Transcriptor Hydraulic Reference on sale at UK
 

On 2009-09-10, Eiron wrote:
Malcolm Lee wrote:
On 2009-09-10, Eiron wrote:
UnsteadyKen wrote:
Don Pearce said...

Hold an LP up balanced on two fingers at opposite edges - you will see
how much it sags quite easily. Obviously it doesn't sag as much as
that with six suspension points, but it sags much more than enough to
generate a huge signal.
The Hydraulic was designed for the thick'n sturdy pre 73 oil crisis
discs which are a totally different animal to the later floppies.

I got a couple of lp's last week, a Decca ffrr from 1965 and a bog
standard EMI Columbia from 1966 and neither droops on your finger tip
test, on the contrary significant pressure has to be applied to deform
them.
I just rested an LP on two points. The centre drooped by 4mm.
Of course UnsteadyKen didn't measure anything....


I've just rested my LP ("With The Beatles" Mono PMC 1206 pressed
in 1964) on two points. The centre drooped by maybe 0.2mm.

Of course Eiron generalises from his limited personal experience
to the universal...

No, I just picked the nearest LP, 'The Piper at The Gates of Dawn',
from the double reissue 'A Nice Pair', bought in about 1975.
I have a couple of copies of 'With The Beatles'. I'll measure their droop tomorrow.


Ken was specifically talking about pre 73 LPs which is why I chose
the album I did. I also checked another 20 or so 60's/early 70's
LPs and the max droop at the centre was about 1mm. The LPs I
measured from the mid 70s drooped about 4mm. The thickness of the
mid 70s LPs was about 0.75mm and of the 60s LPs about 1.5mm.

Your "With the Beatles" need to be original 60's pressings - the
later re-pressings seem to be just as thin and droopy as other
post 73 albums.

Transcriptor Hydraulic Reference on sale at UK
 

In article , Dave Plowman (News)
wrote:
In article , Patrick James
wrote:


The LP does not behave like a diaphram on the platter for the very
simple reason that for an LP to behave like a diaphram it would need
to be *secured* at the edge, like a drum skin for example.

Really? Is a loudspeaker cone 'secured' at the edge? Hint. It's not - if
anything it's secured by the spider in the middle. But works very
effectively as a microphone. In just the same sort of way as a pickup
does on a poorly supported disc.

The problem does seem to be that Patrick has simply defined the word
'diaphragm' simply so he can say that an LP isn't one. Thus evading the
more significant point that the LP mounted a la the Transcriptor can indeed
vibrate in response to acoustic energy.


Another in the thread has pointed out that when the turntable was
introduced and sold records were much thicker than those sold, say, in
the eighties or nineties. This is very true indeed, and the very thin
records of the eighties were a major reason why turntable
manufactureres stopped using point suspension or ridged suspension.

Actually he said "pre 73" not "mid eighties" IIRC.

Err, what other maker used it? The vast majority have conventional
turntables. For good reasons. Oh - I've been buying records from *well*
before the 'eighties and nineties' and there wasn't a universal
reduction in thickness.

I have a feeling that the highly regarded audio maker, Amstrad, also made a
look-alike with multiple point support for the LP. They came up with a
hilarious technogabble description of it IIRC. I'll see if I can find a
copy of the advert I have in mind as it was very funny. This was about the
time Alan Sugar was apparently telling his 'engineers' that if other makers
had four knobs on their amp, he had to have five or six. Didn't matter what
they did, just more knobs. :-)

As a return to that issue it is worth remembering that in the
seventies (and indeed early eighties) point or ribbed suspension was
considered a good thing because it meant that the record was not
sitting right on top of a potential dusty platter. Build up of dust
on records was a great concern in the seventies because people were
not as precious with them as they are today.

Worth remembering something you've just invented? Mats on turntables
come in all varieties. Some using just plain felt. But a ribbed design
supports the LP over most of its area - not in six points.

Actually my impression is that suspending the LP in open are might make the
dust problems *worse*. Reason being attraction to open surfaces by static.
A good mat may be slightly conductive so tend to remove charge as well as
cover the surface.


