The information provided on this page is for imformation only, because these legacy Blue Circle products are discontinued.

The SBT Tube Linestage Preamp

SBT Preamp front

Technical Information

  • Line level inputs (optional additional inputs and loop inputs)
  • 1 Pre-amp output, (optional additional outputs)
  • Tube complement: 2-6922
  • Power requirement: 120Vac 50/60Hz 38Watts - available in 100, 220, 240 Vac
  • Dimensions:

  • preamp chassis: 5.375" (width) x 3.375" (height) x 8.25" (depth); +1.125" front for knobs and 0.5" back for RCA jacks
  • power supply chassis: 5.375" (width) x 3.375" (height) x 8.25" (depth)
  • Weight (without packaging): preamp: 5 lbs. power supply: 8lbs.


  • Residual noise reference to full rated output: >-105dB or <65uV non weighted
  • Residual noise reference to full rated output: >-118dB or <20uV within audio band
  • Hum below 400Hz: >-140dB or <1.5uV
  • Tracking error tube stage: < +/-0.1dB
  • Tracking error volume control: <+/-0.05dB
  • Channel separation: >105dB
  • Frequency response at 5V output: 10Hz to 40K +0.00db, -0.1dB; -1db at 100kHz
  • Distortion at 1V output: <0.05 %
  • Voltage gain: 23.5 dB
  • Maximum output: 18 Vrms
  • volume control range: -95dB to 0db in 62 steps standard in Shallco attenuators
  • input impedance: 100Kohms
  • output impedance: 180ohms
  • Retail Price


    BC109 Preamplifier and CP1 and CP2 Capacitor Packs

    Today, other audio companies are over engineer their products or give them a fresh "coat of paint" to impress their customers. Concepts like more power, bigger is better, and technology that reinvents the wheel are commonplace. Then thereís the cosmetics. If you canít make it sound better you can always make it look "flashier". True to heritage, Blue Circle always remembers what's important and sticks to what they know best, namely simple, elegant designs, resulting in superior sound. A case in point is the the power supply. The new BC109 is a simple yet elegant line stage preamp design that incorporates several elements that allow for a variety of ways to supply it with power.

    BC109 pre amp front

    The basic version of the BC109 is called the BC109*. It has over 110 Farads (110 million microfarads) of capacitance. It will play up to 3 hours without a/c power in one charge. With the CP1 capacitor pack, it totals 550 Farads and will play up to 15 hours. With the CP2, at a total of 1200 Farads, it can play well into the 20+ hours.

    The CP2 also has a built-in automatic charging circuit. It monitors the power supply in real-time and when it drops to a certain level, it will automatically engage the charge circuit so it will seamlessly maintain its power.

    With the CP2 capacitor pack installed, the user can actually calibrate the sound. Youíve probably heard the term "tube rolling" but how about IC rolling? The BC109 incorporates user-changeable ICs. This feature makes the BC109 well-suited to any system. Tune it to your hearts content with the variety of ICs available on the market.

    So why all that capacitance? First, it was designed to run on it own capacitors and not from the power grid. As a result, there is no hum, no buzz and by definition zero powerline noise! Thereís no need for a powerline conditioner.

    Second, by using capacitors instead of conventional batteries, there is no complicated charging circuit to deal with. Unlike batteries, capacitors have no recharge memory. Capacitors charge to 100% every time. Batteries die a little every time they are charged.

    Have you heard battery companies claim their rechargeable batteries can take up to 1000 charge cycles? Capacitors can easily take 100 times more charge cycles than a battery and still remain 100% charged every time. Charge and discharge the unit whenever you like, you canít harm the capacitors. As long as the maximum charge voltage does not exceed the rating, it will not over charge. Capacitors also have a much longer life span than batteries. With 10 years of normal use, a BC109 will use the equivalent of 21,900 AA alkaline batteries!

    As an additional feature, the BC109 can also be charged directly by other energy sources which makes it the very first unit of its kind that can operate totally "off" the power grid. It can be charged directly by a solar panel, a car battery, a windmill or any device that can output DC voltage. It can even be connected to the 12V socket in your car. Any kind of DC source from 10Vdc to 16Vdc can be used to charge the BC109.

    BC109 PreAmp back

    Standard Features

  • Dual differential balanced audio signal paths.
  • Dual decks - balanced 31 position Shallco attenuators with 2 level gain switches for a total of 62 settings.
  • Direct path selector switch, this also allows the BC109 to be used as a final mixer in a multiple mixer set up.
  • Options

  • Dual decks balanced 47 postion Shallco attenuators with 2 level gain switches for a total of 94 settings.
  • Single four deck 31 or 47 position Shallco attenuator with 2 level gain switches with balance control.
  • Processor bypass loop.
  • Remote volume control.
  • Wide range of faceplate and cover options.
  • IC rolling with CP2 option.
  • USB input + digital output
  • Headphone jack output
  • 12V socket and battery charger adaptor
  • Solar Panel charger adaptor.
  • BC109 PreAmp inside view

