dbx makes my recordings to sound like underwater..?

  • Thread starter Thread starter IronWine
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IronWine

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yup..thats the issue pretty much. when i engage the dbx switch on my tascam 234 it makes the recording murky as hell, drenched in low freqs, unusable in any way. maybe some calibration is needed?
 
I tried every way pretty much.
recording with dbx, then play it with/without - murky, super-low freqs, no highs at all. sound better without tho.
recording without dbx - then playing without dbx sounds good, dbx engaged - murky.
 
IronWine said:
I tried every way pretty much.
recording with dbx, then play it with/without - murky, super-low freqs, no highs at all. sound better without tho.
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That doesn't sound right. If you record with DBX on and then play it back with DBX off, it should be all thin and full of high frequencies. Some people do that as a makeshift aural exciter.
Playing back a non-DBX recording with DBX on will give you lots of bass and no high-end, much like you described. So it sounds a bit like it's decoding but not encoding for some reason. I can't think why it would affect all four channels if it was a fault, though.
 
Maybe it is a bias issue? I can't see why it would affect all 4 tracks though. dbx exagerates frequency response errors like anything and if the high frequencies are down because of bias errors they can get stuffed further. Do you get the same effect with different tape brands?
 
There's some confusion here. Recording with Dolby B and then turning it off fro replay results in extra HF and was a popular way to do things, especially if you just backed the treble back a bit - BUT - DBX is a companding system and is frequency neutral - it simply squashed the signal on record and expands it on replay, taking the noise down with it. The result of getting round the wrong way is that you record normally, and then expand it on replay, and then the sound gets kind of spiky - loud notes really hang out, while quiet ones can hardly be heard. If the track is bass heavy already then it sounds wild bass heavy, but a track that has something like a prominent hi-hat pattern cuts your ears off. Do it the other way around and you just get a compressed mess like turning a compressor up really high. Is this what it sounds like? What happens if you record with DBX and replay with DBX - does that sound ok? Dolby let you change the output sound to suit - DBX needed to be on or off - but the same on both recording and replay.
 
rob aylestone said:
DBX is a companding system and is frequency neutral - it simply squashed the signal on record and expands it on replay, taking the noise down with it.
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This is true, but I think you'll find it also uses pre-emphasis on the high frequencies, resulting in a thin, treble-heavy playback of encoded material if the decoder is turned off.
It's immediately apparent if something was DBX-encoded and the decoder is off, which is useful because the TSR-8 defaults to DBX off each time it's powered up.
 
I thought there was no pre-emphasis with dbx noise reduction? Or is that only with Type I, and the Type II the OP is using on the 234 utilizes a pre-emphasis filter?
 
sweetbeats said:
I thought there was no pre-emphasis with dbx noise reduction? Or is that only with Type I, and the Type II the OP is using on the 234 utilizes a pre-emphasis filter?
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Ah, that might be it. Wikipedia does say that both I and II use preemphasis quite aggressively, but you can never quite trust that thing. I only have experience with Type I personally and didn't notice the cassette machine were using Type II.

EDIT: For the original poster, is it maybe worth posting clips of the recording so we can hear exactly what's happening?
 
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