David Gammon knew that attaching the mechanism to a wooden box for a
chassis was crazy. The wooden box simply amplifies the sounds of the
mechanism. So with the THR the plinth is plywood laminated with an
acrylic layer creating a highly damped non resonant base. Remember
that this is in the sixties, no other turntable manufacturer was
exploring these ideas.

What noise does a mechanism make?

I'm curious about the common confusion of physics here that a wooden box
will 'amplify' the sounds. No doubt this is due to an inapporiate analogy
with things like acoustic instruments.

First lets look at platter design which has caused such consternation
for some. The common way to make a platter in the sixties was just to
cast one, fairly thin in a drum shape, aka Garrard and others. However
those designs were very resonant, indeed flicking the edge would
cause them to ring sometimes. David Gammon did not want a resonating
platter. He knew that any, even partial, air enclosure within the
platter was a potential cause of resonance, so in fact he designed a
platter which did not enclose air and which was acoustically
inherently "dead".

More ********.

Not necessarily. Maybe he just wanted to focus on allowing the LP to
vibrate. However maybe his idea would have worked if only used by people
living in anechoic chambers. ;- ...oh hang on, bugger, the stylus will
also generate vibrations. So no stylus contact either, I'm afraid, for his
(alledged) idea to work.

The platter is very heavy (12 kg) and most of the weight is at the
periphery. It has a huge moment of inertia compared with other
turntables of the time. In fact the moment of inertia is very great
even by today's standards. This, of course, was to facilitate
exceptional speed stability. Wow and flutter is extroadinarily low
with the THR even compared with many quality turntables in
manufacture today.

I still have a Goldring-Lenco GL75 somewhere. That also had a very high
intertia. Worked quite well in its day. But lacked the eye-appeal of the
Transcriptor I guess. :-)


The THR was and is probably the single most influential turntable
design.

You really must stop believing adverts. And quoting them wholesale here.

Well, Alan Sugar may have been impressed... or at least decided his punters
would be. :-)

The other is the Thorens upon which the Linn Sondek was famously
based. However the Linn is the only turntable inspired by the Thorens
whereas very many turntables available today are facsimiles in one
form or another of the THR.

Erm. I have the feeling that the Linn was also based on another deck whose
name is now largely forgotten. I seem to recall some patent arguments about
this which only stopped when the (probable) real inventor died. There were
some interesting reports on this some years later by Barry Fox IIRC.

Anyway I won't be posting again in this thread so please do enjoy
music no matter what the medium! -- Patrick

Good luck, I'm sure you will find a buyer.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

Transcriptor Hydraulic Reference on sale at UK
 

In article , Malcolm Lee
wrote:
On 2009-09-10, Jim Lesurf wrote:
In article , UnsteadyKen
wrote:
Don Pearce said...

Hold an LP up balanced on two fingers at opposite edges - you will
see how much it sags quite easily. Obviously it doesn't sag as much
as that with six suspension points, but it sags much more than
enough to generate a huge signal.

The Hydraulic was designed for the thick'n sturdy pre 73 oil crisis
discs which are a totally different animal to the later floppies.

My unreliable recollection is that many 'pre 73' LPs were far from
flat, or even very thick.


I obviously don't know what records you bought in that era but I bought
(and still own and play) roughly 500 or so records made pre 73. I've
just rechecked a ramdom sample (20 or so) and all without exception are
very flat and quite thick.

I don't know how many I have pre 73. Probably only 100 or less as I
coudln't afford many in those days, and was deterred by how often I had to
return them (repeatedly) to try and get one without audible flaws. Nor do I
know what definitions you are using for 'flat' or 'thick'. But my own
impression is that records up to the mid 60s could be fairly 'thick' but
then got thinner and lighter.

Most are UK pop/rock but I also have a fair few classical and some US
rock imports. Even the very cheap classical (eg Fontana and Marble Arch)
are flat and are thick enough not to droop.

In my case it is probably about 50:50 classical:pop. Again my recollection
is that some of the thicker and flatter ones were actually cheap lables
like the 'Wing' label (Philips?) My impression was that this depended more
on the factory than the label as such.


I got a couple of lp's last week, a Decca ffrr from 1965 and a bog
standard EMI Columbia from 1966 and neither droops on your finger tip
test,

Weird. Most of the pre 73 LPs I have are ones I bought when they first
came on sale! :-)


It would be interesting to know which labels made the "floppy" pre 73
LPs you have - if I have any of the same I'll dig them out and check
mine.

