Dirty Digital [sic.]
 

Don Pearce wrote:

Eeyore wrote:

The studio itself is a 3 storey building (rather bland industrial looking type) with vehicle
access on its left (not sure if they were planning to block that up) and a former paint
warehouse IIRC.

It still has the paint references outside - I guessed correctly what
building it was.

Great.


I had far less than 200 turns - more like 20 on a 2 inch former and I was registering -60dBu
on a Radford noise meter.


OK - at this frequency the relationship will be pretty much linear. You
can assume mine added 20dB for the turns and another 12 for the extra
area, so my "measured" field strength would be 32dB higher than you
would have seen.

Yup.


We also used a real guitar and a guitar pickup in a box straight into a Pignose amp and it
was totally unacceptable.

Interesting fact I now recall. The owners had an 'EMC check' run on the site prior to
purchase but since the tests only started at 150kHz, it came back with a clean bill of
health. Then they discovered the horrible truth.

Something radical has clearly changed since you were there.

Stating the slightly obvious, yes a ~ 10m3 cube of 2mm mild steel. Possibly slightly bigger.

Where exactly did you measure ? Did you wander up and down the street at all, or just in front of
the building ?

Graham

Dirty Digital [sic.]
 

Eeyore wrote:




OK - at this frequency the relationship will be pretty much linear. You
can assume mine added 20dB for the turns and another 12 for the extra
area, so my "measured" field strength would be 32dB higher than you
would have seen.

Yup.


We also used a real guitar and a guitar pickup in a box straight into a Pignose amp and it
was totally unacceptable.
Interesting fact I now recall. The owners had an 'EMC check' run on the site prior to
purchase but since the tests only started at 150kHz, it came back with a clean bill of
health. Then they discovered the horrible truth.
Something radical has clearly changed since you were there.

Stating the slightly obvious, yes a ~ 10m3 cube of 2mm mild steel. Possibly slightly bigger.

Where exactly did you measure ? Did you wander up and down the street at all, or just in front of
the building ?


Only 20 yards or so. It didn't seem to be changing at all, so I left it
at that.

d

Dirty Digital [sic.]
 

Don Pearce wrote:

Eeyore wrote:

Where exactly did you measure ? Did you wander up and down the street at all, or just in front
of the building ?

Only 20 yards or so. It didn't seem to be changing at all, so I left it
at that.

I suppose it might have been a hot-spot. Interesting to hear it again though.

I'll see if I can find that MD. I *think* I made one.

Graham

Dirty Digital [sic.]
 

Eeyore wrote:

Don Pearce wrote:

Eeyore wrote:
Where exactly did you measure ? Did you wander up and down the street at all, or just in front
of the building ?

Only 20 yards or so. It didn't seem to be changing at all, so I left it
at that.

I suppose it might have been a hot-spot. Interesting to hear it again though.

I'll see if I can find that MD. I *think* I made one.

Graham


I'd have needed to know what was causing it. An original recording would
be interesting.

d

Dirty Digital [sic.]
 

Don Pearce wrote:

Eeyore wrote:
Don Pearce wrote:
Eeyore wrote:
Where exactly did you measure ? Did you wander up and down the street at all, or just in front

of the building ?

Only 20 yards or so. It didn't seem to be changing at all, so I left it
at that.

I suppose it might have been a hot-spot. Interesting to hear it again though.

I'll see if I can find that MD. I *think* I made one.


I'd have needed to know what was causing it. An original recording would
be interesting.

Well, the intensity did increase with proximity to the railway line. But maybe by only about 6dB from
one edge of the propertry line by the track, to the roadside.

The best possible explanation I can find so far is this.
http://en.wikipedia.org/wiki/Track_circuit

Graham

Dirty Digital [sic.]
 

On 2008-06-25, Jim Lesurf wrote:
At dire risk of pulling this thread back onto the original topic... :-)

People might be interested in

http://www.audiomisc.co.uk/ddd/Dirty...Delusions.html

The article above comments about the use by HFW of "1 kHz" meaning
"1,002 Hz".

The 1,002 Hz undithered test tone HFW uses is presumably 44,100/44 Hz
(1,002.2727.. Hz). With this integer relationship between the test tone
and the sampling rate the quantization distortion products all pile up
at the harmonics of the test tone.

I guess this produces a spectrogram understandable in "conventional"
terms. Using exactly 1,000 Hz (undithered) instead, the quantization
products are distributed much more evenly through the spectrum and the
spectrogram looks less usual.

This is exactly the same issue as with the HFW article's (ab)use of
8,820 Hz (undithered) as a test tone - but actually used to support an
opposing point.

--
John Phillips

Dirty Digital [sic.]
 

In article , John Phillips
wrote:
On 2008-06-25, Jim Lesurf wrote:
At dire risk of pulling this thread back onto the original topic...
:-)

People might be interested in

http://www.audiomisc.co.uk/ddd/Dirty...Delusions.html

The article above comments about the use by HFW of "1 kHz" meaning
"1,002 Hz".

