Sinclair ZX80 / ZX81 / Z88 Forums

Hi

My ZX81 saves data to my iPhone (through a Sony NetMD MiniDisc for amplification).

These files played back to the ZX81 is loaded without problem.

I convert these .m4a to .wav on my Mac.

I have tried every WAV2P-program I have found, but they all show BASIC-garbage when it has been converted.

I have tried

• EightyOne Wav-loader
• zx81stuff.co.uk Java tape converter
• zxprojects.com zx81util

It's strange, as the sound files are understood by ZX81, but no software on the Mac can understand them.

I suspect the only common link here is the m4a -> wav converter. Can you load the converted wav file into - for example - Audacity? How does it look?

What format data do the tools such as wav->p, EO etc. require? Perhaps the wavs are 96khz, quadraphonic, 3d or something Some utilities only take mono 22khz 8 bit sample streams, and perhaps silently fail with data in other formats. WAV is a container, not a format in itself.

C

Could you post a wav exemple ?

I will try to convert it using ZxSpectape.

sirmorris wrote:I suspect the only common link here is the m4a -> wav converter.

I assume QuickTime (which is the foundation for all sound on Mac OS) does not corrupt the sound. So I have not played the '.wav' for the ZX81, but only the '.m4a' recorded.

The only reason for converting to .wav was, that every sound-to-p-file expects '.wav'.

But I see your point, so I'll try to get the ZX81 load the '.wav' - maybe tonight.

Thanks mrtinb,

I had a look to your wav file, and the signal it awfully !
My be a bad wiring between the ZX81 and the wav recorder...
The noise is too high.( due t a loud signal)

Check the sound connectors (ZX81 side), it may be a short-cut on the DIN socket, or on the wiring device...
You get a low input signal, and boost up the signal get wrong noise harmonics!

Get a new sound wiring cable, and retry the wav record without sound enhanced process.

Have a look to the right signal !

http://zx81.ordi5.free.fr/wav/

You also can get the 'Sound' signal on the video ULA pin...
http://zx81.ordi5.free.fr/brico/composite/

Just get the sound signal on the video connector!

You will get a scare signal, up (no signal) and negative pulse (data signal)
Pic up the data trigger on the inverted wav to get the clean Zx81 program.

XavSnap wrote:I had a look to your wav file, and the signal it awfully !
My be a bad wiring between the ZX81 and the wav recorder...
The noise is too high.

Fortunately the audio can be read by my ZX81 again, so the source isn't lost.

Since the save-signal is extremely low, my setup is I think it's the Sony NetMD, that creates the noise.

I'll try to connect the ZX81 directly to my Mac to see if it works.

XavSnap wrote: You also can get the 'Sound' signal on the video ULA pin...
http://zx81.ordi5.free.fr/brico/composite/

Just get the sound signal on the video connector!

I won't modify my ZX81, but I'll see if I can get a cleaner signal without the Sony NetMD.

One thing I have found with digital playback of zx81 audio files , on both a Windows machine and a SanDisk mp3 player is not to use any eq at all, the digital eq's introduce all sorts of weird artifacts you can't hear them but a scope reveals the signal is not at all like it should be

Regards Andy

One piece of advice is to use a MONO cable to record from the zeddy.