Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion Meridian - Systems Need help with Meridian 557

Hi all.

A while ago I bought an used Meridian 557 which was in mint condition. I live in Spain but got the amp from a seller in the UK, who assured that the amp was less than one year old. As the serial number began with #300 I knew that the amp was not very old.
I had previously auditioned another 557 driving N804s. Loved the sound of that combo and supposed that the amp will surely make a good combination with 805s as well.

But since I got the amp have been very busy and never had enough time to listen to it carefully.
Two months ago I began to listen my kit (M588 + M502 + M557 driving Nautiluses 805s) and realized that something was wrong.
There's no noise, distortion or any other sign that indicates that the amp could be malfunctioning, but there is an EXTREME lack of mid frequency impact and high frequency extension and definition when I drive the 805s with the 557. I have other amps and speakers and even a modest NAD 320BEE drives the 805s with more gusto. I have also tried the 557 with Dynaudio Contours 1.4 and Special 25 with similar results. I've used several types and brands of interconnects and speaker cables with no luck. I even borrowed some mains cables from my dealer. IMHO the problem is not there.
And I have also tried another pre-amps to see if the problem could be in the 502.

So I began to think about whether the problem could be in the mains. My unit is a UK one, which is prepared for 240v. The mains voltage here is 220v.
Could this small voltage difference cause such an annoying roll off of high frequencies? Does anyone know if a 240v 557 could be set up for 220v?

At this point I am really lost. I really love the amp looks and build quality, but will have to buy a new amp if I cannot discover where the problem could be.

Any help will be greatly appreciated.

Best,
Rodelius

I take it that you have definitely eliminated all other components by swapping equipment around and that you think the 557 is suspect? If so, ensure that you're not running bridged mode which gives the right channel a thin echoey sound.
I have the same Meridian setup and have occasional problems with the 557 somehow setting itself into bridged mode (I think) - (I use a subwoofer wired into the 557 which I think sometimes causes this strange effect). In my case the 557 'resets' itself when it 'trips' through its protection system (eg if I pull an input cable on the 502) and I then switch it off and on again. In my case, the sub and 557 are interacting strangely but give the effect that you describe - trouble is that it's very intermittent - although permanently disconnectig the sub seems to cure it all. I doubt that it's a main voltage problem - the UK supply can drop to around 220v at times. Try emailing Meridian tech support - they're quite good with replies - although in my case they suggested that I return the 557 to them for a healthcheck.