Cello Chorale preamplifier Owners manual
Thank you for choosing the Cello Chorale preamplifier Your Chorale has been individually made, entirely by hand, from the finest parts and materials available. The Chorale utilizes proprietary circuitry and processes, developed by Matthew James’ Showroom, L.L.C., that represent true state of the art in audio electronics. The Chorale contains the most recent thinking in analog interface circuitry. It offers sonic performance and reliability, and a great deal of flexibility.
WARNING: TO REDUCE THE RISK OF FIRE OR ELECTRIC SHOCK, DO NOT EXPOSE THIS COMPONENT TO RAIN OR MOISTURE. RISK OF ELECTRICAL SHOCK DO NOT OPEN CAUTION: TO REDUCE THE RISK OF ELECTRICAL SHOCK, DO NOT REMOVE COVER. NO USER-SERVICEABLE PARTS INSIDE. REFER SERVICING TO QUALIFIED PERSONNEL. Marking by the “CE” symbol (shown left) indicates compliance of this device with the EMC (Electromagnetic Compatibility) and LVD (Low Voltage Directive) standards of the European Community.
Product Concept and Description In the 17th and 18th centuries, Italian master instrument makers developed and virtually perfected what we regard today as the modern string instruments. The name, Cello, embodies the spirit and concept of our products. We are dedicated to furthering the art of music reproduction by designing and building equipment of only the very highest quality, in limited quantities, by hand.
The second level is a second motherboard that contains precision parts and circuit wiring. The active circuitry is built on individual boards that make up the third level of circuitry and mount on standoffs made from extremely pure copper flashed with silver through which the signal flows to and from the various boards. This practice minimizes any losses and distortions of the signal, while improving contact reliability.
are preserved and the exact location of every performer is discernable. Even the most complex musical passages are reproduced effortlessly, retaining the most delicate nuances. This level of performance is only attained by combining advanced technology with a purist’s approach to design and execution.
Installation Be certain that the Chorale preamplifier and Master power supply are installed so that they have proper ventilation. The ambient temperature should not exceed 122 degrees F (50 degrees C). Check to make certain that the Master power supply is set to be used at the voltage available in your installation.
The balanced output contains four individual, discrete amplifiers for the plus and minus signals for each channel, providing Class A, symmetrical output to drive power amplifiers with balanced inputs. There are also two pairs of fixed outputs, both via RCA connectors. These can be connected to the input of a recording device, or as an input to an audio processor, or to another system.
LEVEL: Centered on the face plate is the output level control. The output level is at its lowest position, no variable output, when the indicator line is centered at the bottom of the knob. Output level is variable between lower than -40dB of the source signal at the softest level and greater than +10dB of the source signal at the loudest level. Only the highest quality parts are used throughout the Chorale preamplifier and it contains many parts not found in any other preamplifier on the market.
This preamplifier has been set to 0dB of gain in the balanced input section and is provided with 10kOhms loading for both the + input impedance and the – input impedance of this signal. This is how most users will connect a source with a balanced signal to perform to its full potential with the Chorale. Instructions for making changes to these settings are contained at the end of this Owner’s Sheet.
Service If you believe your Cello Chorale preamplifier is not functioning properly, please contact your dealer / distributor. If you need to return your component, you will be given a Return Authorization Number (RA#). This number must appear on the outside of the shipping carton. Returns without RA#s will not be accepted. Returns received in original packing material will be returned in original packing.
Warranty of Repair Work Performed Any specific repairs or modifications effected by Matthew James’ Showroom, or authorized service facility, shall be guaranteed for 100% parts and labor for the remainder of the original warranty period for this particular unit, or (1) one year, whatever is longer.
INTERMODULATION DISTORTION, the Upper Limit (U) is 0.03%: Typical measurements are 0.0150%. CCIF, the Upper Limit (U) is 0.1%: Typical measurements are 0.0330%. Channel Crosstalk, the Upper Limit (U) is -45dB: Typical measurements are -53.5dB. 3) For the Balanced Input we check the same parameters: GAIN with the Lower Limit (L) at 0.0dB and Upper Limit (U) at 0.4dB: Typical measurements are 0.2739dB. INTERMODULATION DISTORTION, the Upper Limit (U) is 0.0050%: Typical measurements are 0.0025%.
Making Changes to the Phono and Balanced Input Settings The chasses of the Chorale preamp and Master power supply are manufactured with heavy aluminum plates on all six sides. In order to reduce the deleterious effects of vibration, each individual piece is securely connected to those pieces adjacent. However, the tops/faces/sides assembly connects to the bottom/back assembly, and so the tops/faces/sides assembly needs to be removed from the bottom/back assembly in order to access the internal switches.
BALANCED INPUT: There is one switch for each left and right channel in the balanced input section, with two on/ off rockers each, mounted to motherboard two, inside the Chorale at the left rear. This switch is labeled, on motherboard 2, as SW3. When a balanced line level source signal is connected to the Balanced input (XLR to XLR connectors on the cable) of the Chorale, a 10kOhms load for both the + input impedance and the – input impedance is provided for this signal.
Cello products are designed and built by hand in Connecticut, USA by Matthew James’ Showroom, L.L.C. 84 Long Hill Road Middlefield, CT 06455 Phone 860 349-5999 Email jimm@matthew-james.
