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Re: [Amps] IM distortion and such

To: Gary Smith <>,,
Subject: Re: [Amps] IM distortion and such
From: Joe Isabella <>
Reply-to: Joe Isabella <>
Date: Mon, 26 Jun 2006 08:40:10 -0700 (PDT)
List-post: <>
Since when does management listen to engineers??  They listen to the mighty 
$$$$.  Just like the Space Shuttle Challenger disaster chain of events, the 
engineers said "NO!!", but management said "We'll lose millions!!", so they 
launched with frozen O-rings.  We lost more than millions...
If you want a "perfect" amp, build it yourself.  Better yet, let's all do that, 
swap hardware, and see how perfect they are!!  Bet you a cup of coffee none of 
'em are...
Joe, N3JI

----- Original Message ----
From: Gary Smith <>
Sent: Monday, June 26, 2006 10:26:10 AM
Subject: Re: [Amps] IM distortion and such

Coming from Mr Matney, a most excellent point of view.  Particularly where 
one could be sued into bankruptcy and then oblivion.

----- Original Message ----- 
From: "Will Matney" <>
To: <>
Sent: Sunday, June 25, 2006 5:39 PM
Subject: Re: [Amps] IM distortion and such

> It's according to what kind of audio amp. Guitar amps are designed to 
> purposely introduce distortion. That's where the squeal of the electric 
> guitar comes from. The bands actually prefer this. However, if one is an 
> engineer, and you have a maximum rating curve, it is a liability to ever 
> go outside the curve into the over load region. That's like saying I'll 
> put my stamp on this bridge which I know is going to deflect more than 
> allowable published tolerances, and that I think it can get by with the 
> added stress, even though I am over the maximum curves for tensile and 
> yield strength. Then an automobile drives over it and falls in the river. 
> Who's liable? Whether electrical or mechanical engineering, an engineer 
> should always look at this. Though running a tube out of spec probably 
> wont kill anyone, the manufacturer better be ready to replace tubes or the 
> entire amp if the customer is dissatisfied as a suit will sure follow if 
> they don't. If ran in spec, one has nothing to worr
> y about, and has published data to fall back on. This from an engineers 
> point of view.
> Best,
> Will
> *********** REPLY SEPARATOR  ***********
> On 6/25/06 at 4:00 PM k7fm wrote:
>>Tom said:
>>"I think you are really saying an engineer shouldn't ever
>>design outside what is actually published on a spec sheet
>>that only covers a limited number of situations under any
>>condition, even if the component manufacturer, field
>>history, or direct testing show otherwise."
>>It might be easier to grasp what Tom is saying if you think of audio
>>amplifiers.  Assume a tube manufacturer specifies a tube for audio
>>distortion.  However, the manufacturer of the audio amplifier is looking
>>minimum distortion.  If he finds that running the tube outside of the
>>specified by the tube manufacturer gives consistently lower distortion,
>>it would be good engineering to do so.   In some cases, tubes might be
>>selected for those parameters that met the goals of the engineer.  In some
>>cases, the plate dissipation might be exceeded to get closer to class A.
>>Colin  K7FM
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