Alpha VHD Pre - Receiver Solid State Logic - Free user manual and instructions

Product Type	Microphone preamplifier with Variable Harmonic Drive (VHD)
Dimensions (W x D x H)	482 mm x 230 mm x 44.5 mm (with rack ears)
Weight	2.6 kg (unit only)
Power	100-240 VAC, 50-60 Hz, <20 W, via external IEC320 power supply
Inputs	Balanced XLR microphone (1 kΩ / 10 kΩ in Hi-Z), Instrument 6.35 mm jack (1 MΩ), Line via 20 dB Pad
Outputs	Balanced XLR, max output level +24 dBu
Input gain range	+20 dB to +75 dB
Output gain range	±20 dB
Main functions	Hi-Z switching, 20 dB Pad, +48 V phantom power, Variable Harmonic Drive (2nd and 3rd harmonic)
Safety	Do not open the device, refer all repairs to qualified personnel
Maintenance and cleaning	Clean with a dry cloth only
Warranty	12 months against defects in materials and workmanship
Repairs	Contact your dealer or Solid State Logic with a valid RMA number
Power connector	3-pin IEC320, external power supply included
Operating temperature	+5 °C to 30 °C
Operating relative humidity	20% to 80% (non-condensing)

Frequently Asked Questions - Alpha VHD Pre Solid State Logic

How to use the Variable Harmonic Drive (VHD) function?

The VHD control allows adding variable harmonic distortion. Turn it from '2' (second harmonic, warm) to '3' (third harmonic, aggressive). The input level and gain influence the effect. Use the 20 dB Pad for strong signals.

What is the difference between the microphone input and the instrument input?

The microphone input is on balanced XLR with an impedance of 1 kΩ (or 10 kΩ in Hi-Z mode). The instrument input is on unbalanced 6.35 mm jack with an impedance of 1 MΩ, automatically activated when a jack is inserted.

How to connect the Alpha VHD Pre power supply?

Use the external power supply provided with an IEC320 cable. Connect the 5-pin DIN connector at the back of the unit. The mains socket must be easily accessible. Disconnect during thunderstorms or prolonged non-use.

What to do if the input is saturated?

The Pad button turns red when the input saturates. Enable the 20 dB Pad to reduce the input level. You can also lower the input gain. Saturation is normal with the VHD circuit, but avoid it for a clean signal.

How to clean the device?

Clean the device only with a dry cloth. Do not use liquids or chemicals. Disconnect power before cleaning.

Can I open the device to repair it?

No, the device contains no user-serviceable parts. Opening voids the warranty. Refer all repairs to qualified personnel.

What is the warranty of the Alpha VHD Pre?

Solid State Logic offers a 12-month warranty against defects in materials and workmanship from the date of purchase. Keep the original invoice as proof of purchase.

How to obtain warranty repair?

Contact your dealer or Solid State Logic to obtain an RMA number. Return the device in its original packaging with proof of purchase. Do not include the power cable or manual.

What cables are included with the device?

The package contains the Alpha VHD Pre unit, an external power supply and a power cable suitable for your region. The installation manual is also included.

How to use the line input with the Pad?

For line level signals, activate the Hi-Z switch to set impedance to 10 kΩ and enable the 20 dB Pad to avoid saturation. Adjust the input gain accordingly.

USER MANUAL Alpha VHD Pre Solid State Logic

Safety and Installation Considerations

This section contains definitions, warnings, and practical information to ensure a safe working environment.

Please take time to read this section before installing or using this unit. Please do not dispose of these instructions.

General Safety

- Read these instructions.

- Keep these instructions.

- Heed all warnings.

- Follow all instructions.

- Do not use this apparatus near water.

- Do not expose this apparatus to rain or moisture.

- Clean only with dry cloth.

- Do not block any ventilation openings. Install in accordance with the manufacturer's instructions.

- Do not install near any heat sources such as radiators, heat registers, stoves or other apparatus (including amplifiers) that produce heat.

- There are no user-adjustments, or user-servicable items, inside this apparatus. Do not remove the covers of this apparatus; doing so will invalidate your warranty.

- Refer all servicing to qualified personnel. Servicing is required when the power supply has been damaged in any way, liquid has been spilled or objects have fallen into the apparatus, the apparatus has been exposed to rain or moisture, does not operate normally or has been dropped.

