Bookshelf Speakers

Paradigm Signature S2, Version 3 Bookshelf Speakers and Anthem Integrated 225 Amplifier

ARTICLE INDEX

On The Bench

The on-axis response of the S2s was very nice, with a very flat response out to near 20 kHz, and solid bass down to 50 Hz as well. There is a large suck out from 55 Hz up to 110 Hz that is caused by the room itself and not the speaker, and curing this issue will be my next project.

The off-axis measurements are almost as good as the on-axis ones. The bass suck-out is more pronounced without the microphone right in front of the bass port, as well as a dip at 5.5 kHz as well.

The THD+N numbers for a 10 kHz test tone all the way at 100 dB were very low, with under 0.5% and secondary harmonics at over 50 dB below the primary one.

The numbers should look very similar for the 1 kHz tone, with again just under 0.5% THD+N and the harmonics coming in over 50 dB below the primary.

Next I started to see how deep I could go before I couldn't hit 100 dB with less than 10% THD+N. I finally had to drop all the way down to 35 Hz, where I maxed out at around 93 dB, though as you can see the harmonics are far higher as you try to push a bookshelf speaker this hard.

Back in its comfort zone, as seen on the initial frequency response graphs, with a 50 dB tone we had right around 0.75% THD+N at 100 dB of output.

Since the 75 Hz frequency was centered right in that suck-out area of my frequency response chart, I expected performance to drop off when I tested it here and I was right. THD+N shot up to over 4% at 100 dB, with harmonics far above what I was seeing with the more demanding 50 Hz tone. This lets me know that I really need to look at the issues with my room and how I can fix this dip in my frequency response.

Overall, the S2s did very well on the bench, staying within a +/- 3 dB range all across their rated frequency response range, with the exception of the bass issue that is caused by my new room and needs to be addressed shortly. Now, we move onto the Anthem bench results.

The numbers for all four measurements here are around 0.004% THD+N with the values dropping as the amplifier puts out more power, or into a harder load, which is typical of Class AB amplifier designs.

With a 10 kHz tone, the numbers move up a bit compared to 1 kHz. We stay right around 0.012% into the 4 ohm load, and drop down to 0.008% into the easier 8 ohm load.

On the IMD test, the measurements were close to 0.005% IMD or lower, with the secondary peaks being around 90 dB below the fundamental.

On the 19 kHz, 20 kHz test we see some sidebands at 18 kHz and 21 kHz, but those are both around 90 dB below the fundamentals as well.

On the frequency response test, we see that the Anthem is within +/- 0.1 dB across the spectrum, with the exception of a bump that kept appearing for me right around 60 Hz when I ran the test. I imagine this is a bit of line noise or something else interfering as there was no hum present through the speakers, which you would expect if that was actually correct.

Finally, the THD+N numbers against frequency were very low across the board. Ignore the spike in the 8 ohm graph and that spike was showing up at a random point in the graph whenever I ran it, but it was not in a consistent location. It happened in the 4 ohm graph once as well, but I was able to run it again with no issue, leading me to think it is line noise or something else causing the issue.