Titanium Sound

Having had my Titanium for a while, I thought it was about time I investigated the sound outputs.

As a start, I found an 8ohm speaker, and plugged that in to PL100 internally. That indeed produced ‘sound’ fit for beeps etc. However, for much of the time it also had a low-level crackling sound, which was not a loose connection so I thought it would be interference. But it was not affected by where the wire was routed, so eventually I disconnected it as it would be annoying.

I then found an external amplifier, and investigated the 3 sockets on the back – Blue, Green and Red. I can find no reference to relate these to the mic in, headphone out or two line in sockets listed in the web page under main features. I think the Green (middle) one is an output, as I could hear sound from it. However, like the internal speaker, it also had the crackling sound.

Has anyone else experienced this?
Better still has anyone got any solutions?

I can’t speak for the crackle, but the industry standard for audio jacks is as follows:

Green is line/headphone out.
Pink/red is mic input.
Pale blue/blue is line input.

Since RISC OS has no clearly defined input API or drivers, don’t expect anything to happen on the input front. It’s one of those projects that needs a keen soul to define an Open Source API and code a “API manager” module and example hardware driver(s). I suspect it could be done in such a way that the hardware stuff is HAL-based, but it may be better as a software driver stack like PlayIt.

Green is line/headphone out.

Gah. What idiot thought they’re the same thing? A true line out is supposed to drive a load of a few thousand ohms.
Hook up some headphones, you’re looking at maybe 32 ohms. Use a speaker instead, it’s usually in the range of 4-8 ohms. Effectively short circuiting the output. There’s a reason why older equipment kept these two separate – and putting a line out load into a speaker or headphones IS PROBABLY WHY YOU HAVE TO TURN THE SOUND RIGHT UP IN ORDER TO HEAR ANYTHING.

don’t expect anything to happen on the input front

Wasn’t there audio input for the Beagle family? I wonder if the idea could be recycled?

it may be better as a software driver stack like PlayIt.

Hmm, now does PlayIt talk to all of the audio hardware directly, or does it put data in place which is then used by the HAL audio driver? ;-)

In reality, it’ll require a combination of both. A low level driver that talks to the hardware, and a higher level stack that provides a unified API and bridges the gap between the driver and the user.
If it’s advanced enough it may also be able to apply real-time filtering to provide, for example, data in MP3 format (instead of PCM samples).

@Martin.
The sound using a pair of computer speakers is ok here, no crackle. Tried using mp3’s of rock.pop a little classic and spoken voice. (Bob Newhart.) I can control the volume, tone and on/off via the speaker controls.

Of course the speakers are self powered via wall wart.

Regards Ron.

One of the points of having USB Audio supported is that it the bypasses problems of this kind. So it continues to puzzle me why there is so little interest in the path which all other OSs have already used.