The single-channel Skulpter starts with a Class-A transformer-less mic pre-amp with a repeatable, stepped-gain attenuator control using a continuous rotary encoder and not a conventional potentiometer. The encoder has 20 steps per revolution with gain adjustable over 40 steps (two whole revolutions) in 1.5 to 2dB increments. Total gain ranges is from just 3dB at full CCW up to 65dB at full CW. As I turned the Gain control, "under the hood" I could hear various relays toggling in cascades of precision resistors.

On the front panel is a balanced DI instrument TRS jack that uses a JFET buffer circuit with a 1 meg-ohm input impedance. I had no problem plugging in a regular (unbalanced) guitar cord and recording bass, synths or a direct guitar. Both the DI path and the microphone input will accept up to a +19dBu signal.

When used, this DI path takes priority over the mic input path automatically. If phantom power is switched on the mic input, when plugging into the DI, the output will mute automatically. I could keep a mic plugged in all the time and just plug in a DI bass into the front panel with no worries. Pretty handy!

Both the microphone input and direct input are set with the same Gain control, and can have and store different settings. When switching between them, the gain changes automatically to the previously selected numerical value for each. When the module is powered off, both gain values are held in a microprocessor chip that also stores the input switching state, LED clip metering, as well as the state of rest of the front panel controls and switches.

Specifications are given at minimum gain at 3dB and medium gain at 29dB. Frequency response is 10Hz to 170kHz (-3dB) and THD+N @ +6dBu input level is 0.007 percent. The noise floor (A-weighted) specs at the same two gain settings are -97dBu and -93dBu respectively.

Complete Signal Chain Pre-Amp/DI/Compressor

The Skulpter 500 signal chain is arranged in this order: Instrument Buffer (DI) or Mic Pre-Amp section, variable 10Hz and 375Hz 12dB/octave Lo Cut filter (high pass), the Shape section, and a fixed, 3:1 ratio soft knee compressor. Front panel buttons include: Output Mute, +48-volt phantom, Phase (polarity) reversal, and Shape 2 select.

Skulpter's Shape process is a combination of saturation and an especially designed band pass filter both controlled simultaneously by the single Shape control located directly under the Gain control on the front panel.

Shape 1 (the default and Shape 2 button up) is designed for musical instruments and is characterized by a broadband EQ curve with a high frequency (6dB/octave) roll-off starting at 4kHz. As it should be, the amount of Shape's saturation is dependent on the applied input signal level, the Gain control setting and the setting of the Shape control. I liked that with Shape at fully CCW, it is out of circuit.

Skulpter 500 Front Panel

Pushing the Shape 2 button changes the filter to have a shelving boost of up to 10dB at 4.5kHz (6dB/octave) and a high frequency roll-off starting at 10kHz (another 6dB/octave filter). Shape 2 is said to be for vocals but I found it most useful for overly "dark," somber-sounding drums and guitars.

Included with Skulpter is an excellent, spiral-bound, compact printed handbook with response curves for the two Shapes as well as the compressor's transfer function graph. Bring back printed manuals like this!

The single knob compressor changes gain by placing a VCA made from a "discrete transistor array" (not a VCA chip) in the negative feedback path of the output amp. Here, the audio signal is "looked at" but does not actually pass directly through it. The compressor uses a version of Elysia's Auto Fast attack time feature found on their xpressor 500 module. Release time is an exponential shape that works well--it always seemed as fast as possible but without adding distortion.

The front panel has a dual-scale multi-function LED Meter. I immediately noticed that when adjusting the Gain encoder, pushing in on it toggles the meter between reading the numerical pre-amp gain value printed on a scale on the right side of the meter and the actual output level of the module is on the left side.

But the meter also has a red LED at the bottom than varies in brightness to indicate compression amount. There is another red LED at the top of the meter that also varies in brightness to show input overload intensity. In practice, I found it was better never to light either of these two red LEDs. It would be a good to be able to push on the Compressor knob to toggle the meter again to show gain reduction.