- Adjustments or alterations to this apparatus may affect the performance such that safety and/or international compliance standards may no longer be met.

Power Safety

• This apparatus is supplied with a universal power supply, approved and certified for operation in this apparatus. There are no user-replaceable fuses.
• A power cord is supplied with this unit. Alternative power cords may be used if rated 2.5A or above and fitted with a 3-pin IEC320 connector.
• Use only the Solid State Logic provided power supply. Use of any other power supply is not covered by your warranty and may cause fire or explosion.
• Any external power supply may become hot during normal operation of the unit. Use care when handling the power supply.
• Do not attempt to modify the power supply unit in any way.
• If an extension power cable or adaptor is used, ensure that the total power rating of the power cable and/or adaptor is not exceeded.
• The power socket used for this apparatus should be located nearby and be easily accessible.
• Unplug this apparatus during an electrical storm or when unused for long periods of time.

stallation Notes

• When installing this apparatus, place the apparatus on a secure level surface.
• Ensure that no strain is placed on the cables connecting to this apparatus. Ensure also that such cables are not placed where they can be stepped on, pulled or tripped over.
• Do not operate this apparatus whilst it is covered or boxed in any way.
• Do not operate this unit with the covers removed. Performance may be adversely affected.

1. Un-pack

Your Alpha VHD Pre box should contain the following:

The Alpha VHD Pre Unit

* The cord supplied will be correct for the territory where Alpha VHD Pre is purchased

Installation Guide (this document)

2. Connect

Rear Panel Connections
	5-pin 180° DIN 3-pin XLR-F 3-pin XLR-M
Pin 1 0V 0V 0V
Pin 2 0V +ve +ve
Pin 3 +5V -ve -ve
Pin 4 -15V
Pin 5 +15V

Front Panel Connections
Instrument 1/4"	Mono Jack
Tip Signal
Sleeve 0V

3. Play!

Input Switches

Hi Z Switches Mic Input impedance from 1kΩ to 10kΩ. Use with PAD for Line Level inputs.

PAD Fixed 20dB attenuation for high level signals. Glows 'red' when input is in 'overload' condition.

48V Switches +48V ('phantom power') to the Mic Input. Always switch OFF before connecting/dis-connecting microphone.

Input Gain

Provides +20dB to +75dB gain

Output Gain

Provides ±20dB of adjustment

Power/Standby

Bright when unit is on, dim when in standby

Instrument

Mono 14 " Jack for high impedance Instrument Input. Inserting a jack will automatically select this input in place of the standard microphone input (on the rear of the unit).

Variable Harmonic Drive™

Adds level dependent colouration; initially warm 2^nd harmonic then more aggressive 3^rd harmonic (see opposite)

Using VHD

VHD – Variable Harmonic Drive ^™ – allows a signal (microphone or line) to be over driven from subtle harmonic colouration through to full on distortion. The level of the incoming signal will have an affect on the VHD circuit, as will the PAD button which offers 20db of gain reduction for loud signals, allowing the Alpha VHD Pre to work with line as well as microphone level signals.

Each Alpha VHD Pre input features a control labelled 'VHD' with a range of adjustment indicated as 2^nd to 3^rd . Adjusting the VHD control changes the character of the added distortion from predominately 2^nd harmonic to almost entirely 3^rd harmonic when fully clockwise; interesting blends between the two can be achieved at intermediate settings. The character of 2^nd harmonic distortion is akin to the warmer sound produced by overdriven valves whilst 3^rd harmonic distortion is associated with the harder, brighter sound achieved from solid state devices.

The VHD control will have a far more noticeable effect at higher gain settings so the input gain should be used in combination with the VHD control to affect the amount of distortion being added to the input signal. The PAD button will glow red when the input stage is starting to overload; the VHD circuit is designed such that this is part of the normal operation, though this should be avoided for a cleaner signal.

An over driven pre-amp may obviously have an effect on the gain of all parts the signal chain which follow the unit and the output gain may need to be taken down to interface correctly with other equipment. The output level control makes this adjustment a simple process.

FCC Notice

This equipment has been tested and found to comply with the limits for a Class A digital device, pursuant to part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference when the equipment is used in a commercial environment. This equipment generates, uses, and can radiate radio frequency energy and, if not installed and used in accordance with the instruction manual, may cause harmful interference to radio communications. Operation of this equipment in a residential area is likely to cause harmful interference in which case the user will be required to correct the interference at his own expense.

