". . . a stark alternative to every preamp on the market today." TheAudioBeat
While choice can be a dual-edged sword, there's no denying that the Blue Circle BC307 represents a stark alternative to every preamp on the market today -- and probably tomorrow as well. Whether having three parallel gain stages is your thing or not, the BC307 will please many listeners and its performance is in the upper crust here and now Theaudiobeat
But even within the Blue Circle product line, the BC307 preamp stands out. It cleverly scratches an itch that many audiophiles can't identify but know exists: the desire to tailor the sound to taste or recording quality or type of music. It does this not with tone controls that contour the preamp's frequency response. Rather, it allows the user to dial in the effect of three different gain stages, balancing each against the others to add a bit more presence here or a touch more linearity there. The BC307 is fully balanced and available with various user options, including an MM/MC phono stage and headphone amp, making it the true functional and sonic centerpiece of an audio system.
The BC307 is a two-box affair, with a separate power supply housed in a shoebox-shaped chassis. Both the preamp and power supply can be ordered in different matching finishes, including all stainless steel, my preferred look for Blue Circle equipment. No matter the finish, the glowing Blue Circle logo has a central spot on the front panel.
The power supply is characteristically stout and connects to the main unit via two detachable umbilicals that you can't connect improperly because they have a different number of pins. It's within the audio chassis where things get interesting. Gilbert Yeung calls the BC307's circuit a "cross hybrid." A "specially designed splitter circuit" sends the signal down separate gain paths that use two tubes -- 6922 and 6SN7 -- along with a third that's completely solid state. On the BC307's front panel, in addition to the normal input and volume controls, there are potentiometers for each of the three gain stages, the output of which "a special adder circuit" combines.
When you begin fiddling with the three gain controls -- and "fiddling" is accurate until you understand just how they affect the sound of the BC307 -- you begin to discover the real heart of this preamp. The BC307 has a fixed 23.5dB of gain, and the 6922, 6SN7 and solid-state circuits are unity gain, so they don't increase or decrease that 23dB figure. The BC307's main volume control, a Shallco attenuator, governs the preamp's output, reducing the signal more or less, depending on its setting. This is the theory anyway. In practice, when you increase or decrease one of the gain controls, you also increase or decrease loudness. But this is the wrong way to think of it. Instead of thinking of those controls as influencing the amount of audio stew you'll make with the BC307, they are instead spices added to the recipe. More or less of any of them doesn't appreciably change the portion but does affect the final flavor. Blue Circle also stresses that the BC307's ability to "make the marriage between your preamp and amp much happier." It doesn't do this because those gain pots alter the preamp's electrical properties -- its output impedance, for instance. Rather, they allow for the tailoring of the sound, matching it better to that of your amp -- "better," in this instance, being something that you and you alone decide.
We truly believe that this is a breakthrough component and once again shows that Blue Circle will not be limited by conventional
thinking when it comes to sound reproduction. We will not just keep reinventing the wheel and calling it progress. It is, and always
will be, all about the music.
Here, we take on the challenge of creating unique products to satisfy your specific needs.
If you can conjure it up, then very likely, we can build it.
All of our products can be made in a variety of different finishes and colors.
If you have something in mind and don't see it as an option contact us.
The Custom Shop isn't limited to finishes. If you're looking for a unique combination of inputs/outputs and functions or want something brand new built from the ground up just let us know.
We enjoy the challenge of creating something unique for our customers
BC307 Line stage preamp
User controlled 6922-based, 6SN7-based, and solid-state circuitry all in parallel with L3 power supply