Appearance of Stereo LP's

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Was there some change made in stereo LP's (cutting or pressing) during
the late 60's or early 70's? I seem to remember that the grooves of
earlier stereo LP's were different-looking than later records. In my
1960's LP's of Peter, Paul, and Mary, for instance,the grooves looked
very deep and distincly different from the mono LP's I had bought
earlier of the same albums.

This very 'deep' look seemed to disappear in later stereo LP's.

 

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Uranium Committee wrote:
> Was there some change made in stereo LP's (cutting or pressing) during
> the late 60's or early 70's? I seem to remember that the grooves of
> earlier stereo LP's were different-looking than later records. In my
> 1960's LP's of Peter, Paul, and Mary, for instance,the grooves looked
> very deep and distincly different from the mono LP's I had bought
> earlier of the same albums.
>
> This very 'deep' look seemed to disappear in later stereo LP's.
=======================================================

There was a definite different look to stereo LP grooves when compared
to mono, because the depth of the groove varied, due to vertical
modulation in the grooves, necessary due to each wall of the groove
carrying a separate channel's information. Mono LPs had horizontal
modulation only.

I'm not familiar with the "very deep look" disappearing in later stereo
LPs; perhaps grooves were cut less deep as records were made thinner;
or, as in the case of some companies' product, summing of the low bass
between channels may have made those low frequency modulations
essentially mono, with little vertical component. When record companies
discontinued mono records, some summed the low bass to reduce tracking
difficulties with mono phono cartridges.

 

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"Gene Poon" <sheehans@ap.net> wrote in message
news:cosq5r02fmn@news1.newsguy.com...
> Uranium Committee wrote:
>> Was there some change made in stereo LP's (cutting or pressing) during
>> the late 60's or early 70's? I seem to remember that the grooves of
>> earlier stereo LP's were different-looking than later records. In my
>> 1960's LP's of Peter, Paul, and Mary, for instance,the grooves looked
>> very deep and distincly different from the mono LP's I had bought
>> earlier of the same albums.
>>
>> This very 'deep' look seemed to disappear in later stereo LP's.
> =======================================================
>
> There was a definite different look to stereo LP grooves when compared to
> mono, because the depth of the groove varied, due to vertical modulation
> in the grooves, necessary due to each wall of the groove carrying a
> separate channel's information. Mono LPs had horizontal modulation only.
>
> I'm not familiar with the "very deep look" disappearing in later stereo
> LPs; perhaps grooves were cut less deep as records were made thinner; or,
> as in the case of some companies' product, summing of the low bass between
> channels may have made those low frequency modulations essentially mono,
> with little vertical component. When record companies discontinued mono
> records, some summed the low bass to reduce tracking difficulties with
> mono phono cartridges.
>

In addition to Gene's response, I'd hazard a guess that the difference
you're seeing may be due to the change over, not in the way the discs were
cut, but in the materials used (lacquers, vinyls, different polymers).

Bill Balmer

 

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"Cosworth" <billbalmer@worldnet.att.net> wrote in message news:<cotiuk0lif@news2.newsguy.com>...
> "Gene Poon" <sheehans@ap.net> wrote in message
> news:cosq5r02fmn@news1.newsguy.com...
> > Uranium Committee wrote:
> >> Was there some change made in stereo LP's (cutting or pressing) during
> >> the late 60's or early 70's? I seem to remember that the grooves of
> >> earlier stereo LP's were different-looking than later records. In my
> >> 1960's LP's of Peter, Paul, and Mary, for instance,the grooves looked
> >> very deep and distincly different from the mono LP's I had bought
> >> earlier of the same albums.
> >>
> >> This very 'deep' look seemed to disappear in later stereo LP's.
> > =======================================================
> >
> > There was a definite different look to stereo LP grooves when compared to
> > mono, because the depth of the groove varied, due to vertical modulation
> > in the grooves, necessary due to each wall of the groove carrying a
> > separate channel's information. Mono LPs had horizontal modulation only.
> >
> > I'm not familiar with the "very deep look" disappearing in later stereo
> > LPs; perhaps grooves were cut less deep as records were made thinner; or,
> > as in the case of some companies' product, summing of the low bass between
> > channels may have made those low frequency modulations essentially mono,
> > with little vertical component. When record companies discontinued mono
> > records, some summed the low bass to reduce tracking difficulties with
> > mono phono cartridges.
> >
>
> In addition to Gene's response, I'd hazard a guess that the difference
> you're seeing may be due to the change over, not in the way the discs were
> cut, but in the materials used (lacquers, vinyls, different polymers).
>
> Bill Balmer

I think I remember something about 'compatible' stereo discs. Is that
what the summing accomplished? Anyway, if you have pre-1968 stereo
discs, take a look at them and see if you notice what I'm talking
about.

 

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Archived from groups: rec.audio.high-end (More info?)

In article <cotiuk0lif@news2.newsguy.com>,
Cosworth <billbalmer@worldnet.att.net> wrote:

There were some technology changes in cutting engines towards the end of the LP
era; one of them was to have the cutter head vary the spacing between the
grooves based on the signal and spectral content of the next groove.

These LPs would look different from the ones with uniform spacing.

RCA had something called "DynaGroove" which controlling the cutter head based
on the incoming signal, but I don't remember the specifics. I remember
these looking very different from the earlier RCA LPs; audiophiles in the 60's
hated the DynaGroove LPs.

There were other modifications, such as making certain that the final master
didn't exceed preset limits for required tracking.

Mike Squires, who still has about 1000 LPs and a turntable (TD-125 II/SME).

--

Mike Squires (mikes at cs.indiana.edu) 317 233 9456 (w) 812 333 6564 (h)
mikes at siralan.org 546 N Park Ridge Rd., Bloomington, IN 47408

 

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Archived from groups: rec.audio.high-end (More info?)

On 3 Dec 2004 22:25:42 GMT, uraniumcommittee@yahoo.com (Uranium
Committee) wrote:

>Was there some change made in stereo LP's (cutting or pressing) during
>the late 60's or early 70's? I seem to remember that the grooves of
>earlier stereo LP's were different-looking than later records. In my
>1960's LP's of Peter, Paul, and Mary, for instance,the grooves looked
>very deep and distincly different from the mono LP's I had bought
>earlier of the same albums.
>
>This very 'deep' look seemed to disappear in later stereo LP's.

By accident I have two copies of Paul Simon's Greatest Hits, Etc. The
sleeves are different (one is a "two page" sleeve that I can fold out,
the other is single sleeve), the labels are different (one has an
orange to yellow gradient, the other is stark red), the vinyl is
different, the pressing is different and the grooves are different.
They are both CBS.

You can not only SEE that the grooves are different, you can also HEAR
a difference.

The red label pressing (England) seems "flatter", whereas the
orange/yellow pressing (Holland) seems "deeper". Both are late 70's
pressings, I presume.

Normally I use the dutch pressing, and keep the other one as a spare
copy.

Ernesto.

"You don't have to learn science if you don't feel
like it. So you can forget the whole business if
it is too much mental strain, which it usually is."

Richard Feynman