TZX/TAP to Cassette/Spectrum

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namco
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TZX/TAP to Cassette/Spectrum

Post by namco » Mon May 28, 2018 3:20 pm

I can't seem to be able to get my laptop to load spectrum files to my ZX Spectrum+ through Tapr or Audacity, or use PlayZX/TeeZiX through my phone. It almost picks up a signal but doesn't load it - you can see it almost trying but then it stops.

I've used the black/grey cassette leads from the spectrum to load from the laptop and the Stereo to mic/ear from Retro Computer Shack (+3 lead) to load from my mobile.

I have tried using winTZX too - the same thing happens.

Cassette-wise I can get it to record to the tape but the spectrum never picks it up on playback!

Tapes work normally on the Spectrum and I've not had any loading issues. The blanks tapes I used were Maxell UR Type I 90 minutes.
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hikoki
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Re: TZX/TAP to Cassette/Spectrum

Post by hikoki » Mon May 28, 2018 4:17 pm

Someone from ZX-Uno's forums recommended this sound booster: https://play.google.com/store/apps/deta ... me.booster
make sure it is only enabled when loading spectrum games so you don't get deaf or fry your phone speakers
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R-Tape
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Re: TZX/TAP to Cassette/Spectrum

Post by R-Tape » Mon May 28, 2018 4:26 pm

Yep as hikoki says you probably need more volume. On my old laptop I used to be able to record to cassette (laptop output near max) and play onto Speccy. My new laptop doesn't seem able to do it.
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namco
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Re: TZX/TAP to Cassette/Spectrum

Post by namco » Mon May 28, 2018 4:46 pm

Weirdly on the laptop, if I put it to about 50 - 60 on volume (around 45 on audacity) it tries to load but any higher and the signal goes again.
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Ast A. Moore
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Re: TZX/TAP to Cassette/Spectrum

Post by Ast A. Moore » Mon May 28, 2018 5:00 pm

Spectrums were designed to be used with tape recorders from the 1980s. They put out a much stronger signal designed to driver loads with impedances of around 150–250 Ohms or more. Modern devices—MP3 players, smartphones, and PCs—are designed to drive headphones with a typical impedance of an order of magnitude lower: 16–32 Ohms. Even if you try to boost the volume on your laptop (assuming you’re turning up the physical output gain, not simply amplifying it digitally in a file), you might end up with distortions, which will add high-frequency harmonics and actually make the signal worse.

Older Spectrums, particularly earlier issues of 48K machines, require a somewhat hotter signal than the 128K or later. In addition, the ULA’s EAR input may drift as it warms up.

That said, not all modern audio devices are created equal. For example, I can successfully load games into my 128K and +2A from both my laptop and my phone, but I can tell that the signal is barely strong enough.

Invest in a headphones amplifier that can drive high-impedance loads. Alternatively, since you already own a tape recorder, you can get a tape adapter. Might be a cheaper option.
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Every man should plant a tree, build a house, and write a ZX Spectrum game.

Author of A Yankee in Iraq, a 50 fps shoot-’em-up—the first game to utilize the floating bus on the +2A/+3,
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hikoki
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Re: TZX/TAP to Cassette/Spectrum

Post by hikoki » Mon May 28, 2018 5:05 pm

A few solutions to reduce distortion: http://www.thewindowsclub.com/sound-dis ... windows-10
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PeteProdge
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Re: TZX/TAP to Cassette/Spectrum

Post by PeteProdge » Tue May 29, 2018 7:52 am

Also, isn't it a mono headphone lead that's needed?

I bought a Speccy cassette a few years back, and using the only cassette player and a 3.5mm-to-3.5mm lead, I could just about get a loading screen out of it, but it was always corrupted (never the exact same corruption), falling to R Tape loading error. Turns out the lead being in stereo was the reason why. I know I should get round to getting a mono lead at some point, 'cos I've still yet to play this game.
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djnzx48
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Re: TZX/TAP to Cassette/Spectrum

Post by djnzx48 » Tue May 29, 2018 8:06 am

I'm sure I've gotten games to load from a PC using a stereo lead, but I think it was through an external amplifier with the pan turned all the way to the left? (Might've been the other way, not sure.) It was still pretty difficult to load anything, and we never got any turbo loaders to work.

There was something about inverting the phase of one of the audio channels using Audacity, but I can't remember if that ever helped anything.
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Ast A. Moore
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Re: TZX/TAP to Cassette/Spectrum

Post by Ast A. Moore » Tue May 29, 2018 9:39 am

djnzx48 wrote:
Tue May 29, 2018 8:06 am
There was something about inverting the phase of one of the audio channels using Audacity, but I can't remember if that ever helped anything.
That would only make matters worse; potentially, it would cancel out the signal altogether.

The 48K/128K EAR sockets are technically mono, but mechanically (at least on the 128K) they connect to the tip and ring terminals, not the tip and the sleeve (the sleeve terminal being the ground and the tip the signal), so feeding a stereo signal will likely result in not signal reaching the Spectrum. The +3 expects the input on the ring terminal, i.e. the right channel, the tip being the output.

What you can do is use a stereo jack on the source side with the ring and tip terminals wired together—this will add the signals from each channel thus boosting the overall level somewhat. The other end should either be wired to a mono jack (TS) or a stereo jack (TRS) with the sleeve and ring terminals shorted together. For a +3, the signal conductor should be soldered to the ring terminal, leaving the tip non-connected.

I made a “universal” lead with one end terminating in a mono jack and the other a stereo jack with the signal wire soldered to the ring terminal. If I want to load a game on the 128K, I plug the stereo jack into the source (the computer or the phone) and the mono jack into the Spectrum. I reverse the lead for my +2A (which I modified to use the +3 audio socket wiring).
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Every man should plant a tree, build a house, and write a ZX Spectrum game.

Author of A Yankee in Iraq, a 50 fps shoot-’em-up—the first game to utilize the floating bus on the +2A/+3,
and zasm Z80 Assembler syntax highlighter.

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djnzx48
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Re: TZX/TAP to Cassette/Spectrum

Post by djnzx48 » Tue May 29, 2018 9:44 am

Well, it does seem a bit weird to do the phase inversion, but it was just something that I read about here: https://retrocomputing.stackexchange.co ... ette-world
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