This is a review and detailed measurements of the IOM 500 Hypex NCx500 class D based stereo amplifier. It was sent to me by the company and costs €1,099.00 ex VAT (US $1,199).
We have a more premium case for the class with good bit of weight. The amplifier comes with both fixed or variable gain. The latter is what I have for testing:
I like the hefty weight and solid feel of the gain selector but it is squeezed tight between binding posts, making it hard to turn. It has a wide range of 11 dB to 34 which is very convenient as far as matching to the source output voltage. I tested it at 11 and 16 dB as you see below.
IOM 500 Stereo Amplifier Measurements
I started with the lowest gain which matches the Hypex NCx500 reference design:
While performance is a few dBs short of reference, it is still excellent enough to land in the middle of the top 20 amplifiers ever tested:
Naturally there is some loss when you increase gain:
For some reason though, the differential in SINAD between channels increases as gain is increased. I played with the wiring but could not resolve this.
Using RCA output made things much worse:
So I stayed with balanced input for rest of the measurements:
Left side says you have full transparency at just 5 watts for 16 or even 17 bit content! And at full power, you have better dynamic range than any content you are likely to have.
Frequency response is load independent and excellent:
But for crosstalk, it is not as good as I expected:
Intermodulation distortion is kept very low:
Name of the game here is lots of power and indeed, that is what we get:
Allowing 1% THD, gets us even more:
I wanted to add low frequency power measurements using the same metric and noticed that only 50 Hz is supported in CEA-2006/490A so went with that for both max and peak power:
So you lose about 15%. Here is 8 ohm performance:
Sweeping at different frequencies, I see more noise at 20 and 500 Hz at lower levels:
Warm up showed variable response until it stabilized:
Finally, power on noise is kept in check but turning off, many create noise:
We see the same warm up effect in one channel even though the amplifier was warm when I ran this test.
Conclusions
The IOM 500s is built on the excellent "bones" of the Hypex NCx500 OEM amplifier modules and it shows. Addition of a selectable gain stage has boosted distortion and noise a bit which could use some refinement. But as is, I expect the amplifier to be very powerful to drive any speaker and do so with minimum of noise and distortion if you use XLR. RCA performance may not keep up.
I am going to recommend IOM 500 stereo class D amplifier.
----------
As always, questions, comments, recommendations, etc. are welcome.
Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
We have a more premium case for the class with good bit of weight. The amplifier comes with both fixed or variable gain. The latter is what I have for testing:
I like the hefty weight and solid feel of the gain selector but it is squeezed tight between binding posts, making it hard to turn. It has a wide range of 11 dB to 34 which is very convenient as far as matching to the source output voltage. I tested it at 11 and 16 dB as you see below.
IOM 500 Stereo Amplifier Measurements
I started with the lowest gain which matches the Hypex NCx500 reference design:
While performance is a few dBs short of reference, it is still excellent enough to land in the middle of the top 20 amplifiers ever tested:
Naturally there is some loss when you increase gain:
For some reason though, the differential in SINAD between channels increases as gain is increased. I played with the wiring but could not resolve this.
Using RCA output made things much worse:
So I stayed with balanced input for rest of the measurements:
Left side says you have full transparency at just 5 watts for 16 or even 17 bit content! And at full power, you have better dynamic range than any content you are likely to have.
Frequency response is load independent and excellent:
But for crosstalk, it is not as good as I expected:
Intermodulation distortion is kept very low:
Name of the game here is lots of power and indeed, that is what we get:
Allowing 1% THD, gets us even more:
I wanted to add low frequency power measurements using the same metric and noticed that only 50 Hz is supported in CEA-2006/490A so went with that for both max and peak power:
So you lose about 15%. Here is 8 ohm performance:
Sweeping at different frequencies, I see more noise at 20 and 500 Hz at lower levels:
Warm up showed variable response until it stabilized:
Finally, power on noise is kept in check but turning off, many create noise:
We see the same warm up effect in one channel even though the amplifier was warm when I ran this test.
Conclusions
The IOM 500s is built on the excellent "bones" of the Hypex NCx500 OEM amplifier modules and it shows. Addition of a selectable gain stage has boosted distortion and noise a bit which could use some refinement. But as is, I expect the amplifier to be very powerful to drive any speaker and do so with minimum of noise and distortion if you use XLR. RCA performance may not keep up.
I am going to recommend IOM 500 stereo class D amplifier.
----------
As always, questions, comments, recommendations, etc. are welcome.
Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
