Power Amplifiers

Bel Canto S500 Stereo Power Amplifier

ARTICLE INDEX

The Sound

In order to give the S500 the fair shake it deserved, I used my trusty Radioshack analog dB meter and Elite 94 MACC test system pink noise generator to check speaker levels. Because I usually listen at 75 dB @ 2meters reference, I made sure output levels were at 75 db. Here is where things first got interesting. I found the S500 was consistently 1-2 dB louder @ 2 meters during the MACC test as registered on the dB meter and in the MACC test results when compared to my home system amp. I verified this by checking both the MACC test results and my dB meter. This difference is just enough to subconsciously skew your ear and possibly the listening test results. The appropriate level reduction was made to normalize the amp output. Now, since Bel Canto literature states that all amps are level matched to make balancing multi amp systems simpler, I suspect this is the way they all are configured.


Here is a list of my test system:

• UPS/Line conditioner: APC s15
• Preamp: Elite 94 Txi used only as preamp/processor. I also used Pioneer's MACC test system to set-up the preamp/amp/speaker combination. The setup was stored to memory and used during the appropriate listening session.
• Amp: Rotel 1090, 380 w/ch @ 8 ohms
• Interconnects and speaker wires: 75 Ohm coax and 10 gage OFC copper
• Speakers: Nautilus N804
• Source Material: Various CDs: Dallas Wind Symphony "Pomp and Pipes," Rod Stewart " The Great American Songbook," Pirates of the Caribbean Sound Track "track 16," HTPC lossless HDCD "Gibson Presents Hot Tones in High Definition," other miscellaneous acoustic CD tracks.

When the S500 was first delivered and inserted it into the system signal chain, it was in use continuously (100+ hours) for 3 weeks to give it time to settle in. It is a very quiet amp (very low noise threshold,) and its compact size and low weight made the added equipment install a breeze.

Daily casual listening of both stereo music and home theater began. Random blind switching between amps initially revealed no identifiable difference between my home stereo amp and the S500. I often listened for days without realizing to which amp I was listening. It wasn't until the formal listening samples began were any discernable differences found. The first check was with the "Pirates of the Caribbean" sound track: track 16. Track 16 contains a robust mix of symphonic instrumentation and hearty rhythms. Here the S500 showed its first identifiable characteristic. It sounded as if the S500 was ever so slightly leaving out details of the entire string and percussion sections when compared to my home system amp during the driving rhythm sections.

With listening levels at 75 dB @ 2 meters reference and 90 dB spl @ one meter speaker efficiency the S500 should have provided more than enough power to drive the speakers. Again and again I tried listening to the variety of sources listed above, finishing with the "Pomp and Pipes:" Track 1. Each check revealed the same almost imperceptible minute loss of midrange detail. However my reference amplifiers have almost twice the power which could make a difference in transients during loud passages. Also, switching amplifiers often tend to sound "dry", meaning extremely neutral with absolutely no character of their own. I simply may just be used to the sound of my Class A/B amplifiers and prefer their sound quality.

Remember, in casual stereo music and home theater listening, I could not specifically identify to which amp I was listening, my own or the S500. Overall the bass was solid, midrange clear, and highs crisp and well defined. I enjoyed the imaging, especially during Rod Stewart's vocals. The lossless HDCD guitar tracks were mesmerizing. It was if I was seated center, row seven. After continued listening I completely forgot about the equipment and just enjoyed the music.