B&W MM-1 speaker drivers buzz/distort at 50Hz!!? Help!

[mattc76]

Dear All,

I hope you can help with this annoying problem!

I purchased some 2nd hand MM-1 speakers "opened but not used" on ebay a while back to use with my Mac mini. Playing my itunes library through them they are great - no problems at all. The problem is I use Logic X for some amateur music production and I have noticed particularly on the kick drum that the right hand (powered) speaker "buzzes" with the kick. It sounds like a mechanical type buzz of something vibrating in the box. It DOES NOT occur with the slave speaker. Scanning up and down the frequencies with the EQ I tracked it down to the 50Hz band - if I roll it right off then the buzz disappears and frequencies below it can still be heard ok with no buzz. So my question is: do I have a faulty speaker driver or is it some other funny resonance-type affect with something in the box??!!

Your thoughts would be most appreciated!

Thanks,

Matt

 

[Thompsonuxb]

You actually found the frequency it 'buzzes at.... thats impressive.

iit could be the screws on the internal amp need tightening.

is 50khz loud?

 

[proffski]

You actually found the frequency it 'buzzes at.... thats impressive.

iit could be the screws on the internal amp need tightening.

is 50khz loud?

50kHz?

 

[Thompsonuxb]

50hz..... what is that? lower midrange?

these are desk top speakers right, - are you playing them loudly and do you use a sub with them?

if you can open them make sure its screwed together tightly.

 

[MajorFubar]

50hz..... what is that? lower midrange?

Think you need to gen-up on your understanding of audio frequncies lol. 50Hz is very low bass.

It's likely something is rattling inside the box,but it can be legion tracking it down. I once had a Wharfedale Diamond 2 which 'buzzed' at 75Hz. It was tiny blob of glue under the woofer's dustcap!

 

[mattc76]

Hmmm - think I might try and open it up and have a look. If not, where would be the best/cheapest place be to take it for someone to look at?

 

[AlmaataKZ]

It may be tricky opening them up - they seem to be glued.

http://www.soomal.com/doc/20100001990.htm

 

[AlmaataKZ]

Have you tried to use them with different gain structures? As far as i know they have dsp based equalisation eg for loudness compensation and i think it is dependent on vol level setting. So try using them at two extremes: high input level and low vol setting on mm1 vs low input setting and high vol setting on mm1. Try the middle as well and see if there is any difference - it may be too much bass lift somewhere. Failing that, send them to bw for repair. Being 50hz it is likely to be mains or grounging related.

 

[TrevC]

I think you discovered why they were on Ebay.

 

[proffski]

I think you discovered why they were on Ebay.

Or as I call it, ePrey these days. :shifty:

 

[mattc76]

I think you discovered why they were on Ebay.

Or as I call it, ePrey these days. :shifty:

Thanks for all the great tips! - I think I'll probably send them back to b&w and see what they think as I don't want to b*gger them up myself!

Thanks again!