Apple IIgs Stereo Board

Charlie

.. . Mouse . ..
Joined
Jan 20, 2008
Posts
690
Country
UK
Region
Wirral
Here's a picture of my initial musings:

IIgsStereo.jpg

As anyone with a IIgs will know the computer has a very good sound chip - eight independent channels..? Sadly Apple only gave the machine a cruddy mono internal speaker, but at least supplied a header for expansion. I hear the IIgs can sound pretty awesome with some decent output and stereo->multichannel output cards have been available for a looong time.
-Hard to come by
-Expensive for what they are
-Where's the fun in buying stuff if you can make it..?

I've got to admit I'm no electronics engineer and the multiplexing the IIgs's sound chip uses for it's output has been 'doing my head in' but I think I've finally got it and can hopefully get proper stereo out of it... for now.

The above layout basically takes input from the IIgs audio header, demux's it so four (I think) channels each go to Left and Right, but I have some decisions to make:

-Do I want it as a plug-in card or not? ATM I've covered both bases; the edge connector only picks up power so could be regarded as a waste of a slot, hence my including a power header.
-More importantly what about output?
...I could:
a) Add some caps and just leave it as a line-out - external powered speakers
b) Put in some amplification - headphones, internal speakers
c) add a 3.5mm stereo jack and/or a header

If anyone's interested I'd appreciate comments. For myself I'd go for:
-Keeping the option to plug in to a slot or tap lines for power
-Have a line out header and the option of a small Amp plus header for internal speakers... the latter much as my Mockingbird card utilising an el-cheapo Amp board off fleaBay.


*Edit*
So far so good?
IIgsStereoLayout.jpg

*Edit*Edit*
By Jove I think this may be it:
Capture.jpg

...a bit of tidying, the option to add a potentiometer for volume control of the Amplified output and baring any obvious mistakes / suggestions I think a prototype is called for. I guess I'd better do a wire-wrap jobbie before ordering boards - still not sure I've sussed the multiplexing thing.
 
Last edited:
I think using a slot for power is fine on the GS as due to the onboard hardware less slots are required for the user.

on the other hand, a module that could plug straight into the Mobo header would be cool.

Please put me down for 1

;)
 
nice thing about the GS is that I didn't need a disk controller board or a serial card, or a mouse card for that matter, which I did need for my Apple IIEs, since ADB takes care of the mouse, built in serial/printer ports and disk drive port...80-column built in...all I really needed for the GS was memory expansion...

a cheaper SD card solution would be nice, however. (hard disks are few and far between :/)

not sure i'd have much use for a stereo board.
 
:)
Thanks for the feedback chaps, here's hoping it actually works (I'll need to order the IC and do a test board first)

@Bas - of course, old chap :) If this works I've had a vague thought about doing a IIgs specific Mockingbird

@SaviorX - Fingers crossed, there will be a cheaper 'HDD' solution in the near future. Not me.
 
Quick Update:
IIgsStereoBoard.jpg
:D:D:D

...there's just one small fly in the ointment - I've run out of female PCB headers so I can't finish and try it out just yet. (nervous frustration) I could bodge it, of course, but as my IIgs is already a bit special I don't want to risk it in any way. Parts on order; fingers crossed.

PS:
Assuming it actually works I'll send a free PCB to the first person who can spot the two (thankfully non-serious) errors in the above piccie. Observational skills, not electronics experience, needed.
 
Last edited:
Your chip notch directions are non sychronous and the tea towel isn't anti-static? :)

As ever, very very good charlie!

ps I havent got a GS so I'm just being flippant /unhelpful as usual:) :) :)
 
The reversed G and R on the ampout circuit bit thing?

Good spot! I actually thought that would be the harder one to notice. Get the other and I'll gladly send you a PCB :)

Your chip notch directions are non sychronous and the tea towel isn't anti-static? :)

As ever, very very good charlie!

ps I havent got a GS so I'm just being flippant /unhelpful as usual:) :) :)

Thanks again for the encouragement Iain :)

Um, I believe my notches are fine (fnar, fnar). On the subject of anti-static tea towels I admit to not being to most careful person with electronics.

