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The NSP Solid-State Stereo Power Amplifier
This amplifier was never supposed to go into production. Those of you who are familiar with Gilbert Yeung, the resident mad genius
and designer here at Blue Circle Audio, know that he doesn’t approach problems, or even think the same way that the rest of us do.
That is a part of what makes him such a unique personality in the high-end audio world. Sometimes his ideas can lead him into, let’s
just call it uncharted waters. The NSP started out as one of those unusual ideas that Gilbert started exploring. He wanted to see if he
could produce a reference-quality amplifier, of reasonable wattage, that could run on four 12 V deep-cycle batteries. This is why the
NSP is 90 W into 8 Ω. With supply rails of ±24 V, this is what the power rating turned out to be. Running this amp on battery power is
indeed one of the available options on the production model of the NSP.
Gilbert worked on the NSP prototype for quite some time. It actually spent more than a year in his bedroom (yes he has a workbench
in his bedroom) as he tinkered away. As the months passed the NSP slowly evolved into its current form. From the start of his research
to the first production model, more than two years had elapsed. During that time the BC1022 power amp came into being as a kind of
side project of the NSP. The BC1022 actually went into production first, but it was rooted in the research that Gilbert was doing with the
NSP. They share a number of design parameters. Both have fully differential inputs and use the fully-balanced M-2 output stage. Both
use core-band technology to suppress EMI from the transformer and both power supplies employ a dc-blocking circuit. However, at
some point in the tinkering, the focus of Gilbert’s NSP research changed focus.

When the BC1022 went out for evaluation to a number of dealers and friends, the feedback that we got back was, to say the least, very
positive. As many people know, Blue Circle has been one of the leading proponents of the absolute necessity of treating the power
supply as part of the signal path. We truly believe that the power supply has such a significant effect on the sound of an amplifier, or
any other audio component for that matter, that upgrading the power supply is the first thing you should look at when doing any
component upgrade. Gilbert decided that he wanted to see just how far he could push a power supply and continue to get increased
performance. The NSP currently in production is the culmination of that research….well sort of.

This amplifier has (now hold onto your hats) 5.6 million microfarads of filtering in the power supply. That is 5,600,000 μF or 5.6 Farads!
Keep in mind that our now out of production, very highly regarded, 150 W/channel, 14.5 kilo-dollar, four-chassis, AG8000 reference-
quality power amps had a measly (a reviewer referred to it as a “whopping”) 300,000 μF. Why 5.6 F and not 5.5 or 5.7? The answer is
that he simply ran out of room in the chassis, and this is not a small chassis. He really believes that he not yet found the limits.
And there is more to the NSP story than just more and more capacitance, though that certainly does help. Gilbert spent those many
months experimenting with different value caps, different types of caps, and different combinations of caps. The production NSP is the
result of all that research. This amplifier has the most sophisticated power supply that we have ever put into production.

In all honesty, this amp is definitely not for everyone. It is large (it will not fit on any conventional audio rack) and it is heavy (like over
65 lb.), and it is not particularly cheap (though far from crazy expensive), but what it does to music is nothing short of a revelation. As
many of you know, we tend not to talk about how our components sound. We try to leave that to the reviewers and those who own our
gear. But what I can tell you is that those who have lived with this amp for any extended period of time did not want it to leave. Have a
look at our online forum to see what those who have listened to this amp have to say. One other thing to note: Due to what some would
say is its ridiculous amount of filtering, this amp takes a very long time for it to reach its optimum performance. Settling in times of
months is not unheard of. The wonderful thing is that it just keeps getting better the longer you live with it.

After much listening, we believe that this amp sounds very, and we do mean VERY good. And if you want to understand what Gilbert
has been saying about the importance of power supplies for so many years, then spend some weeks listening to the BC1022 and the
NSL side-by-side. Many of those who have done this comparison started out by thinking that the BC1022 was just about as good as
it could reasonably be expected to get. The laws of diminishing returns would suggest that there is really not much need to go any
further unless you simply needed more power, or had an uncontrollable lust for those mesmerizing glass bottles. But after listening to
the NSP they came to realize that there really is more to be discovered, more beauty to be found in the music. That is what we have
always strived to do. The NSP is one more step down that endless, exciting, surprising, and sometimes breathtaking road.
     *90 W per channel into 8 Ω and 135 W into 4 Ω
*Fully differential input
*Fully-balanced M-2 output stage
*More than 5,6
00,000 μF of power supply filtering
Core band technology used in the transformer
*dc offset blocking circuitry in the power supply.
Contact:  bcircle@bluecircle.com  /  519-469-3215
(illustrated with optional wood faceplate)
Dimensions: 19" Wide” x 21" Deep x 9" high
Weight       : 75 lbs.