Need help with Cambridge Audio 550A
Greetings,
I am new to the forum and would appreciate some input from fellow music lovers.
A few years back, my CD player took a dump and I decided it was time to step up a bit in quality. My receiver was over 30 years old (Realistic STA-64) and was a bit noisy. On power up you can hear what sounds like a 60hz transformer hum and as the volume is turned up there is plenty of background hiss. The volume pot was getting scratchy as well. Time to move on.
I did a bit of research and settled on a matched set of Cambridge Audio 640A amp and 640C cd player. I unboxed and carefully installed the equipment. Pop in a CD, hit play. I was completely disappointed in the sound. The sound stage was all messed up. Detail was lacking. And, what happened to the bass? After a bit of pondering, I tried reversing one of the speaker wires. BINGO!!!. Wow! What sound! What detail! I’ve never been a fan of CD based music. It just seemed sterile and lacking detail (yet oh so quiet). I’d never really heard any CD music on decent gear and just assumed there was just too little sampling being done for CD’s to have any real fidelity. I was now officially blown away.
I was still bothered about spending so much on an amplifier (I know it’s relative) and having a polarity issue like this. What about resale if I tried to sell it later? I talked to the folks at Audio Advisor and they sent me a new 640A. Same problem. Reverse polarity on one speaker output to get good sound. They tested my return unit and said nothing was wrong with it. I had over a decade of experience as a computer network engineer and was pretty handy with cables in general. I tested everything on my end. The only fix was reversing the polarity of one speaker. I sent the replacement amp back and just plugged my trusty STA-64 to the 640C (topped off with Paradigm Atom speakers). Despite the hum and hiss, it still sounded light years better than any previous stereo system I have owned.
In retrospect, I should have just kept the 640A, reversed the cable and be done with it. I did a google search at the time and found two references with links regarding a reverse polarity issue with the 640A. Both links were dead. Now, even the google references to this issue are gone.
Fast forward to the present day…
Audio Advisor upgraded their components to the 650 series. I patiently waited for the 650A to go on sale, but no joy. They finally put the lower wattage 550A on sale, so I pulled the trigger. I read a couple of reviews and it looks to be a fine replacement. After arrival, I carefully cabled up and hit the power button. I fired up Spock’s Beard “Day for Night” (being a Prog lover) Alas, disappointment. The whole thing just sounds mediocre and messed up. The treble and bass are both weak, with lack of detail. The whole sound stage sounds jumbled and compressed. The specs on this should crush my STA-64, but it just sounds so lousy. I tested all the cables and verified polarity of all connections. Nothing. On a hunch, I tried reversing polarity of one speaker. Still sounds like crap. I tried switching right and left channels from CD to amp. Crap. I just don’t get it .
I put the STA-64 back in line and it sounds great (ignoring the hum and hiss). I can’t believe that 3 different amps from Cambridge would all have similar sound problems, but I have quadruple checked my cables and nothing seems wrong on my end. The bad variable is always the Cambridge amp. If my STA-64 ever dies (35 years and counting), I’m toast. I have approval from Audio Advisor to return the 550A, but I would really prefer to solve this problem and keep the amp. I would appreciate any sincere input provided from the group.
Thank you in advance. TR