On Thu, 10 Sep 2009 08:44:23 +0100, "Geoff Mackenzie"
wrote:


"Dave Plowman (News)" wrote in message
...
In article ,
Patrick James wrote:
Hi

I hope that it is fine for me to mention that I have put my
Transcriptor Hydraulic Reference turntable for sale at eBay.

Here is a link to it:

http://is.gd/35C9Q

Just in case the link goes wonky for some reason here is the item
number: 260474245281


Normal listening will now resume...

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

--
*I'm really easy to get along with once people learn to worship me

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

Wasn't it originally designed as a film prop ? - A Clockwork Orange, I
think, although it may have been 2001 A Space Odysee. Fortunately they got
it right with the Gyrodek.

Geoff MacK


Any deck that supports the record on six points can never be described
as "right". It is a ridiculous thing to do. The record must sag
between the points and cause a rhythmic 3.3Hz vertical thump through
the stylus, severely compromising headroom in the preamp.

The best a turntable can do, of course, is not make things any worse -
they can never be great.

And I thought that the hydraulic reference was mid-tide at Newlyn.

d

"Don Pearce" wrote


Any deck that supports the record on six points can never be described
as "right". It is a ridiculous thing to do. The record must sag
between the points


This is a joke - right?

On Thu, 10 Sep 2009 11:53:17 +0100, "Keith G"
wrote:


"Don Pearce" wrote


Any deck that supports the record on six points can never be described
as "right". It is a ridiculous thing to do. The record must sag
between the points


This is a joke - right?


Of course not. How could a flexible plastic record not sag between
those suspension points? Remember that we are talking thousandths of
an inch to create a big signal, not a sag like a row of bunting. A
record needs to be supported over its whole surface, as flat as
possible.

d

"Don Pearce" wrote in message
news:4aa8db1e.1466875@localhost...
On Thu, 10 Sep 2009 11:53:17 +0100, "Keith G"
wrote:


"Don Pearce" wrote


Any deck that supports the record on six points can never be described
as "right". It is a ridiculous thing to do. The record must sag
between the points


This is a joke - right?


Of course not. How could a flexible plastic record not sag between
those suspension points?


Stiffness.


Remember that we are talking thousandths of
an inch to create a big signal, not a sag like a row of bunting. A
record needs to be supported over its whole surface, as flat as
possible.


And yet they are so often not, for one reason or another - without any truly
discernable effect on the sound....

On Thu, 10 Sep 2009 12:24:00 +0100, "Keith G"
wrote:


"Don Pearce" wrote in message
news:4aa8db1e.1466875@localhost...
On Thu, 10 Sep 2009 11:53:17 +0100, "Keith G"
wrote:


"Don Pearce" wrote


Any deck that supports the record on six points can never be described
as "right". It is a ridiculous thing to do. The record must sag
between the points


This is a joke - right?


Of course not. How could a flexible plastic record not sag between
those suspension points?


Stiffness.

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.

Remember that we are talking thousandths of
an inch to create a big signal, not a sag like a row of bunting. A
record needs to be supported over its whole surface, as flat as
possible.


And yet they are so often not, for one reason or another - without any truly
discernable effect on the sound....


You won't hear it, because the frequency is too low, but what it does
is create a huge subsonic signal that the preamp has to cope with.
That eats into the overload margin, and can result in premature onset
of distortion with loud bass notes. So as a piece of engineering, it
is ****. Some may consider it pretty, but I'm not among them because I
can't separate form from function that easily. If I can see why it is
bad, it will not please me aesthetically.

d

"Don Pearce" wrote in message
news:4aa9e20e.3243421@localhost

You won't hear it, because the frequency is too low, but
what it does is create a huge subsonic signal that the
preamp has to cope with.

The flexing also creates wow.

I don't know whether or not it is audible given all the other speed
variations that are inherent in LP playback, but its there.

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.

--
Ken O'Meara
http://www.btinternet.com/~unsteadyken/

"UnsteadyKen" wrote in message
...
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.


There's all sorts of horse**** to do with coupling/supporting records
(vacuums, clamps, felts, rubber mats, glass platters &c. &c.) and plenty of
followers of each and every 'theory' - you just go with what you like, I
find. And I have to say I have never been able to tell the difference
between similarly good recordings on the various thicknesses of vinyl - a
good example that springs to mind is a series of compilations called....

called....

erm...

heaves arse off chair and goes to look

'Reflections'! (CBS10034 to name but a few)

Which are on really *whippy* vinyl but which are beautifully recorded and
sound fine! (I might use that one for the Tic Tac Test later!)




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.


And some will hang like an uncooked pizza - I have yet to hear any *audible*
consequence therefrom, but what were the records? I'm always curious!!

:-)

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 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! :-)

However, a sensing system like a stylus might be able to detect variations
from flat thay you can't see using your mark 1 eyeballs. So your "neither
droops" may simply tell us something about your eyes, not the LP. :-)

You could check by holding a straight-edge just above the LP, touching at
the suspension points. Then see if daylight floods though the gap. That way
you may be able to see a droop which your eyes would otherwise not notice.

That said, since most LP sensors are essentially velocity sensitive that
might help here given the low frequency of 6-point support at 100/3 rpm. I
guess it then depends on the suspension of the cantilever and the response,
etc, of the preamp. And with luck the unwanted ripple will be below the
arm/cart resonance, not spot-on that value!

on the contrary significant pressure has to be applied to deform
them.

....to the extent you find visible.

I have a vague feeling this topic did feature in a magazine set of
measurements a few decades ago. If I can find that sometime I'll let people
know.

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

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....

--
Eiron.