SPL Director MK2 | DA Converter and Pre-amp (Red)

Additionally, there are now a total of six analog inputs. Two of which are balanced with XLR connectors. The housing has grown in height to provide space for the big aluminum volume control with marker LED and two mechanical VU meters.

Director MK2 is the heart of the stereo system to which all components are being connected: computer, player, phono preamp like the Phonos, headphone amps like the Phonitor xe or the Phonitor e, and power amplifiers like the Performer s800 or Performer m1000.

Preamplifier
Director MK2 is a full-fledged stereo preamplifier for connecting up to ten stereo input sources. Six inputs are in the analog domain offering two balanced XLR and four RCA stereo inputs. Four inputs are in the digital domain: AES/EBU, USB, COAX, OPTICAL. Power amplifiers or active loudspeakers are connected via balanced XLRs and a headphone amplifier is connected to the Direct Out.

Volume
Volume is controlled strictly in the analog domain – for good reason. Commonly volume is set in the digital domain as part of a DAC chip's functionality. The down side is that the full bit resolution is only present at maximum playback volume.

But we never listen with the preamp' volume turned up fully clockwise. As a result we always listen at a lower bit resolution and therefore with a diminished audio fidelity. An average listening level is about 30 dB below maximum (0 dBfs) and as the resolution shrinks by 1 bit per 6 dB level drop the playback will have a 5 dB lesser resolution. It does not make a lot of sense to listen to high-res audio then, does it?

Therefore SPL opted for an analog solution that gives you full bit resolution at all listening levels. To control the 120 V rail VOLTAiR volume stage SPL use an ALPS RK27 "Big Blue" potentiometer with excellent feeling and channel matching. Being motorized, Volume can be remotely controlled. Please refer to the chapter "Remote Control" for more information.

Source
The rotary switch selects the input source, which is then shown in the dot matrix display: IN 1 to IN 6 for the analog inputs and AES/EBU, USB, COAX, OPTICAL for the digital inputs. The detected sample rate of the selected digital input is displayed after about 2 seconds (e.g. U768 = USB input, 768 kHz sample rate). The input source selection can also be remotely controlled when the selector is set to "Remote."

Remote Control
Volume as well as source input selection can be remotely controlled using any existing infra-red (IR) remote control. The cool part is that the Director MK2 learns the remote commands.

Take, for example, the remote control of the CD player. Out of the many buttons there are maybe four you hardly use if at all and which do not directly trigger a function on the CD player.

Alternatively er suggest using the Apple remote control which is small, slick and offers just the buttons you need.

Assign Volume Up/Volume Down to two buttons and Next Input/Previous Input to two other buttons and let the Director MK2 learn them. The procedures are described in the manual and in the video "Learning Remote Control".

Make sure that the source selector switch is set to "Remote."

DA converter (DAC)
The Director MK2 is equipped with a completely new digital-to-analog converter board. It is an all new design based on the AK4490 Velvet Sound DAC chip from AKM. The new DAC supports PCM audio up to 768 kHz sample rates with 32-bit and DSD audio playback up to DSD4 or DSD256. It sports four digital stereo inputs: AES/EBU, USB, COAX, OPTICAL.

DAC with VOLTAIR
SPL have been looking at many DAC designs and have always wondered why all the innovation happens on the digital side. Almost no innovation is to be found on the analog part for the DAC. Perhaps it is because most designers have a background in digital engineering and as a result they apply standard 'cook book' designs on the analog side.

Having a 30+ year background in analog audio designs, SPL find cook book circuitries boring, inefficient and far from being superb. As already proven with the DAC in the predecessor SPL also put innovation into the analog side of the DAC with astonishing results.

The output of the DAC chip is to be filtered with a low pass filter. This stage is typically designed with the same reference voltage that the DAC chip works on e.g. 5 V. Think about this: the first stage that the analog waveform is exposed to has a headroom limited this tiny voltage. Now imagine this to be 120 V! This is what SPL have done in the Director and of course in the MK2.

The low pass filter runs on a 120 V rail - VOLTAiR technology. The incredible headroom and the enormous dynamic range lets the analog wavefront come to life and evolve without any limitation. And that is audible. Very much so.

VU meters
The two VU meters display the source's input level. It's mechanical design 'slows' the measurement, averaging out peaks of short duration, and reflects thereby more the perceived loudness or "energy."

VU means Volume Units. A typical VU meter shows a range of -20 dB to +3 dB. SPL VUs go up to +5 dB. A mastered CD can produce levels of up to +15 dB which would glue the needles to the right side.

To prevent this the VU toggle switch allows selecting either 6 or 12. Meaning that in position 6 with the needle pointing at 0 the true value is +6 dB and set to 12 means a true value of +12 dB when the needle points at 0.

With the VU switch set to +12 dB the VU meter can display levels up to +17 dB. If the needle goes beyond that it does not indicate that the Director MK2 is clipping. Thanks to the VOLTAiR technology there is still more than 15 dB headroom. The Director MK2 clips above +32.5 dB input level!

Tape Monitor
The Tape Monitor function has become part of the MK2 because many audiophiles requested it to insert tape machines or external processing gear.

In the 70s and 80s cassette recorders were very popular and a hifi preamp offered a tape monitor. Later this feature went away, but fans of recording and processing found the lack of this feature in today's preamps being a real drawback.

Well, so SPL introduced this feature in the MK2. It is now possible again to insert a tape machine and listen back while recording (tape monitoring) or to insert beloved equalizers or other processing devices to tune sound.

On the rear of the unit is a level calibration switch besides the tape send and tape return sockets. Consumer tape machines, cassette desks or consumer equalizers may clip when exposed to the levels that the Director MK2 handles. To prevent peaks and distortion this switch reduces the outgoing level by 10 dB and lifts it again by 10 dB when coming back into the Director MK2. Thereby no level difference will be audible and your gear perform on levels it is used to.

For more information on this or any SPL product, visit www.spl.info