[Hallicrafters] SX-42 Phone Jack

[Edward B Richards]

Nick, et al;

Do you suppose they were concerned with too much volume damaging
someone's ears? Those p-p 6V6's put out quite a wallop.

73 from Ed Richards K6UUZ
Simi Valley, CA. Home of 
Ronald Reagan Library
 
On Wed, 12 Sep 2007 18:42:24 EDT HallicrafterSX28 at aol.com writes:
> Hi
> If you look at the schematic ,the headphones are driven by the   
> voltage 
> amplifier 6SL7 tube ,not by the final power stage.So for 
> satisfactory  performance 
> the headset should be of HIGH impedance. It is interesting that on  
> the the 
> SX-28 the headphones were driven by the final power stage which 
> gives  more 
> volume in the headphones.But then for some reason only known to  
> Hallicrafters 
> Engineers they reverted back to the headphones being driven by the  
> Audio 
> voltage amplifier as was done on the models preceeding the SX-28. So 
> if  you have a 
> high impedance headset ,and volume still sounds kinda low that is  
> typical.
> In fact on my Sx-42 I modified the wiring so that the headphones are 
> driven  
> by the 500 ohms output which is a perfect match since the military 
> headset I 
> use  is also rated at 500 ohms.
> Nick
> 
> 
> 
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