HEADPHONE AMPLIFIER HPA V281 USERS MANUAL 1
Content Theme Page About Violectric Safety Instructions The Earth / Grounding Concept Connection / Connectors General Block Circuitry Operation Things to know Disposal Technical Data Dismantling Jumper Setting Conformity Statement Warranty 3 5 7 9 10 13 11 24 29 30 31 32 34 35 CAUTION !! THE HIGH OUTPUT LEVELS ACHIEVABLE WITH THIS UNIT MAY DAMAGE YOUR HEARING OR THE HEADPHONES IF OPERATED CARELESSLY !! 2
Cordial thanks for your decision in favour of a product ! is a trademark and product line of Lake People electronic GmbH. Lake People electronic GmbH develops, manufactures and distributes products in the professional range, for broadcast, television, airports, exhibition halls, festival venues, theatres, large-scale installations, private studios and more. In the private sector as well, Lake People products become increasingly popular due to their outstanding quality.
How do devices get to the customer ? devices can be obtained from respective specialist suppliers. If there is none such accessible regionally, the customer is supported by transregional distribution partners (google may help...) and, of course, by Lake People electronic GmbH themselves. … and if it doesn't work like it should ? devices are covered by a 24-month warranty. In case of any malfunction during this period, they can be shipped to the manufacturer directly.
General Safety Instructions WARNING For your protection, please read the following: Water, Liquids, Moisture: This appliance should not be used near water or other sources of liquids. Care should be taken so that objects do not fall and liquids are not spilled into the enclosure through openings. Power Sources: The appliance should be connected to a power supply only of the type described in the operating instructions or as marked on the appliance.
Mains Fuse: The mains fuse of this appliance is soldered in place and accessible from the inside only!! A blown fuse may indicate an internal problem and should be replaced during qualified servicing or repair work !! Switchable Power Supply: Connect this unit to the power source indicated on the equipment rear panel only to ensure safe operation !! This unit is provided with an internally settable mains supply for 115 / 230 V AC.
The Earth / Grounding Concept General GROUND-LIFT Jumper ( accessible from the inside. Mind the SECURITY INSTRUCTIONS !! ): Ex-works this jumper is set to the LIFT position. The internal ground potential is “lifted” by means of this jumper. As a result, the interconnection for DC voltages and lower frequencies (< 150 Hz) will be cut. Higher frequencies will be bled off to earth potential through the RC filter.
hum or jitter caused by different ground/earth potentials. Of coarse full electrical protection is granted as the case is always connected to ground/earth potential ! See page 32 "Technical Appendix" for details. Unfortunately there is no general recommendation how to solve hum and jitter problems - or even minimize them.
Connection / Connectors for Analog Signals 9
GENERAL INFORMATION The HPA V281 is a stereophonic headphone amplifier designed to drive low-, medium- and high-Z loads (16...600 ohms) as usually represented by high-quality headphones. Because of its 4 built in amplifiers and the 4-pin XLR socket on the front it is also suited to connect balanced headphones. Due to its specific, variable and low-noise and distortion circuit design especially optimised for dynamic headphones, the HPA V281 fulfils even highest demands.
With its small dimensions, the HPA V281 ensures optimum flexibility combined with high output power. During design, high emphasis was put on operational safety even when the unit is operated inappropriately. The HPA V281 is equipped with internal filters to prevent damage to the connected headphones due to high-frequency overload beyond the audible range. THE CASE The HPA V281's case as well as the front / rear panels are made of solid aluminium.
MAINS FUSE The 0.25A time-lag fuse is soldered in place on the circuit board. In case, it must be replaced with a fuse of the same type only.
POWER SWITCH The unit is put into operation by means of the power switch. Power-on status is indicated by the blue LED below. The power-on procedure takes about 5 seconds. During this time the LED of the last selected input is flashing and the outputs are muted. Always the last setting is recalled. BALANCED SIGNAL INPUTS The balanced signal inputs are situated on the rear panel of the unit and are labelled as "BAL IN LEFT" and "BAL IN Balanced XLR RIGHT".
UNBALANCED INPUTS For the use with unbalanced signals, gold plated premium RCA sockets are provided. They are labelled as "UNBAL IN LEFT" and "UNBAL IN RIGHT". Input impedance for all inputs is 10 kohms. Maximum input level should not exceed +21 dBu. This value is reduced to +15/+9 dBu if PRE-GAIN is set to +6/+12 dB !! THE OPTIONAL DIGITAL INPUT Currently the HPA V281 can be fitted with one out of six D/A converter types, with three different inputs and a max.
NOTES: - After inserting the USB connector, it may be necessary to close and restart running media applications on the host computer. - Volume of the host application should be set to 100%. INPUT SELECTION / ACTIVATION By means of the “XLR / RCA / DIG“ pushbuttons on the HPA V281’s front panel, either of the analog inputs or the digital input (if present) can be activated. The LED next to the corresponding button will light up accordingly.
THE VOLUME CONTROL The desired volumes for left and right channel are set simultaneously by means of the “VOLUME“ control. Volume can also be set via remote control. For this purpose, the volume control is actuated by a servo motor. Manual operation of the knob at the same time is possible without the risk of damage (although not useful…). Press the rocker button “Volume Up/Down” in order to increase or decrease volume. Pressing “left/right” on the directional pad will have the same effect.
Too loud ? Too soft ? The PRE-GAIN method The V281 is specially designed to drive headphones. Headphones however can present load impedances from 8 to 2000 ohms and efficiency ratios from 85 to 115dB per milliwatt. Thus it can be quite tricky to fulfil all demands, since... … owners of high-efficiency headphones will rarely set the volume control higher than 9 o'clock in order to exclude hearing damage, while ...
