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ARSCLIST  June 2018

ARSCLIST June 2018

Subject:

Re: Noise Reduction Companders (was: question about baking cassette tapes)

From:

"Gary A. Galo" <[log in to unmask]>

Reply-To:

Association for Recorded Sound Discussion List <[log in to unmask]>

Date:

Mon, 4 Jun 2018 18:41:34 +0000

Content-Type:

text/plain

Parts/Attachments:

Parts/Attachments

text/plain (1 lines)

Thanks, Melissa. Now I see what they mean by "5 Popular..." No Dolby C.. 

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 Melissa Widzinski
Sent: Monday, June 04, 2018 2:35 PM
To: [log in to unmask]
Subject: Re: [ARSCLIST] Noise Reduction Companders (was: question about baking cassette tapes)

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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