ESU 5XL Sound Decoder Install - Motor Hum Noise


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Yes, auto cal... notice you say the loKProgrammer settings are fine, but the motor still buzzes... So if it was me, I would try the auto cal, in case it does better, I really don't see how you can assume the stock settings are the best... and how you can be sure they have nothing to do with the buzzing.

Again, turning BEMF off stops the buzzing, right? Auto cal affects BEMF settings, right? Your statement says they have nothing to do with each other.

I did make a recommendation on PWM frequency, something ultrasonic... which is normally defined as over 20 or 21 KHz....

I don't know what the decoder can do but I can give you a recommendation that is normally the most quiet for any motor... maybe not the best performance for all motors.

on the supressor circuitry, I have never found it inside the motor.

Greg - Appreciate your knowledge and advice......very helpful. I found in the ESU LokSound 5 Instruction Manual the following guidance: "In the LokSound decoders load control works with 40kHz normally. Sometimes it can be useful to reduce this frequency by half for motors with little power due to high inductivity, or if suppressors (e.g., capacitors, chokes, etc) disturb load control but cannot be removed."


G Scale, 7/8th's, Electronics
5 Jun 2013
Tamworth, Staffs.
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To answer the question about suppression components within the case of the classic LGB / Buhler motors:
There are no such components fitted..
As Greg says, it is very unusual, for such components to be fitted inside the casing of a motor.

The only LGB model I have ever seen with suppression components fitted to the motor, is the earliest versions of the E10.
This had a nasty, horrible (my opinion) motor mounted vertically within the loco. - I believe a different motor was fitted to later models, but am not able to confirm this.


Greg Elmassian

8 Mar 2014
San Diego
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Tom, glad there is some sensible material in that manual, I was getting worried about the 16k recommendation.

I have not had any problems with highly inductive motors like USAT, but I have had BEMF overload with some pittman double lead gearboxes, and really weird results with BEMF and Bachmann locos with caps and inductors on the motors.

That's what I have found out in the short 20 years I have been doing this, still learning every day.



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Hi Tom,

With regard to Massoth's BEMF PWM frequency. Massoth recommends 16 kHz because of the four options their XLS decoders have, 60 Hz, 250Hz, 2 kHz, or 16 kHz, it is by far the best choice for LGB motors. To quote the Massoth manual "Basically the motor runs quieter and smoother when the control frequency is increased." This does not necessarily mean 16 kHz is the optimum PWM frequency, If the Massoth decoders offered 40 kHz as a PWM frequency my guess is they would recommend it over 16 kHz but perhaps not.

The following is quoted from the ESU V5 decoder manual:
"11.3. Adapting Load Control Frequency
In the LokSound decoders load control works with 40 kHz normally. Sometimes it can be useful to reduce this frequency by half: For motors with little power due to high inductivity. If suppressors (such as capacitors, chokes, etc.) disturb load control but cannot be removed (e.g. some older Gützold® locos). The PWM frequency can be set in CV 9 as a multiple of 1000 Hz. The range of 10 to 50 allows frequencies from 10 kHz to 50 kHz."

By the way, I've looked at the motors of many LGB locos in the course of adding decoders/maintaining my fleet dating from early 1980 Stainz to current MLGB production. I can't recall ever seeing noise suppression caps or chokes on the motors. That's not to say they may not exist within the motor shell itself but that would be unusual. I admit that I've never pulled apart one of the Beuhler motors so don't know. Perhaps others can chime in with their experience.
Hi Phils2um - I just now saw your response and you'll see I quoted the same section from the LokSound 5 manual in my last posting. The Rugen locomotive operates well and the Loco's owner and I are going to live with the slight buzz noise for now using the Load Control/EMF settings ON. It would have been interesting if I had tested a Massoth XLS sound decoder in the locomotive to see if it had the same buzz sound or not. In fact, since Massoth used to be the original LGB company's electronics partner, I might contact Massoth to see if they recommend any special motor settings for these unique motors. Or, maybe better, I might contact the Buhler company in Germany about the buzz issue and see what they might recommend.