Interesting experiment

[ruffrecords]

Many years ago I recorded some tapes on a TEAC A3440 with its associated dbx encoder. I recently scored a TEAC A3440 on its own and in good conduction so I can play these tapes but I cannot decode them. I also have an old TASCAM 238 8 track cassette which uses the same dbx noise reduction. So I tried an experiment. I turned the dbx on the Tascam 238 OFF and transferred all four tracks from the TEAC A3440 to the Taacam 238 first four tracks. The I turned the TACSAM 238 dbx ON and played back the cassette I had just recorded. The result was surprisingly good.

Cheers

Ian

 

[JohnRoberts]

Yes DBX uses 2:1 companding full range without a threshold so you don't have to worry about matching levels (like with Dolby NR). DBX NR also used HF pre/de-emphasis, but likely same EQ curves for both machines.

The companding can exaggerate frequency response errors but was designed to work with the tape medium, so filters in the NR side chain can desensitize it somewhat from tape's poor LF response.

JR

 

[Tubetec]

I take it you got the Tascam working again ?
Maybe theres a VST based noise reduction decoder out there or at least something you can set up to do the inverse of the DBX companding . You might get a better result than dubbing tape to tape .

 

[ruffrecords]

I take it you got the Tascam working again ?

Not yet. Still struggling with that. I have managed to replace one of the SMT caps and the zener, both of which simply dropped off when I took the transport out. It is made very difficult because I cannot un plug the connector from the speed control board and this limits how far out I can get the transport. in the meantime I have made a cardboard platform for the transport to sit on.

Cheers

Ian