There's a u-he forum that had this helpful info about the five types of NR.
This info comes from the Satin manual. No Dolby C, unfortunately.
---
No tape machine plugin should be without a noise reduction encoder/decoder!
You can use these purely as coloration effects, or for decoding old
cassettes (for instance) that have been recorded with noise reduction
switched on. Satin includes five different types - all models of well-known
hardware (or parts thereof), despite the "obscured" names...
A-Type
First implemented in early professional video recorders, this type also
became the noise reduction standard for multitrack tape and, to a lesser
extent, optical movie soundtracks. A-Type processes four different
frequency bands, with the two higher bands overlapping so that typical tape
hiss frequencies are companded more strongly. The A-Type typically provides
about 12 dB of noise reduction (A-weighted).
A-Type Mod
This type mimics the 'Cat-22' modification that was popular among users of
the original A-type hardware from the early 70s. All four bands were
realized on a single card, and the signal that was added to (or subtracted
from) the main path was mixed via four resistors. By simply cutting or
desoldering the resistors of bands 1 and 2, only the treble bands remained
active, resulting in the very 'airy' sound heard on numerous hit records.
A-Type Mod works especially well with vocals, acoustic guitars or anything
that would benefit from a very 'up-font' and bright top end without
sounding harsh or shrill.
B-Type
This was added to countless consumer products, for instance pre-recorded
compact cassette tapes. B-Type is a single-band system that only processes
high frequencies. With its relatively mild compansion, B-Type typically
provides about 9 dB of noise reduction (A-weighted).
uhx Type I
This 2:1 broadband compander was meant for professional systems using tape
with a signal-tonoise ratio of at least 60 dB, and a relatively flat (+/-3
dB) frequency response within a range of at least 30 Hz to 15 kHz.
uhx Type II
This related method was destined for the cheaper, more noisy consumer media
with a much more restricted frequency response. Type II rolls off high and
low frequencies in the control signal path (the sound isn't affected) to
desensitize the system to frequency response errors.
---
On Mon, Jun 4, 2018 at 1:18 PM, Gary A. Galo <[log in to unmask]> wrote:
> Hi Richard & John,
>
> The U-He Satin web site now says they're doing "5 popular" NR systems, so
> I wonder if they've added Dolby C. What do they call the various systems,
> if they're not using the trademarked names?
>
> The dbx I and II units are all built around single-ended, discrete
> transistor circuits, which will certainly add low-order THD compared to
> full-complementary topologies. So, I think you're right regarding where the
> "warmth" is coming from.
>
> I hope my Dolby A (360) units continue to work for a long time to come!
>
> Best,
> Gary
>
> ____________________________
>
> Gary Galo
> Audio Engineer Emeritus
> The Crane School of Music
> SUNY at Potsdam, NY 13676
>
> "Great art presupposes the alert mind of the educated listener."
> Arnold Schoenberg
>
> "A true artist doesn't want to be admired, he wants to be believed."
> Igor Markevitch
>
> -----Original Message-----
> From: Association for Recorded Sound Discussion List [mailto:
> [log in to unmask]] On Behalf Of Richard L. Hess
> Sent: Monday, June 04, 2018 12:46 PM
> To: [log in to unmask]
> Subject: Re: [ARSCLIST] Noise Reduction Companders (was: question about
> baking cassette tapes)
>
> Hi, John and Gary (and Listmembers),
>
> Yes, U-He Satin does four flavours of noise reduction. None of them are
> called what they are because of copyright/trademark restrictions
> outliving patent restrictions.
>
> These are equivalent to:
>
> DBX I, DBX II, DOLBY A, and DOLBY B.
>
> I have not evaluated DBX II or DOLBY B to any significant extent.
>
> U-He's DBX I is very close to a hardware decode, but the client thought
> that the hardware decode was "warmer." My take on it now is that the
> warmth in the hardware decoder is potentially additional distortions.
>
> The U-He DOLBY A decode, while initially exciting is not good. It showed
> the way towards eliminating some of the darkness (loss of
> brightness/highs) that the Dolby hardware decoders seem to add to
> certain dynamic regions. It is possible to come much closer in software
> than U-He.
>
> --------------
>
> I do not use the DOLBY B U-He plug in because I have multiple Dolby 422
> units (currently only one wired in the rack). What I have found is that
> I can better adjust Dolby B by having one hand on the output knob of the
> Dragon and one hand on the studio monitor level control...keeping the
> levels constant and listening for minimum pumping on the Dolby B
> decode...in real time with a hardware decode. I then record two stereo
> files: Raw and decoded.
