Signature 650 PSU: Antec's Challenge

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These recordings were made as 24-bit / 88 kHz WAV files with a high resolution, lab quality, digital recording system inside SPCR's own anechoic chamber (11 dBA ambient), then converted to LAME 128kbps encoded MP3s. We've listened long and hard to ensure there is no audible degradation from the original WAV files to these MP3s. They represent a quick snapshot of what we heard during the review.

These recordings are intended to give you an idea of how the product sounds in actual use — one meter is a reasonable typical distance between a computer or computer component and your ear. The recording contains stretches of ambient noise that you can use to judge the relative loudness of the subject. Be aware that very quiet subjects may not be audible — if we couldn't hear it from one meter, chances are we couldn't record it either!

Each recording starts with 6~10 seconds of room ambient, followed by 10 seconds of the product's noise. For the most realistic results, set the volume so that the starting ambient level is just barely audible, then don't change the volume setting again while comparing all the sound files.

Sound Recordings of PSU Comparatives in the Anechoic Chamber

Older Recordings made with Sennheiser microphone in Live test room

Caution! It's important to understand that these recordings cannot be compared directly to the recordings made in the anechoic chamber. The live room in which they were made echoes and has a noise floor 4~8 dBA higher, the microphone has a much brighter sound quality and a different output level, and even the dBA measurements are wrong below ~25 dBA — they are higher by 2~8 dBA than they would be in the chamber with the new test gear. These recordings are here mostly for the record.
  • Enermax Modu82+ 625W at 20~150W output, 19 dBA@1m: One meter
  • Enermax Modu82+ 625W at 300W output, 22 dBA@1m: One meter
  • Seasonic S12 Energy Plus 550 at 0~150W, 20 dBA@1m: One meter,
  • Corsair TX650W at 250W, 21 dBA@1m: One meter
  • Corsair TX650W at 300W, 23 dBA@1m: One meter

Ambient acoustics of the anechoic chamber vs the live room - Some of you will be interested to hear this difference. The recording begins with 8 seconds in the anechoic chamber, then 8 seconds in the live room, followed by a few seconds in the anechoic chamber. The SPL levels, as mentioned before, were 11 dBA and 18 dBA respectively. It's interesting to note that the hiss many SPCR forum members attributed to electronic noise is, in fact, not so; it's part of the live ambient, due at least partly, to reflections at higher frequencies in the room. This is obviously absent in the chamber. (However, we did make a change to a new microphone which also has considerably less noise than what we were using before the anechoic chamber, so some of the hiss in past recordings was caused by microphone noise.)


The Antec Signature 650 performs better electrically in most areas than any other PSU that's been through the SPCR test bench. Voltage regulation, AC ripple, energy efficiency, power factor, cooling — not a single measured parameter was less than excellent. The build quality matches its electrical performance; we've never seen better. The technological advancements — such as the ingenuity of the physical / cooling design, the use of DC-to-DC conversion for the sub-12V lines, and PWM fan control — deserve to be lauded. This is no me-too product, but a declaration of innovation in a field rife with copycats.

Acoustic performance is also exceptional, at least up to 250W~300W load. The overall noise signature is good enough to rival the best of the best, as it could be quiet enough in some environments to be masked by either the natural ambient noise or the noise of other components in the PC. Beyond about 300W, however, the noise level rises quickly and its quality becomes less benign as the 80mm fan increases in pitch. For the silence lover, the trick is to keep the power demand below 300W or use the Signature 650 in a case with an isolated, independent PSU intake (like the P180 series, the Fusion and others, including systems that use a custom-made intake duct for the PSU). The latter option keeps heat from the rest of the components out of the PSU and pushes the fan ramp-up point to much higher power loads, making the internal cooling of the PSU the most significant factor in fan speed and noise. In such a setup, the high energy efficiency and the innovative cooling arrangement in the Signature should push the fan ramp-up point way up.

The Antec Signature 650 really is a statement, it's Antec's challenge to the overpopulated computer power supply world: Here's our best, go ahead and match that if you can. Whether the exacting performance lends any tangible benefits over a competitive product that's merely very good could be questioned, but there's no denying the engineering savvy and attractiveness of this power supply. This is just the beginning of Antec's partnership with Delta Electronics. We can all look forward to more interesting products in the future, and for some of this good technology to trickle down to more affordable levels. In the meanwhile, the $160 and $199 selling prices of these Signatures are looking pretty good after all.

Much thanks to Antec Inc. for this review sample.

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SPCR Articles of Related Interest:
Power Supply Fundamentals
Recommended Power Supplies
SPCR PSU Test Rig V.4
SilverStone DA700 power supply
Enermax Modu82+ 625W
Seasonic S12 Energy Plus 550 and 650
NesteQ ECS7001 700W PSU: A Modular Twist
Corsair HX520 & HX620
Zalman ZM1000-HP: Quiet KiloWatt PSU

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