"Saving" Cassette tape recordings

Charlie Guthrie · **Joined:** Thu Aug 28, 2003 8:14 pm **Posts:** 832

I have a few tapes from the distant past that I would like to preserve/rescue and discovered that I only one functioning cassette player and that is similar Panasonic version of a Walkman (except for the one in my wife's car as an addition to the CD changer). These tapes are not music and audio quality is only so-so. I would just like to preserve these for listening in monaural format.
I considered trying to play tapes in the portable cassette player and inputting the player headphone output to the Line In input on my PC computer's sound card. I need some help in determining the proper impedance matching for the two components. (I actually played around with this type of stuff a few decades ago before the PC was invented.)
I'd love to hear from anyone out there who has solved this problem elegantly or who has suggestions.
Thanks,
Charlie G

George Bright · **Posted:** Sun Jul 24, 2011 6:29 pm

Since you are driving a fairly high mpedance input the impedance mismatch should not be much of a problem. I expect you will have to run with the volume contol set fairly low on your tape player. You might need to add a couple of resistors as a voltage divider to match the line inputs of your PC card. I have dubbed some of my old vinyl albums to CDs by patching from the line out of my old reciever to the PC sound card.

Several decades ago I built an impedance matching box so that I could couple my reel to reel tape deck to drive the phone line. The tape deck was an unbalanced source and the phone lines are 2 wire balanced. The tape deck was patched to be an echo unit.

Frank Catena · **Joined:** Wed Aug 27, 2003 1:08 pm **Posts:** 418

Charlie,
Should be fine, as George mentions since your are driving a high impedance input. This effectively keeps the electrical signal current output from your source device low which is a good thing. Not much current capacity there.

Impedance "matching" is typically required in high frequency applications as the mismatch creates reflections on the line. Not a problem here. Now if you were moving video it would be ...

Frank

Charlie Guthrie · **Joined:** Thu Aug 28, 2003 8:14 pm **Posts:** 832

Thanks for the input guys. I have a complete selection of 1/4 watt resistors (courtesy of a company "garage sale") so if anyone wanted to hazard a guess as to a good starting point for building a bridge I would gladly follow the lead. I haven't measured the resistance of the tape player head phones, but I suspect it is 8 ohm, but could be higher. Based on the low wattage and maximum 1.5 VDC battery supply I don't anticipate finding a high impedance headphone.
Man, I have forgotten a lot since being an electronics test technician at UL in the '70s...must be all of the racing.
Charlie G

Stacy King · **Posted:** Wed Aug 03, 2011 7:58 am

Funnily enough, I just happened across some cassettes I'd like to preserve as well.

Maybe a dumb question... but why not just get an 1/8" to 1/8" cord and run directly into the mic jack on the PC? Then record as a .wav file or something for later conversion to mp3?

Frank Catena · **Joined:** Wed Aug 27, 2003 1:08 pm **Posts:** 418

Audio "mic" levels are typically very low levels maybe 40 db lower than line levels (mic level voltages are typically not amplified). Line levels have amplification. You should always be fine matching a "line out" to "line in". "Line in" impedance is typically on the order of 10,000 ohms whereas "Line Out" is 100 ohms . Line out signal levels are on the order of 2V pk-pk.

So in Charlie's example, I'd take the output and try the line in on the PC. It may be too hot as its not a line level, but the volume control (variable resistor) might fix that. If not, a voltage divider will.

If all you really want is low quality you could attach a mic to the sound card "mic in" and "play" the tape to it in a quiet room.

Frank

Steven Carter · **Posted:** Wed Aug 03, 2011 10:29 am

Frank Catena wrote:

Audio "mic" levels are typically very low levels maybe 40 db lower than line levels (mic level voltages are typically not amplified). Line levels have amplification. You should always be fine matching a "line out" to "line in". "Line in" impedance is typically on the order of 10,000 ohms whereas "Line Out" is 100 ohms . Line out signal levels are on the order of 2V pk-pk.

So in Charlie's example, I'd take the output and try the line in on the PC. It may be too hot as its not a line level, but the volume control (variable resistor) might fix that. If not, a voltage divider will.

If all you really want is low quality you could attach a mic to the sound card "mic in" and "play" the tape to it in a quiet room.

Frank

I've had success with this, running from my 1/4" headphone jack on the receiver/amplifier into the 1/8" linein on my PC sound card. Software that came with the soundcard adjusted volume to acceptable levels, although as cassettes, they aren't exactly great fidelity to begin with (obviously not your goal as you stated earlier.)

Charlie Guthrie · **Joined:** Thu Aug 28, 2003 8:14 pm **Posts:** 832

Ding, ding, ding....I have a winner! Thanks for all of the input. The idea of using a mic "in a quite room" misses the point that Pete still lives here (quiet?). Steve suggested the idea that I was considering most likely. I figure that if I start with the cassette player volume at Min, I can play around with the results on the computer. I just wanted some reassurances that I wasn't missing some obvious difference between computer sound cards and typical audio gear and wind up blowing an input circuit on the computer. I have enough busted stuff already and don't need to create more busted stuff. I can't remember ever using an audio input on a computer; if it wasn't a download or a CD, it just didn't happen.
Thanks again for participating in my continuing education,
Charlie G

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