ZX Spectrum+ Tape Recording Not working

[CsabaiGD]

Hello everyone!

I need some help fixing the recording on my Spectrum+. So, when I tried to record my program onto the voice recorder on my phone(with a stereo jack to microphone adapter) there is only noise. I tried to listen closely to these recordings but I didn't heard anything "usable"(the machine can't read it too)... So I tried to use an actual tape recorder, but there is still nothing. Suddenly, when I plugged a regular headphone into the Speccy's output, I could hear the recording coming out very clearly, without any noise. So my question is why I cant record the audio from the machine? Someone told me that I should use a Mono jack instead of a stereo one, but I have several problems with it. First, some guys on Youtube says that you can simply use a Stereo one. Second, when I listened the output with headphones, I could hear everything, and the headphones were stereo too. And when I plugged the speccy's output(with the same cable) into an amplifier, it was same with the Headphones. No noise, very clear signals. Possibly, my other tape recorder is mono, but I'm not sure about that. And to be honest, I dont have a mono 3,5" jack, and its very hard to find nowadays... so, what do you think guys, what should I try?

Regards,
Csabai Gábor "GD"

[1024MAK]

Okay, a couple of points.

The Ear and Mic sockets on all ZX Spectrum computers from the rubber key, the plus through to the 128K (toastrack), are all of the mono type.

The alignment of the electrical contacts is different between a mono type and a stereo type.

On a mono plug, the tip is the contact for the audio signal. The other larger contact (called the sleeve) is the common or ground.

On a stereo plug, the tip is the left channel audio signal, the middle contact (called the ring) is the right audio channel, and the remaining contact (the sleeve) is the common or ground.

If you compare a mono plug side by side to a stereo plug, note how the ring contact is in the same area where the sleeve common/ground is on a mono plug.

See also the Wikipedia article (here), especially this section.

With the type of sockets used by Sinclair for the ZX Spectrum, a stereo plug will not work correctly.

Here, have a look at this photo:

Mono plug alignment on a ZX Spectrum

You can see the contacts on the plug and the two contacts on the top of the socket. They line up nicely, or would do if the plug had not moved during the time I took the photo

And compare with this photo:

Stereo plug alignment on a ZX Spectrum

Here only the tip and the ring make electrical contact, the sleeve on the plug has no contact in the plug to make contact with. So whatever is connected with have no common/ground connection. This is bad.

The reason that the headphones work is because the electrical signal from the ZX Spectrum is going through the tip, through to the left speaker, then back to the plug to the common (ground), from the common (ground) to the right speaker, then back to the ZX Spectrum. Thus, there is a complete electrical circuit. Even though the common (ground) contact of the plug is not making electrical contact with any contact in the socket on the ZX Spectrum. As the speakers don’t care about the polarity, it works. The speakers also don’t care about their common/ground connection not actually being the same as the common/ground of the ZX Spectrum.

However, the same is not true of electronic equipment. With electronic equipment, the common/ground MUST be properly connected. Otherwise you are very likely to just get loud noise. Worse, depending on the device, the left and right audio channels may be connected together, in which case you are now shorting out the signal from the ZX Spectrum. Or the signals may be electrically combined, in which case the result is zero…

So you need to obtain a suitable lead.

If your equipment uses stereo 3.5mm phone / jack connectors, you need a “3.5mm STEREO Jack Plug to 2 x MONO Jack Plugs SPLITTER Converter Cable Lead”, for example like this one (eBay link). Other similar leads should be available from other sellers.

If your equipment (cassette deck recorder) is mono, then you need a 3.5mm mono to 3.5mm mono cable.

I hope this helps explain.

Mark

[CsabaiGD]

Hello, and thanks for the response!

That helped me to understand how the Speccy's jack works. I found a cable like what you sent (that 1 stereo to 2 mono converter). But other than that, I made a DIY mono AUX cable(sorry, but I don't have picture from) by connecting the Right line(middle part of the stereo) to the ground. And that works perfectly! And also, I found an old tape recorder which has Mono input, so I could connect a Stereo cable with it, because the ground went to the Right pin, like on the Speccy, so it wasn't a problem. Sorry for bad composition, and also, thanks for help!

Csabai GD

[1024MAK]

Don’t worry, your description is good enough to be understandable

I’m glad that I could help. Have fun

Mark