On 2009-09-10 10:06:56 +0100, "Dave Plowman (News)"
said:

In article ,
Patrick James wrote:
On 2009-09-10 00:26:48 +0100, "Dave Plowman (News)"
said:

A prime example of design over engineering. Ideal coffee table exhibit.
Just don't try and use it.

I've used it for over twenty years and found it to be quite superb.

You can't be serious? Unless only using headphones. Mounting the disc like
that turns it into a near perfect diaphragm. Causing feedback at very
modest levels. Then there's the likelyhood of smashing the pickup to bits
if being slightly careless when playing a 7". Then there's the care needed
when closing the lid to avoid the pickup jumping - those soft springs
cause the whole unit to tilt alarmingly.

It always amuses me how on Usenet people will present themselves as
experts on things that they have so little knowledge about.

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.

Your imagination is running away with you.

The Transcriptor Hydraulic Reference does not have soft springs at all.
The later Michell versions did have leaf springs which were soft, but
the Transcriptor Hydraulic Reference sits on three fairly hard feet
which have rubber at the bottom.

As an aside and a credit to Michell Engineering the soft leaf springs
they introduced were very good. However if you popped into a shop or
something and just played around with a Michell Hydraulic Reference
then you might have thought that it was as Dave has imagined.

Playing singles places the stylus at no risk any differently than with
a rubber platter that was common at the time. Remember that when the
Transcriptor Hydraulic Reference was intruduced all turntables
supported the platter on ridges or points. This is true of the Garrard
401, the Thorens turntables etc.

Oddly enough dropping the cartidge on the platter of the THR was less
likely to damage the stylus because the weights just bob the arm out of
the way. Dropping the stylus on a rubber ridged platter would see the
being battered to death. It is true that dropping styli on any platter
without a record is not a good idea

So here in Daves post are the usual tedious things people say about
Transcriptor turntables when they have no experience of them or perhaps
just saw one in a shop once.

I am going to address a couple of other points I saw in the thread.

The turntable was not designed to be a prop for a set used in Clockwork
Orange. Kubrik loved this turntable and used it a set.

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.

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.

Now I hope to give a brief idea of just how great an advance in
turntable design the THR represented. It was in fact the brain child of
a brilliant engineer called David Gammon, who very sadly passed away a
few months ago. It was David Gammon's intention to make a turntable
which provided better speed stability and minimised rumble to an extent
far greater than that of any other available turntable. He achieved
this by applying plain engineering science to the device with an
uprecedented thoroughness. In fact the unconventionl appearance of the
THR is because it is the first turntable in which form follows
function. Previously turntables had been designed firstly with a view
to how they look, then the mechanism fitted into that design.

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.

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".

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.

To give you an idea of the attention to detail on these issues. The
pinion for the belt on the motor is attached using a screw aligned with
the axis. Other belt drive turntables would attach the pinion with a
grub screw at 90 degrees to the axis. That was easier, but if you
attach a pinion the second way the tightening of the screw moves the
pinion off-axis such that it become eccentric, albeit to a tiny degree.
However David Gammon would not have even the possibility of that kind
of speed instability even that small.

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

If you do get hold of a THR in good condition (not necessarily mine)
and you set it up correctly then you will be simply amazed at how good
it sounds. You will be immediately in love with it.

The record won't magically become a diaphram, it won't wobble around in
some mysterious way, the stylus won't mysteriously dive bomb the
platter...

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