Native IDE Optical Drive Audio...

[giZmo350]

I have a Fast ATA MKIV in my A1200 and a nicely shoehorned slim CD-DVD under the keyboard that ejects out the back. Yesterday I won 6 excellent Amiga CD titles on ebay and got to thinking "how am I going to get the audio from the optical drive to my speakers?". The board I bought for the optical drive is a IDE to slimeline with audio breakout (4 pins). Question is... how do you guys get the audio out to the speakers from the board without a sound card? Yea, I will get a Prizm when available but, can I just connect the audio out from the board to the audio out RCA connectors on the miggy without blowing anything up? Will that even work? Thanks for any replies and maybe how others may have accomplished audio out without a sound card.

[giZmo350]

Hmmm, yea I guess a mixer would be the best bet. Although, I know the miggy audio is real hot, does the little laptop optical unit even have enough output to drive the mixer/speakers to mix the two audio signals properly? Matt, does yours? Do you get any distortion from the optical drive if it doesn't have enough gain?

I was looking again at the discussions about the Prizm... will that have a stereo input and mix optical audio with the miggy audio?

Pricey little mixer for something I'll never use again if the Prizm board does what I want it to do...  when's that thing going to be released to manufacturing anyway?

[giZmo350]

If the analogue audio stage is getting hot, you have a major hardware problem.  The op-amp U15 will dissipate a few milliWatts of heat at the most.  Also, the output power of the audio stage will be in the order of (2Vsq / 1k Ohm)= 4mW at the most.

If you're talking about the 8364/Paula being normally warm, that's just due to the relatively high quiescent current of the device due to the technology used at the time.  It doesn't dissipate any more or less heat while the digital to analogue converters are being used.

LOL! I meant the miggy audio is real hot as in LOUD at low volume! Sorry... :roflmao:

Castellen, thanks much for the info (I'm willing to try it!). Makes a guy wonder why C> didn't add a small circuit and input pins like that on the MB (they thought of everything else!).

Also, were Amiga CD/CD32 titles ever purposely produced for any other machine other than the CD32? I mean, did the A3K/A4K have a proper on moherboard preamp to mix CD audio with? If so, maybe an A3K/A4K schematic, or even a CD32 schematic, would provide proper circuit values.

[giZmo350]

Thanks Mike! That's not bad but way over-techy, external (for an A1200 wedge), and requires a PSU.

This was pretty funny at the bottom of the mixer page though "*Peak Music Power Output (PMPO) is a bull sh!t marketing term to make a  product look as though it has large power output, when in reality it  does not. I just made the figure up like most manufacturers do." :lol:

Anyone have an A4K schematic they could check out and reverse engineer a board? I think you could sell a ton of these! Kipper?

Maybe I should get a spare A1200 mobo to try this out on...  not that I doubt Castellen but, I wouldn't want to hork my production Miggy!

[giZmo350]

But the information I gave you is probably the easiest, tidiest solution.  Don't get hung up on the resistor values, if my estimated value ends up with audio way too loud, just increase the resistor by a factor of two or four and keep going until you're happy.  It's a summing amplifier, not rocket science.  Or you could use 10k pots instead, but personally I wouldn't bother.

Right Then! It's a go!

Just one other question... can I get to these pins on U15 on the top side of the Mobo? I ask 'cause getting my mobo out with all the mods I have would be a real pain in the arse!

Thanks again Castellen and all responders!