BC501 Digital and Analog Convertor

The BC501 is the very first D/A converter that Gilbert has designed for the audiophile community. Gilbert has been working on DACs for a number of years and has built several for his friends and himself. Finally, after some arm-twisting, we convinced him to build one for everyone else.

Simplicity, functionality and the ability to play music are what the BC501 is all about. There is one selector knob, one phase switch, and three small indicators for de-emphasis, phase and signal lock. Special attention has been paid to LED brightness so you won't be blinded when you look straight at them. Most manufacturers drive their LEDs to maximum brightness to catch your eye in a showroom. Gilbert adjusts his LEDs so they won't be a distraction or an irritation while you are listening to music. Gilbert is particularly fussy about this and it shows on the BC501 front panel.

The BC501 comes with ST-Glass fiber, RCA and XLR as standard inputs. Tos link and BNC inputs are available as options.

Why didn't we talk about the sound? Well, if you know Blue Circle sound and how picky Gilbert is when it comes to DACs you wouldn't ask. The BC501 is simply designed with music only in mind. There's absolutely no hype here and it utilizes all the best components available. They may not be "fashionable" but that shouldn't be a surprise. No bells. No whistles. No flashing lights, Just quiet understated elegance and music. After all, it's a Blue Circle product.

BC 501 DAC


$4785.00. Various faceplate and cover options available.

Read the StereoTimes review.

Read the SoundStage! review.

BC501ob Digital and Analog Convertor

The BC501ob has the same specifications as the BC501 with the exception of the power supply.

BC 501ob front

It has over 880,000 uF

BC 501ob back

and the separate power supply housed in a chassis with the same dimensions as the BC501 chassis. The BC501ob employs dual DC powercords. One for analog and one for the digital domain.

Price $8629.00. Various faceplate and cover options available.

BC509 and BC507

Today's modern audio signals are stored in digital form (CDs, wave files, etc.) and in order to be heard through speakers they must first be converted into an analog signal. Digital to Analog Converters (DACs) are found in CD players, digital music players, and PC sound cards. DACs are NOT all created equally.

BC 509 front

Blue Circle is known for their hand-crafted, state-of-the-art products and their DACs are no exception. Blue Circle does everything possible to ensure musical accuracy. Every signal trace on the BC509 circuitboard has been carefully designed and tested. The DAC microprocessor is not used in the control circuit. Why? The less the clock contaminates the signal the better. The unique analog output stage uses a design similar to those in Blue Circle's best solid-state preamp, the BC109CP2.

While the heart of a DAC is it's microprocessor, the soul of the BC509 is it's power supply which has a filtering capacitance over 200,000uF. This is more than most 100 watt stereo power amps. This provides not only stabilty but also contributes no sound of its own to blur your musical enjoyment.

The BC507

The BC507BA raises the bar on the BC509 by adding a whopping 1,000,000uF (1 million micro Farad) battery power pack. When running on battery power, there is NO ground hum or any sort of powerline noise that can infiltrate the audio circuit and pollute the music. The result is the most detailed musical presentation you've ever experienced. This is one of the major factors which contributes toward that elusive sense of effortless and dynamic yet relaxed musicality.

The proprietary circuit design switches between battery and A/C power silently and seamlessly. When the battery runs low, the DAC simply powers itself off.

The BC507NB substitutes an additional 1 Farad of capacitance internal to the BC507.

BC 509 back

The Sound

"Images beautifully." "Sounds like an analog presentation". "Very accurate. "Spot-on imaging and a soundstage was so precise you can easily pinpoint EVERYTHING even under complex passages." are just a few of observations by delighted BC509 owners.

The Value

The BC509 offers the best price vs. performance ratio of any DAC that we've experienced, many of which have a much higher asking price.


Standard: (1) Toslink, (1) SPDIF, (1) AES/EBU

Optional: USB 24/96 (will also support 16/44 and 16/48), USB 16/44, additional SPDIF


Standard config: (1) pair of XLR balanced, (1) RCA unbalanced

Optional features

Manual or remote volume control BNC jack (replace RCA jack) for SPDIF input at no additional cost.

BC509 Price: USD $1,199

BC507 Price: USD $2,195


The SBU is a battery-powered USB D/A, and D/D converter, headphone amplifier and line stage preamp built into a compact chassis. Its internal DAC supports 16-bit and 48kHz operation. It's on-board battery pack allows you to enjoy music stored on your computer using headphones without the need for an A/C outlet or having an outboard battery pack.

While at home, the SBU can be used to drive a pair of active speakers or a power amp with a computer as source. A line-level RCA input or a 1/8" mini jack are available options so that you can connect your favorite CD, MP3, or iPod of player your choice.

