General Asylum: REVIEW: American Power Conversion S15 Power Conditioner/Surge Protector by Ulas

Model:	S15
Category:	Power Conditioner/Surge Protector
Suggested Retail Price:	$1499
Description:	1500VA power conditioner with battery
Manufacturer URL:	American Power Conversion
Model Picture:	View

Review by Ulas ( A ) on September 24, 2006 at 09:15:36
IP Address: 65.19.17.44

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I live in a remote area and get my power from a rural electric coop. The upside is that I have no problems with EMI/RFI because there are no power polluters on the grid. The downside is frequent momentary dropouts and occasional, prolonged outages. The former is usually weather related and most annoying. With each dropout I hear a loud pop from the speakers, the preamp enters its 30-second power-on mute cycle, and the CD player reboots and waits for me to press play. I have a backup generator for outages but it takes several minutes for the generator to start-up, warm-up, and activate the transfer switch. I was hoping the S15 would let me sail through both kinds of interruptions with nary a glitch.
The S15 is described as a 1.5kVA power conditioner with battery backup and sine wave output. I canâ€™t vouch for the 1.5kVA claim because I was unable to plug all my components directly into the S15. The standard on-center spacing for a duplex wall socket is 1-1/2 inch and many heavy-duty power cords have 1-1/2 inch diameter plugs. The sockets on the S15 have 1-3/8 inch on-center spacing, which makes it impossible utilize the two high-current sockets intended for amps and sub-woofers unless the power cords have molded-on plugs.
The S15 uses the line-interactive UPS topology. As long as the input power is within the defined parameters, the input power is filtered and passed to the AC sockets. As soon as the input power goes too high or too low, the S15 switches to battery power until the input power returns to normal. Each time the S15 is powered-on it goes through a self-test cycle that includes momentarily switching to battery power. This is described in the userâ€™s manual and is standard operating procedure for most UPS devices.
Thatâ€™s the theory. In practice, the situation is not so nice. When I powered-on the S15, it started with its internal self-test, which included beeping, clicking, and flashing lights. Next, it powered-on most of the AC sockets and started the delay timers for the timed sockets. After all the sockets had power, the S15 switched to battery power to test the battery and inverter. As soon as it did that, my CD player rebooted. At the same time a rather loud fan in the S15 started buzzing. The fan runs whenever the S15 is on battery power. When the self-test was completed, the S15 switched back to utility power and my CD player rebooted, again. This happened every time I switched the S15 on and every time the utility power was interrupted. While the S15â€™s UPS operation eliminated the major pops, it didnâ€™t eliminate the interruptions to the music.
The line-interactive UPS topology is discussed in the APC White Paper #79. The advantages are lower cost and higher reliability. The disadvantage is a momentary glitch when the power is transferred to and from the battery. That is not a problem for computers and similar devices that use switch-mode power supplies. Such power supplies are designed to ride through interruptions as long as 18ms. The problem is, none of my audio equipment uses switch-mode power supplies and however long it took the S15 to switch to and from battery power was long enough for my CD player to shut down and restart.
When on battery power, the S15 didnâ€™t produce a clean sine wave. When viewed with an oscilloscope, the output sine wave had large spikes just after the zero crossing on both the rising and falling slopes. This made the power transformers in the sub-woofer amplifiers buzz. This anomaly was observed whether or not anything was plugged into the S15.
All the S15 reviews Iâ€™ve read claimed significant improvement in sound due to the S15â€™s power conditioning and filtering. I heard no such change. As I said, I have no noticeable EMI/RFI contamination. My only power problems are some harmonic distortion and interruptions. The S15 didnâ€™t do anything to correct either one.
No doubt, the S15 I received was defective. Although APC would likely have been able to fix some of the problems I had with the unit, I doubt they would have been able to fix all of them: Notably the socket spacing and the power switching glitch. Because no audio retailer in my state carries high-end, APC AV products, the S15 was a special order arranged by the distributor and the retailer wouldnâ€™t take it back. After much discussion, APC agreed to take S15 back and gave me a real UPS of comparable value. Thank you APC!

In the exchange I received a SmartUPS RT 1500 with an extra battery pack. The unit uses the on-line UPS topology, which means it is always running on battery power. As long as the utility power is there, the battery is being constantly recharged as it is being drained. The result is constant 120VAC, 60Hz, sine wave power with absolutely no glitch when the utility power is interrupted.

Product Weakness: see review
Product Strengths: Appearance

Associated Equipment for this Review:
Amplifier:	Art Audio Jota monoblocks (20wpc)
Preamplifier (or None if Integrated):	Hovland HP-100
Sources (CDP/Turntable):	Sony CDP 707-ESD, DIY DAC, SME-30, SME IV-iV, Cardas Heart
Speakers:	Avantgarde Trio Omega (110dB)
Cables/Interconnects:	DIY
Music Used (Genre/Selections):	Classical, vocal, jazz, world
Type of Audition/Review:	Product Owner

Product Weakness:	see review
Product Strengths:	Appearance