PCM Y-6 and Link Recordings
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nw-modeling-list at nwhs.org
Thu Sep 21 10:00:34 EDT 2006
Some comments on the Y6b model sound taken from the PrecisionCraftModels website:
Y6b Sound Notes:
The PCM Y6b sounds were created using the best available sound recordings of the Y6b as a reference. These included recordings from the late Mobile Fidelity's Brad Miller and the Sounds of Steam Series. Since no Y6b is still running, we carefully listened to and digitally analyzed these actual recordings. However, since these recordings don't provide the level of isolation required, they could not be used directly in creating the sounds for the model.
Here is just one example of how these original recordings are used to provide prototypical sounds in our models. The sound of a whistle can change dramatically dependent on several factors including, steam temperature, steam pressure, atmospheric pressure, surrounding terrain, distance the listener is from the whistle, and the engineers ability to play the whistle. We have to take all this into consideration when choosing the prototypical whistle sound for our models. An N&W Hooter whistle used on the Y6s, Y5s, and Class As was digitally recorded at a whistle blow 280 psi steam manifold by our recording engineers using 24 bit digital recorders. When we listened to the original recordings of the Y6B whistle, we noticed a very slight change in the pitch from our new recordings. This can be caused from any of the previous reasons or that a Y6B operated at 300psi and the whistle was blown with superheated steam. In any case, we painstakingly matched the base frequencies and
harmonics of our new recordings to the originals. Similar steps are taken to match the sounds of air pumps, bells, injectors, and exhausts to provide the most prototypical sounds available today in a model.
There has been much discussion regarding the Y6B and its ability to switch between simple and compound modes. We spoke with many steam operation experts including Jack Wheelihan to get some answers on how best to configure our model's operation. Mr. Wheelihan fires for the UP steam program on #844 and #3985, the Southern Pacific Daylight #4449, and is the General Manager at Railway Equipment Associates Company. Mr. Wheelihan explained that when in simple mode, the Y6B had a tractive effort of 152,206 lbs and in compound mode it was 126,838 lbs. He says that, contrary to a popular conception, the Y6B most often started in compound mode because the added steam for simple mode required filling the large front cylinders with tremendous amount of high-pressure steam and that would reduce the operating efficiency of the locomotive. This compound mode operation resulted in the steam being exhausted at four times per driver revolution as the high pressure from the rear cylinders
was moved to the front cylinders before being sent through the stack. However, when the added tractive effort was required, the engine could use high-pressure steam in all four cylinders resulting in eight exhausts per revolution of the drivers. This simple mode operation usually lasted only for the first few miles per hour of the locomotive and then the locomotive was switched back to compound mode.
We have made this option available in the enhanced sound mode. By pressing F5, the simple mode startup is faithfully reproduced with steam cocks open and the locomotive giving all she has to move the train. This continues until the locomotive exceeds speed step 2.
Finally, there have been discussions as to why our Y6B model appears to get softer in volume at higher speeds instead of louder. As we rode in the cabs of steam engines accelerating and then roaring down the tracks, we recorded the engine's exhaust. We immediately noticed that as the chuffs got closer together, the distinctive "chuff chuff chuff" sound was replaced by a quieter wooshing sound as valves opened and closed too quickly for distinct chuffs to be heard. This makes our model sound very different form our competitors at high speeds. We believe that it is a more prototypical sound.
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