DE- / ACTIVATING THE HEADPHONE OUTPUTS The headphone outputs can be activated or deactivated by pressing the “HEAD“ button on the front panel. The green LED displays the activated status. This function can also be switched via remote control. Press „RED“ ( the red button). THE BALANCED HEADPHONE OUTPUT The HPA V281 offers a balanced headphone output. This is equipped with a gold plated female 4-pin XLR connector.
On power-up and power-down, the outputs are cut from the amplifier circuitry by relay. THE BALANCED LINE OUTPUTS are located on the rear panel of the unit and are marked as “BAL OUT LEFT” and “BAL OUT RIGHT”. Gold-plated, metal-flange Neutrik XLR connectors are implemented here. Hint: With a balanced-to-unbalanced adapter this connection may also be used for unbalanced cables. PLEASE NOTE THAT IN THIS CASE PIN 3 HAS TO BE LEFT OPEN ! See also page 9 for details.
THE UNBALANCED LINE OUTPUTS are located on the rear panel of the unit and are marked as “UNBAL OUT LEFT” and “UNBAL OUT RIGHT”. Gold-plated premium RCA connectors are implemented here. ACTIVATING / DEACTIVATING THE LINE OUTPUTS The line outputs can be activated and deactivated by means of the “LINE“ pushbuttons on the front panel. The green LED indicates the activated status.
PLEASE NOTE: It is generally possible to use the unbalanced and balanced outputs simultaneously, but slight sound deterioration might occur depending on the following devices connected. In order to ensure optimal sound quality, only one output type should be made use of at a time. Switching between “Pre“ and “Post“ is effected via software: Press and hold the “LINE“ pushbutton for about two seconds until the green LED starts flashing.
Muted status is indicated by the red “MUTE“ LED. The activated / deactivated status of the amp´s outputs however - as indicated by the green LEDs - remains unchanged ! ERROR EVALUATION In order to guarantee flawless operation and optimum protection of your valuable headphones, the V281 is equipped with various protection circuits: - the delayed activation of the headphone outputs upon power-up prevents your headphones from potentially adverse signal peaks from the preceding circuitry.
Things to know … Why makes it sense to make such huge efforts ? A headphone amplifier is a device designed to condition audio signals with regard to the very specific requirements of headphones. This doesn't sound too spectacular at the first glance and can be achieved relatively easily. As with many things however, the devil is in the details and much more effort is required to design one amplifier for all current headphone models.
difference between the interference contents: (s) – (s) = 0. Thus - in an ideal situation - all interference on the signal path is eliminated. Why are discrete signal paths important ? Twin op-amps are the most common design for operational amplifiers, i.e. two amplifier circuits are integrated in one device. If left- and rightchannel signals are processed simultaneously by such a device, interaction between both cannot be excluded.
reduced by 12 dB (a fourth), with 0,5 V instead of 2 V input as the result. This 0,5 V is again amplified by 4.5, then equalling 2.25 V. Now the volume control can be turned over almost the entire range. 2nd example:: The (pre-) amplifier provides 1 V, whereas the headphone requires 20 V to release 120 dB of sound pressure. With the volume control fully clockwise, the V281 would provide 4.5 V at +14 dB gain only - much too low for the headphone.
Conductive-plastic resistive tracks, high-quality multi-tap wipers and separated chambers for the individual sections are highly desirable for sophisticated applications, and high quality is inevitable to ensure trouble-free operation for years. Since the market for really good pots is a small one, manufacturers like Noble or Panasonic don't offer these any more. A current sample of top of the line pots is the RK27 by ALPS, which is also used in your HPA V281.
“standard” amps. Why does a relay make sense when switching power ? Amplifiers generate unwanted output signals when applying or removing power, which can damage the connected headphones. The relay breaks the connection between amplifier and headphone and thus protects the latter until electrical conditions have stabilized. Some words about the different digital input options. At the moment there are 6 different digital inputs for the V281.
Why does 100% host volume setting make sense ? Volume control within the host is always accomplished digitally, i.e. bits are removed from the data stream. This may affect the signal quality because the resolution will become lower and the distortions may rise.
TECHNICAL DATA HPA V281 All Measurements RMS unwtd., 20 Hz - 20 kHz, Pre-Gain set to 0 dB Inputs: Max.
Dismantling / Jumper Setings Please note: In the following, the internal settings of the HPA V281 are discussed. For changing these, a TORX T10 screwdriver or a 3mm Allen Key is required and you should by all means PULL THE MAINS PLUG !!! Only thereafter the settings can be altered without any hazard. Dismantling 1. screw off both upper screws on the front panel 2. screw off both upper screws on the back panel. 3.
JUMPER SETTINGS HPA V281 32
JUMPER SETTINGS HPA V281 33
EU CONFORMITY STATEMENT: We herewith declare that the following unit Name: VIOLECTRIC HPA V281 Serial No.
WARRENTY Since 1986 we are constructing and manufacturing sophisticated electronics for ambitious customers. Since the early beginnings we are trying hard by accompanying measures, the use of 1st choice components and multiple quality checks during production to avoid faults at large. We are quiet effective in that and this is – amongst others - why we enjoy such a good reputation. Despite all accurateness faults may appear which may derogate the proper operation of your product.
Additional gear from HEADPHONE AMPLFIERS: HPA V90 HPA V100 HPA V181 HPA V200 HPA V220 HPA V281 D/A CONVERTER: DAC V800 PHONO PRE-AMPLIFIER: PPA V600 LINE PRE-AMPLIFIER: PRE V630 36