Instructions for Disposal of WEEE by Users in the European Union

The symbol shown here is on the product or on its packaging, which indicates that this product must not be disposed of with other waste. Instead, it is the user's responsibility to dispose of their waste equipment by handing it over to a designated collection point for recycling of waste electrical and electronic equipment. The separate collection and recycling of your waste equipment at the time of disposal will help to conserve natural resources and ensure that it is recycled in a manner that protects human health and the environment. For more information about where you can drop off your waste equipment for recycling, please contact your local city office, your household waste disposal service or where you purchased the product.

Standards Conformance

This apparatus fully conforms with the current protection requirements of the European community council directives on EMC and LVD.

Warranty

This product is warranted against failure resulting from faulty materials or workmanship for a period of 12 months from date of purchase.

In Warranty Repairs

In the event of a fault arising during the warranty period, please contact your local dealer or distributor who will arrange either for repair or replacement as appropriate (a list of dealers and distributors can be found on the Solid State Logic website: www.solid-state-logic.com). Note that no units will be accepted for repair by Solid State Logic unless accompanied by a valid RMA number, obtainable from Solid State Logic prior to shipping. All units should be shipped to Solid State Logic in their original packaging. Solid State Logic cannot be held responsible for any damage caused by shipping units in other packaging. In such cases Solid State Logic will return the unit in a suitable box, which you will be charged for. Do not include the power cable, manual or any other items – Solid State Logic can not guarantee to return them to you. Please also note that warranty returns will only be accepted as such if accompanied by the original receipt or other proof of purchase.

Out of Warranty Repairs

In the event of a fault arising after the warranty period has expired, return the unit in its original packaging to your local distributor for shipment to Solid State Logic. You will be charged for the time spent on the repair (at Solid State Logic's current repair rate) plus the cost of parts and shipping. Note that no units will be accepted for repair unless accompanied by a valid RMA number, obtainable from Solid State Logic prior to shipping.

Specifications

Physical \*

Depth 230mm / 9" casing only

Height 44.5mm / 1.75" (1 RU)

Width 438mm / 17.25" casing only

482mm / 19" inc' rack ears

Weight 2.6kg / 6 pounds

Power < 20 Watts

Boxed size 320mm x 550mm x 80mm

12.75" × 21.75" × 3.25"

Boxed weight 3.5kg / 8 pounds

* All values are approximate

Environmental

Temperature Operating: +5 to 30 deg. C

Non-operating: -20 to 50 deg. C

Max. gradient: 15 deg. C/hour

Relative Operating: 20 to 80 %

Humidity Non-operating: 5 to 90%

Max. wet bulb: 29 deg. C

(non-condensing)

Vibration Operating: < 0.2 G (3 - 100Hz)

Non-operating,

power off: < 0.4 G (3 - 100Hz)

Shock Operating: < 2 G (10ms max.)

Non-operating: < 10 G (10ms max.)

Altitude Operating: 0 to 3000m

(above sea level) Non-operating: 0 to 12000m

Connections

Power Supply IEC320 3-pin connector, 100 - 240 Vac, 50 - 60 Hz

Analogue I/O

Microphone Balanced, 3-pin XLR-F, Zin = 1kΩ (10kΩ for Hi Z)

Instrument Un-balanced, 3/4" Mono Jack, Zin = 1MΩ

Output Balanced, 3-pin XLR-M, Zo = 40Ω

Power 5-pin 180° DIN connector, +5Vdc, ±15Vdc

Der Alpha VHD Pre

Höhe 44,5mm / 1.75 Zoll (1HE)

2. Connect

Entrées microphone

Salida Balanceado, 3-pin XLR-M, Zo = 40Ω

Alimentación

Conector DIN 180° de 5 pines, +5Vdc, ±15V de CC

power off: <0.4 G (3 - 100Hz)

Visit SSL at URL: http://www.solid-state-logic.com

© Solid State Logic

All Rights reserved under International and Pan-American Copyright Conventions

VHD, VHD logo, Xlogic and Xlogic Alpha are trademarks of Solid State Logic

All other product names and trademarks are the property of their respective owners

No part of this publication may be reproduced in any form or by any means, whether mechanical or electronic, without the written permission of Solid State Logic, Oxford, OX5 1RU, England

As research and development is a continual process, Solid State Logic reserves the right to change the features and specifications described herein without notice or obligation

E&OE