    BC109 PreAmp side view


  • Residual noise referenced to full rated output: >- 100 dB or < 60 uV non weighted
  • Residual noise referenced to full rated output: >- 110 dB or < 20 uV within audio band
  • Tracking error: < +/- 0.05 dB
  • Hum below 400Hz: <1.0 uV
  • Frequency response at 5V output: 10Hz to 55K Hz +0.00db, - 0.00 dB; -1db, -1db at >100 kHz
  • Distortion at 5V output: < 0.0028 %
  • Voltage gain: 20 dB
  • Maximum output: 8.5 V
  • volume control range: -95dB to 0db in 62 steps standard in Shallco attenuators
  • input impedance: 100K ohms
  • output impedance: 2.5 ohms

    BC109 and BC109-CP1 Dimensions: 17.5" wide x 3.5" height x 15.5" deep Weight: 35 Lbs

    Retail Prices

    Retail for BC109 standard: $4725.00 Retail for BC109 CP1: $7695.00

    BC301FY Preamplifier

    In their over 20+ years of designing various audio components Blue Circle has always strived for value regardless of price point. Buyers can, for the most part, have product cosmetics either cheap or elegant. The BC301FY is something of a departure. There are no elegant cosmetic options offered. The BC301FY is housed in ABS. Although the appearance is novel the BC301FY is by no means a novelty product. This is a reference quality preamp - in an unusual enclosure.

    BC301FY PreAmp

    Yes. Those are ABS pipe caps and other plumbing accessories that you see in the above pic. What's important is what's inside those pipe caps. The sonic quality is more than worthy of a "BC" model. The BC301FY is equivalent in performance to 90% of the BC3000-GZpz but at a cost of over 40% less.

    How is that possible? Cosmetics. The phonostage is a stripped down version of BC's best phonostage. The headphone amp is the best amp that can be built in this chassis design. The USB DAC is a new design specifically for this preamp. If you compare it performance-wise to a comparable product it's 50% less because the off-the-shelf ABS rather than the conventional cosmetics.

    Go GREEN and save Money For cosmetics ONLY, Blue Circle used common materials and leftovers from other jobs. Thatís why the top and bottom plate of the power supply and the base of the preamp all look different. They are all grade A parts that have accumulated in inventory from previous custom jobs. Blue Circle is passing on the savings to you. However, all the essential parts used in the BC301FY are brand new and carry the standard Blue Circle parts and labor warranty.

    Modular Design For Add-ons/Upgrades

    The base preamp unit consists of four pipe caps. Individual modules can be added on when or if you want to upgrade. Phonostage, headphone amp, USB DAC and regular DAC are examples of add-ons. Buy what only what you need.

    Read the SoundStage! review.

    Standard Features

  • 3 line level inputs
  • Gold plated Grayhill selector switch, of course itís the same one we use in the BC3000.
  • 31 x 2 position Shallco attenuator
  • 3ft x 2 umbilical cord
  • Optional Features

  • 47 x 2 position Shallco attenuator
  • RF remote controlled motorized Shallco attenuator (must be 47 positions)
  • Regular RF remote volume control
  • Tape loop
  • Processor bypass loop
  • Various loading plugs for phonostage
  • Specifications

  • Residual noise: >-110dB un weighted
  • Frequency response: 10Hz to 50Khz, +/- 0.1db, -3db >300Khz
  • USB DAC: 16 bit 48kHz non up sampling design.
  • Weight: preamp 20 lbs to 25 lbs, depends on number of modules :power supply 22 lbs to 26 lbs, depend on various options

    Price (basic unit):$4950.00

    BC3 Despina MKII and Galatea MKII single-ended or fully balanced tube linestage preamps

    If you have been in the audiophile circle for the past 10 years, you must be familiar with the BC3 Despina and BC3 Galatea tube linestage preamps from Blue Circle Audio. The very first BC3 Despina rolled off Gilbert's (the chief Blue Circle Audio designer) bench in 1992. Since then, it has been critically acclaimed and set many industry standards. The sound was light years ahead at the time. This was simply because Gilbert Yeung of Blue Circle believed that the ulitmate goal of making a piece of audio equipment is to play music.

    BC3Mk2 PreAmp front

    In 2003, Gilbert decided the BC3 Despina and BC3 Galatea needed an upgrade to incorporate what he had learned in the previous 11 years. The result is the BC3 Despina MKII and BC3 Galatea MKII. These two preamps are completely redesigned and housed in a more attractive slim-line chassis each with untra high-speed power supplies. This technology and the parts to build it simply weren't available 11 years ago. They have the same features as the original versions. This includes: 5 line level inputs, dual Shallco attenuators, loop switches, and two preamp outputs.

    A major bonus with the MKII design is that these units also come configured in a fully balanced version. The number of line level inputs increases to a total of 3 in the balanced version. We think the BC3 Despina MKII and BC3 Galatea MKII really deserve a new name because they are far superior to the original version in every respect.

