Hi, due to the age the best thing would be to change all the capacitors. For some people switching from 220v to 240v or vice versa helped but that is not a permanent solution. Please check if it is safe to change the voltage in your area. In Austria we have 230v so both 220v and 240v work fine.

Disconnect the transformer secondary to see if the humming is caused by a load or the transformer itself.

Martin 

Waiting for a rainy day to work on the capacitors I (belonging to "some people") now followed your advice and switched to (temporarely ) 240V:
The result is that I am now all the more gratefull for having these new hearing aid devices: impeccable full power on the treble and no disturbing hum; 
how long may I stay in the "not a permanent solution"? Because I am also in the process of trying to get some other B&O appliances in fully working order, which is difficult enough..

Thanks anyway,

Aad

Waiting for a rainy day to work on the capacitors I (belonging to "some people") now followed your advice and switched to (temporarely ) 240V:
The result is that I am now all the more gratefull for having these new hearing aid devices: impeccable full power on the treble and no disturbing hum; 
how long may I stay in the "not a permanent solution"? Because I am also in the process of trying to get some other B&O appliances in fully working order, which is difficult enough..

Thanks anyway,

Aad

Switching to 240V turns out not to be the ultimate solution: the humming is back ;I spoke too soon; I will test the transformer later after having disconnected the secondary.

Aad

Aad Jansse wrote:

I got a pair of hearing aid devices the other day, which gives me access to the higher frequencies in  surrounding sounds. It is only too bad that these things also amplifies the nasty sound that the BM1200's transformer produces. It was not a disturbing thing before.

Apart from taking away these devices from my ears (I appreciate the improved sound reproduction through the speakers very much) what could be done to eliminate this humming?.

I'm slightly confused by your description of the problem.
You're talking about the improved high frequency range that these hearing aids offer, suggesting that this "hum" is in the higher frequencies. On the other hand a classic mains hum in Europe should be at 100Hz, i.e. that's at the other end of the spectrum common hearing aids can "hear". (When my mom got hers I looked into technical details and it seems that even the top of the crop devices only have a frequency range of 80-8000Hz.)

To come to the point, I guess my question is: is it a physical noise coming from the transformer or is it induced noise that is coming from the speakers - and then of course, is it high or low frequency?

I'm interested in your post and progress because I have a similar problem on my BM1000. I haven't gotten around to pin it down yet but in my case it is a physical noise coming from the power supply or transformer and it only starts approx. 30seconds after switching on. I think it has to do with the current drawn from the transformer because when I disconnect the speakers the hum doesn't appear, well at least not so annoyingly prominent.
In my case I'm guessing it has to do with leaky old capacitors that put some strain on the power supply, but I haven't gotten around to recapping...let's hope that corona is around for a while longer, so that I can find the time...

I will come back to this topic later, I will be outdoor during this weekend.

As to the “hum” or whatever I may call it, it is definitely straight from the transformer during load, therefore I will follow up on Martin’s suggestion when I am back home.

As to the hearing aid devices I can only add to my description of the improved sound sensation without going into details of frequency ranges, that any sound from mechanical switches, human voices, cracking nutshells, turning paper pages, etc. are now audible on a much more transparent level.

Aad