Liberty Audio B2B-1 Phono Preamplifier

THE NEWS IS OUT, THE NEWS IS OUT, READ ALL ABOUT IT ! IN STEREOPHILE June issue, Page 122 followup review by the editor Mr. John Atkinson.

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Below for our website

THE LIBERTY AUDIO PHONO Preamplifier
MADE IN THE USA
FACTORY DIRECT with 2 week return policy* 
ONLY $1749.00

INTRODUCTION
The B2B-1 Phono Preamp form Liberty Audio is a very high quality, low noise, all FET (Field Effect Transistor) Moving Magnet / Moving Coil Amplification device. It is housed in a heavy duty aluminum enclosure finished with a crinkle baked-on powder coating. 
A 3/8” thick solid black anodized aluminum faceplate adorns the front. 
The Liberty Audio B2B-1 is supplied with one set of RCA inputs and one set of RCA outputs located on the back panel of the amplifier. A Ground Lug for securing the ground wire from your turntable is also provided on the back panel. In addition, one input XLR connector and one output XLR connector have been implemented here.
A total of 5 internal cartridge-load settings are offered for resistive loads of 100R, 221R, 332R, 499R and 47K. A 220 pF Silver Mica capacitor is available and can be engaged for MM operation and disengaged for MC operation. Custom Resistive and Capacitive load settings can be ordered if desired at a very minimal up charge.

Each B2B-1 phono pre-amplifier uses a cascaded two amplifier topology instead of the usual single amplifier method. This approach has allowed us to optimize the B2B-1 for even lower noise, a more perfect gain structure and an exceptionally refined capability to meet today’s dynamic range demands. The input amplifier is a very high gain design with a completely flat frequency response. By a simple adjustment of two internal jumpers it can be set to have a gain of 40dB (MC) or 20dB (MM). The output amplifier provides 24dB (at 1KHz) of additional gain while, at the same time, implements the Bass boost according to the RIAA characteristic. A very simple, but cleverly placed, RC network between the two amplifiers provides the 75uS roll off as specified by the high frequency section of the RIAA Equalization curve.  The B2B-1 offers a better than 0.1dB RIAA accuracy and provides 44dB of gain in MM setting and 64dB in MC setting.

But there’s more! The Liberty Audio B2B-1 phono pre-amp has been designed with the ultimate connoisseur in mind. Each B2B-1 Phono Preamplifier can be set for MONO operation to turn the B2B-1 into a fully differential amplification device. The conversion is accomplished by adjusting 2 internal jumpers and by making connections to the Balanced input XLR connector and the Balanced output XLR connectors Now all the benefits of a differential topology are realized: better dynamics, lower noise floor, inherent immunity from RFI, and, of course, double the speed. All essentially important attributes which position the Liberty B2B-1 in a completely different league (practically a league of its own). For stereo operation you would, obviously, need TWO B2B-1 amplifiers.  When configured as a differential mono block, the gain is 50dB for MM and 70dB for MC.   

For ease of use the Liberty Audio B2B-1 has been designed with an internal power supply. To prevent interference from contaminating the delicate signal amplification circuits, the power supply is completely sheltered by a number of impenetrable aircraft grade aluminum shields. This power supply is a completely dual mono design featuring separate low mechanical-noise, 50% duty cycle transformers for each channel powered from a fused/switched/filtered IEC AC inlet socket thus allowing the choice of custom AC power cords. 

The B2B-1 uses FET transistors throughout even in the on board regulators. While the commonly used bi-polar devices provide excellent low-noise characteristics, they lack the ultimate resolution capability and linearity demands necessary for low-level signal circuits like a phono preamplifier. In addition, they tend to contribute a grainy and irritating sound. JFETs, on the other hand offer exceptional resolution as well as natural and transparent sound in combination with low noise. Bi-polar devices do not come close in performance as far as refined resolution is concerned. In some instances tubes have excelled in terms of resolution, but ultimately, they can't match the low noise and neutrality of the JFETs, which is why we have chosen to use them in this groundbreaking amplifier.

