This is a review and detailed measurements of the Neurochrome Modulus-286 Power (speaker) amplifier Kit. It is on kind loan from company designer and member, @tomchr . It is to ship by end of this month and costs $1,299. See: https://www.neurochrome.com/product/modulus-286-kit-2/ As you may recall from my review of Tom's headphone amplifier, Neurochrome designs strive for very low distortion and good, objective performance. So I have been quite excited and anxious to measure one of Tom's power amplifiers.From the outside, the Modulus-286 is rather small but very chunky look with massive heatsinks (for its size) on each side of the unit:The heart of Modulus-286 and other solid state amplifiers Tom designs are the integrated LM3886 IC from Texas Instruments. I suspect this is from the National Semiconductor team though which was acquired by TI.The LM3886 is a pretty powerful little IC capable of producing about 70 watts at 4 ohm. The Modulus-286 uses a pair of them to get over 100 watts of power at the same rating for each channel. Typical of mass market amplifier ICs though, the distortion rating is nothing to write home about at 0.02% (SINAD of 71 dB). In Tom's design, an active feedback loop (i.e. uses an op-amp) brings this distortion way down as you will see in the measurements.The LM3886 is a class AB amplifier unlike other products we have tested that use much more efficient class D. So while the LM3886 by itself is small, it requires pretty large heatsinks to cool it which is the reason for them being included in Modulus-286. But in addition to the amplifier circuit, another source of size, weight and some heat is the power supply. Here, Modulus-286 deviates from classic class AB designs by using a switching power supply to gain its size and weight advantage. You can see it in the center of the Modulus-286:It is a commercial switching supply which Tom says has been customized for his use.The amplifier modules are actually hard to see on each side of the central power supply. I tried to take a picture of them but it was hard:You can see the two LM3886 ICs mounted to the heatsink at the bottom. I am sure there are better pictures at Tom's website.So let's get into the measurements and see how she does.As usual, I start with my dashboard view with 5 watts of output and in this case, XLR balanced inputs:SINAD (signal over noise and distortion) breaks the 100 dB barrier which is nice. You can see that the distortion of 0.0009% is orders of magnitude better than the specified level by TI (although that number is likely at higher powers).I noticed a lot more mains/power supply noise in one channel than the other. Nothing I did would impact its level. I could also feel the "tingling" sensation from the case which indicates mains leakage. This is legal and safe (allowed in safety standards) but does explain the elevated levels there. Of course at -110 dB is not audible since our hearing is so poor in low frequencies.Next, I measured the all important power versus distortion+noise:Compared to our best measured so far, Hypex NC400, the Modulus-286 nearly matches it in noise level. On distortion, one channel also tracks the NC400 until its max power of 95 watts. This was with 0.975 millivolts of input. Attempting to feed it strong signal would cause it to go into protection so I could not quite get to the specified power rating.One channel deviates some though as you see in light red. the better channel goes as low at 0.0007% of THD+N or SINAD of 103. Seeing how this is at max power, it is very nice figure to arrive at. Performance is basically noise dominated with no distortion until the shut down.The Hypex DIY NC400 has more power but its distortion starts to rise from where Modulus-286 stops. It produces 226 watts at the point I have marked in blue. So it has more headroom.Frequency response shows somewhat early roll off:We are down 0.4 dB at 20 kHz. Would have been nice to see this flatter seeing how this is a traditional class AB design. Likely it is part of the computation to keep the amplifier stable with different loads. Of course not an audible concern for most of us who can't even hear 20 kHz let alone 0.4 dB of drop in there.Signal to noise ratio is quite good:Broadband spectrum analysis to 1 MHz shows very little of concern:We see some indication of the switching frequency of the power supply around 160 kHz but its level is quite low at nearly -100 dB. With class D amplifiers we see levels as high as -30 dB! Note that since this is a class AB amplifier, I did NOT use my AES-17 filter with any of the tests.I tested THD+N versus frequency at 6 different power levels as you see on the graph:As expected, distortion rises at higher frequencies (feedback gain is lowest there). At 97 watts, the Modulus-286 could produce frequencies above 1 kHz but below that, it would enter into protection mode as indicated by vertical lines in orange.At the lowest power level (0.25 watt) we are dominated by noise and hence the elevated line in red for that. That is true of any power amplifier.Finally here is the crosstalk for one channel (the other is better):Please take this as worst case response. I am testing the amp using a bunch of wires everywhere which can impact crosstalk (and noise levels at low amplification). I need to build a dedicated module with tight wiring for tests like this. Regardless, numbers like this are amply good enough as far as audibility is concerned.The Neurochrome delivers good power with very low distortion using a combination of active feedback and off-the-shelf amplifier IC. Use of a switching power supply keeps costs, size and weight down. It produces nearly 100 watts of very clean power into 4 ohm load. Personally I like to have much more power than that.But if you have subwoofers, or don't listen as loud and/or have more efficient loudspeakers, you should be fine.I am not sure what value judgement to put on the amplifier. Certainly at $1,300, the Modulus-286 amplifier is "cheap" compared to any high-end amplification. At the other externe, the DIY Hypex NC400 I tested produced more power at I think $1,500. Purchasing the Neurochrome Modulus-286 would let you support a smart, Canadian designer and entrepreneur. I let you decide how valuable that is.Overall, I can recommend the Neurochrome Modulus-286 as a well-engineered product with no design faults.------------As always, questions, comments, recommendations, etc. are welcome.Please considerfunds using: https://www.patreon.com/audiosciencereview ), or https://audiosciencereview.com/foru...eview-and-measurements.2164/page-3#post-59054 ).