G4 Cube Internal Speaker Functionality Dilema

[jajan547]

I've been slowly discovering a lot about the G4 Cube which in my opinion is one of the best looking Mac's Apple ever made. After looking for one for a while my good friend @Jockelill gave me a great deal on one and I've been loving the device a whole lot since receiving it. I've slowly discovered some of its strange development choices and have been questioning one choice more than any, the removal of an internal speaker? I know this has been brought up before but the answer I don't believe has ever been found. If you ever look at the internals of a G4 Cube most of us have seen that there is a white connector and an empty space for a G4 speaker (photos below) the same speaker found on the tower models. Now if you put two and two together you'll see that the speaker not only fits perfectly but also appears as though it would connect simply to that white connector and by slapping the Cube back together you'd expect sound or something. However, one would find this simply doesn't happen. Obviously this was planned but ultimately removed.

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Proof of the original idea for internal speakers I believe can be further backed by the serial number labels of some early G4 Cubes that give away this with the inclusion of the text "SPEAKERS" (I borrowed this photo below from an Ebay listing HERE in case you're interested in this listing, not that this means it's special there are many other examples like this).

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Now here's where it gets even more interesting. I happen to know someone with a few prototype G4 Cube's that have an internal speaker which as it turns out is the same as a tower G4's internal speaker. However when I asked if this individual's Special G4 Cube's chimed on boot up or ever output sound I was surprised to hear the answer was "No" and even on an example with totally preproduction ROM's the answer was the same. So I decided to do a little more research. If you look on a G4 Cube's logic board you will see a chip labeled "MICRONAS DAC3550A" the data sheet can be found HERE. This chip is what controls audio for the G4 Cube and you'll be surprised (or not) to learn that upon pulling up the data sheet there is an internal amplifier and pins for audio out. Albeit it nothing loud there still should be sound.

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Pins 5 and 7 are most important here. The chip should be able to output any sound from the machine on these pins if a speaker is hard wired in and that's exactly what I did. However I discovered I still received no sound out. So at this point I'm questioning if maybe the audio output is software controlled in a way that the OS will only output sound through USB and the infamous Hardon-Kardon speakers. I haven't tried installing Linux or Windows on these (nor am I going to) so I can't confirm if maybe hardwiring in a speaker the same way would work. But if anyone has any ideas or wants to give it a shot and share, please by all means do. I would love to have an internal speaker in this machine without any crazy mods or wires going in and out of the back. But as it stands these are my findings.

 

[GRudolf94]

Hrm. The Cube is theoretically based on the Sawtooth architecture, which uses Screamer (Crystal) audio. The DAC will have been wired to Paddington's (Lucent 1258U) I2S lines - pins 16 and 15 on the 3550. If the machine is telling it to do anything, it'll be on there.
However, looking at earlier machines, in fact, what I recall being the first UniNorth Mac released (the Clamshell iBook), audio there is also a DAC3550. On the slotloader iMac I think it's back to Screamer, despite them both being similar.

Nobody knows what caused Apple to not properly implement Cube audio. I suspect you could look at a toilet seat iBook's OpenFirmware and get some better clues from the I2S-audio entries - from there it should be possible to write a patch. I think the Cube just has stub entries for pseudo-audio, whatever that means.

 

[pizzigri]

Very interested, as I also would love to have a simple “bong” and system sounds without having to connect the HK loudspeakers - which I do not own

 

[jajan547]

Hrm. The Cube is theoretically based on the Sawtooth architecture, which uses Screamer (Crystal) audio. The DAC will have been wired to Paddington's (Lucent 1258U) I2S lines - pins 16 and 15 on the 3550. If the machine is telling it to do anything, it'll be on there.
However, looking at earlier machines, in fact, what I recall being the first UniNorth Mac released (the Clamshell iBook), audio there is also a DAC3550. On the slotloader iMac I think it's back to Screamer, despite them both being similar.

Nobody knows what caused Apple to not properly implement Cube audio. I suspect you could look at a toilet seat iBook's OpenFirmware and get some better clues from the I2S-audio entries - from there it should be possible to write a patch. I think the Cube just has stub entries for pseudo-audio, whatever that means.

I’ll try looking into the connection there as you mentioned and see if it works. If not I believe it really is something in the software that was just never finished and removed altogether as a result.

 

[jajan547]

I can't find a data sheet for the Lucent 1258U, also the Lucent chip on the G4 Cube is a Lucent 1258AK5 (Don't know the difference). If I can get that that should actually give us what we need. Because you are right pins 16 and 15 on the 3550 control in out sound clock and data.