The 1,002 Hz undithered test tone HFW uses is presumably 44,100/44 Hz
(1,002.2727.. Hz). With this integer relationship between the test tone
and the sampling rate the quantization distortion products all pile up
at the harmonics of the test tone.

Yes. I suspected he'd done that as a result of his persistent use of
undithered tones. Although he may have used 1002 not 44100/44 if his
waveform generation applied rounding to get each second of data to be the
same as the others. However 1000, 1002, or 44100/44, you still get no
distortion if dither is correctly employed. :-)

This is exactly the same issue as with the HFW article's (ab)use of
8,820 Hz (undithered) as a test tone - but actually used to support an
opposing point.

Again, yes I suspect this is so. Problem here is we are trying to make
sense of nonsense to a large extent. So are trying to find logical reasons
for the oddities in the source being examined.

I find it hard to fathom why he persistently follows the same muddled line
of his articles over many years. But I suspect that it stems from a 'cart
before horse' thought process. This starts with his belief that CD
inherently and unavoidably has the alleged 'hard grey sound' and then
jumping onto what he reports as the 'reason'. Alas, that approach seems
classic with some people in audio. Founded on a faith held as certainty,
then 'factoids' are assembled to provide (unreliable) 'support'. Shame.

Slainte,

Jim

--
Change 'noise' to 'jcgl' 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

Dirty Digital [sic.]
 

Eeyore wrote:

Don Pearce wrote:

Eeyore wrote:
Don Pearce wrote:
Eeyore wrote:
Where exactly did you measure ? Did you wander up and down the street at all, or just in front
of the building ?
Only 20 yards or so. It didn't seem to be changing at all, so I left it
at that.
I suppose it might have been a hot-spot. Interesting to hear it again though.

I'll see if I can find that MD. I *think* I made one.

I'd have needed to know what was causing it. An original recording would
be interesting.

Well, the intensity did increase with proximity to the railway line. But maybe by only about 6dB from
one edge of the propertry line by the track, to the roadside.

The best possible explanation I can find so far is this.
http://en.wikipedia.org/wiki/Track_circuit

Graham



I've done a bit of work on that recording and isolated what is most
certainly a track circuit block monitoring signal (first five seconds,
band pass filtered).

http://81.174.169.10/odds/tcb.wav

Quite reasonable to pick it up this close to a railway, but I wouldn't
expect that to cause interference problems.

d

Dirty Digital [sic.]
 

Don Pearce wrote:

Eeyore wrote:
Don Pearce wrote:
Eeyore wrote:
Don Pearce wrote:
Eeyore wrote:
Where exactly did you measure ? Did you wander up and down the street at all, or just in front
of the building ?
Only 20 yards or so. It didn't seem to be changing at all, so I left it
at that.
I suppose it might have been a hot-spot. Interesting to hear it again though.

I'll see if I can find that MD. I *think* I made one.

I'd have needed to know what was causing it. An original recording would
be interesting.

Well, the intensity did increase with proximity to the railway line. But maybe by only about 6dB from
one edge of the propertry line by the track, to the roadside.

The best possible explanation I can find so far is this.
http://en.wikipedia.org/wiki/Track_circuit


I've done a bit of work on that recording and isolated what is most
certainly a track circuit block monitoring signal (first five seconds,
band pass filtered).

http://81.174.169.10/odds/tcb.wav

Yup, that has the characteristic warble. ISTR a lower fequency content around 400Hz ? too.


Quite reasonable to pick it up this close to a railway, but I wouldn't
expect that to cause interference problems.

Well .... if I do find that MD.

In the meantime since you're the expert in this, can you estimate the field intensity that would give ~
-60dBu from 20 turns on a 2 inch former ?

Graham

Dirty Digital [sic.]
 

Eeyore wrote:

Don Pearce wrote:

Eeyore wrote:
Don Pearce wrote:
Eeyore wrote:
Don Pearce wrote:
Eeyore wrote:
Where exactly did you measure ? Did you wander up and down the street at all, or just in front
of the building ?
Only 20 yards or so. It didn't seem to be changing at all, so I left it
at that.
I suppose it might have been a hot-spot. Interesting to hear it again though.

I'll see if I can find that MD. I *think* I made one.
I'd have needed to know what was causing it. An original recording would
be interesting.
Well, the intensity did increase with proximity to the railway line. But maybe by only about 6dB from
one edge of the propertry line by the track, to the roadside.

The best possible explanation I can find so far is this.
http://en.wikipedia.org/wiki/Track_circuit

I've done a bit of work on that recording and isolated what is most
certainly a track circuit block monitoring signal (first five seconds,
band pass filtered).

http://81.174.169.10/odds/tcb.wav

Yup, that has the characteristic warble. ISTR a lower fequency content around 400Hz ? too.


Quite reasonable to pick it up this close to a railway, but I wouldn't
expect that to cause interference problems.

Well .... if I do find that MD.

In the meantime since you're the expert in this, can you estimate the field intensity that would give ~
-60dBu from 20 turns on a 2 inch former ?

Graham


The formula is volts/(4.44 * freq * turns), which comes out for 1700Hz
to (I think) 5 * 10^-9 Webers per square meter

I'm not certain about this.

d