Again, I'm not sure of your definition of 'floppy' here.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

Transcriptor Hydraulic Reference on sale at UK
 

In article , Malcolm Lee
wrote:
On 2009-09-10, Eiron wrote:


I just rested an LP on two points. The centre drooped by 4mm. Of
course UnsteadyKen didn't measure anything....


I've just rested my LP ("With The Beatles" Mono PMC 1206 pressed in
1964) on two points. The centre drooped by maybe 0.2mm.

Of course Eiron generalises from his limited personal experience to the
universal...

I agree. One measurement isn't a good basis for generalisation. So here we
have two. Yours and his. The implication is that the droop varies over a
range convering from 0.2 to 4 mm.

At this point I have no measurements at all so can only go on my
impressions and the measurements people have kindly provided in this
thread.

BTW How flat was your LP when unsupported? Did you turn it over and repeat
the measurement? That seems like an obvious check for the effects of the LP
being inherently 'dished' by a small amount.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

Transcriptor Hydraulic Reference on sale at UK
 

On 2009-09-11, Jim Lesurf wrote:
In article , Malcolm Lee
wrote:
On 2009-09-10, Eiron wrote:


I just rested an LP on two points. The centre drooped by 4mm. Of
course UnsteadyKen didn't measure anything....


I've just rested my LP ("With The Beatles" Mono PMC 1206 pressed in
1964) on two points. The centre drooped by maybe 0.2mm.

Of course Eiron generalises from his limited personal experience to the
universal...

I agree. One measurement isn't a good basis for generalisation. So here we
have two. Yours and his. The implication is that the droop varies over a
range convering from 0.2 to 4 mm.

At this point I have no measurements at all so can only go on my
impressions and the measurements people have kindly provided in this
thread.

BTW How flat was your LP when unsupported? Did you turn it over and repeat
the measurement? That seems like an obvious check for the effects of the LP
being inherently 'dished' by a small amount.

Slainte,

Jim


Yes, I measured both sides and averaged the droop. In fact some 60s
albums had a negative "droop" one way up - ie. they were slightly dished
so that when supported at two points on the edge, the centre was proud of
the edges.
The LP I mentioned above was one of these - about 1mm droop one way
and circa 0.6mm proud the other.

Transcriptor Hydraulic Reference on sale at UK
 

On Fri, 11 Sep 2009 09:58:20 +0100, Malcolm Lee
wrote:

On 2009-09-11, Jim Lesurf wrote:
In article , Malcolm Lee
wrote:
On 2009-09-10, Eiron wrote:


I just rested an LP on two points. The centre drooped by 4mm. Of
course UnsteadyKen didn't measure anything....


I've just rested my LP ("With The Beatles" Mono PMC 1206 pressed in
1964) on two points. The centre drooped by maybe 0.2mm.

Of course Eiron generalises from his limited personal experience to the
universal...

I agree. One measurement isn't a good basis for generalisation. So here we
have two. Yours and his. The implication is that the droop varies over a
range convering from 0.2 to 4 mm.

At this point I have no measurements at all so can only go on my
impressions and the measurements people have kindly provided in this
thread.

BTW How flat was your LP when unsupported? Did you turn it over and repeat
the measurement? That seems like an obvious check for the effects of the LP
being inherently 'dished' by a small amount.

Slainte,

Jim


Yes, I measured both sides and averaged the droop. In fact some 60s
albums had a negative "droop" one way up - ie. they were slightly dished
so that when supported at two points on the edge, the centre was proud of
the edges.
The LP I mentioned above was one of these - about 1mm droop one way
and circa 0.6mm proud the other.


Do bear in mind when measuring that the droop continues to increase
for quite some time. If you measure straight away, it will be an
under-measurement.

d

Transcriptor Hydraulic Reference on sale at UK
 

In article ,
Keith G wrote:
But all you have to do is lower the pickup onto a stationary disc,
increase the gain and note the point feedback occurs. Then do the same
with a good conventional turntable. The difference is so great even
you will note it. With a decent turntable this will likely be at a
higher gain setting that you'd ever use for listening. With the
Transcriptor, not.