 

[GRudolf94]

I probably got the suffixes mixed up - 1258 is all one family. There's no datasheet because it's an ASIC designed by Apple - we'd need a document called Paddington ERS or KeyLargo ERS (1258AK is probably KeyLargo? Memory spotty there) to know more about how that works. In any case, AFAIK that document hasn't leaked.

 

[Phipli]

Proof of the original idea for internal speakers I believe can be further backed by the serial number labels of some early G4 Cubes that give away this with the inclusion of the text "SPEAKERS" (I borrowed this photo below from an Ebay listing HERE in case you're interested in this listing, not that this means it's special there are many other examples like this).

No, this is because they shipped with external speakers. You wouldn't call a single internal speaker "speakers" plural.

 

[Phipli]

I haven't tried installing Linux or Windows on these (nor am I going to) so I can't confirm if maybe hardwiring in a speaker the same way would work.

Erm... You'd struggle to install Windows on a cube even if you tried really hard!

 

[3lectr1cPPC]

With enough of a crack at the source code, getting NT 4 running is possible in theory
Depends on your definition of "trying really hard".

 

[Arbee]

I probably got the suffixes mixed up - 1258 is all one family. There's no datasheet because it's an ASIC designed by Apple - we'd need a document called Paddington ERS or KeyLargo ERS (1258AK is probably KeyLargo? Memory spotty there) to know more about how that works. In any case, AFAIK that document hasn't leaked.

Paddington and KeyLargo are the "Mac IO" chips, basically the PCI descendants of the IOSB/PrimeTime/PrimeTime II "south bridges" on some of the Quadras. They have the DMA controller and interface to the actual audio chip (AWACS, Screamer, Burgundy, and a few others) but don't produce the sound.

 

[Arbee]

With enough of a crack at the source code, getting NT 4 running is possible in theory
Depends on your definition of "trying really hard".

The beige G3 was originally designed to be CHRP compliant and boot NT, but that's about as close as Apple got (and that plan was discarded about 5 seconds after the NeXT deal happened).

 

[3lectr1cPPC]

It makes an interesting alternative scenario to think about...

 

[GRudolf94]

Anyway, I'm sure we'll find out the issue is: the audio hardware is left dangling there, curiously stuffed on every production board, without having a suitable entry in the device tree to pipe it into the system so that it can be seen as an audio device by either ROM or OS.

I won't be close to my toilet seat iBooks to check for a few days more, but ya.

 

[LaPorta]

No, this is because they shipped with external speakers. You wouldn't call a single internal speaker "speakers" plural.

Exactly.

 

[jajan547]

No, this is because they shipped with external speakers. You wouldn't call a single internal speaker "speakers" plural.

Apologies newish to the G4 lineup. So haven’t done too too much but yeah makes sense for units that shipped with those external speakers. Rookie mistake on my end. These came out literally the year before I was born so want to learn more about potentially modifying these and so forth. I suppose a good place to start is with an iBook so I guess I’ll pick one up and see what’s what. I’m still leaning towards the fact it’s simply something in the software that was never finished so they shipped these as is I suppose to cut down on cost. But still should be possible to I guess enable it with a bit of editing or trial and error.

 

[LaPorta]

Apologies newish to the G4 lineup. So haven’t done too too much but yeah makes sense for units that shipped with those external speakers. Rookie mistake on my end. These came out literally the year before I was born so want to learn more about potentially modifying these and so forth. I suppose a good place to start is with an iBook so I guess I’ll pick one up and see what’s what. I’m still leaning towards the fact it’s simply something in the software that was never finished so they shipped these as is I suppose to cut down on cost. But still should be possible to I guess enable it with a bit of editing or trial and error.

So you’re trying to call me old??

 

[jajan547]

So you’re trying to call me old??

Wasn’t that long ago haha. Time flies.

 

[Ncc74656]

just want to throw this out there - in my G4 performa build ive used a cheap class D 12v amp to peg off the headphone (line out) 3.5mm jack and amp a dayton audio speaker. you could use fiberglass to make a speaker enclosure in there and stick a small amp to it once you have that input. it worked well for me.

 

[GRudolf94]

As promised, iBook device tree dumps. The DAC3550 lives at /pci@f2000000/mac-io@17/i2s@10000/i2s-a@10000/sound

Also attached are the . properties for each subdevice in this configuration.

Sorry for the crappy images, but this iBook's panel is on the way out with vinegar syndrome.

 

[jajan547]

Thank you so much for sharing! This is great information.