HEADPHONE AMPLIFIER HPA V181 USER´s MANUAL 1
Content Theme Page About Violectric Safety Instructions The Earth / Grounding Concept Connection / Connectors General Operation Things to know Dismantling / Jumper Settings Disposal Technical Data Conformity Statement Warranty 3 5 7 9 10 11 19 26 27 30 31 32 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. The LIFT position is helpful in case of hum or jitter caused by different ground/earth potentials.
Unfortunately there is no general recommendation how to solve hum and jitter problems - or even minimize them. The best way to succeed is to check different options !! In case of balanced cables, it should always been verified if the shield of the cable is connected to the shell of the XLR connector. The shell is ALWAYS connected to earth potential when the connector is inserted !! Concerning ANALOG inputs and outputs, the relationship between ground and earth may be modified.
Connection / Connectors for Analog and Digital Signals 9
GENERAL INFORMATION The HPA V181 is a stereophonic headphone amplifier designed to drive low-, medium- and high-Z loads (16...600 ohms) as usually represented by high-quality headphones. V181 contains four amplifiers (2 x stereo) to enable proper driving of balanced headphones. Due to its specific, variable and low-noise and distortion circuit design especially optimised for dynamic headphones, the HPA V181 fulfils even highest demands.
THE CASE The HPA V181's case as well as the front/rear panels are made of solid aluminium. This choice of material ensures high mechanical stability and resistance. EARTH AND GROUND The HPA V181's case is grounded. Internal reference ground is bridged to protective earth by means of a jumper. If required, the jumper can be set to 'LIFT' position (see also: page 7 "Earth/Ground concept", page 28 "Technical Appendix").
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 RIGHT". They are fitted with XLR sockets. Please note: Unbalanced signals can be injected as well by means of an adaptor. Also see page 9. Balanced XLR pinout: PIN 1 GND PIN 2 (+) PHASE PIN 3 (-) PHASE UNBALANCED INPUTS For the use with unbalanced signals, cinch sockets are provided.
Cinch sockets as inputs: The cinch sockets are factory-preset as inputs and are equipped with integrated switch contacts ! When a cinch plug is inserted, it cuts possible signals applied to the balanced input automatically. I.e. the cinch input has priority. 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 !! Cinch socket as outputs: The cinch sockets can also be operated as outputs.
The OPTO input is made according to the TOS-Link standard and is waiting for digital PCM audio data with a sample rate between 28 … 108 kHz. The USB type-B inputs on can be used to connect a host computer (desktop or laptop PC). The headphone amp will be automatically detected as an audio device. The USB input is 1.1- and 2.0-compatible. Audio files stored on the host can be sent to the headphone amp, whereas audio formats 24 bit with 44.1, 48 or 96 kHz are supported.
... the maximum setting may still be too soft for low-efficiency headphones, but … all users expect highest quality at lowest noise and distortion. Thus, the circuitry must adapt itself as the headphone won't ! WE CALL THE SOLUTION TO THIS PROBLEM PRE-GAIN The alignment between amplifier and headphone is provided by the preamp stage, which can boost or attenuate the input signal in four steps of 6dB each.
If you find your HPA V181 should provide more gain, do so with the switch labelled "+6 dB" (double gain) or "+12 dB" (quadruple gain). Ex-factory, all switches are set to their lowest position - i.e. 0 dB or unity gain - which should be sufficient for most applications. OPERATION Most control elements and indicators are located on the front panel. 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 individual-channel design provides optimum crosstalk rejection. The amplifier's frequency range stretches from DC to over 200kHz (-3dB cutoff frequency) in order to obtain absolutely linear characteristics within the audible range. Overall gain is set to +8 dB in order to provide sufficient reserves also for high-impedance headphones. THE BALANCED HEADPHONE OUTPUT The HPA V181 offers a balanced headphone output. This is equipped with a gold plated female 4-pin XLR connector.
Please note: the RIGHT phone jack is connected to the in-phase stereo signal, whereas the left phone jack is connected to the 1800 phase shifted signal. On power-up and power-down, the outputs are cut from the amplifier circuitry by relay. ALTERNATIVE BALANCED HEADPHONE CONNECTION The phone jacks sockets of HPA V181 may be configured by means of internal jumpers to provide balanced operation with two phone jack. To configure the the sockets please refer to page 29 technical Appendix".
