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The post is a bit outside the box for a general audio problem in the AVS forums. It deals primarily with the differences between sound coming from an audio cassette vs. CD. Most of this post is a copy/paste from a thread I started in a machining forum. For the purpose of this post the initials 'NC' stand for a Numerical Control Grinding Machine (grinding as in cutting metal parts). The machine works by using a program to tell it where to go. The programs are saved/backed up to cassette tapes. If you listen to the cassette all you hear is high pitch tones. I am trying to go from cassette tapes to CD and it isn't working well.


I am running an Overbeck 600I ID/OD grinder with an 'Overbeck' NC control. Our programs are saved via a cassette tape backup system. The machine has no internal memory. When we perform a setup we 'play the tape' that corresponds to the part we are setting up. Since we are using old school cassette tapes I thought it would be a 'no brainer' to put everything on CD. I started out by connecting the 'audio' output of the NC to my laptop and used Sound Forge to capture the program and saved it on the hard drive. To test whether the NC could listen to something other than an old cassette player I hooked the 'audio' input of the NC to my laptop and replayed the program back to the NC. It worked fine. I then spent several hours collecting each program one at a time by playing the tape to the NC then sending it back from the NC to the laptop. Again, I tested the data by randomly playing a program from the laptop to the NC and everything worked fine. My next step was to burn the audio to a blank CD and play it back from a portable CD player. I could not get any programs to successfully load from the CD player to the NC. If I use headphones I can hear the programs so I know that something is on the disk. I tried a second portable CD player and still no luck. I then thought that I had a bad disk and burned a second CD. Still no luck. I then tried to play the CD from the CD player in my laptop and it worked fine. Next I started looking at the specs. on the cassette player and comparing them to the specs. on my CD player. Both CD players have far better signal to noise ratio and frequency response specs. than the cassette deck. I can't figure out why I can successfully send a program to the NC with a cassette and/or with the laptop but not with a CD. I also tried using an MP3 player and a digital voice recorder and neither worked. Can anybody help me make this work?


One other thing that I have done is to play a program back from the laptop to the NC using Winamp software. I used the equalizer to turn down certain frequency bands to see any effects. Turning down some bands had no affect on playing back the program. Turning down others would cause the NC to return an error. If I turned down bands from 70Hz to 1000Hz there was no affect on the process. When I changed bands 3000Hz and higher the NC would return an error. Could it be that portable CD players perform poorly when delivering sound in the mid to high ranges? If this is a possibility, is there a way to increase the volume and/or quality of just the 3000Hz and higher bands?


For this project to be a success I have to be able to upload programs to the NC with either a CD player or an MP3 player. There are several other people who use this equipment and I am reluctant to leave MY laptop for them to use. Plus, the process has to be simple and easy for the 'old timers' who are not as tech savvy as the younger operators.


Thanks,


PR
 

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You can transfer the cassette content to a CD-R disc by using a CD recorder like the Teac CD-RW890 or the Phillips CDR-600 or CDR-778 or CDR-770 etc. etc. The Teac is available cheap now on Amazon; only $160 new; others are on E-bay.


Just feed the audio output of any cassette player to the record input of the CD Recorder and burn an AUDIO CD-R disc.


Once you have burned the disc, you can store its contents in your audio files on your computer as if it were a music disc. That will allow you to use that file to make more AUDIO CD-R copies of each program with your computer disc drive if needed.


The digital data is represented on the tape by using one frequency, for example 3000 Hz, for a binary ZERO and another frequency, say 2600 Hz, for a binary ONE.


This is exactly the same thing that a computer modem or fax machine uses to communicate over a standard telephone line in the old FSK system (which is so slow as to be obsolete now).


The CD recorder is also a player and can play the disc back for transfer to your other equipment.
 
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