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The BC660 Series of Powerline Filters
Things Keep Changing
About 5 years ago we found that many of the switching devices that we were using in our own homes, devices like switch-mode power
supplies or CFL and LED lighting, were producing noise in a lower frequency spectrum. This noise was focused much lower, from about
5 kHz to 50 kHz. Gilbert’s answer to this new problem was the X1e low-frequency filter module that we employ in our higher quality
PLCs like the BC60X1. And then, to make sure that those of us who do not have deep pockets had access to this new technology,
he developed the X0e low-frequency filter module. We introduced it into our Thingee line of affordable PLCs and got rave reviews. But
now, things have changed again.
This time the main culprit, strangely enough, is our own audio components. Computer-based music devices such as laptops, streamers
and media servers are producing a different type of noise in a different frequency spectrum. This digital component noise product tends
to be in the ultrahigh-frequency range above 750 MHz. Gilbert’s answer to this new challenge is the CxT Ultrahigh-Frequency Filter
Module. CxT stands for Cross Hybrid Transfer and is exclusive to Blue Circle Audio. Specially selected materials are formed into
tubes that wrap around the filter’s internal wiring and actually absorb this UHF noise. There is a small gap between the tube and the
wire that we fill with non-conductive silicone. The filtering tubes do not come in direct contact with the wiring. The BC660 series is the
first Blue Circle product to incorporate this new filter technology, but we will be introducing it, in one form or another, into most of our
other PLCs in the near future.
More is Better
The BC660 series of PLCs contains three separate filter networks; each one is designed to address a specific noise problem. The main
filter network is a broadband filter similar to those we use in all of our PLCs. It is capacitor based and is totally non-current limiting.
This filter covers the range from about 50 kHz up to about 750 kHz. To handle the ultra-high frequencies above 750 kHz is the job of the
CxT filter. Below 750 kHz, it transfers the filtering function to the broadband filter. This is where the name comes from. Finally, to filter
out noise between 5 kHz and 50 kHz a new low-frequency filter has been developed. We call this filter system the X0.5e. As the name
implies, it is more complex than the X0e but not as sophisticated as the X1e.
The BC660 series PLCs are extremely effective for both analog and digital systems, but they were developed with digital systems in
mind. Computer-based components are the primary source of ultra-high frequency noise and the 660 series addresses this in two
ways. First of all, it has the CxT cross-hybrid transfer filter to specifically address this frequency spectrum. Another important
characteristic of these filters is that each duplex outlet, or deck, is isolated from every other deck. This means that noise generated
by any one component will not transfer to another component or back into the AC supply. The last thing that you want is for the noise
produced by your media server being picked up by your highly sensitive phono stage. But again, the BC660 series is highly effective
when used on purely analog systems as well since there is still UHF noise on the power line, not just from components in your own
home, and keeping components isolated from each other is always a good idea.
Not Just For 1s and 0s
Four Decks or Six?
The BC660 currently comes is two versions. The BC660-8 has eight outlets on four decks and the BC660-12 has 12 outlets on six
decks. As stated earlier, each deck is isolated from every other deck. And there is another option that can be added to one of the
decks. If you are using a large power amp and have DC-offset issues causing its transformer to growl, we can incorporate a DC-offset
blocking circuit on one deck of the filter. We can also offer different types of outlets for our international customers. For North American
applications standard NEMA industrial quality outlets are used, but if you require Schuko or some other type of outlet, just let us know.
We can most likely accommodate you. Keep in mind however that due to the increased size of some of these outlets, we may not be
able to offer the same number of decks. Contact us for details.
It can get a bit frustrating. Designing power
line filters and conditioners is kind of like
trying to cure a disease that is constantly
mutating. This is because the very nature of
the noise itself keeps changing. When
Gilbert first started designing PLCs some 20
years ago, Most of the noise on the grid was
RF noise that was introduced into the AC by
RFI and/or EMI. To combat this noise we
produced high-quality broadband RF filters
since that was where the preponderance of
the noise was. The noise spectrum tended
to be from about 50 kHz up to a few hundred
MHz. But things keep changing.
Photo to follow
Dimensions: 13.5" x 5" x 3.25"   Weight: 8 lbs
January 9, 2018
The most common question Gilbert receives from customers is "can you put
that in a pipe?" Sometimes yes. Sometimes no. In the case of the BC660, yes.
The BC660-6 Si..With the same filtering power as the BC660 and only 6 outlets.

Dimensions : 8" long x 4.5" dia.        Weight : 5 lbs.
BC660-6 Si
Contact:  bcircle@bluecircle.com  /  519-469-3215