It does indeed. The secret of this sound is 4 poles in DC motor. There are 2 parts of the motor that make sound: rotor and stator. In older DC motors there were 4 poles www.electronics-tutorials.ws/wp-content/uploads/2013/08/io31.gif, thus stator pulled and repelled rotor coils x number of times, while rotor was pushing and attracting itself 2x number of times at given rpm. 2x frequency difference is an octave apart pitch, notice low and high hum simultaneously here kzfaq.info/get/bejne/n7VkrJN2z5iddGw.html another good DC motor acceleration kzfaq.info/get/bejne/bZuPp69j0L23n5c.html With 3 phase AC motors 3 phase stator has 6 coils qph.fs.quoracdn.net/main-qimg-79cb962d35d28849446c2fb11821a2ef-lq, while central magnet remains 2-sided, north and south. Thus the same magnet has to repell and attract itself to stator 3x times, while stator still pushes and pulls rotor magnet x number of times. 3x frequency difference makes this "out of sync" perfect fifth dissonance upload.wikimedia.org/wikipedia/commons/transcoded/5/5c/Just_perfect_fifth_on_C.mid/Just_perfect_fifth_on_C.mid.ogg but when it is stationary it sounds fine but when these 2 pitches slide - it sounds awful. Thus I like more the 4-pole DC motor sounds like this once PWM inverter fades at about 20mph. To be honest for the sake of comfort for ears I would go with 4 phase motors, not only hearing pleasure but practical efficiency too: one wire can carry 2 phases provided they are 180 degrees apart. With three phases there is no 180* pair, so 3 wires needed. With 4 phases there are 2 pairs of phases 180* apart, so only 2 wires needed, each being 90* displacement. If I had more money I would love to experiment with this idea and check if my theory of 2 phases per wire works, trying to custom-build 4-phase motor running off 2-phase generator. 4-phase AC motor would sound very similar to this DC motor.

For the motor sound but not with the choppers which sounds like the MI 79/84.

From memory I believe the `plastic pig' Wessex Electrics Class 442 have been retrofitted with electronic motor control. I was amazed that they didn't have electronic motor control from day one seeing as they were quite modern units (they spun their driving wheels like mad on a wet rail). From Wikipedia on BR Class 442 (I had to take a look!) :- `SWR awarded Kiepe Electric a contract to undertake the £45m refurbishment. Work will include replacing the life-expired DC traction equipment (which was salvaged from older trains built during the 1960s) with an AC package incorporating IGBT technology from Kiepe Electric Düsseldorf. New brake controls from Knorr-Bremse Rail Vehicle Systems will permit regenerative braking.' I assume the old EE motors have been replaced, I'm not sure.

yes, GTOs! the same components that ended up in those delightful 3 phase ac traction units. the ones that sound like they're changing gears

Aren't they a bit slow for that route?

that route is operated by sprinter and pacers they can only do 75mph were as the 319s can do between 90-100mph depends on the line speed plus these are a 4 car set wich will put an end to overcrowding ,well that's what northern rail are saying but ,we'll see.

***** Class 325s had DC PWMs as well

class 325's are mechanically identical to 319's

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A lot of DC PWM trains that I have been on don't use PWM when on 50% power after exceeding the inrush stage. Although I don't know about this train. I can't hear the PWM above the other sounds when it gets going. The french VAL automated metro system doesn't use PWM to reduce power when it reaches its speed. The PWM sound doesn't come back on. Instead it appears to go back to the old way of grouping motors in 2s and switching them between series and parallel. On the VAL you can feel it jerking between 50% and 100% power to maintain the speed rather than using PWM to set the correct amount of power. As for AC PWM. On the older AC PWM trains which use a pattern to produce the wave (rather than pulsing continuously like on new trains). These can't use the pulsing to change the power as they are set to a certain pattern. And again the old series parallel method is used. I love the way the older AC PWM trains change the pattern to remove pulses as they speed up to stop the total pulse rate exceeding the transistors limit. It makes such an awesome sound.

Yeah because they're operating on AC overhead lines and not DC third rail like in this video. They sounded exactly the same as Northern's ones currently do north of City Thameslink/Farringdon. The 769s GWR will use on the 3rd rail section of their route will sound like this, and in diesel mode if you sit in the MSO it will sound like this too, because the traction motors are not powered by AC current collected by the pantograph. The 769s will sound like the Northern 319s when they're powered by the overhead cables.

@@lukeyboi2302 That's not what I meant by that, there were no audible motor sounds on the first few I went on when I posted that comment. The first time I went on one I had the understanding the layout was the same underneath as most other EMU's with traction motors and control gear being under the end two coaches (the same as 323's) whereas they are actually under the pantograph which I thought at the time was a PTS or PTSL, after finding out the real layout I managed to get a ride on one from Piccadilly to Eccles and it sounded way better from the start. I even got another later on the same day when I was trying to get one of the elusive Perkins 158's.

@@FM60260 Oh you made the same mistake I did back in the days, sat in the DTSO of a FCC 319 thinking it would be loud and was in for an extreme disappointment! The 769s do sound good in the DTSOs now though with their new MAN engines!

the 3000 and 4000 (and 2000) are soooo lovely, also they use the chopper when they brake, I think the 319s can't do that isn't it?

