Stereo Mod for Color Classic

[Tim S]

Hi.... first post here.

I would like to do the stereo mod to my Color Classic like mentioned here: http://colourclassicfaq.com/general/stereo.html

It mentions some smd capacitors with an unknown value.  I've tried contacting the original author but never go a reply.

Anyone know of the correct value parts that I would need to order for this modification?  My forum searches have come up empty.

Thanks,

Tim

 

[Tim S]

Has anyone ever done this mod??

 

[Bunsen]

I think copying the values from the existing mono output circuit on the CC might be your best bet.

 

[Bolle]

Bunsen, problem with that is that some caps are marked with codes which don‘t seem to be standard.

But why not remove one of those and just measure their value?

 

[Trash80toHP_Mini]

Took a look around for an LC or CC DevNote at work and came up empty. Anybody got linkage for either? IIRC the LC might be the one that's never been found?

LCII DELTA DevNote addendum to the MIA LC DevNote looks VERY grim for any possibility of doing a stereo hack at the MoBo level for LC/CC.

"Sound: monaural sound input and output system identical to that of the Macintosh LC. A microphone is included as standard equipment."

If I can bring one of my LCs to life I could test stereo output via LC PDS version of the PAS16. Doubtful it's even supported though, so that's likely a non-starter. Should have the docs in the boxed set somewhere in the StorageBoxen pyramid. I'd almost bet the LCIII is the minimum supported by PAS16.

IIRC the NuBus version of the PAS16 couldn't manage to do the job of uncoupling the fused R&L signals of the Duo sound system. That's based on the far more advanced, stereo capable Apple Sound Chip ASIC. Had to use a Sound Accelerator II in the DuoDock with some esoteric brew of OS and drivers to coax stereo out of my favorite little NoteBooks for my DuoBoomBoxDock™ entry in an applefritter contest. Never got to the NuBusMiniDock™ required and there was no way I could have afforded the pair of DeWalt Job Site Radio/Battery Chargers and pair of 12V batteries required to power the amps and the 24V Duo kluge in that time frame. Sigh! :-/

 

[Trash80toHP_Mini]

I couldn't read the CC thread before this, it's filter blocked at work. Doesn't sound at all like a stereo hack. He's hacking an amplifier to run a decent speaker for the "monaural sound input and output system" on the mobo. Unless the CC is different than LC and LCII, my understanding is the Original and II versions of each are twins at the architectural level?

IDidn'tRC the DuoBoomBoxDock™ thread outcome. The DigiDesign Sound Accelerator II gave me what sounded crappy, but was in stereo.

MediaVision's Pro Audio Spectrum 16 wound up giving me nice clean stereo out of the mono-lamed ASC setup of the Duo. 190/5300/1400 series were lamed the same way IIRC. Stereo sound and speakers debuted in the 3400, which was a Humvee monster truck edition to the Duo's cute lil' Schwimmwagen.

Thread mentions the PDS version of the Pro Audio Spectrum 16 being for the LCIII. I either got that wrong or mis-spoke because an LCIII was what I had on hand in that time frame.

Just opened up my boxed PAS16/LC set and the manual says it's compatible with LC, LCII and LCIII! Looks like I ought to be able to cobble together a Stereo CC if I ever got over my aversion to that espresso design language tainted, appearance challenged, little  .  .  .

 

[Bunsen]

Last time I recall looking into this, the conclusion was that the sound IC on the CC does in fact produce a stereo signal, but it's mixed down to mono off-chip.  Hence the possibility of stereo.

 

[Trash80toHP_Mini]

Check the DevNotes, IIRC my last was was a summary of the mono sound setup of the LC/LCII hardware specified therein.

I was in error there, the CC is a (Mono I/O) LCII chipset reworked to the primal MedusaMess edgecard interface?

The CCII was the vastly more capable LCIII chipset, the same driving the LC 520 stereo speaker output? Don't have the LCIII Devnote in front of me, but I'll wager the ASC missing on the LCII block diagram can be found there.

In short, there could be some confusion about the CC's lame mono sound I/O and the CCII's lamed STEREO ASIC output that may be possible to hack for unmixed sound output at the board level. If the CCII wasn't such an ugly little turd I'd feel challenged. [}] But is my LCIII lamed in the same manner?  []

Dunno, that's conjecture based on a sparse data set and where the pieces fall the way I see 'em.

Haven't got CC or CCII DevNotes, linkage anyone?

 

[Trash80toHP_Mini]

Not tempted, but very curious. Rounded the DevNotes up well enough: what I gots:

LCIII has the same lame LC/LCII sound system:





Things get much more interesting in the LC520 DevNote:





Looks to me like it boils down the the Sound ASIC combinations involved:

DFAC appears to mono however, wherever, forever.

CC = DFACII which ought to show some promise, hobbled by Spice System Controller ASIC? = mono

LCIII = DFAC without promise, hobbled by the Sonora System Controller ASIC as well = mono

LC520 = DFACII + new Ardberg System Controller ASIC = Stereo



I'd love to be proved wrong on this, but it looks to me like the first Macs capable of stereo sound came with two speakers, one per in their monster elephant feets. If someone studies the schematics they might find a chink in the hardware, but it doesn't look promising from the DevNote descriptions of the chipsets.

CC Block Diagram:

 

[Tim S]

Awesome information!  

 

[Tim S]

UPDATE:

Well, I completed the mod as described in the above link mentioned in my initial post. 

It does work with the speaker connected to the new audio amp but the volume is way reduced for some reason. 

I rechecked my work and everything is correct so I am thinking that maybe in these instruction the locations for some of the surface mount components (caps, resistors) got somehow reversed or something?  It seem strange that I would

get audio output okay but at such a reduced volume.  Without a schematic (or maybe even with one) I am now totally lost at what to try.

So close yet so far.  It would be nice to get this sorted and then can call this project complete.

Ideas?

 

[mraroid]

Hi

Chris Lawson, who wrote the FAQ you are loking at, hangs out on a Facebok forum on old macs. It is called "Low End Macs".  Here is the link:

https://www.facebook.com/groups/lowendmac/

You might ask about the mod on that forum.

mraroid

 

[CC_333]

Hmm, I *think* this can sometimes happen if an amp isn't biased correctly?

Or so says a vague, 16 year old memory.

c

 

[Tim S]

Thanks for the input.

I don't have facebook so for now I am kinda stuck here. 

A schematic would help also so I will start to dig online but I am still really taking a stab in the dark on this thing.  I might just go with having the 2 speakers even if the volume from one is reduced - at least it kinda works! :\