[Milsurplus] WW II Morale Amp

[Bruce Gentry]

konrad werzner wrote:
> I think they may have used this type of phonograph for the RBO speaker
> system:
> http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rt=nc&nma=true&item=330513646160&si=16iJvh3ru8NoeFno6zjp02Cqck8%253D&viewitem=&sspagename=STRK%3AMEWAX%3AIT
> This Navy phonograph has an actual "RBO" output jack if you look very
> closely in the photo.  This amp uses loctal tubes and uses a power
> transformer.  Price was a little high for my liking, though I may start
> looking for this one for our RBO system hookup.
>
> Konrad
>
> On Mon, Jan 17, 2011 at 3:19 PM, J. Forster <jfor at quik.com> wrote:
>
>   
>> Opinions please:
>>
>> The more I look at a 1 tube Morale Amp from the MASSACHUSETTS the more I
>> believe it was a modified cheap phonograph. The design is AC/DC with a
>> single 117N7 tube; input and output transformers, and very little else.
>> The purpose was to amplify audio from a 600 Ohm bus to drive a small
>> speaker in the officers' staterooms. The buses were driven by RBOs in
>> Radio 2.
>>
>> I suspect some of the crew went into Boston to Radio Shack and bought a
>> few record players. This would have been in 1941-42.
>>
>> A cheap phonograph could have had a high output, crystal cartridge and a
>> simple, very low parts count amp, probably built on an "L" shaped plated
>> steel chassis.
>>
>> The crew would have bought a couple, pulled the chassis and speaker and
>> added the input transformer and possibly changed the volume control.
>>
>> Does this seem plausible?
>>
>> Best,
>>
>> -John
>>
>> =============
>>
>>
>>
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>   
I had one of these when I was in high school 40+years ago, I got it from 
the audio-visual service via very aggressive dumpster diving.  There 
were several companies making this sort of phonograph, both military and 
commercial.  This model was unique in that  the turntable drive  had 
both a conventional speed change for 33 or 78, but also a mechanical 
governor to allow the selected speed to be varied within a range. This 
was to allow use on 50 or 60 cycles.  The sound quality was  restricted 
frequency range and fairly low distortion,  in keeping with some 
self-serving customer research done by RCA in the late 1930's. It was 
not high fidelity by any means, but could be pleasing in the right 
setting and context. It is quite interesting to see packets of actual 
surplus steel needles included with it. I changed the tonearm 
counterweighting in mine and installed  a newer cartridge with a 
sapphire needle. It sounded surprising good playing acoustic and early 
electric 78s.