Related Manuals for Bandwidth Audio 22A3
Summary of Contents for Bandwidth Audio 22A3
- Page 1 22A3 Monaural Amplifier Owner’s Manual www.bandwidthaudio.com sales@bandwidthaudio.com...
- Page 2 With the volume turned all the way down, the bias should be set between: 50 - 60mA. This current can be read directly off of the 2 analog meters on the back of the amplifier after power on and warm up. See Section 3.3 – Biasing. 22A3 Monaural Amplifier Rev 1.0...
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Page 3: Amplifier Setup
Never turn on your amplifier without speakers connected to the proper output load impedance. Operation of the amplifier without a speaker load or open circuited loudspeaker voice coil can permanently damage the output transformers as well as other major components. 22A3 Monaural Amplifier Rev 1.0... -
Page 4: Powering On And Off
This amplifier is designed to drive a speaker load to its full rated output power based on typical line level input signals via the RCA connector on the back. Depending on the input source components, an additional preamp may be needed to achieve full output power. See Section 3.4 – Typical Specifications. 22A3 Monaural Amplifier Rev 1.0... -
Page 5: Controls And Layout
A stepped attenuator eliminates noise during rotation and also maintains volume balance between a pair of amplifiers driving separate speakers. Due to its construction, the volume knob will click into each slot, giving precise volume control. 22A3 Monaural Amplifier Rev 1.0... - Page 6 This can damage speakers rated close to the amplifier’s maximum RMS output power. 3. Power Switch The power switch is used to turn the amplifier on and off. On is in the up position, and Off is in the down position. 22A3 Monaural Amplifier Rev 1.0...
- Page 7 Fuse is in series with V3 and V4 output tubes to protect the output transformers and other circuitry from a shorted or bad tube. If blown, check performance of the output tubes before replacing the fuse to prevent damage from a failed tube. 22A3 Monaural Amplifier Rev 1.0...
- Page 8 See Section 1.2 – Setting the Load Impedance. 11. Input RCA line level input jack designed to accept audio signals from common See Section 1.4 – Input Setup. audio components. 22A3 Monaural Amplifier Rev 1.0...
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Page 9: Top Features
“Closed Loop” Mode for operating the amplifier with feedback. Closed Loop Mode is suggested for higher output power close to the amplifier’s rated output. This will reduce distortion (THD + N) and help to maintain linearity. 22A3 Monaural Amplifier Rev 1.0... - Page 10 This is tuned from the factory with the output tubes provided for lowest noise. If 60-cycle hum is auditable, adjust this with screwdriver. This stetting will directly impact the SNR and background noise of the amplifier. 22A3 Monaural Amplifier Rev 1.0...
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Page 11: Technical Information
3.2 Replacing Tubes Vacuum tubes should be replaced when a lack of power becomes apparent. Dynamics and transients may seem lazy and less crisp compared to how they sounded when new. Under extreme 22A3 Monaural Amplifier Rev 1.0... - Page 12 Preamp tubes V1 and V2 should also be tightly matched between channels. Using matched tubes ensures that the signal level is identical between amplifier channels in a stereo configuration. This is critical in the 22A3 amplifier due to the lack of negative feedback. 22A3 Monaural Amplifier Rev 1.0...
- Page 13 All tubes from Bandwidth Audio are matched in this fashion. 3.3 Biasing Your amplifier has been biased from the factory. However, the bias setting should be checked on first startup and periodically thereafter to maintain performance as well as longevity of the power tubes.
- Page 14 This can be so excessive that the glass envelope of the tube melts! If red plating occurs, turn off the amplifier immediately and let it cool completely. Then turn it back on and quickly re-bias if the ammeters overshoot the 53mA bias target. 22A3 Monaural Amplifier Rev 1.0...
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Page 15: Typical Specifications
SNR 1-Watt into 8ohms (600-ohms source impedance, volume set to maximum) -90dB A-Weighted Open Loop -91dB A-Weighted Closed Loop SNR 5-Watts into 8ohms (600-ohms source impedance, volume set to maximum) -95dB A-Weighted Open Loop -96dB A-Weighted Closed Loop 22A3 Monaural Amplifier Rev 1.0... - Page 16 1x 6SL7, 1x 6SN7 Rectifier Tube GZ34 Power Consumption 100 Watts Dimensions 20” x 13” x 9.5” Due to the open loop design of this amplifier, actual performance will vary depending on vacuum tube quality. 22A3 Monaural Amplifier Rev 1.0...
- Page 17 V4_____________ Date: __________________ Bias Current: V3______________ V4_____________ Date: __________________ Bias Current: V3______________ V4_____________ Date: __________________ Bias Current: V3______________ V4_____________ Date: __________________ Bias Current: V3______________ V4_____________ Notes: ___________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ 22A3 Monaural Amplifier Rev 1.0...