In article , Dave Plowman (News)
scribeth thus
In article ,
tony sayer wrote:
I've ordered up a toroidal transformer and Eddystone box to put it in
from CPC. Still free carriage. ;-)



A Toriod tranny?, best bet for hum field reduction.

Yes - quoted at 1/10th of a 'normal' type.

Make sure there no
shorted turns thru it..

Quite - although since they are single hole fixing with a kit usually
provided you'd have to do something very silly to achieve that.

Yes but I've seen it done more then the once but not implying of
course!..

Snag is the smallest toroidal I could find is way over sized for this
application. Are there any 6VA or so trannies made with low external field?



RS components do very small ones from 1.50 VA upwards by Nuvotem not
that cheap of course!..
--
Tony Sayer

On Thu, 29 Aug 2013 10:45:01 +0100, tony sayer wrote:

In article , Dave Plowman (News)
scribeth thus

I've ordered up a toroidal transformer and Eddystone box to put it in from
CPC. Still free carriage. ;-)


A Toriod tranny?, best bet for hum field reduction. Make sure there no
shorted turns thru it..

It is *so* tempting to use a ring crimp on that nice big mounting bolt though!

--

Bits arrived from CPC today so fitted and hum gone. Noise measured on the
output is about 4mV peak to peak, output being standard domestic line
level.

--
*60-year-old, one owner - needs parts, make offer

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

In article , Dave Plowman (News)
scribeth thus
Bits arrived from CPC today so fitted and hum gone. Noise measured on the
output is about 4mV peak to peak, output being standard domestic line
level.


So thats 4 mv reference to what -10 dBm?..
--
Tony Sayer

In article ,
tony sayer wrote:
In article , Dave Plowman (News)
scribeth thus
Bits arrived from CPC today so fitted and hum gone. Noise measured on
the output is about 4mV peak to peak, output being standard domestic
line level.


So thats 4 mv reference to what -10 dBm?..

On the same scope, the output shows about 2v peak to peak. Which would
suggest the noise is some 54dB down. But I'm sure there is a more sanitary
way to measure such devices.

However, at a high listening level, it sounds pretty good noise wise when
you lift the pickup.

--
*I tried to catch some fog, but I mist.*

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

In article , Dave Plowman (News)
scribeth thus
In article ,
tony sayer wrote:
In article , Dave Plowman (News)
scribeth thus
Bits arrived from CPC today so fitted and hum gone. Noise measured on
the output is about 4mV peak to peak, output being standard domestic
line level.


So thats 4 mv reference to what -10 dBm?..

On the same scope, the output shows about 2v peak to peak. Which would
suggest the noise is some 54dB down. But I'm sure there is a more sanitary
way to measure such devices.

Yes a wideband audio meter. I'd have thought that would be a bit better
than that Dave, what's in-between the input device and the output?..



However, at a high listening level, it sounds pretty good noise wise when
you lift the pickup.

....
--
Tony Sayer

On 31/08/13 18:50, tony sayer wrote:
In article , Dave Plowman (News)
scribeth thus
In article ,
tony sayer wrote:
In article , Dave Plowman (News)
scribeth thus
Bits arrived from CPC today so fitted and hum gone. Noise measured on
the output is about 4mV peak to peak, output being standard domestic
line level.

So thats 4 mv reference to what -10 dBm?..
On the same scope, the output shows about 2v peak to peak. Which would
suggest the noise is some 54dB down. But I'm sure there is a more sanitary
way to measure such devices.
Yes a wideband audio meter. I'd have thought that would be a bit better
than that Dave, what's in-between the input device and the output?..

yes it should be: with a shielded cartridge plugged in the theoretical
max SNR of a moving magnet cartridge amp with RIAA eq is around 60-70dB.
60dB is easy. 65dB is not hard., but 70-dB is getting towards 'hand
selected devices' and nitrogen cooling :-=) THats with reference to a
standard 2mV or so RMS input.,



However, at a high listening level, it sounds pretty good noise wise when
you lift the pickup.

....


--
Ineptocracy

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