BT Mains Conditioning Filters

BT MCU-250 Mains ConditionerBT

Mains Conditioners have always been one of those products that I have stayed away from mainly due to cost and sceptism. Mains Conditioners have become more popular in recent years particularly in the Audio Visual market which makes sense when you think of the increase of people buying expensive large plasma and LCD televisions. If you are going to spend £2500 on a brand new HD television then the last thing you want is a mains surge damaging the set and the smooth clean power supply on offer should improve picture quality.

Isotek have recently released their £150 Mira Mains Conditioner that features two filtered mains outlet, and lalthough a worthy product, I thought there must be something cheaper on the market that offers similar performance. A quick search on Ebay brought up several BT mains conditioners that come in a plain grey case and are usually used by BT when installing telephone systems to filter out spikes and clean the mains supply. This got me thinking if BT are installing these as standard then our mains supply in this country cannot be that good at all.

So I ordered one of these units, a MCU-250 that offers a 1 amp load which I intended to use with my Quad 405 II amplifier and Quad 99CDPII set up - total outlay on Ebay £19.99! The first thing you notice about the BT mains conditioner is the weight - it's extremely heavy due to the large transformer inside which I guess is operating as some kind of isolation transformer and then there are a couple of very large blue capacitors which I assume filter and smooth the supply to the 240V AC outlets.

With the mains conditioner plugged in, there was a noticably difference and improvement to the sound quality. The first thing to note was a more accurate open performance of the music being played and on a typically well recorded CD such as Diana Krall's latest Best of, there was clearly more studio echo and air in her vocal performances and the piano notes seem to resonate and hang in the mix much longer. Deeper bass was now more evident and the sense of realism of the music had intensified. More so than ever the sytem had got closer to that "pin drop in the studio" level of reproduction. Overall I was truly impressed how cleaner and more musical the sound quality had become.

Given that the unit had cost only £20, the upgrade in performance was significant and one far greater than the initial outlay. I can honestly say this unit is truly "Hi-Fi", it is just a shame that it does not have the necessary specs to filter the rest of my equipment, however given the price it wont be too long before I invest in a second one for my plasma screen and sky+. These boxes really do work and given their minimal price on Ebay at the moment are worth every penny to someone wanting a serious cost effective upgrade.

This entry was posted on Friday November 16th, 2007 at 2:37 PM and is filed under Tweaks. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response.

11 Responses to BT Mains Conditioning Filters

Gerald king Says:
January 5th, 2008 at 6:51 PM

I am very interesed in this article. Can you tell me more about inexpensive solutions to better reproduction by cleaning up the mains. Where can I purchase the mains conditioning filter refered to in your entry?

Many thanks in anticipation


Brian bateman Says:
October 30th, 2008 at 12:06 PM

Hi Gerald, Did you manage to get one of the above units. If not and you would like one I have a brand new one available. Kindest Regards. Brian

Mark welsh Says:
November 20th, 2008 at 12:22 AM

Hi Brian:
I'd very much like one! Actually a few for friends, too . . . I can be contacted at

Kris Says:
December 14th, 2008 at 5:50 PM

hi, I have always been on the lookout for a cheap alternative to a good quality mains conditioner - do you know where I could get hold of one also? Many thanks.

Oz Says:
April 15th, 2009 at 4:02 PM

Hi guys and girls. I have 2 of these units id like to sell. Mail me if interested

Alan daniel Says:
April 20th, 2009 at 5:06 AM

Hi Oz, please contact me me if you still have the BT mains filters, I would like to buy them. Thanks. Alan.

Jason Says:
May 14th, 2009 at 8:49 AM

If anyone has a unit with 2 or more sockets for sale, i would be interested in it.


Nat Says:
August 18th, 2010 at 6:09 AM

Odd that people are asking where the author obtained the mains filters...

He states clearly that he searched ebay for them! If you search, you find.

Paul martin Says:
September 20th, 2010 at 11:54 AM

I purchased one of these from it was spot on. I know they do have the 2 and 4 port units available.


Anonymouse Says:
June 5th, 2011 at 8:52 PM

Check this one out too:

Tacima CS929 6 Way Mains Conditioner

£25 delivered on ebay at the time of writing.

5 star rating from what hi-fi.

Emma Says:
June 16th, 2011 at 6:24 PM

Hi guys,

We do 1, 2 and 4 port mains conditioners. 2 ports are £30 + Vat and delivered next day for 7.50. :-)

Paul, I see you have had one already. :-)

Leave a Reply


Subscribe to RSS feed