Things to know … The HPA V181 offers balanced and unbalanced inputs. Which advantages do balanced signals offer ? In contrast to unbalanced signals, balanced signals are carried by two wires (plus ground/shield). In the transmitting device, a balanced signal is created by generating an inverted original signal (180ˆphase shifted). The "hot" wire carries the original signal (a), the "cold" wire the inverted signal (-a).
Why are op-amps ideal for low-level signal processing ? Discrete amplifiers (designed with transistors) are very popular in highend audio design also for preamplifier stages. This is often marketed as an optimization measure, but the partially exorbitant extra expenses are of course to be paid by the customer. But an op-amp consists of transistors as well... Moreover, its structure has the advantage of thermal coupling between its internal components. Also ageing issues play a much less important role.
Your HPA V181 may provide a USB input as an option. It has priority over all the other inputs and mutes these when a valid input signal is detected. Since the HPA V181 is a terminal device after USB regulations, it has a type-B interface. Which USB devices can be connected to the HPA V181 ? Connections can be established to tabletop or laptop PCs. MP3 players or similar gear cannot be connected.
The HPA V181 is DC-coupled, i.e. it can transduce DC voltage as well. For good measure, a low-cut filter can be inserted by setting the corresponding jumpers. After input buffering, the signals are forwarded to a simple 6dB-per-octave filter stage which can be set to two characteristics: AC (12 Hz), or DC (0 Hz). Why does frequency bandwidth limiting make sense ? In signal processing, sound is represented by AC voltages. Sound is audible - for young people - from about 20 to 20000 Hz.
The pot is followed by the power amplifier, which is made with special operational amplifiers which are famous for their power and their transmission speed. To enable balanced operation, each stereo channel is equipped with two amplifiers. These are operated at +/-18V supply voltage. Overall gain is set to 8dB (factor 2.5). In balanced mode this amplifier delivers one of the highest voltage swings available which is useful for high impedance phones.
Headphones per se are quite diverse, and there are two essential parameters: impedance and sensitivity. In general, headphones with higher impedance can be regarded as less sensitive than headphones with low impedance (which is not generally true, but in the majority of cases). The sensitivity of headphones is usually stated in dB (sound pressure level) per milliwatt.
And thus a fast transient can easily push an average amplifier with +/-15 volts supply to its limits. Due to two amplifiers per stereo channel and the balanced “push-pull” operation, V181 offers double as high output voltage compared to normal unbalanced equipment. The headphone outputs are disconnected by relay during power-up / power-down.
DISMANTLING / JUMPER SETTINGs Hint: Here we are talking about internal adjustments inside your HPA V181. You are in need of two screw drivers TORX style size T8 and T10. You should by all means PULL THE MAINS PLUG !!! Only thereafter the settings can be altered without any hazard. DISMANTLING As the 4-pin XLR socket is fixed to the back side of the front panel, the front panel may NOT be disassembled !! To avoid damages please follow the instruction below: 1.
Towards the low end, your HPA V181's frequency response is not restricted at all. This means that even extremely low frequencies - right down to DC - will be amplified. "DC-coupling" as this technique is called, is not necessarily useful since neither DC nor very low frequencies are audible, but may damage your headphones on the other hand. Therefore, the HPA V181 offers a low-frequency limiting option as well.
JUMPER SETTING HPA V181 28
ALTERNATIVE BALANCED HEADPHONE CONNECTION Both phone jacks sockets of HPA V181 situated left and right from the balanced connector are configured to match “normal” unbalanced jacks ex works. (see page 17) By means of internal jumpers these sockets may provide balanced operation with two phone jack.
TECHNICAL DATA HPA V181 All Measurements RMS unwtd., 20 Hz - 20 kHz, Pre-Gain set to 0 dB, Highpass active Inputs: Max. Input Voltage: Input Impedance: Buffered Outputs: Nominal Input Sensitivity: Amplifier Overall Gain: Overall Gain with PRE-GAIN: Frequency Range: Damping Factor: Dynamic Range: Noise: THD+N (1kHz/2x10V/100R = 1W) THD+N (1kHz/2x4V/32R = 0,5W) Crosstalk: Headphone Outputs: Max. Output Level: (1kHz / < 0.
EU CONFORMITY STATEMENT: We herewith declare that the following unit Name: VIOLECTRIC HPA V181 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 occure which may derogate the proper operation of your product.
