<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
</head>
<body>
<p>Excess noise is important in some cases, and it is material
dependent. I agree that the 150 for the noise measurement can be
"any: 150 Ohm. <br>
</p>
<p>Regarding "A weighting", I just publish both figures. In most
cases it is 2dB difference.</p>
<p>Regards</p>
<p>Dan Lavry<br>
</p>
<div class="moz-cite-prefix">On 6/14/2021 11:03 AM, Bill Whitlock
via ProAudio wrote:<br>
</div>
<blockquote type="cite"
cite="mid:207546559.5029273.1623693788111@mail.yahoo.com">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<div style="color:black;font: 12pt Arial, Helvetica, sans-serif;">Dan,
I'm glad you caught that one! Noise is a "stand alone" that
needs no reference except a unit of measure - and, as frequently
omitted by marketing types, a stated bandwidth. And I have no
problem in using weighted figures as long as it's clearly
stated.
<div><br>
</div>
<div>In my mind, the biggest barrier to understanding noise and
its implications is the lies, distortions, and half-truths
perpetrated by marketing folks! A measurement, with test
conditions and references fully disclosed, is not subject to
interpretation. Sadly, many folks are "educated" by such
misleading information and will believe, for example, that the
150 Ω resistor used for testing preamp noise must be a special
"low-noise" resistor. In fact, thermal noise has no
dependence on the resistive material at all. So-called
"low-noise" resistors are low in "excess noise" that occurs
when DC current flows in it - and there's a huge difference
among those! Anyone whose ever heard me lecture is well aware
that no love is lost between me and marketing people.
<div><br>
</div>
<div>Bill Whitlock<br>
<br>
<br>
<div
style="font-family:arial,helvetica;font-size:10pt;color:black"><font
size="2">-----Original Message-----<br>
From: Dan Lavry via ProAudio
<a class="moz-txt-link-rfc2396E" href="mailto:proaudio@bach.pgm.com"><proaudio@bach.pgm.com></a><br>
To: Mike Rivers <a class="moz-txt-link-rfc2396E" href="mailto:mm1100@yahoo.com"><mm1100@yahoo.com></a>;
<a class="moz-txt-link-abbreviated" href="mailto:proaudio@bach.pgm.com">proaudio@bach.pgm.com</a><br>
Sent: Mon, Jun 14, 2021 9:27 am<br>
Subject: Re: [ProAudio] Microphones question<br>
<br>
<div id="yiv8592778151">
<div>
<div>I think you are confusing things. EIN does not
need to be measured at full scale, and it is a
real representative of the noise contributions.</div>
<div><br clear="none">
</div>
<div>Micpre noise is low and not easy to measure
directly. Say you test system can measure down to
1uV, but your signal is 0.1uV. It would be
difficult to measure the noise directly. Say you
set the gain at 60dB, the noise will become 100uV,
and a 1uV system can measure that. At 40dB gain
you get 10uV, still good enough to measure. In the
first case Ein is 100uV/1000, in the second case
10UV/100, both yield 0.1uV which is the real input
noise.</div>
<div><br clear="none">
</div>
<div>Of course that will not hold if the design is
poor. Any reasonable design will yield very
similar ein at 60dB and 40db. </div>
<div><br clear="none">
</div>
<div>Regards</div>
<div>Dan Lavry</div>
<div><br clear="none">
</div>
<div><br clear="none">
</div>
<div><br clear="none">
</div>
<div><br clear="none">
</div>
<div id="yiv8592778151composer_signature">
<div style="font-size:85%;color:#575757;">Sent
from Samsung Galaxy smartphone.</div>
</div>
<div><br clear="none">
</div>
<div><br clear="none">
</div>
<div style="font-size:100%;color:#000000;"
align="left">
<div class="yiv8592778151yqt8014364626"
id="yiv8592778151yqtfd24721">
<div>-------- Original message --------</div>
<div>From: Mike Rivers via ProAudio
<a class="moz-txt-link-rfc2396E" href="mailto:proaudio@bach.pgm.com"><proaudio@bach.pgm.com></a> </div>
<div>Date: 6/14/21 8:07 AM (GMT-08:00) </div>
<div>To: <a class="moz-txt-link-abbreviated" href="mailto:proaudio@bach.pgm.com">proaudio@bach.pgm.com</a> </div>
<div>Subject: Re: [ProAudio] Microphones
question </div>
<div><br clear="none">
</div>
</div>
</div>
<div class="yiv8592778151yqt8014364626"
id="yiv8592778151yqtfd29035"> How about a little
discussion on the value of knowing the EIN of a
preamp and how the figure is useful to the
designer? <br clear="none">
<br clear="none">
Here's why I ask:<br clear="none">
<br clear="none">
When I was writing reviews regularly, EIN was (and
still is) often quoted in the product's specs. The
numbers ranged from -125 dBu (just a couple) to a
majority being either -127 or -128 dBu.
