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PowerPre™ Using & Applications

The PowerPre has been designed to be extremely easy to use while delivering unsurpassed sonic performance. The concept is simple: plug in a microphone, turn up the volume, listen. If you want extra character, try driving the PowerPre harder into the red or change the Vox setting and you are set to go!

Complete details on using the PowerPre 500 module and making connections to and from your 500 series rack can be found in the manual (PDF download).

Connecting and Using Microphones

Connect your microphone to the PowerPre using a standard 3-pin XLR cable. You can use either the front panel XLR or the rear panel female XLR as the input as they are wired in parallel. The PowerPre has been wired following the AES standard with pin-1 ground and pin-2 hot. Most devices are wired this way, but older vintage equipment should be checked to ensure compatibility. To ensure the lowest noise, always use a high quality balanced cable from a reputable manufacturer.

Front Panel Connection Workhorse Rear Panel Connection 500 Series Rack Rear Connection

Depending on what type of microphone you are using, you may or may not need to engage the 48V phantom power. This is designed for condenser microphones. If you are using a dynamic microphone or ribbon microphone you can leave the phantom power off. The switch is recessed to prevent accidentally turning it on or off. An easy to see LED indicator tells you when phantom is on.

Using the Accustate™ Output Control

The PowerPre has a lot of gain (+55dB) and is very quiet. This is achieved because, unlike most preamps that use the level control as a variable attenuator to reduce the input signal (and end up with a fixed noise level), the PowerPre is equipped with our unique Accustate™ circuit. Accustate automaticaly maintains the best possible signal-to-noise ratio at all gain settings.

Traditional Preamp Design
To understand Accustate lets first look at the signal-to-noise ratio of a traditional preamp input stage. Most professional preamps employ a potentiometer or rotarty switch to adjust the ‘volume level’. But these ‘volume’ controls are in fact not the amplifier gain control at all. They are attenuators that reduce the input signal going to the preamp's amplifier stage.

In either case you are not actually controlling the gain, only the input. Herein lies the problem: Preamps that employ an input attenuator are basically running at ‘full-on’ gain all the time making their noise floor fixed and the signal-to-noise ratio dependant on the input level. When the ‘volume control’ (read attenuator) is turned all the way up, you enjoy maximum SN performance. But as you reduce the input sensitivity by ‘turning down the volume’ you are actually increasing the amount of noise in the recording.

At maximum input you enjoy the best
signal-to-noise performance.
Attenuating the input reduces the
signal-to-noise ratio.

Accustate™ The PowerPre's Accustate output control adjusts both the input sensitivity and the preamp gain proportionately, accurately tracking the input while reducing the background noise. As the input level is attentuated the amplifier gain is also reduced and the noise floor goes down with the input level. This makes it super easy to set the signal gain while maintaining the lowest noise.

Accustate provides consistent
signal-to-noise performance.

Start talking in the microphone as you increase the level. It is a good idea to always test at a low level during setup. If you notice the VU meter is going into the red, simply back off the gain control. If you are using a super hot source like a keyboard you can engage the -15dB PAD to reduce the input sensitivity.

Adding Character To The Signal

In the world of preamps, there are many colors. One can make 'ultra-clean' sounding preamps using miniaturized electronic chips, but these tend to sound sterile and listless. On the other hand, you can produce a preamp that is loaded with personality. This is the direction we chose with the PowerPre. As soon as you plug it in, you will find that it is very warm sounding. This is attributed to the full size discrete electronics that are employed throughout and the Hammond output transformer. Driving the PowerPre into the red adds wonderful grit and texture while still remaining quiet and noise free.

Taking this one step further, the PowerPre is equipped with a 3 position switch called VOX which is slang for voice. This has three settings: The LINEAR setting removes the EQ from the circuit so that you hear the pure sound of the preamp. This setting is ideally suited for recording acoustic instruments or recording electric guitar for later Reamping where you want the original tone of the instrument. We recommend that you start with the PowerPre in the LINEAR position so that you can first hear the natural sound of the instrument or voice.

The other two settings are named "Breath' and 'Punch'. The Breath setting is designed to add zest to the recording by introducing a greater degree of harmonic content in the upper end. You will find that this will flatter most voices by introducing a sense of air. It is also terrific on acoustic instruments. For instance, it can add some upper clarity and shimmer to a 12 string acoustic guitar. The Punch setting is designed to beef up the bottom end. This works really well on electric guitars and bass to fatten tracks. You can also use it to warm up a thin female vocal track or 'enlarge' the sound of a snare. Try, listen and decide. The intent here is to make it easy and fast to get great sounds.

Low-cut Filter

World class engineers always think in terms 'layers' when they record. In other words, they will position the bass in the lower octaves, guitars in the mid-range and cymbals in the upper registers. This allows each instrument to cut through the mix without overtaking another space. The PowerPre VOX control is helpful for this as is the low-cut (high pass) filter.

Low cut filter begins to work at 150Hz and becomes noticeable below 100Hz where excessive bass can cause the mix to be muddy. For instance by eliminating low frequency resonance from an acoustic guitar, you can clean up the mix without affecting the sound of the instrument. Keep in mind that bass contains way more energy than high frequencies. By focussing the bass transients on drums or bass guitar, you can increase the dynamics.

Setting the Polarity

Sometimes, when recording an instrument, you may want to use two microphones at the same time. One may be positioned near the instrument while the second may be set further away to capture some of the room's natural ambiance. Switching the 180º polarity reverse switch can often help focus the signal to bring certain frequencies in phase (Devises like the Radial Phazer take this to another level by allowing you to adjust the phase incrementally).

The 180º polarity reverse is also sometimes used to correct the phase of older vintage equipment that may have been made before the AES standard was established. Most equipment today employs the standard with pin-1 ground, pin-2 hot (+), and pin-3 (-). Depressing the 180º polarity reverse switch will toggle pins 2 and 3.

Omniport™ - Using the PowerPre with Instruments

The PowerPre 500 Omniport is configured for direct hi-Z instrument input when installed in a Workhorse 500 series rack . The PowerPre is not only designed for microphones, but it is also well suited for instruments of all types. The most common application in the studio is direct recording a bass guitar. When used with the Workhorse, the PowerPre is equipped with an instrument input that is accessed via the Omniport jack. This 'switching jack' automatically reroutes the signal from the front panel XLR input to the Omniport as soon as a jack is connected.

You can also set the PowerPre for high output devices like digital pianos, samplers or drum machines. Even though the PowerPre is capable of tremendous signal handling, a 'traditional' input pad has been added that attenuates the signal by -15dB at the input. Simply connect your instrument turn up the volume and check the LED bar meter. If the signal seems to be pushing the red, depress the -15dB pad.

The PowerPre 500 Omniport is configured for direct hi-Z instrument input when installed in a Workhorse 500 series rack

Internal Ground Lift

At the back of the PowerPre, adjacent to the card edge connector is a hidden ground lift switch. This lifts pin-1 on the front panel XLR only. Although this will likely never be used, we have incorporated it into the design so that in the rare occasion that you may want to run a keyboard into the PowerPre to take advantage of the warm sounding signal path, it is possible you could encounter a ground loop. Lifting the ground can often help by eliminating this ground path.

NOTE: It is important to note that if you do set the ground to the lifted position, it will turn off the phantom power going to the front panel microphone input as DC current from phantom power needs the ground wire to be connected.

As you can see, the PowerPre is amazingly versatile for such a compact device. But even with all this versatility, it is extremely simple to use. This, we believe sets it apart from others and will provide you with years of enjoyment.

Location of internal ground lift switch