Power Amplifier Reviews

Legacy Audio Powerbloc2 and Powerbloc4 Amplifiers Review Test Bench

Test Bench

PowerBloc2

617legacyamps.meas.jpg

This graph shows the Powerbloc2’s left amplifier channel (green), with two channels driving 8-ohm loads. Measurements for THD+noise, crosstalk, signal-to-noise ratio, and analog/digital frequency response were all within expected performance parameters.

0.1% THD 1.0% THD
Two Channels Continuously Driven, 8-Ohm Loads 310.3 watts 367.1 watts
Two Channels Continuously Driven, 4-Ohm Loads 598.8 watts 714.6 watts

PowerBloc4

This graph shows the Powerbloc4’s amplifier channel 1 (red), with channels 1&3 driving 8-ohm loads. Measurements for THD+noise, crosstalk, signal-to-noise ratio, and analog/digital frequency response were all within expected performance parameters.—MJP

0.1% THD 1.0% THD
Channels 1 & 3 Continuously Driven, 8-Ohm Loads 309.6 watts 364.1 watts
Channels 1 & 3 Continuously Driven, 4-Ohm Loads 599.9 watts 709.4 watts
Channels 1 & 2 Continuously Driven, 8-Ohm Loads 363.6 watts 427.0 watts
Channels 1 & 2 Continuously Driven, 4-Ohm Loads 370.6 watts 430.5 watts
Four Channels Continuously Driven, 8-Ohm Loads 307.8 watts 362.8 watts

COMPANY INFO
Legacy Audio
(800) 283-4644
legacyaudio.com
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COMMENTS
sysdawg's picture
Submitted by sysdawg on July 20, 2019 - 1:42pm

Other amp reviews in a similar timeframe that include bench testing also include THD, SNR, crosstalk etc numbers. It would be great to see those for the Legacy Audio Powerbloc2 and Powerbloc4.

dmusoke's picture
Submitted by dmusoke on September 5, 2019 - 2:37pm

MJP, thanks for the nice review ... but a few things are off or odd.

1. The distortion specs you measured, though respectable, are 10x -20x higher than legacy specs. The spec 0.005% THD at rated output (325W) but you measured 0.1%, a 20x increase from their spec and yet this was never mentioned.

2. The measured output power at their rated distortion does not measure up to Legacy's specs.

3. Where are the SNR, Xtalk, IMD numbers?

hk2000's picture
Submitted by hk2000 on June 12, 2020 - 11:25pm

Parasound uses the same class D modules in their ZM 2350 amp and their specs match these measurements. Legacy must've done something to skew their results!

hk2000's picture
Submitted by hk2000 on June 1, 2020 - 7:13pm

While others are complaining about the extent of the measurements, I'm surprised and slightly relieved to see any measurements at all. It's been a while since S&V published any measurements. I hope you maker this the rule, and not the exception.

hk2000's picture
Submitted by hk2000 on June 1, 2020 - 7:15pm

This is a lot older than I thought!

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