CONFIGURATION
The B2B-1 can be configured for almost any cartridge by internal jumper settings, to access them simply remove the small cover on the left side of the top of the amplifier.
MAKE SURE THE B2B-1 is OFF and power cord is COMPLETELY REMOVED before attempting to configure your amplifier. Also MAKE SURE that you do not have a static discharge - TOUCH EARTH GROUND before opening the B2B-1
Remove the 4 Phillips screws (#1) used to secure the cover, use the supplied screwdriver and take care not to damage or scratch the cover when removing the screws. Beneath the cover you will find 3 groups of jumper pins, the front one is settings for the left channel the middle one is for Stereo / Differential Mono operation and the one the furthest back is for the right channel. From front to back on the channel settings are as follows MM - MC - 100 - 220 - 330 - 500 Ohm loading, the last one is capacitive loading for MM setting at 220pF. JUMPER MUST BE IN PLACE ON EITER MM OR MC. If no jumper in any of the resistive settings the input impedance of the B2B-1 is 47500 Ohms or 47K5, by inserting one or more jumper you can select the desired resistive loading to suit your listening preferences, you can adjust for lower than 100 Ohms by inserting two or more jumpers in any of the 4 resistive settings, example; if you have a jumper in the 100R and the 500R, the loading on the cartridge is approximately 83 ohms. The resulting value of more than one resistor engaged is calculated as follows
R = 1 / (( 1/100) + (1/500)) , based upon above example
For easy configuration use the supplied set of tweezers and make sure the jumper(s) are properly inserted (if a very specific loading is desired you may return your B2B-1 to Liberty Audio for load optimization for a nominal fee)
REPLACE the cover after you are done configuring the B2B-1 and NEVER operate the B2B-2 without the cover in place.
DIFFERENTIAL MONO BLOCK OPERATION
If you have two B2B-1 amplifiers you can configure them as differential mono blocks by internal jumper settings as well, (move the two jumpers in the middle section between the two channels furthest to the right - DO NOT ATTEMPT TO OPERATE THE B2B-1 as a differential mono block using the RCA sockets use the BALANCED connectors only.
Note in Differential Mono operation the load setting have to be half of what you would normally use so if you have engaged jumpers in the Left (Negative node) and Right (Positive node) 100R jumper positions, the load your cartridge sees is 200R

CONNECTIONS
To connect the B2B-1 to your system you will need a high quality set of interconnects to connect it to your line-level preamplifier, the set of RCA sockets located middle back of the B2B-1 are the outputs, upper one is LEFT (black) lower one is Right (red)
Then connect the tonearm cable to the B2B-1 to the RCA connectors on the right side(when looking in from front) of the amplifier again RED (lower) connector is Right, BLACK (upper) is LEFT, also secure the CAHSIS ground wire to the Ground lug furthest to the right (this is connected to EARTH ground inside the B2B-1)
Lastly connect the supplied power cord to the B2B-1 and connect it to an AC power source, CHECK on the back panel that your B2B-1 is correctly set up for your AC power, “117V” is good in all areas with AC power form 100V to 125V and if labeled “ 234V” you can use it with AC power from 220V to 240V, The B2B-1 have adequate internal regulation to ensure proper operation with in the above specified voltage ranges.

Internally the B2B-1 can be configured for either 117V or 234V operation by the removal / insertion of hard soldered jumpers ONLY TO BE PERFORMED BY QUALIFIED PERSONNEL, LETHAL VOLTAGE IS INSIDE THE AMPLIFIER and irreparable damage can happen if not configured correctly.

The B2B-1 is equipped with an AC input socket also containing an AC fuse and a power “on” switch, it should never be necessary to replace the AC fuse if the B2B-1 functions properly in the unlikely event the B2B-1 does not power up, first check that the outlet its connected to is “hot” if so THEN check the fuse, the power cord have to be removed to do this its located in the middle of the inlet, there is a spare fuse there as well - ALWAYS use correct value fuse which is 250 mA for 234V operation and 500 mA for 117V operation.

PLACEMENT
The B2B-1 is a pure class A amplification device so it runs warm, please make sure that you leave adequate space around the amplifier and make sure that you do not cover the ventilation holes on the top cover as well as the ones at the bottom of the amplifier.

Technical Specifications

Input Stage
Gain.................................................20 or 40 dB, Depending on Jumper Setting (MM/MC)
THD@ 20dB gain............................3V/1kHz 0.001%, 3V/10kHz 0.0028%
Max Output Voltage.........................10V RMS
Rise Time @ 20db Gain..................300nS
Equivalent Short circuit input noise..100nV
Current consumption........................40mA

Output Stage
Gain @1khz......................................24 dB 
THD...................................................3V/1kHz 0.001%, 3V/10kHz 0.0015%
Max Output Voltage...........................12V RMS
Rise Time...........................................300nS
Current consumption..........................70mA

RIAA Accuracy.....................................0.1%
Total Current consumption..................130mA (on-board regulators use 20mA)
Dimensions.........................................17 x 10.5 x 3.25 (WxDxH)
Weight, net..........................................11 lbs 
AC input Voltage..................................100V to 240V depending on internal setting
AC Consumption..................................25W

Liberty Audio, www.LibertyAudio.com
 email [email protected], Phone 619 579 6450, FAX 619 579 6451