*Edit*
I'll change my offer:
-The first to see two of my 'mistakes' gets a PCB, regardless
...and if the darn thing actually works:
-The first to spot *three* of my mistakes can have a fully built and tested one. :)

Yep, I spotted another error, "mumble, mumble". Thankfully none are show-stoppers, or need ugly mods to fix.
 
Last edited:
hmmmm is it the "insert right way around" text which extends beyond the end of its box?

Sorry, I like a challenge like this! I should say though, if I'm right, you should send my PCB to theCorfiot as I have never even seen an Apple II in the flesh, I just cant resist a good challenge !

Oh and I should probably add, this is great work, as I think nearly all homebrew mods like this are. This place is full of amazing folks like you and inspires me every day
 
Last edited:
Thank you and apologies for being cruel... The text that extends out of the box is actually Seeed's mistake - I checked the files I sent and they are fine. Hence the reason for my typing "two of my 'mistakes'". I know, what a miserable so-and-so I am. :evil:

Feel free to keep guessing. The remaining mistakes (at least the ones I'm currently aware of) will likely make you go "Doh!" when you spot them. ;-)

Yes, Bas is going to get one... again, assuming it actually works - there's no fun without the risk of public humiliation. Um, if one of these boards is of no use to you maybe something else?
 
Last edited:
I'm enjoying this, but sadly the only other thing I can spot after much staring and squinting is that to me, the numbering of the resistors and caps seems odd given the layout, but that may be electronically logical, not human logical. Either way, I enjoyed the game!
 
Yes, the numbering is a consequence of how the schematic is laid out. Shall I spill the beans?
 
Last edited:
Well, that's up to you, but I officially declare. No idea :)

Prepare to shout "D'oh!", or possibly "Not fair."

The grey thing soldered to the right side of the board by some ribbon cable is a 3.5mm audio socket...
#1: If the audio out is to be attached though a panel how am I going to push the connector though a mounting hole when it's already attached to the board? I do this all the time, sadly. But not as often as I forget to put the DIN connector sleeve over the cable before soldering the plug on the end.
#2: Same connector, second mistake - oops! Trying to be tidy, for once, I put some shrink-wrap over the end of the connector to hide the solder joints. Yes, the nut to secure the audio connector won't go on any more, which is why it's stuck over the shrink-wrap.

Ho-hum, I doubt it will be the last time I do this.

PS
Volume pot(s) arrived and soldered. I just need the female PCB connector(s) to turn up and I can find out if this thing actually works.

PPS
I've been so busy fiddling with my IIe over the last few months I'd quite forgotten what a nice little machine the IIgs is. I quite agree with the 8 bit guy:

 
Last edited:
Ya know, I'd been thinking along those lines, but not knowing the IIe very well, I assumed you knew what to do with it :)

Whatever though, it's great work. You should see the state of the Gotek I just crammed into this 500 here... There's a reason there's no pictures up here of it!
 
Ya know, I'd been thinking along those lines, but not knowing the IIe very well, I assumed you knew what to do with it :)

Whatever though, it's great work. You should see the state of the Gotek I just crammed into this 500 here... There's a reason there's no pictures up here of it!

If it works... I have an old thread on here somewhere titled "ghetto CPC"

Update:
Confusticate And Bebother These Dwarves!
Yes, the female pin-headers arrived today... But I bought a size too small. I've always been in the Hobbit of not checking things carefully enough. Hmm, to fix the job properly and order the right size or, in spite of my comment earlier in this thread, do I just bodge it?

Very tempted.
 
Last edited:
The Good, The Bad, and The Ugly... an Update
https://www.youtube.com/watch?v=AFa1-kciCb4

The Good:
My first IIgs Stereo Card is finished, fitted, and no escapes of magic smoke:

20180418_161259.jpg20180418_161310.jpg
20180418_161314.jpg20180418_161412.jpg

The Bad:
It turns out I don't have anything on my GS's 'hdd' that would prove the stereo output is working... suggestions?
(I've got a cr*ap ton of IIgs software running on my IIe, just to be perverse)

The Ugly:
I couldn't wait for parts any longer, so I bodged it. Ribbon cable from the board to the IIgs audio header attached by means of 1/2 a DIP14 chip socket. I'll fix it when the right parts finally arrive.

*Edit* Piccies inserted
 
Last edited:
Back
Top Bottom