Tape recording theory
 

David Looser wrote:
"Scott Dorsey" wrote in message
Dave Plowman (News) wrote:

Think the best it can do is about 1%.

You're about an order and a half of magnitude off. More than that if
you're
willing to live with restricted dynamic range, which we often are. On the
other hand, if you want distortion, we have that too.

Distortion is quoted at standard reference levels, typically 185 nWb/m, and
the last time I looked most tape formulations were producing around 1% 3rd
harmonic at those levels.

That was back in the red oxide days. One of the interesting things about
modern tapes (ie. much hotter than HOLN tapes... folks today regularly run
at 520 nW/m while still avoiding saturation) is that the onset of saturation
is very abrupt on many of them. This means you can get very low distortion
figures if you wanted. Back then it was normal to select the operating level
as the point where you got 3% distortion on a 1KC tone. Things have changed.

Even with the old red oxide stuff, you could drop your distortion figures
considerably by reducing your operating levels.

These days lots of people are running at elevated levels because they like
the coloration it gives you, but there's no reason you have to run at
elevated levels.

It's not "coloration", it's distortion. If you say that "lots of people"
like distortion I'll have to believe you, but it seems that those of us who
have been under the misapprehension that a recording machine should simply
reproduce as accurately as possible what was fed into it have been wasting
our time.

If you want accurate reproduction, we can do that. If you don't want accurate
reproduction, we can do that too.

I referred earlier to the obvious distortion (read muddiness and mush) on so
many classic 60s pop albums, if people like that then they have peculiar
tastes. Of course it can be done better, much better, such as by a digital
recorder.

Actually, most of that muddiness and mush came from two things: the room
issues of the day, and the fact that most of that music was mixed without
attention to the lower midrange because it was expected to be removed in
mastering anyway. So many of those old 45s had massive low-cutting done
in order to make them playable on jukeboxes and crappy portable phonographs.
When they get reissued on CD, if the mastering engineer attempts to restore
what was removed in the original issue, they often get a big shock.
The tape machine distortion was the least of the problem.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Tape recording theory
 

"Dave Plowman (News)" wrote in message
...
In article ,
tony sayer wrote:
Oh, I can make it pretty blatant and nasty-sounding too, if the
customer wants that. I've done that before too. Blues singer brings
in a record, says he wants to sound like that.... I set up 641 with a
teeny bit of underbias (using 1KC peak method), set operating levels
to the point where I get first audible distortion on a 1KC tone at -1dB
on the mark... voila! --scott


Above all noted..

Except that what I'm describing is seemingly a -lack- of distortion!.

Think the best it can do is about 1%.

At what level? Typical performance of a good recorder with good tape at 0 VU
is about 0.1% harmonic distortion, midband, almost entirely 3rd harmonic. At
higher levels, as previously noted, the HD stays low until you hit the point
where all of a sudden it takes off skyward, typically around +10 or +11 VU
for a tape where 0 VU = 320nW/meter..

Peace,
Paul

Tape recording theory
 

"David Looser" wrote in message
...
"Scott Dorsey" wrote in message
...
Dave Plowman (News) wrote:

Think the best it can do is about 1%.

You're about an order and a half of magnitude off. More than that if
you're
willing to live with restricted dynamic range, which we often are. On
the
other hand, if you want distortion, we have that too.

Distortion is quoted at standard reference levels, typically 185 nWb/m,
and the last time I looked most tape formulations were producing around 1%
3rd harmonic at those levels.

When did you last look? 1958?

By the mid-1970s, when I ran tests, typical professional tape (Scotch 250,
Ampex 456, etc.) were producing about 0.1% HD at 320nW/meter.

Peace,
Paul