My pal who had one used to record to tape so he could listen at a
reasonable level...


My experience is that 'airborne FB' only occurs at volumes *way beyond*
even loud listening levels, so I've just checked with and without Tic
Tacs and find there's not a great deal in it 'volumewise' and it is way
up there past any setting I'm likely to use, but I'm quite surprised to
discover that a lid appears to do nothing to prevent FB and really only
alters the pitch - on my little Technics deck!

Not sure using small spacers on an ordinary turntable reproduces the
Transcriptor 'experience'. The distance between record and the reflecting
surface of the turntable will make a difference to the resonant frequency
- as can any covering on the turntable.

All I can say is being utterly amazed some 30 odd years ago that this
incredibly expensive device could be so useless at doing its job. As if
the designer had never used it to play an actual record.

--
*When you've seen one shopping centre you've seen a mall*

Dave Plowman London SW
To e-mail, change noise into sound.

Transcriptor Hydraulic Reference on sale at UK
 

In article 4aaa1236.6036468@localhost, Don Pearce
wrote:
On Fri, 11 Sep 2009 09:58:20 +0100, Malcolm Lee
wrote:

On 2009-09-11, Jim Lesurf wrote:
In article , Malcolm Lee
wrote:


BTW How flat was your LP when unsupported? Did you turn it over and
repeat the measurement? That seems like an obvious check for the
effects of the LP being inherently 'dished' by a small amount.

Yes, I measured both sides and averaged the droop.


Do bear in mind when measuring that the droop continues to increase for
quite some time. If you measure straight away, it will be an
under-measurement.

It occurs to me that, statistically, a simpler test might be useful. This
is simply to weigh each LP and note if the values change with year of
manufacture, etc. It won't allow for deliberately shaped discs, nor changes
in density or stiffness. But it would avoid the difficulty of trying to
allow for creep, departures from inherent flatness, etc, that can affect
measurements like the above.

That said, I'm not personally rushing to do any of this. :-) I rarely
bother with LPs these days. But I am interested in results people get.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

Transcriptor Hydraulic Reference on sale at UK
 

On Fri, 11 Sep 2009 11:55:58 +0100, Jim Lesurf
wrote:

In article 4aaa1236.6036468@localhost, Don Pearce
wrote:
On Fri, 11 Sep 2009 09:58:20 +0100, Malcolm Lee
wrote:

On 2009-09-11, Jim Lesurf wrote:
In article , Malcolm Lee
wrote:


BTW How flat was your LP when unsupported? Did you turn it over and
repeat the measurement? That seems like an obvious check for the
effects of the LP being inherently 'dished' by a small amount.

Yes, I measured both sides and averaged the droop.


Do bear in mind when measuring that the droop continues to increase for
quite some time. If you measure straight away, it will be an
under-measurement.

It occurs to me that, statistically, a simpler test might be useful. This
is simply to weigh each LP and note if the values change with year of
manufacture, etc. It won't allow for deliberately shaped discs, nor changes
in density or stiffness. But it would avoid the difficulty of trying to
allow for creep, departures from inherent flatness, etc, that can affect
measurements like the above.

That said, I'm not personally rushing to do any of this. :-) I rarely
bother with LPs these days. But I am interested in results people get.


Oh, this is all pretty well academic only. Vinyl is not for quality
any more - it is for nostalgia and dinner party bragging rights. It
doesn't actually matter how saggy it is. In fact the way this all
works, somebody will soon be claiming that it actually enhances the
sound.

d

Transcriptor Hydraulic Reference on sale at UK
 

Not necessarily. Maybe he just wanted to focus on allowing the LP to
vibrate. However maybe his idea would have worked if only used by people
living in anechoic chambers. ;- ...oh hang on, bugger, the stylus will
also generate vibrations. So no stylus contact either, I'm afraid, for his
(alledged) idea to work.


Wasn't there a turntable in the seventies which dispensed with the stylus
altogether, using instead some sort of optical pickup? Called the Finial,
or something like that. Got reinvented and asked for more funding every six
months or so.
IIRC only one escaped and was reviewed in HFN - worked reasonably well, but
was completely defeated by surface pops which came out at ear-shattering
levels.

Geoff Mack