>
> --------------
>
> I have never seriously used dbx for recording. I bought an early model
> 124 and tried it out at my sideline gig of recording the St. Thomas
> Church (Fifth Avenue, NY City) choir of men and boys (and organ) for one
> concert (alongside a Dolby B recording). I still have the unit, but it
> only got used for one or two spoken word things down the road.
>
> The sharp attack of the boys' singing on certain pieces caused the dbx
> II to behave horribly. I ultimately bought a pair of 361s from George
> Schowerer (which I also still have).
>
> -------------
>
> Long term, I believe software decoders are more sustainable than
> hardware decoders, especially considering the proprietary nature of the
> "select on test" resistors and such.
>
> I hope there will be a better Dolby A SW decoder available. One of the
> challenges is how far to go to eliminate the artifacts of the gain
> riding within the decoder.
>
> Since I changed the subject, I left the thread intact below.
>
> Cheers,
>
> Richard
>
>
> On 2018-06-03 4:59 PM, John Haley wrote:
> > Gary, yes U-He Satin will decode dbx--but I am not sure about dbx-II.
> > Satin has to call it something else, and I will have to look at the
> program
> > to see what they are calling it, but it is just dbx.
> >
> > If Richard Hess sees this--what about dbx II, Richard? Does U-He Stain
> > decode that? I have not seen that.
> >
> > As you know, live music recorded on cassettes is very often problematic!
> > I have a good many important live concerts recorded on them with no
> other
> > source. From a restoration viewpoint, cassettes can be real disasters,
> but
> > the Nak Dragon helps that.
> >
> > I used dbx years ago but never for cassettes. And you will recall that
> > there were LPs that were encoded with dbx. You needed a decoder and they
> > never caught on much.
> >
> > The problem with making recordings with dbx was always that there could
> be
> > a bit of audible pumping. Usually it wasn't a big deal, but it could be,
> > depending on what was being recorded-- whether the noise was being masked
> > by the content. Dolby B and C were better in this regard (noise
> pumping),
> > when they were working right. Dolby NR was not nearly compatible enough
> > from one machine to the next. dbx was thought to be better with respect
> to
> > compatibility. At least that was the common belief at the time.
> >
> > You may recall that when VHS machines with the matrixed Hi-Fi sound (as
> > opposed to the mono edgetrack) first became available, they were very
> good
> > to use as just tape recorders for music, although you needed a machine
> with
> > defeatable automatic level control (ALC). You could copy CD's, which
> were
> > still fairly new then, and the results were fairly close to the sound of
> > the CD, with great frequency response and dynamic range. I was always
> told
> > that the noise reduction used to get that good result was nothing but
> dbx,
> > although they called it something different. It worked very well for VHS
> > tapes, at all three speeds. As I recall the sound was FM modulated.
> >
> > The advent of digital recordings caused all of these various noise
> > reduction complications to vanish. That is all fine with me--they are
> not
> > missed.
> >
> > Best,
> > John
> >
> >
> > Best,
> > John Haley
> >
> >
> >
> >
> >
> >
> >
> >
> > On Sun, Jun 3, 2018 at 3:20 PM, Gary A. Galo <[log in to unmask]> wrote:
> >
> >> Hi John,
> >>
> >> Sounds like you're making the best of a BAAAD situation (which cassettes
> >> invariably are). Have you dubbed any cassettes with dbx II noise
> >> reduction? In my view, dbx II was a huge mistake for cassettes. dbx was
> >> very sensitive to errors in playback frequency response. Cassettes made
> >> with dbx II would often sound fine played back on the same machine they
> >> were recorded on. But, when you moved them to another playback machine,
> >> they would pump and breathe and otherwise sound lousy. Does U-He Satin
> do
> >> dbx NR? If so, how well does it work?
> >>
> >> dbx I was made for fast speed reel-to-reel recording - usually 15-ips.
> It
> >> extended the high-frequency boosts in record up to the top end of the
> >> audible spectrum, so accurate machine alignment was necessary for proper
> >> high-frequency tracking in playback. I used it successfully at 7.5-ips,
> but
> >> you had to really make sure your machine was properly aligned.
> >>
> >> dbx II was intended for slower-speed reel-to-reel recording, usually
> >> 7.5-ips, and it would work OK at 3.75. The HF boost in record was
> limited
> >> to, as I recall, around 10 kHz, so it wasn't as sensitive to
> high-frequency
> >> alignment in playback; it more forgiving of frequency response errors in
> >> the top octave. But, it was never intended for cassettes, and should
> never
> >> have been used on them.
> >>
> >> Best,
> >> Gary
> >>
> >> ____________________________
> >>
> >> Gary Galo
> >> Audio Engineer Emeritus
> >> The Crane School of Music
> >> SUNY at Potsdam, NY 13676
> >>
> >> "Great art presupposes the alert mind of the educated listener."
