sierra desktop (thanks to the auto-login preset),
- From another Mac computer, ssh to the iMac and type the sudo -nVRAM command.
- Reboot the iMac to confirm the system audio volume has been turned down.
- Now reassemble GPU and Windows SSD and remove High Sierra HDD.

Allow a remote computer to access your Mac

Allow remote login on your Mac so you can use SSH or SFTP to access it from another computer.

support.apple.com

The foam will affect the volume and quality sound later, I'm sticking to the hardware mode for the incoming months, not right now because I'm a bit busy.

I had difficulties getting the GPU I have right now, getting another (supported) will be very difficult and time consuming, ordering from the web takes time too much time for the items to arrive with the risk of receiving a non working unit (like many others), or a used GPU soon to fail. This is part of the problems of living in a country where imac parts are difficult to find.

I actually tried to do what you suggest with the HDD, but for some reason it didn't work. I didn't expect to have full video due to the unsupported GPU, instead I thought I would get basic (non accelerated) video for boot repair or install, but instead got a black screen. That's fine, I thought about remote login too, but the thing is, while the drive proved to be fully working and booting, it eventually restarted the iMac after several minutes. And sadly, messed up something on my other boot drive pushing me to do some extra work there. I'm not trying this again.

Linux, as explained I was trying, but found enough evidence on the web regarding the risks, and people who confirmed it worked, but messed up something and required tech support to repair the bios.

Thanks everyone, I'm sticking to the hardware mode. I will update when done, perhaps on January as I'm currently busy to do it right now. Will choose between relays shutting the audio signal off on boot temporarily, or just reducing the volume temporarily.

 

[Nguyen Duc Hieu]

The hardware mod, then.
The foam will mute the sound, but I suppose you apply the shortly right after power up the iMac, not all the time, though....

 

[exploradorgt]

The hardware mod, then.
The foam will mute the sound, but I suppose you apply the shortly right after power up the iMac, not all the time, though....

Yes, hardware mode.

The problem with the muting foam is... the sound volume was left too loud. I tried something like you describe, even covering the output with my hands, but the sound still bothers me. During the day it's ok, but not so much for the early morning or late in the evening. This iMac has pretty nice sound quality and levels.

 

[niteflyr]

A much cheaper solution. Try these.

 

[Nguyen Duc Hieu]

A much cheaper solution. Try these.

Definitely. They can block even gun firing sound.....

 

[exploradorgt]

Well... mission aborted.

Instead of 2 cables per speaker (and one in common, like in headphones), this iMac has 5+4 cables. One speaker connector has 5 cables, and the other has 4 cables. Not encouraging for an intervention, or at least not right now that I'm feeling lazy.

 

[exploradorgt]

Ok, mission accomplished 👍

Suddenly I couldn't take it anymore 😫. After testing sound and music without the screen attached (via remote desktop), only the black cable needs intervention, this means 2 cables, one for each speaker.

It's funny because the left speaker goes on the connector identified as "right" speaker, and so for the other (inverse), but in audio tests each one correspond to it's name. Also, the (physical) left speaker, identified as "right speaker", has 5 pins, but only 4 cables.

Anyway, 1 resistor on each speaker did the job. Grabbed all the resistors from my box and started testing live during music playback. Color code: brown-black-brown.

Now the boot sound is quite soft.

The music playback remains smooth, all I need is to increase the volume a bit when needed. No relays or digital variable resistors were needed. The best thing about this mod is, it doesn't matter if I ever need to reset the VRAM.

 

[Nguyen Duc Hieu]

Ok, mission accomplished 👍

Suddenly I couldn't take it anymore 😫. After testing sound and music without the screen attached (via remote desktop), only the black cable needs intervention, this means 2 cables, one for each speaker.

It's funny because the left speaker goes on the connector identified as "right" speaker, and so for the other (inverse), but in audio tests each one correspond to it's name. Also, the (physical) left speaker, identified as "right speaker", has 5 pins, but only 4 cables.

Anyway, 1 resistor on each speaker did the job. Grabbed all the resistors from my box and started testing live during music playback. Color code: brown-black-brown.

Now the boot sound is quite soft.

The music playback remains smooth, all I need is to increase the volume a bit when needed. No relays or digital variable resistors were needed. The best thing about this mod is, it doesn't matter if I ever need to reset the VRAM.

Great work! Nice testing method.
I guess they are 100Ohm +/-5% through-hole resistors. You used 4 resistors in total, correct?
It's strange for you to have a bunch of resistors but no multimeter.

 

[exploradorgt]

Great work! Nice testing method.
I guess they are 100Ohm +/-5% through-hole resistors. You used 4 resistors in total, correct?
It's strange for you to have a bunch of resistors but no multimeter.

Yes, it's working pretty well.
The resistors are 100 Ohms 5%, measured 99.9xohm on the multimeter (I have 3 of them, 3 multimeters).

Nope, only needed 2 resistors:

Anyway, 1 resistor on each speaker did the job. Grabbed all the resistors from my box and started testing live during music playback. Color code: brown-black-brown.

While each speaker has 4 wires, only 2 are used for the boot sound, only the black wire needs intervention.

This iMac runs pretty well.