Loading data files from tape issue

[CPC 72]

Hi
My first post on this forum

Last summer I found my old Amstrad games and homemade programs in my parants's attic. My computer was broken in the nineties and I thought all the programs was long gone. After some months searching I finaly manage to get a Amstrad cpc 664 with a green monitor.Exactly like the one I had back in the days  

After some time I also bought a joystick and a cassette cable. I then figured out how to save cdt files from internet on my music software, cubase, and then load it into my Amstrad cpc. I now have lots of games

And then a question maybe the forum can help answering.
I have trouble with loading data files into programs from tape. ( saved in wav/cubase) Especielly longer files. I have a homemade game that can save records, and it works fine. Just a short data file. But I also have a football manger game with longer data files that not can be loaded. I works fine to save the files, but not to load 

I have downloaded a tape game, Space Invaders, it can save the records on tape. It save the data file well, seems to load it well too, but the record list was not updated

I also downloaded the fantastic Emlyn Hughes International Soccer from cdt to wav. (tape) If I am right, the disc version of the game is for 6128 with 128KB RAM and will not run on my cpc 664, so I have to go for the tape version with 64KB. The same problem with this game. I can save teams and season, but no chance to load them back into the computer.  Because I am saving into å music program and not a real tape player I'm not use the REM cable. Could this cause the problem or do you have any other thoughs on this matter?

[SerErris]

You maybe want to start very simple.

From my guess from here:
1. Your write process actually does not work correctly. The CPC has no control if the write process actually has written anything usable. Whatever happend you are not doing a "proper" write. That might be because of the signal getting filtered by the tape or any other reason I cannot really think of now.
2. The read process is than not able to reliably read the files back from the tape. Maybe it is just the combination of write and read, where both parts are very close to the limit and then in combination it fails.

If you CDT to Tape recordings actually work (you can read them), Then my guess is, that the tape drive is actually not recording it correctly from CPC (maybe to low signal) or it may be also too loud. 

In the time I had a classic tape deck I had some input gain POTs in there, that I could adjust the volume to the perfect level. If your tape has this capability, try to play around with it and set the level indicators, so that they are rarely get into the red area. 

Can you listen to the written data with your audio hifi system or even record it into audacity etc. to check if the recording looks correct ? (square waves with variable width). The square waves actually always need to be a full wave and have a long period or (half) short period. This needs to be pretty exact, otherwise the read will fail. 

Another reason could be, that your tape drive does not run in a continous speed, but changes speed tooo much in variance, so that the bits are missaligned to the expectation. If there is too much variation, the read will eventually fail and short reads might survive that better than long reads.

So this is what comes to my mind reading your input, maybe it helps to solve the issue.