[BC] Re: 317 and MW-50

[Xmitters@aol.com]

In a message dated 1/2/06 5:09:48 PM Central Standard Time, 
broadcast-request at radiolists.net writes:

<< That said, the 317 always sounded a little cleaner, but comparatively
 less loud than the MW50, driven by the same chain.  I always assumed it
 was slightly higher IMD and distortion from poor high freq. negative
 carrier pinchoff in the 50 that contributed to the very slight apparent
 loudness increase ('filling in the holes'). >>

To be totally correct, the envelope, and not the carrier pinches off at the 
negative modulation trough. Vector sum of the carrier and the two sidebands is 
zero at that instant.

IMD was an issue with our 317C-3 as well. We usually had to swap PA tubes 
around and tune up again to see which tube worked the best in which position. A 
good friend of mine can hear the difference between the 317 and MW50 with the 
317 sounding "warmer". I often wondered what the PA screen audio coupling 
transformer did to performance regarding overshoots and distortion from the iron in 
general. There was a nice audio feedback loop that worked very well that 
probably killed most of it, but I often wondered what exactly that transformer was 
doing to the audio and the effect on loudness. At the time I was in Chicago, 
of the 50 kW stations almost everyone was using the 317 so engineering got 
little pressure from programming about loudness. I think WJJD had their DX-50 
sometime in the mid 90's when I was in that market. anyone remember?

Jeff Glass, BSEE CSRE
Chief Engineer
WNIU WNIJ