RickO, I listened, what was I suppose to hear and/or NOT hear? What I did hear is a secondary recording (of a moving device with natural Doppler) made in a non-sound studio then played through a 2-inch set of Mac speakers.
I am fortunate in that I lived through the last dozen years of steam engine operation in a town served by five class one RR’s, two of which were the countries’ largest. And there were a more than a dozen secondary road with hand-me-down steam. Personally witnessed 611, 1218, 4501, and 2716 Oh and the 0-4-0 that I drove. Have DVDs with sound of all Big Boys, many Pennys steam, sound track of UP 9000 series etc. And I still do not know what I missed! Now I never heard a BR18 so who knows.
The BR-18 was a four cylinder fixed frame compound engine. As such there would be four chuffs/rev and the secondary low-pressure cylinder exhaust of very energy depleted steam. This engine will not sound like the 765, 1225 or others I referenced above. In fact the long tapered stack would change the sound.
Now if we are talking of loudness, I never cease to be amused of members here that say they are Audiophiles and then evaluate these sounds based on “loudness.” True Audiophiles seeking Fidelity first look at THD, Response, etc.etc. Loudness is the very last criteria since loudness is a pure function of physics power vs. efficiency.
So pray tell what did I miss?