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From: crs@lanl.ARPA
Newsgroups: net.micro.cbm
Subject: Re: Re. sound for monitor
Message-ID: <25619@lanl.ARPA>
Date: Thu, 9-May-85 10:21:22 EDT
Article-I.D.: lanl.25619
Posted: Thu May  9 10:21:22 1985
Date-Received: Sat, 11-May-85 02:06:06 EDT
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Organization: Los Alamos National Laboratory
Lines: 39

> Responding to the person who had bought a monitor without a speaker,
> (or anyone else who may be in the same predicament)....
> 
> There are a few things you can do.
> Radio Shack sells a small amplified speaker (approx 10in by 10in) that
> plugs right into the audio output.
> The price of this I think was approx $20.
> On the cheaper sided (for those who want sound but not excellent quality
>  I suggest just hooking the output to a regular 8 ohm speaker. If you
> don't have the appropriate plugs, Radio Shack sells these very cheap.
> like I said the sound quality is about as good as a TV speaker but the
> only difference is that you cannot adjust the volume. Those who are
> experienced at fiddling with electronics could probably fix this.
> 
> I hope I was of some help to someone out there.
> 
>                              Ron Zinnato

Will the audio output of the C-64 drive a speaker?  I'm not familiar
with the output circuit of the C-64 but I know that most amplifiers
(for which I assume the output was intended) have an input impedance
of several thousand ohms while many speakers have impedances as low
as 4 ohms.

What I really wonder is whether damage to the 64's output circuit will
ultimately result from excessive load.  (I don't have a 64 and haven't
seen the circuit diagram.)

There are some speakers with higher impedance (40 or 50 ohms) but even
this is a pretty heavy load for a circuit that is expecting several
thousand ohms.

[For non-hardware types, the higher the *impedance* of a load the less
*current* it draws, thus 50,000 ohms is *less* load than 50 ohms.]


Charlie Sorsby
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