Wheatfield Audio HA-4 Headphone Amplifier Users Manual DRAFT 2/17/00 Wheatfield Audio LLC Andale, Kansas USA www.headphoneamp.
Contents Contents....................................................................................................... 2 Important Information................................................................................ 3 Power requirement: .......................................................................................... 3 Fuse type: ........................................................................................................... 3 HA-4 Headphone Amplifier - Front Panel ............
Important Information ! CAUTION: For protection against electric shock, do not open covers. No user-serviceable parts inside. Refer servicing to qualified personnel. Replace fuse only with same type and rating. Before connecting AC power, ensure that the voltage selector switch is set correctly for your local power. Power requirement: 100-135 -or- 200-250 VAC, 50-60 Hz Fuse type: IEC 127/III 250V 0.
HA-4 Headphone Amplifier - Front Panel +8dB +4dB +12dB +8dB +4dB +12dB +8dB +4dB +12dB Wheatfield Audio HA-4 Wheatfield Audio HA-4 Users Manual -4-
HA-4 Headphone Amplifier - Front panel controls POWER ON LED This YELLOW LED is on whenever AC power is applied OUTPUT ON LED This GREEN LED is lit when the output is turned on VOLUME CONTROL Controls the gain of the amplifier, and hence the loudness of the sound heard in the headphones CROSSFEED SWITCH Selects the amount of inter-channel crossfeed between the Left and Right channels as follows: No crossfeed - full stereo Light crossfeed - a small amount of signal is fed between channels Medium crossfee
HA-4 Headphone Amplifier - Rear Panel OUT I LC UDIO L FIELD A m WHEAT eamp.co LIFIER adphon NE AMP www.he ADPHO HA-4 HE MODEL USA MADE IN OFF O AC INPU T 90-135V 200-250V 50-60 10 W VOLTAG E SELEC T 115V 90-135V = 115V 200-250V = 230V Wheatfield Audio : ON POWER CAUTION FUSE 0.2 A 250 VS IEC 127-2/ III R ! L ENSURE VOLTAG E SELEC CORREC T SWITC TLY BEFO H IS SET RE CONN REPLAC ECTING E FUSE W POWER. ITH SAM TO PREV E TYPE A ENT ELE ND RATI CTRIC S COVERS NG.
The HA-4 Headphone Amplifier The Wheatfield Audio HA-4 is a audiophile-quality solid-state headphone amplifier, designed to solve a number of the issues faced by the home headphone listener.
Connecting your HA-4 Power IMPORTANT: Before you connect the power cord to the HA-4, make sure that the voltage selector switch is set correctly for your local power. If you are in North America, Japan, or anywhere else that your line voltage is between 100V and 135V, set the voltage selector to "115". If you are in Europe, or anywhere else where the voltage is 200-250V, set the voltage selector to "230". If you set the voltage selector incorrectly, one of two things will happen.
Using your HA-4 After connecting your HA-4, you're ready to listen. Start with the volume control all the way down (counterclockwise), and the EQ controls and crossfeed selector all at mid-range. When you turn on the power (with the power switch, located on the back next to the cord), the yellow POWER ON LED will illuminate.
The HA-4 controls in detail The Volume Control The volume control adjusts the listening level by attenuating the signal before the main power amplifier. By doing so it controls the overall gain of the amplifier. The EQ controls The three EQ controls adjust how much the level of the audio signals in each of the three frequency ranges is boosted. The three center frequencies - 90 Hz, 2.
Specifications Frequency Response (filters bypassed): 10Hz - 30kHz +/- 3 dB THD (1kHz, 1V RMS out, filters bypassed): <.01% Noise: < 10mV RMS Maximum output voltage: 35V P-P (12V RMS) Maximum output current: 250 mA Peak Maximum continuous output power: 1W @ 32 ohm load; 0.5W @ 600 ohm load Output impedance: 2.5 ohms EQ response plot 12 Bypass EQ Min (CCW) EQ Mid EQ Max (CW) 10.5 9 Response dB 7.5 6 4.5 3 1.5 0 -1.5 -3 -4.
Serial Number ____________________________________ Purchase date____________________________________ Wheatfield Audio LLC Andale, Kansas USA www.headphoneamp.
