[Boatanchors] Audio matching xformer

[WA5CAB at cs.com]

Barry,

The concept is that if you have (in this case) a 10 watt audio distribution 
amplifier with 500/600 ohm output and from one to 16 remote loudspeakers, you 
run parallel pairs of wires from the amp to each of the speakers (or you can 
run a loop or buss - it doesn't matter).  In the speakers (which is where the 
transformers are located) you connect the wires to common and to the tap 
correlating to the total number of speakers in the system.  For one, use the 10 watt 
tap, for two, use the 5 watt tap.  Etc.  Local volume controls (if provided) 
will be on the secondary side between the transformer and the speaker.

To get back to real boatanchors, this is why loudspeakers like the LS-3 or 
LS-7 have matching transformer primarys rated at 7000 or 8000 ohms and headsets 
like the HS-23 are 8000 ohm while the receiver audio output transformer 
secondary is rated 4000 ohms.  You can jack one to three of them into the receiver 
without much effect on the ones already connected.  Likewise the later war 600 
ohm components work with receivers with 250 ohm output impedance.  

In a message dated 10/14/2007 6:42:08 PM Central Daylight Time, 
robert at isquare.com writes: 
> At 07:11 PM 10/14/2007, Barrie Smith wrote:
> >Hello, All:
> >
> >I usually listen to my SX-73 using an old and tired Hallicrafters 600 ohm 
> >speaker, because 600 ohms is the audio output on that receiver.
> >
> >I'd like to try a better quality speaker, but the speakers I have are all 
> >8 ohm.
> >
> >I have a 70 volt, 10 watt line-transformer, but I can't make sense of the 
> >schematic.
> >
> >The secondary is marked 4, 8 and 16 ohms, so that's FB.
> >
> >The primary is marked in watts: Common, 10, 5, 2.5, 1.25 and .62 watts.
> >
> >I would think that if this transformer could match 600 ohms to 8 ohms the 
> >primary would be marked in ohms.
> >
> >I do not want to damage the receiver, so does anyone have an idea what's 
> >going on?
> >
> >73,
> >Barrie, W7ALW, DN36au,
> >QRV 6M, 432 &1296 EME
> 

Robert & Susan Downs - Houston
<http://www.wa5cab.com> (Web Store)
MVPA 9480
<wa5cab at cs.com> (Primary email)
<wa5cab at comcast.net> (Backup email)