review@drutx.UUCP (Millham) (04/26/85)
If anyone can remove themselfs from the exciting, year-old discussion of how terrible CD's sound (I have a Fisher, and haven't listened to a record since buying it), I have a question. I would like to build/buy either a Compressing or Limiting stereo amplifier. Is there anything on the market at a reasonable price? If not, does anyone know how to build one? I need this to operate a small 15 watt FM stereo transmitter. My current setup overmodulates, especially when talking. For this use, which is better, compression or limiting, or both? Thanx, -------------------------------------------- Brian Millham AT & T Information Systems Denver, Co. ...!inhp4!drutx!review
newton2@ucbtopaz.CC.Berkeley.ARPA (05/01/85)
I can't believe it-- a question about *audio* instead of bombast about bullshit! Let me just brush the dust of centuries off this tablet-- there! OK, first of course you'll want to gang both stereo channels (so your precious stereo image doesn;'twander when one channel's gain changes WRT to the other). Second, just what are you doing with a 15 watt FM transmitter? If it's a translator or repeater, fed by a broadcast program, the modulation should already be limited, so I'd guess you'd only "need" a safety limiter to guard against improper gain-setting. Come to think of it, you said "when I'm talking", didn't you? So I'd advise first of all a clipper (or limiter, to use the polite term) to avoid wasting all your dynamic range on the useless fricatives and glottal stops (git th' tar 'n' feathers, boys, he's a-stompin on our dy-namic range..). If that doesn't allow a decent average loudness without instantaneous overmod, you might consider adding compression to taste. If you're using the US standard 75 microsecond preemphasis, you might give some thought to a frequency-sensitive compressor that is less tolerant of spectral components most likely to overmod- ulate. The late and apparently unlamented Dolby FM system will reward study. Yours for less crap about imaginary problems and their illusary solutions, Doug Maisel