In The Studio

When I first powering up my 500 rack, Skulpter comes up in Output mute for about a three seconds. All previous front panel settings are recalled automatically including the phantom power on/off state. To turn on phantom, you have to hold down the "48V" until it changes from flashing to solid red and then to turn phantom off, hold it down again. Phantom power is only available at the rear edge connector (for microphones) and not at the front panel TRS DI input.

First use was on a pair of drum overhead tracks with Skulpter patched as a line level hardware insert in a Pro Tools mix. For this use, I got in the habit of starting with the Gain control at minimum with all controls CCW or off. The compressor attacks quickly and up to about mid-way in its range, doesn't soften the transients too much. I used the red compressor overload LED as a warning.

Past about mid-way with constant LED warnings, you'll "put the kibosh on" and start to lose overall level. Here I could use a separate makeup gain for this squashed effect but it works to just crank the track up in the mix.

I liked the Lo Cut filter's gentle action--it's before the compressor and cleans up the low frequencies exactly as you'll want. However, I wish it could be routed to the compressor's side-chain. I tried paralleling this effect with the original overhead pair and it works great to bring up low level sound---ride cymbals, room tone and snare and kick ambience.

Settings were: Shape 2: 50%, Gain: 9dB (indicated), Lo Cut: 80Hz, Comp: -15dB

For a full kit drum loop, Shape 2 will brighten it without problem but I ended up with Shape 1 so that the cymbals didn't get too loud. With a lot of compression, it is easy to hear the room recorded in the overheads and all the kit's parts clearly.

Settings were: Shape 1: 70%, Gain: 3dB (indicated), Lo Cut: off, Comp: -1dB

With Shape fully off at CCW, Skulpter is an extremely clean mic pre-amp and compressor channel! Extreme gain reductions are possible with minimum artifacts and noise. I found as you increase the Compressor knob, there will be an obvious point where it is just right--and then I would back it down a couple of clicks. It all made perfect sense after a short time.

Electric Guitars

Using Skulpter to record electric guitar worked completely differently than I expected; it's more like setting the overdrive channel on a guitar amp.

For recording my 5-watt MOD Kits DIY MOD 102+ Guitar Amp kit, my starting setup was all Skulpter controls full CCW (off) and the gain set to 35dB. I used a Royer R-10 ribbon mic positioned off-center of a Hellatone (Celestion) 12-inch speaker in an open-backed Avatar cabinet.

With my Fender Strat and setting my tube amp to clean, I was able to hear the different tones possible with the Skulpter. Using Shape 1 thickens up the sound nicely and much differently than using an equalizer. Shape 2 brightens the sound greatly--I liked it too. Turning up the compressor "compacts" the sound well as expected but I did have to make up recording level--again I miss an output level control here.

I tried recording the same guitar direct and just love adding some Shape 2 to its sound. This is the best direct path for a super clean sounding guitar with just a little colored saturation and compression. I would always use Skulpter for this instead of any DI box of guitar pedal! There is more control over the finished sound and it is cleaner even with lots of compression.

Acoustic Guitars

I also tried recording a Taylor 110 acoustic guitar. I used a Lewett LCT 540 S cardioid condenser with 80Hz roll-off placed over the 12 fret at about 8-inches away. Even though the guitar could use some new strings, I got an incredibly clean and focused tone with no pre-amp noise. I did notice "zipper" noise when dialing in gain while the guitarist played. It is the relays switching in gain resistors and not advisable while recording. But this always true for rotary switched gain controls such as Neve 1073 modules.

Lead Vocals

When connected to my Soundelux Bock U195 cardioid FET condenser microphone, Skulpter produced a warm, rich sound. I used no pad or low cut filter on the mic itself but did switch in the mic's FAT switch. This microphone has tremendous headroom and can distort a mic pre-amp without an attenuator pad switched in.

Having a minimum gain position on the Skulpter 500 of just 3dB is perfect for this mic and other modern microphones that supply ample output level. As on the acoustic guitar recording session, my singer's super loud vocal tracks recorded super-quiet, clean and sounded great.

Settings were: Shape 1: 30%, Gain: 3dB (indicated), Lo Cut: 45Hz, Comp: off

Super Skulpter