> >> Arnold Schoenberg
> >>
> >> "A true artist doesn't want to be admired, he wants to be believed."
> >> Igor Markevitch
> >>
> >>
> >> -----Original Message-----
> >> From: Association for Recorded Sound Discussion List [mailto:
> >> [log in to unmask]] On Behalf Of John Haley
> >> Sent: Sunday, June 03, 2018 3:05 PM
> >> To: [log in to unmask]
> >> Subject: Re: [ARSCLIST] question about baking cassette tapes
> >>
> >> I second the suggestion of getting a NAK Dragon for serious dubbing of
> >> cassettes. I bought one a few months ago, and it has completely changed
> >> what I can get out of a lousy old cassette (which refers to most of
> them).
> >> And I used a nice TASCAM deck before that. I could adjust the azimuth
> on
> >> the TASCAM and always did that, but it's not much fun. Adjusting the
> >> azimuth is essential for music cassettes.
> >>
> >> I really love using the NAK Dragon. It will play cassettes that won't
> play
> >> on other machines--the double capstan system is great. In many older
> >> cassettes, the foam pressure pad that is supposed to press the tape
> against
> >> the head has fallen off--that's no problem in the Dragon.
> >>
> >> The Dragon has one drawback--no speed control. If a cassette is off
> pitch
> >> (and plenty of them are--the old machines, even expensive ones, were
> >> notoriously inexact on the speed, which matters a lot for a tape that is
> >> moving at only 1 7/8 IPS), and if that cassette is also Dolbyized, you
> need
> >> to dub it with Dolby off, correct the pitch on the computer in the
> digital
> >> domain, and then apply Dolby NR with software. U-He Satin is a good
> >> program choice for doing that.
> >>
> >> Best,
> >> John Haley
> >>
> >>
> >>
> >> On Sun, Jun 3, 2018 at 12:14 PM, Dan Gediman <[log in to unmask]>
> wrote:
> >>
> >>> Folks,
> >>>
> >>> I can’t thank you all enough for your thorough and very helpful
> >>> suggestions about dealing with cassette tapes. I am reassured that old
> >>> cassettes generally have fewer problems than RTR tapes of the same
> >> vintage.
> >>> It seems like having a playback deck with an azimuth adjustment and
> some
> >>> empty shells available to rehouse troublesome tapes are the most
> >> important.
> >>> My primary deck is a portable Sony D5M which I used for years as my
> main
> >>> deck for field recording, and have generally used it to play back
> tapes I
> >>> have recorded. I also have another Sony deck in my studio. But I am
> >>> entirely open to investing in one of the Nakamichi decks that have been
> >>> suggested for both the dual capstan and azimuth adjustment.
> >>>
> >>> Thanks again for all your good counsel!
> >>>
> >>> Best,
> >>> Dan
> >>>
> >>> Dan Gediman
> >>> [log in to unmask]
> >>> 502.299.2565
> >>>
> >>>> On Jun 3, 2018, at 12:00 AM, ARSCLIST automatic digest system <
> >>> [log in to unmask]> wrote:
> >>>>
> >>>> There is 1 message totaling 19 lines in this issue.
> >>>>
> >>>> Topics of the day:
> >>>>
> >>>> 1. Question about baking cassette audio tapes
> >>>>
> >>>> ------------------------------------------------------------
> ----------
> >>>>
> >>>> Date: Sat, 2 Jun 2018 00:28:11 -0400
> >>>> From: Jeff Willens <[log in to unmask]>
> >>>> Subject: Re: Question about baking cassette audio tapes
> >>>>
> >>>> What Peter said.
> >>>>
> >>>> There are a very few brands of cassettes that do indeed shed, and can
> >>> benefit from a limited amount of baking time. I’m dealing with several
> >>> boxes of them right now. But before doing that, I would check to see if
> >>> rehousing them in new shells would help first. These tapes did not
> >> squeal.
> >>> They just flat out didn’t move. Some needed a better tape path. Some
> >> needed
> >>> baking. But itis generally less common than for RTR tapes.
> >>>>
> >>>> ------------------------------
> >>>>
> >>>> End of ARSCLIST Digest - 1 Jun 2018 to 2 Jun 2018 (#2018-116)
> >>>> *************************************************************
> >>>
> >>
> >
> --
> Richard L. Hess email: [log in to unmask]
> Aurora, Ontario, Canada 647 479 2800
> http://www.richardhess.com/tape/contact.htm
> Quality tape transfers -- even from hard-to-play tapes.
>
--
Melissa Widzinski
Audio Preservation Engineer
Media Digitization and Preservation Initiative <https://mdpi.iu.edu/>
Indiana University
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