First Capital connect was the worst train operator ever. Trains were delayed, jam packed and they didn’t care about their passengers, Govia is crap as well but not as crap as First Capital connect

Motor's magnet. In fact there are 6 of them: 2 stator magnets, likely 4 rotor magnets. Stator magnet has to repell/attract rotor's magnet 4 times per turn while each rotor magnet attracts/repels stator twice per motor's rotation. Thus sound frequencies of two different sets of magnets are octave apart, what you hear is two pitches actually rising parallel in octave as magnets are soft iron so traction pull causes deformation in them (like a guitar string), except unlike musical instrument here it goes in hand with speed of motor rotation. If you know what octave is in music you can clearly hear those octave-apart pitches on 0:31 when small rotor solenoid magnet deforms enough to be audible. Here in older version of TGV rotor has 6 solenoid magnets, while stator always 2, thus 3x pitch difference, giving P13th or fifth across the octave pitch interval (the way modern 3 phase motors sound, just louder)...so ugly sound in my opinion kzfaq.info/get/bejne/p8h7eMh539ump5c.html Here's my facebook post about this facebook.com/anton.dyak/posts/501189446968142

@@masteristscalerailroadmodels you hear that sound at 48 seconds ..idk but I always hear it at around 45mph on these units.

Well I hat new Heard this morning all the 319s will be going to Northern and the new 387s will be going to first great western and gatwick express, also some of the 365 are going to FGW aswell, I've been doing some resherch this morning so let's see what happens because they always change there mind. The first great western ain't even being electrified yet and the class 800/1s are already at Southampton docks!

+Train spotter UK Just learnt that Northern has lost the contract, and they currently run 321/322's on the Doncaster-Leeds line. I believe Arriva will be taking over from April 2016, so I wonder if they'll replace them, add 319's or something entirely different on the electric routes. I've also heard that the 321's are being upgraded with new motors/drive gear, so guessing we'll lose this great sound one way or another :(

Don't worry errbody the motors are the same

That is Siemens EuroStar (Taurus) which sounds pretty nice when running

+MrOpenGL That is like the RER double deck trains in Paris. Transistors can not switch too fast. When they switch beyond a certain speed then some of the power will dissipate in the transistor. Transistors are not designed to dissipate power, they are meant to do a clean switch from off to on with no half way stage. The way that DC PWM is meant to work is that the frequency of the switching is meant to stay the same at any percentage of power. A lecturer at uni actually told everyone this incorrectly when programming arduinos. he said to change the voltage of an output you should turned on for 10ms and vary the amount of time it is switched off. Doing it this way is not good practice as this is effectively changing the frequency. With trains I have never come across DC PWM where it does strange things with the frequency. The frequency is always constant, unlike AC PWM where to generate the motor frequency they often crazy things with the switching patterns being used. With DC PWM using a fixed frequency there is a problem that when above 90% power and below 10% power the turn on and turn off are too close together. So when the Paris RER first starts its power must be below 10%. To stop power being dissipated by having 2 switching too close together (switching off as soon as it switches on) they reduce the frequency. In the UK the switching is only used to start the train. It goes back to series and parallel modes to control the motor voltage when the driver changes the amount of throttle when moving at speed. On the belgium coast tram the DC PWM is used for both startup and throttle control. This makes the tram very noisy. The only time it is not switching is when it is either coasting or is at 100% throttle when above 30 mph.

***** Thanks for your exhaustive answer! The E632 is a Full Chopper loco, so it uses PWM at all times to control the speed like the Belgian tram. We had also a prototypically modified E444 (traditional rheostatic locomotive) where instead of gradually excluding the rheostat with mechanical contactors, it short circuited it using some thyristors. It was known as "shunt chopper" and offered great speed control but at a lower price than full chopper. It never took off and the loco was scrapped soon.

+MrOpenGL I have never heard of this system. I am wiring up a lift for my garden shed. It is a converted stairlift. It has a DC motor with separate windings for the main winding and the core. I was wondering if I should pluse both or just one. I will probably use a mosfet addon for arduino.

+Beno Shunt chopper was mostly a failure :D that's why it is not famous. You should leave the field windings connected permanently, and pulse only the rotor windings.

​@@benoliftsthis RER one (Z 20500) sounds closely with 200/300/600 Hz on it. And this uses asynchronous motors because it's a 1988 one.

Peter Downey class 456 doesn't have PWM. I seem to remember reading somewhere that they have recycled motors from 1930s slam doors.

+Beno Are you sure? They sound almost identical, but they sound slightly muffled compared to the 319's, but as far as I know they have 2 less motors.

+deafyboy86 But the 456 doesn't have any PWM sound. They sound very different. We are talking about the same train? The little 2 car trains that are a rebuild of slam door SUB. They have slam door motor sound and vintage westinghouse compressors.

***** That is indeed what I'm on about, they serve my local station. They do indeed sound very similar, the motor sound is not all that different, they whine the same on setting off, it just sounds slightly quieter, almost muffled in a way, but the sound is definitely there.

deafyboy86 I think it's the 455 with motors recycled from 1930s trains. That's why South West Trains plans to fit new motors to its 455 units.