dbx Type I vs Type II & open reel speed
- Thread starter Blue Jinn
- Start date
lo.fi.love
Functionally obsessed.
Type I is preferred for 7.5ips. Definitely use it, if you want noise reduction.
Type I would also work at 3.75ips, but Type II might be better for that speed. You should try for yourself.
Blue Jinn
Rider of the ARPocalypse
well of course that means I'll have to go out and BUY ANOTHER PIECE OF GEAR! (but I don't really intend to record at 3.75 ever again.)
BTW I realize now that my 180 probably isn't the best suited for a -10dB operating level....
Audiophallic
New member
What's the difference between dbx type I/II and Dolby A/B/C etc?
Blue Jinn
Rider of the ARPocalypse
dbx is basically a 2:1 compression 1:2 expansion. Type II is designed for cassette and slower open reel where to compensate. Dolby uses a different method. eg Dolby A applies compression over four bands, SR is even more sophisticated. This manual contains a good explanation of dbx http://www.dbxpro.com/product_downloads/Owner_Manuals/180 Owners Manual.pdf also check out the dolby site analog library:
http://www.dolby.com/DocLibTechLanding.aspx?taxid=174
The wiki articles are pretty good also took this from here http://stason.org/TULARC/entertainm...e-difference-between-Dolby-A-B-C-S-and-S.html and here http://www.audiotools.com/noise.html
The Dolby A, B, C, SR, and S noise reduction (NR) systems are
non-linear level-dependent companders (compressors/expanders). They
offer various amounts of noise reduction, as shown in the table
below.
Dolby HF NR LF NR Number Of Active Target
System Effect Effect Frequency Bands Market Year
------ ------ ------ ---------------------------- --------- ----
A 10 dB 10 dB 4 fixed Pro audio 1967
B 10 dB -- 1 sliding (HF) Domestic 1970
C 20 dB -- 1 sliding (HF) Domestic 1981
SR 24 dB 10 dB 1 sliding (HF), 1 fixed (LF) Pro audio 1986
S 24 dB 10 dB 1 sliding (HF), 1 fixed (LF) Domestic 1990
------ ------ ----- ---------------------------- --------- ----
DBX type I noise reduction
A system introduced shortly after the Dolby system and known today as the DBX type I, although intrinsically a simple 2:1:2 compander ...for consumer devices like open reel recorders running at 9,5 or 19cm ... it has to be said that the type II is a much better match, it's slightly less effective as a NR but the RMS circuit makes it close to being foolproof and it is much more tolerant of recording conditions than even the Dolby systems
http://www.dolby.com/DocLibTechLanding.aspx?taxid=174
The wiki articles are pretty good also took this from here http://stason.org/TULARC/entertainm...e-difference-between-Dolby-A-B-C-S-and-S.html and here http://www.audiotools.com/noise.html
The Dolby A, B, C, SR, and S noise reduction (NR) systems are
non-linear level-dependent companders (compressors/expanders). They
offer various amounts of noise reduction, as shown in the table
below.
Dolby HF NR LF NR Number Of Active Target
System Effect Effect Frequency Bands Market Year
------ ------ ------ ---------------------------- --------- ----
A 10 dB 10 dB 4 fixed Pro audio 1967
B 10 dB -- 1 sliding (HF) Domestic 1970
C 20 dB -- 1 sliding (HF) Domestic 1981
SR 24 dB 10 dB 1 sliding (HF), 1 fixed (LF) Pro audio 1986
S 24 dB 10 dB 1 sliding (HF), 1 fixed (LF) Domestic 1990
------ ------ ----- ---------------------------- --------- ----
DBX type I noise reduction
A system introduced shortly after the Dolby system and known today as the DBX type I, although intrinsically a simple 2:1:2 compander ...for consumer devices like open reel recorders running at 9,5 or 19cm ... it has to be said that the type II is a much better match, it's slightly less effective as a NR but the RMS circuit makes it close to being foolproof and it is much more tolerant of recording conditions than even the Dolby systems