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Andy Murray · Posts: 23

I am new to this game, need a quick bit of advice. I have a number of tapes recorded on to cassettes between 6 & 12 years ago. I love to listen to them, and want to get them into digital format before they deteriorate any further. Quality wasn't great to start with, so I'm not looking for perfection. I know that FM radio does not broadcast up to the full 20K Hz, so I thought a good start to cleaning these up would be to chop off the audio outside the range that was transmitted.
Is there a standard range of audio frequencies broadcast by FM stations in North America? (I'm in Canada) If so, what are the min and max frequencies?

Tks.

-- Andy

Syntrillium M.D. · Location: USA Posts: 5124

Hi Andy - though I cannot comment on specific broadcast frequency limitation, I will suggest that you DO NOT chop off ANY audio (or frequency bands) before doing your restoration. You will only further limit the possibilities of restoring your cassette. If you have a soundcard that supports 20/24-bit recording, I would transfer it into CEP (using a nice tape deck, with cleaned heads!!) at 24-bits. 44.1/48k is just fine. Of course, if you have 96k capability, you may in the end yield better results by initially A/D converting at this rate. After transfer, all processes (noise reduction, EQ, verb, whatever) will greatly benefit from the upper bit rate/sample rate transfer.

---Syntrillium Support

Edited by - syntrillium support on 01/16/2001 09:14:51 AM

Andy Murray · Posts: 23

Not being argumentative here, just trying to understand. So even though the original broadcast didn't go above, for example, 10kHz, and the rest above that would be noise, it would benefit me to keep that upper range until the restoration steps are all done?

-- Andy

Syntrillium M.D. · Location: USA Posts: 5124

Yes. Tape has a significantly high frequency range. Granted, these tapes are worn, but the reality is that there probably exists some information above that 10k range. Regardless, it makes sense to transfer your signal with the widest frequency range possible. It's much easier to cut/eliminate than it is to recreate once it's gone.

---Syntrillium Support

shel777 · Posts: 14

From my understanding, FM freq. response doesn't go much above 14 kHz. Don't recall the bottom end. But wouldn't it be nice if we could restore airchecks off an AM radio to FM fidelity? I THINK IT IS POSSIBLE! Just don't know how. I believe the respone is "in" the audio, albeit compressed in some way. Hey, they can colorize black and white movies based on the shades of gray... why not the same for music?

Syntrillium M.D. · Location: USA Posts: 5124

hey. Well, though the colorizing analogy is a neat thought, it really just isn't the same for audio. With colorizing, you are applying something completely externally. Its effect on the source material is that you have something that looks 'added-to', but doesn't necessarily alter the original. With audio, if you try and artificially boost 14k (on a signal that was truncated down to 8k) at best all you'll have is noise, and maybe a little more 'breath' on top...Certainly, crafty EQ can restore the original to it's best-sounding form...But take for example, old 78 recordings transferred to CD (or pre-50s vinyl stuff, like Louis Armstrong and the Hot-5) The limited frequency response to begin with means limited frequency to work with. You can synthesize lost upper harmonics (with an 'exciter' type process) but it must be used sparingly, as over0use is very noticeable and quite undesirable. it's just difficult to put something there that wasn't there to begin with.

---Syntrillium Support