Thinkpads Forum

I'm a bit of an audiophile, and I just purchased a 15" 4:3 T60 (1952-CTO). While I was upgrading the RAM, I noticed the PCMCIA cage and it's proximity to the headphine jack. Has anyone tried replacing the PCMCIA cage with a CMOY or simmilar DIY headphone amp? From just eyeballing it, it looks like it would fit, the battery might be an issue, but I was wondering if anyone has tried something simmilar and had any experience/advice.

If the components are small enough, you could probably gut out a pc card cage and build one, but I'm at a loss as to why you'd want to do this. As for the battery, the pc card cage plugs into the motherboard which suplies it with voltage, so you shouldn't need a battery if it's well designed, but if I had to chose between a pcmcia/express card port or a headphone amp, even if the amp was free and didnt require a lot of work, I'd still not want it, but I guess you have your reasons so have fun, and be careful you don't damage anything on such a mod.

ps. If you want an extra pc card assembly to work with, I have some, but I don't have a schematic for them, but you can probably reverse engineer the power supplies from a combination of testing and looking up the pcmcia pinouts, and you're going to have to be really good at soldering to pull this off.

In my case I would preffer a heaphone amp to a PCMCIA/Express Card slot, even if it takes some work I know PCMCIA supplies 5v and 3.3v, the CMOY requires 9v, so that would take some work. I will take a look at the pinouts of the two slots. PM'd about a spare cage.

There are a lot to think about when designing an audio circuit.

Is the power supply noisy? Computers have particularly noisy power supplies in general. ThinkPads have relatively clean audio at least compared to my Asus notebook, but if you use a noisy power supply for your headphone amp, you can introduce significant noise.
What would you use as ground? Headphone amps require both positive and negative voltage sources, so "ground" would be between positive and negative of the power source. With a battery-powered amp this is not a problem, but when your audio signal and power come from the same source (i.e. your ThinkPad), there are serious potential for ground loops or a shorted power supply.

This is even before thinking about practicality issues like whether ExpressCard / PC Card slots can supply enough power, switching between speakers / headphone, etc etc.

I wasn't going to wire it to the speakers, it would only amplify the headphone jack. As far as the power supply - I didn't think of that, I guess I will have to find a way to integrate a battery. Maybe a rechargable 9v and a charging circuit....

By "switching between headphone and speaker", I meant the automatic switching between speakers and headphone when you plug in / remove headphones. If you would like to replicate that feature, you'll have to figure out how it is implemented in the first place.

A battery charging circuit is another can of worms entirely...