[Boatanchors] Disc caps vs paper caps

[J. Forster]

I bet I could easily construct a fair test where nobody could tell the
difference.

-John

==============



> I don't have a "golden ear"!  However, I can often tell a slight
> difference between using a disc ceramic and other types of capacitors in
> audio coupling circuits.  Now my ability to hear high frequencies is
> better than most.  Back when a number of television remotes used
> ultrasonic tones for control, I could easily hear those tones.  That
> ability may have some effect in being able to tell a slight difference.
>
> However, I definitely agree that most people cannot tell any difference
> and, for all practical purposes, replacing audio coupling capacitors with
> disc ceramics will have no apparent effect on the quality of the audio.
>  This is especially true of "communications" audio which is generally
> limited to the 300 Hz to 3000 Hz segment.
>
> As for the snubbing capacitors:  Back when vibrators were in widespread
> use, every new vibrator came with replacement snubbing capacitors.  If the
> capacitors were not replaced, the warranty on the vibrator was void.  I
> believe that this was because failure of the snubbing capacitors played a
> significant role in the fact that the vibrator needed to be replaced.
>  
> Glen, K9STH
>
>
> Website:  http://k9sth.com
>
>
> ________________________________
>  From: J. Forster <jfor at quikus.com>
> To: Glen Zook <gzook at yahoo.com>
> Cc: Mark Foltarz <foltarz at rocketmail.com>; "Boatanchors at mailman.qth.net"
> <boatanchors at mailman.qth.net>
> Sent: Thursday, September 27, 2012 9:58 AM
> Subject: Re: [Boatanchors] Disc caps vs paper caps
>
>> There have been cases where using disc ceramic capacitors as the
>> coupling
>> capacitors in audio circuits has resulted in problems.  This is usually
>> due to the fact that, under certain circumstances and with certain
>> capacitors, the capacitors can act as a transducer and the audio can
>> actually be heard from the capacitor!
>
> True. This is the piezoelectric effect I mentioned a couple oif days ago.
> Because they are reversible electro-mechanical transducers, they equally
> can avt as crude microphones, vicking up vibration auch as hum.
>
>> Many people can tell a slight difference between the use of disc ceramic
>> capacitors and the new "poly" types of capacitors when used as coupling
>> capacitors in audio stages.  
>
> Somehow, this is very suspect to me. Hum level, perhaps.
>
>> However, for practical communications use,
>> that difference is so slight as not to make any real difference in how
>> the signal "sounds".  For high fidelity audio applications, that
>> difference may, or may not, be noticed.
>
> IMO, only noticable with the "golden ear" crowd.
>
>> For bypass use, at both r.f. and audio frequencies, use of a disc
>> ceramic
>> capacitor works fine with the advantage of the disc ceramic capacitors
>> being that they are usually much less expensive than the other types of
>> capacitors.
>>  
>> Glen, K9STH
>
> As to use as vibrator snubbing capacitors, they are PROBABLY OK. I am not
> 100% certain. Some years ago, I set out to formally analyze a vibrator
> circuit. It is by no means anywhere near as simple as it looks. I suspect
> most of the design and application information has been gained by "cut and
> try".
>
> Generally, you want the capacitor to be big enough such that the capacitor
> will store an equal amount of energy as the inductor without overvoltaging
> the contacts.
>
> Best,
>
> -John
>
> =================