$ 1,899.00 -16%
$ 1,599.99

The SSL Alpha VHD-Pre is a four-channel microphone preamp taken from the flagship Duality console, featuring with variable distortion circuits that can be switched in and out of the signal path, plus 75dB gain on each channel

They say that character is destiny, but with the SSL Alpha VHD-Pre, character is more of a choice. The Alpha VHD-Pre's proprietary Variable Harmonic Distortion (VHD) circuit gives you the choice of dialing in analog character from the days of yore for tracking old-school, or, you can go super-modern by simply cutting the VHD out of the circuit entirely and take advantage of SSL's signature transparency. First appearing on their flagship and highly acclaimed Duality console, the SSL Alpha VHD-Pre gives you four VHD-Pre circuits in a 1U sleek chassis featuring the instantly recognizable SSL metallic silver finish. Each VHD-Pre has XLR in/out on the rear panel and an instrument-level 1/4" DI on the front panel with Hi-Z switch to accommodate mic, line, and instrument level signals. Each channel also has a 20dB pad switch for line-level processing, as well as a 48v phantom power switch. The Alpha VHD-Pre front panel also plays host to three rotary controls, which include input level, VHD, and output level. Each VHD-Pre also offers you a ribbon mic-friendly 75dB of ultra-clean gain.

SSL Alpha VHD-Pre - Just the Facts:

  • Four ultra-clean SSL preamp with 75dB of gain
  • Individually switchable +48V phantom power
  • 20dB Pad switches that illuminate to indicate overload
  • Hi-Z switches to accommodate mic, line, and instrument-level signals
  • Four independent Variable Harmonic Drive systems
  • Front-panel 1/4" jack instrument/line level inputs with passive DI-type impedance detection and level matching
  • Individual input, output, and VHD controls for each section
  • Rear-panel XLR mic/line inputs and XLR outputs

SSL Alpha VHD-Pre - Under the Hood

The VHD Pre is a proprietary design that can deliver ultra-clean SSL console-grade recordings with user-controllable amounts of harmonic distortion. The ability to add harmonic distortion to taste is made possible by SSL's Variable Harmonic Drive VHD circuit, which can be switched in or out of the signal path (mic or line) - like smooth or crunchy peanut butter, except the 100% analog VHD lets you add as many nuts as you like (mind out of the gutter, now!). As you increase the input gain, the Variable Harmonic Drive circuit introduces either 2nd- or 3rd-order harmonic distortion, or a blend of the two. At lower gain settings it adds gentle tube-style warmth or a touch of transistor edge - great for sounds you want forward in a mix without having to take up headroom using EQ. As the gain is increased, distortion becomes more extreme until at high-gain settings it delivers fierce trashy transistor grunge.

Not just based on the amount of drive from the VHD rotary control, the level of the incoming signal will have an effect 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.

Tube, tape, or a little bit of both

Each Alpha VHD Pre input features a control labeled “VHD” with a range of adjustment from “2nd” to “3rd.” Adjusting the VHD control changes the character of the added distortion from predominately 2nd-order harmonics (octaves) to almost entirely 3rd-order harmonic when fully clockwise; interesting blends between the two can be achieved at intermediate settings. The character of 2nd harmonic distortion is akin to the warmer sound produced by tube overdrive, whereas 3rd-order harmonic distortion is associated with tape and the harder, brighter sound of solid state devices. This control is great for bringing instruments forward without EQ or taming transients.  

The VHD control has a far more noticeable effect at higher gain settings. As such, the input gain should be used in combination with the VHD control to affect the amount of distortion being added to the input signal. In case you get carried away, the Pad button will glow red when the input stage is starting to overload; the VHD circuit is designed with this as part of normal operation, though it should be avoided for a cleaner signal.

Gain changer

An overdriven preamp will have an effect on the gain of all subsequent units in a signal chain. Therefore, you may need to reduce output gain interface correctly with other equipment. The output level control makes this adjustment a simple process.

SSL Alpha VHD-Pre - Outside the Box

The front panel of the VHD-Pre is separated into four sections (one for each preamp). Starting with an illuminating power switch on the far left, each channel has a 1/4" instrument input; illuminating Hi-Z, Pad, and 48V switches; and three rotary controls including +20-75dB gain, -20dB to +20dB output level, and VHD, labeled from 2nd to 3rd.

The rear panel has four balanced XLRF microphone inputs (max. input 0dBu - +20dBu with pad) and four balanced XLRM outputs (max. output +24dBu). There is also a DC power receptacle for the external power supply (which keeps AC noise and hum out of the Alpha VHD-Pre's circuitry).  

SSL Alpha VHD-Pre gives you the ultimate versatility from a studio grade-preamp. Order yours today, or for more information, call or chat online with your PAD Studio Specialist today. 


  • Power supply: IEC320 3-pin connector, 100 - 240VAC, 50 - 60Hz
  • Microphone Balanced, 3-pin XLR-F, input impedance = 1k ohm (10k ohm for Hi-Z)
  • Instrument: Un-balanced, 1/4" Mono Jack, input impedance= 1M ohm
  • Output: Balanced, 3-pin XLR-M, output impedance = 40 ohm
  • Power: 5-pin 180° DIN connector, +5VDC, ±15VDC
  • Power consumption: < 20 watts

Physical (All values are approximate)

  • Height: 1-3/4" / 44.5mm (1 RU)
  • Width: 19" / 482mm with rack ears (17-1/4" / 438mm casing only)
  • Depth: 9" / 230mm (casing only)
  • Weight: 6 lb. / 2.6kg





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