Saved programs too noisy

General Chit Chat about Sinclair Computers and their Clones
CarolineZX81
Posts: 4
Joined: Fri Feb 21, 2020 11:39 am

Saved programs too noisy

Post by CarolineZX81 »

Hi,

I am new here and joined today so please be gentle.

I am trying to save programs from my ZX81 to a cassette tape for the first time. The machine displays the black and white bars on the screen. When I play the tape back there is a very loud deep toned buzzing over the program, which is barely audible. It does not load suffice to say, it just shows the white screen with thin black diagonal bars.

I am using a Philips 1001/05 cassette recorder: https://www.philips.co.uk/c-p/AQ1001_05 ... tte-player and TDK D90 cassettes. I have the volume set to 3/4.

Do you have any ideas what might be wrong?

Many thanks.
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1024MAK
Posts: 3164
Joined: Mon Sep 26, 2011 10:56 am
Location: Looking forward to summer in Somerset, UK...

Re: Saved programs too noisy

Post by 1024MAK »

What leads are you using? Mono or stereo?

What type of mic socket is this tape deck fitted with? If 3.5mm jack sockets, does the instruction book/manual say if it is mono or stereo?

Stereo 3.5mm jack sockets are not compatible with mono 3.5mm jack plugs.

Stereo 3.5mm jack plugs are not compatible with mono 3.5mm jack sockets.

So if the socket is mono, you should use a mono plug. If the socket is stereo, you should use a stereo plug.

More info on these connectors here.

If you connect the lead to the tape deck, but leave it unconnected at the computer, does the tape deck record silence or does it still record the unwanted noise that you described in you post?

Mark
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XavSnap
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Re: Saved programs too noisy

Post by XavSnap »

HI,

The main problem may be the jack connector and the cable.

Sometime, the socket/wire have a bad connection.
We can experiment noise if the live sound wire is shortcut by the ground (Shield) wire.

3/4 of sound level is too high to deliver a pur sound signal.
Check the wiring device, the cable quality...
Xavier
Moggy
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Joined: Wed Jun 18, 2008 2:00 pm

Re: Saved programs too noisy

Post by Moggy »

My past experience of superimposed buzzing over the signal was due to the cassette player being too close to the TV which was a cathode ray tube type which looks like what you are using in the picture posted in the introduction thread.

Try and keep the the cassette rec/player as isolated as possible from sources such as power packs, stand/desk lamps with internal transformers etc.
CarolineZX81
Posts: 4
Joined: Fri Feb 21, 2020 11:39 am

Re: Saved programs too noisy

Post by CarolineZX81 »

Hi,

Thank you for your replies. Moggy, yes, the tape machine was about 40cm from the CRT.

When I recorded to tape and the audio cable was not attached to the computer, there was no buzzing.

When I recorded to tape and the audio cable was attached to the computer, but the computer was not saving, there was loud buzzing.

Mark: The jack plugs are stereo but the tape player and computer are mono. I'll try and change the plugs and see if the buzzing reduces.
Last edited by CarolineZX81 on Sat Feb 22, 2020 9:41 pm, edited 1 time in total.
CarolineZX81
Posts: 4
Joined: Fri Feb 21, 2020 11:39 am

Re: Saved programs too noisy

Post by CarolineZX81 »

Hi Xavsnap.

I will adjust the volume setting and see if that helps!
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1024MAK
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Location: Looking forward to summer in Somerset, UK...

Re: Saved programs too noisy

Post by 1024MAK »

Here is a photo showing a stereo 3.5mm jack plug sitting on top of one of the ZX81’s 3.5mm mono jack sockets. In this case the 9V DC input, but all three (DC input, Ear and Mic) are all the same type.
Stereo plug no good!
Stereo plug no good!
As you can see, the 0V/GND connections do not line up :(

Mark

Edited to correct a typo where I said “As you can see, the 9V/GND connections do not line up”, instead of “As you can see, the 0V/GND connections do not line up”.
Last edited by 1024MAK on Tue Feb 25, 2020 8:29 pm, edited 1 time in total.
Reason: Correct a typo...
diskman
Posts: 20
Joined: Tue Apr 02, 2019 9:23 pm

Re: Saved programs too noisy

Post by diskman »

Make sure you are using a MONO cable between the computer and tape player. Also, try running the tape on batteries if it can. You may be getting mains noise. Seconding the moving as far from the CRT as possible.
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Erm
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Joined: Thu Jun 20, 2019 7:07 pm

Re: Saved programs too noisy

Post by Erm »

Try saving the prog to a PC/laptop running Audacity set to record, then see if the result shows the usual peaks of a program and whatever else (you may have to enlarge the screen). It can be a bit fiddly as most laptops have a dual mic/headphone socket and won't like the mono ZX81 jack. My ASUS netbook has a separate MIC input (which I assume is probably stereo) and that seems to work fine.... however to load anything back I always have to amplify it in Audacity, on a stock ZX81 at least.

It's all fun and games with the saving/loading from tape isn't it.
I'm Chris, a Brit in Germany (Chr$ on the QL forum).
Aurelbois
Posts: 8
Joined: Wed Jul 10, 2019 7:36 pm

Re: Saved programs too noisy

Post by Aurelbois »

Could this type of setup be used with your PC and Timex/ZX.
All you need is:
1 mono plug and a cable with a stereo plug at the other end and 3 resistors

Cable from PC to tape recorder

7.5K-10K
o-A-------wwwwwwwww-------------+
From sound card 7.5K-10K |
(Stereo plug) o-B-------wwwwwwwww-------------+------------o tip
|
/
\ Mono plug
47 ohms /
\
o-------------------------------+------------o common
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