On the MTH Electric Trains HO scale GE EP-2 electric bipolar locomotive with Proto-Sound, there is a sound effect that we are unable to identify. Specifically, there is a background, low-level, low frequency, rhythmic sound effect that is speed-sensitive (as the loco speed increases, the sound rhythm increases too), and present with the other system sounds when the master sound control is switched on. This sound vaguely resembles the low frequency rhythm of a diesel engine even though this is an electric loco. We jokingly refer to it as the backup diesel engine in this loco. Our research on this engine and the prototypical sounds have not identified the source of this sound, and we have contact MTH with no reply. Does anyone have an ID for this sound effect? Maybe the blowers or the air compressor?
I agree with your suggestion that it's related to the auxiliary equipment. Motor-driven blowers, compressors, etc. Or some background noise.
Electric motors make noises. That is an often ask about my electric moped. "Does it make any noise?".
Is that sound in addition to the whining of the electric motors? I have a bachmann GG1 that is missing exactly that sound….. while I understand the difficulties in recording the whining of the original, maybe a stand in could heve been found. As it would be like a diesel without the prime mover’s sound. This is an example of it (italian locomotive)
The Milwaukee motor didn't make gear noise or motor noise. It had no pinion or bull gear. They were very quiet. The engines rang a bell whenever they were moving because they were that quiet. In addition, they had no noise from 25 cycle alternating current like the GG-1.The only thing I can think of that made noise on the Milwaukee engine would be the equipment blowers. Randy
Apparently the Proto-Sound people think the traction motors made noise, because no auxiliary would be so dependent on speed.
On the Bipolar you would only hear compressor and any blowers. There obviously would be rail/wheel flange noises. I wish we could hear a recording of what you are describing. As a youngster, I got to see one of these machines pass by me, in Seattle. It was quite overwhelming to see such a monster slide quietly past... Meaning it scared me! It was running around the train, after arriving in Seattle. But these millions of years later, I could not tell you whether it was #15 or #16.
Excellent suggestion regarding samples of the sound. One to sample is the official product video on the MTH website. Note the video and audio is of low quality due to high compression. So, the sound is a little off. However, you can discern the rhythmic sound effect, which make the locos sound like top-loader washer machines. Click on the "Video" tab and skip to 2:55 min on the video: https://www.mthtrains.com/80-2140-1 Additionally, there are many recordings of the MTH HO Bipolar locos on youtube. Here's one with the loco standing still:
I am not certain what all that noise might be, but it sounds more like a diesel. Just sitting, as in the linked video, the possible sounds of a Bipolar would be the pantographs when air was applied or released. The pantograph shoe when raised would make a small sound when it slapped against the trolley. The air compressor would cycle (pantograph raised) just like any steamer or diesel. That would be it. Otherwise it would be quiet.
This sound is one of the best-hidden secrets of the MTH Proto-Sound 2 system. It is not heard when the loco is operating on a DC power pack, but it is definitely heard on DCC and with the new MTH Electric TrainMaster Command Control System.
Anyhow the Italian locomotive is also a 3KV DC, there is for sure some noise from the transmission but most of it comes from the motors themselves. The sound decoders here in Europe all have the motors’ sound.
Having seen an operating Bipolar up close, there was no motor sound. They had no brushes, nothing making any contact, such as a typical electric motor. Quite unique.
They had brushes, no gears though. Two large field poles, a large low speed armature and some massive brushes. After the brushes were seated I doubt they made any noise. The motors didn't turn very fast as there wasn't a gear ratio. On modern EMD locomotives it's roughly 4:1 on 62:15 gears. lots of brush noise on high speed motors. Randy
Exactly, what's all that racket? Seems like some of the accessory equipment in the loco is amplified too high in relation to what we expect to be louder equipment (such as the cooling blowers). Don't have access to a DCS system, but in DCC there does not appear to be any CVs that separate this mystery sound from the main electric motor whine (probably minimal motor winding whine, and no gear whine) and blower noise. The model's owner resorted to reducing the overall volume control to match the expected quieter operation. Does anyone have experience with other sound systems for model electric locos and how well they agree with the prototype?
I have a Bachmann sound value GG1 that i think is completely missing the motors’ whine… in any case it was cheaper than the DC model so i took it. The bipolar was really quite unique, did not think one could build a loco without gearing.