The dual-purpose standard power supply charges the built-in battery or allows the SBU to run on A/C power when the battery runs low. A full battery charge runs the SBU for up to 20 hours

The Sound

When you listen to music with the SBU powered via battery, you here more musical detail and a dramatic improvement in dynamics and soundstage. You'll be amazed at how good 16/44 digitally recorded music can sound through the SBU.

The ABS SBU enclosure is also road-worthy. Put it in your bag, backpack or briefcase, hook up to your computer and headphones, and you're ready to enjoy your favorite music and movies. Since the SBU runs on it's own battery your laptop battery will be conserved. At 20 hours running time, it will out last any laptop battery on the market.



Standard Version: $550.00 + shipping

Includes: a USB input, SPDIF output via RCA jack and an AES/EBU output via XLR jack and batter pack consisting of 12 2450mAh AA rechargeable batteries. Its internal DAC supports up to 16-bit and 48kHz.

Optional features

An RCA input add: USD75.00

High/low impedance switch for the headphone phone output add: USD50.00.

E-mail us for additional options.

USB Tunnel 24/96

The USB tunnel 24/96 is a digital to digital converter. It is designed to be used as the INTERFACE between a USB port on a computer and an external Digital to Analog Converter (DAC). The USB Tunnel supports up to 24 bits/96 Khz, which is ideal for high resolution audio. The USB Tunnel also supports standard CD quality 16/44 resolution.


Standard Version: $439.00 + shipping

SPDIF and AES/EBU Outputs are standard

Add $29 to add Toslink output.

USB Thingee

We are proud to offer for sale the Blue Circle USB Thingee. This is the very same unit that recently received rave reviews in UHF Magazine.

Read the GoodSound review.

Briefly, if you have not yet heard the buzz about the USB Thingee, it is BC's affordable yet highly flexible 'swiss army knife' of DACs.

USB thingee

On one hand the USB Thingee allows you to connect your media PC, laptop or even home computer to your home audio system while bypassing the typically non-HiDef sound card. The USB Thingee allows you to take advantage of the added convenience of using your existing library of online music & video content. This is all made possible while not having to risk compromising your audio sound quality in the process.

USB thingee

Similarly this device allows you to use a laptop or home computer as an alternative to an expensive dedicated CD transport. In this method the PC & USB Thingee in tandem will work amicably with any existing external DAC that you already own. As if this was not enough the unit also contains an integrated 1/8" headphone connection.

USB thingee

This is all made possible by the internal reference DAC that resides inside the USB Thingee's minimalist exterior. To complete the package we offer the USB Thingee with optional AES/EBU & Toslink connections.

USB HO thingee

Why AES/EBU and Toslink Options?

Toslink is used to connect to a home theater processor or receiver. These devices usually have digital inputs but many have only Toslink connectors. This allows you to play music or even internet radio on your Home Theater system.

AES/EBU is handy for connecting laptops to various equipment such as a digital mixer.

Don't let this unit's modest price fool you -- This device is truely a wolf in sheep's clothing. It offers remarkable sound quality and has successfully achieved the highest price-to-performance ratio of any product we've auditioned to date.


Standard Version: $182.00 + shipping

Includes: USB Input, SPDIF Output, Analogue Single-Ended (RCA) Outputs, 1/8" Headphone Jack

The Toslink version: $197.00 + shipping.

The 'FULL MONTY' Version as reviewed in UHF Magazine: $208.00 + shipping.

All of the Standard USB Thingee Connections PLUS:

AES/EBU (XLR) Digital Output, Toslink Digital Output

NEW Options/Addons

Ask us about the optional built-in volume control upgrade, available with all Thingee versions.

Add $145 for the high output version...approximately 3V. This is enough to drive any power amp or integrated amp with passive preamp. You get a full-featured USB DAC in a very compact package with a separate power supply.

Add $12.00 for the optional "stand".

Add $229 for the "beefy"/biggie pipe separate power supply. A separate power supply provides the best possible sound. It has an IEC connector so that users can provide their power cord of choice.

If you already have a regular USB Thingee but want the higher output there's no need to get the USB Thingee HO. Now you can get the USB HO Attachment for $179 and convert your USB Thingee to the HO version. Just plug the attachment into the output of the regular USB Thingee and hook up the power supply. It comes with the standard Thingee power supply. The upgraded Biggie Pipe power supply is also compatable with the USB HO Attachment.

Please read the reviews and make your best decision. The units do what their features and specifications say they do and they do it well.

Read the SoundStageAV USB Thingee review.

Customer Comments-USB Thingee

The Thingee arrived on Thursday, and it sounds great! I'm also having a great time showing it to friends and getting their first aghast, then impressed reactions :) Overall, I'm quite happy with both the product and this transaction. Thanks a bunch!