Manufacturers liked to tout it because it was a
nice low number with "noise" in its name. And it
was always measured at a level within a dB or so
of clipping since that's it looked the best. <br
clear="none">
<br clear="none">
But unless I missed the appropriate chapter, EIN
is a calculated value - the measured noise level
with the gain subtracted out. So a preamp with 60
dB of gain that advertised EIN=-128 dBu could be
expected to put out -68 dBu of noise, measured, of
course to the advantage of the marketing
department with the appropriate input termination
(0, 100, or 150 ohms usually) and output load.<br
clear="none">
<br clear="none">
So, among design engineers, what's the big deal
about EIN? Is there a better way of measuring it
that's more meaningful? And if you can squeeze
another dB of EIN out of a design, how significant
will this be to the user? I<br clear="none">
<br clear="none">
, know "it depends."<br clear="none">
<br clear="none">
<pre class="yiv8592778151moz-signature">--
For a good time call <a rel="nofollow noopener noreferrer" shape="rect" class="yiv8592778151moz-txt-link-freetext" target="_blank" href="http://mikeriversaudio.wordpress.com/" moz-do-not-send="true">http://mikeriversaudio.wordpress.com</a></pre>
</div>
</div>
</div>
<div class="yqt8014364626" id="yqtfd41697">_______________________________________________<br
clear="none">
ProAudio mailing list<br clear="none">
<a shape="rect" ymailto="mailto:ProAudio@bach.pgm.com"
href="mailto:ProAudio@bach.pgm.com"
moz-do-not-send="true">ProAudio@bach.pgm.com</a><br
clear="none">
<a shape="rect"
href="http://bach.pgm.com/mailman/listinfo/proaudio"
target="_blank" moz-do-not-send="true">http://bach.pgm.com/mailman/listinfo/proaudio</a><br
clear="none">
</div>
</font></div>
</div>
</div>
</div>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<pre class="moz-quote-pre" wrap="">_______________________________________________
ProAudio mailing list
<a class="moz-txt-link-abbreviated" href="mailto:ProAudio@bach.pgm.com">ProAudio@bach.pgm.com</a>
<a class="moz-txt-link-freetext" href="http://bach.pgm.com/mailman/listinfo/proaudio">http://bach.pgm.com/mailman/listinfo/proaudio</a>
</pre>
</blockquote>
<div id="DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2">
<br /><br />
<hr style='border:none; color:#909090; background-color:#B0B0B0; height: 1px; width: 99%;' />
<table style='border-collapse:collapse;border:none;'>
<tr>
<td style='border:none;padding:0px 15px 0px 8px'>
<a href="https://www.avast.com/antivirus">
<img border=0 src="https://static.avast.com/emails/avast-mail-stamp.png" alt="Avast logo" />
</a>
</td>
<td>
<p style='color:#3d4d5a; font-family:"Calibri","Verdana","Arial","Helvetica"; font-size:12pt;'>
This email has been checked for viruses by Avast antivirus software.
<br><a href="https://www.avast.com/antivirus">www.avast.com</a>
</p>
</td>
</tr>
</table>
<br />
<a href="#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2" width="1" height="1"> </a></div></body>
</html>