    Conversion is available for the owners of the original version. Please E-mail us for details.

    BC3 Despina MKII can be upgraded to BC3 GalateaMKII, then upgraded to BC3000MKII.

    Home theater bypass loop option available for integrating into a mutli-channel system.

    Retail Prices

    Retail for BC3 Despina MKII $4945.00 Retail for BC3 Galatea MKII $6395.00 For balanced versions of the above, add $190.00 to each retail price.

    Read the Audio Review review.

    Read the onhifi review.

    Read the Stereophile review.

    Read the audioMUSINGS review.

    Read the BlackDahlia review.

    BCG3 Power Supply

    BC3 power supply BC3 power supply front

    When matched with the BCG3 the integrated preamp is called the BC3 DESPINA. The BCG3 comes in a simple black metal case with an integrated D/C cord that mates with the BC3.

    BC3 power internal BC3 power rear

    It features:

    • High current toroid transformer
    • High speed switching diodes in the rectifier circuit
    • Massive filtering
    • Double reverse twisted D/C cord for RF noise suppression

    BCG3.1 Power Supply

    When matched with the BCG3.1 the integrated preamp is called the BC3 GALATEA. The BCG3.1 comes in a beautiful stainless steel case that matches the BC3. It has a detachable D/C cord custom manufactured for Blue Circle by Cardas Audioģ.

    BCG3.1 power supply

    The BCG3.1 features:

    • Dual toroid transformers for greater current capability
    • Hexfed Ultrafast Soft Recovery rectifier diodes
    • 200% more high voltage filtering and 300% more filament filtering
    • All wiring past the transformer is by Cardasģ
    • Integrated Power Line Pillow ac powerline conditioner

    More pics:

    BCG3.1 power supply front

    BCG3.1 power supply inside

    BCG3.1 power supply rear


    All BC3 preamplifiers are lovingly hand-crafted in solid hardwoods and stainless steel. Each individual piece is played and auditioned for a minimum of 50 hours. Each preamp is personally approved by the designer prior to shipping. Even the finest design coupled with the best components is nothing if the execution isn't there.

    Processor Loop Option

    This option will give you the flexibility to bypass the volume control and tube gain stage so you can feed the signal directly from your processor to your power amplifier. Additional cost of this option is USD190.00. Modification into existing units is available upon request. Contact us for further details.

    Technical Information

    • 5 Line level inputs, 1 Tape input
    • 2 Pre-amp outputs, 1 Tape output
    • Maximum output: 25Vrms
    • Left/Right tracking: better than 0.2dB
    • Tube complement: 2-6922
    • Power requirement: 120Vac 50/60Hz 38 Watts

    • Also available in 100, 220, 240 Vac
    • Dimensions:
      • main chassis: 17.5" | 444.5mm (width) x 5.375" | 136.5mm (height) x 14.6" | 370.8mm (depth)
      • BCG3: 5.25" | 133.4mm (width) x 3.25" | 982.6mm (height) x 8.25" | 209.6mm (depth)
      • BCG3.1: 6" | 152.4mm (width) x 5.375" | 136.5mm (height) x 14.6" | 370.8mm (depth)
    • Weight (without packaging):
      • main chassis: 35lbs. | 15.9kg
      • BCG3: 5lbs. | 2.3kg
      • BCG3.1: 16lbs. | 7.3kg
      • Warranty: 3 years parts and labor, 90 days on tube

      BC3PLS Linestage Tube Preamplifier

      The BC3PLS is the evolution of the venerable BC21.1 Popular though it was, the 21.1 chassis was not conducive to the upgrade path that Blue Circle likes to provide its owners. For example, it did not accommodate popular options such as the Shallco volume control or additional inputs and outputs, etc.


      That said, it's not just a BC21.1 in a BC3 chassis. It is a dual mono tube linestage with an internal power supply and an external transformer box that is worthy of the BC3 designation. It is also the entry point for a clear upgrade path all the way to the BC3000GZpz. The BC3PLS has all the same features functions and options as the rest of the BC3 lineup.

      Retail Price


      BC3000MKII single-ended or fully balanced tube linestage preamp

      In 1998, Gilbert improved the original BC3 Galatea one step further. It became the BC3000, the flagship of Blue Circle Audio's linestage preamps.

      Just like the BC3 Despina MKII and Galatea MKII, the BC3000MKII is a redesign of the original version. Housed in the same slim-line chassis as its two little bothers, the similarity ends there.

      The power supply of the BC3000MKII is more than double that of the BC3 Galatea MKII. Its output stage is Blue Circle's own film and foil capacitors. The BC3000MKII simply takes the critically acclaimed BC3 Galatea MKII another two steps further.


      Available options include a fully balanced version and a home theater bypass loop for integrating into a mutli-channel system.

      Retail Price

      Retail for single-ended version is $8795.00. Add $800.00 to the retail price for the balanced version.

      Read the Soundstage! review.