Audio IN mod for 464 Plus, is it possible?

Rurnin Bubber · 07:04, 21 August 22

Hi all,

like the thread title says, is it possible to add an audio input mod for the 464 Plus, as we've seen documented for the regular 464? In my head, it should be more or less identical to the 464, so I'm just asking here as a sanity check.

Cheers

Bryce · 11:02, 21 August 22

https://www.cpcwiki.eu/index.php/DIY_Plus_Tape_Socket

Bryce.

Rurnin Bubber · 13:54, 21 August 22

Quote from: Bryce on 11:02, 21 August 22https://www.cpcwiki.eu/index.php/DIY_Plus_Tape_Socket

Bryce.

Cheers Bryce. Given that's for a native 6128+, would I be correct in understanding that for the 464+ with all the listed components already installed, I'd just need to 'piggy-back' onto "mic" as a tape-in, "tape output" as an internal speaker, and "remote" as a control for start/stopping?

Bryce · 14:02, 21 August 22

The 464+ and 6128+ are exactly the same PCB, just with some components (extra RAM/floppy components) missing on the 464+ and the tape components missing on the 6128+.

Bryce.

Rurnin Bubber · 14:19, 21 August 22

Quote from: Bryce on 14:02, 21 August 22The 464+ and 6128+ are exactly the same PCB, just with some components (extra RAM/floppy components) missing on the 464+ and the tape components missing on the 6128+.

Bryce.

Indeed, I'm almost finished bringing this 464+ up to 6128+ spec (just waiting on the last few components to arrive.) Looking at the circuit diagram though, I'm just a little unsure exactly where I need to piggy back from...am I correct in thinking it's "mic" as a tape-in, "tape output" as an internal speaker, and "remote" as a control for start/stopping?

Bryce · 08:49, 22 August 22

Maybe it's your wording I'm not understanding? "Piggybacking" means mounting one component on top of an existing component. You do not need to do this anywhere for this modification. "mic" is CPC audio out, "tape output" is CPC audio in.

Bryce.

Rurnin Bubber · 12:32, 22 August 22

Quote from: Bryce on 08:49, 22 August 22Maybe it's your wording I'm not understanding? "Piggybacking" means mounting one component on top of an existing component. You do not need to do this anywhere for this modification. "mic" is CPC audio out, "tape output" is CPC audio in.

Bryce.

Apologies Bryce, bad choice of wording on my part. What I mean is, looking at the diagram, am I right in thinking all I need to do is connect a wire to CP07 (5th pin down, Tape Output), and connect the other end of the wire to an audio jack? Obviously I need to ground the connector too. There are no concerns about amplification of the audio signal etc as there are on a regular 464?

Bryce · 12:54, 22 August 22

Well your tapedeck / MP3 player already has an amplifier similar to the one in the CPC tapedeck. However, the CPC tapedeck had a pre-defined signal level. You'll have to experiment with the volume of the external player to find the most reliable level.

Bryce.

Rurnin Bubber · 13:03, 22 August 22

Quote from: Bryce on 12:54, 22 August 22Well your tapedeck / MP3 player already has an amplifier similar to the one in the CPC tapedeck. However, the CPC tapedeck had a pre-defined signal level. You'll have to experiment with the volume of the external player to find the most reliable level.

Bryce.

I was thinking along the lines of something like a tzxduino, so wasn't sure where to connect the cable exactly in the circuit to ensure adequate amplification

Bryce · 13:21, 22 August 22

There's no amplification on the CPC mainboard, the signal needs to be amplified to the correct level before going into the CPC.

Bryce.

Rurnin Bubber · 13:41, 22 August 22

Quote from: Bryce on 13:21, 22 August 22There's no amplification on the CPC mainboard, the signal needs to be amplified to the correct level before going into the CPC.

Bryce.

I just checked the tzxduino specs there, they include a LM386 amplifier built in. So I'm undoubtedly overthinking this thing! Thanks for your help & assistance Bryce

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Audio IN mod for 464 Plus, is it possible?