SFC 2 Sampling frequency converter

The SFC2 is a ver­sa­tile sam­pling fre­quency con­verter with two com­pletely in­de­pen­dent stereo con­vert­ers in a sin­gle 19 inch (1HU) unit. A SFC ba­si­cally con­sists of a high or­der, lin­ear phase, dig­i­tal low pass fil­ter. With the proper de­sign of that low pass fil­ter the qual­ity of the SFC process can be made “ar­bi­trar­ily” good – in­de­pen­dent of the con­ver­sion ra­tio. Like what we achieved in the SFC2.

Stan­dard sam­pling fre­quency con­verter chips con­tin­u­ously mea­sure the in­put fre­quency and then gen­er­ate the out­put fre­quency and the fil­ter spec­i­fi­ca­tions ac­cord­ingly. This re­sults in co­ef­fi­cient “jit­ter” be­cause the in­put sig­nal sam­pling fre­quency jit­ter mod­u­lates the cut­off fre­quency of the dig­i­tal fil­ter. The SFC2 uses a fixed-ra­tio scheme where the out­put is di­rectly de­rived from the in­put sam­pling fre­quency – there­fore no co­ef­fi­cient “jit­ter”, no fil­ter mod­u­la­tion, more transparency.

The main ap­pli­ca­tion of the SFC2 is in­te­grat­ing play­back or out­board equip­ment into an en­vi­ron­ment that ei­ther runs at dou­ble- or stan­dard-sam­pling fre­quency. To al­low this equip­ment to be po­si­tioned any­where in the pro­cess­ing chain, the SFC2 fea­tures two com­pletely in­de­pen­dent two-chan­nel sam­pling fre­quency con­vert­ers to si­mul­ta­ne­ously down- and up-sam­ple a sig­nal. Al­ter­na­tively, it can also be used to con­vert the sam­pling fre­quency and re­duce the word-length of any two stereo au­dio sig­nals at the same time.

The two sections of the SFC2 have the same feature set. They sport AES/EBU inputs and outputs on XLR connectors and work at the four standard sampling frequencies of 44.1, 48, 88.2 and 96 kHz. The word-length at the output can be set to 24, 20 or 16 Bits. For proper word-length reduction, dithering must be switched on. Dithering in the SFC2 uses a second order noise-shaping process. The dither noise can be set to be automatically muted in music pauses.

Power

• Mains volt­age: 115 V or 230 V with volt­age selector

• Fuse rat­ing: 500 mA slow blow

• Power con­sump­tion: 40 VA max

Size

• Depth: 30 cm

• Width: 43,3 cm (19")

• Height: 4,4 cm (1HU)

AES/EBU Input

• Sam­pling fre­quen­cies: 44.1 kHz, 48 kHz, 88.2 kHz, 96 kHz

• Max­i­mum in­put word-length: 24 Bits

• Chan­nel Sta­tus Data: In­put ac­cepts pro­fes­sional or con­sumer format

• Con­nec­tor: XLR fe­male, 110 Ω

 AES/EBU Output

• Sam­pling fre­quen­cies: 44.1 kHz, 48 kHz, 88.2 kHz, 96 kHz

• Out­put word-length: 16 Bits, 20 Bits, 24 Bits

• Con­nec­tor: XLR male, 110 Ω

Dither

Sec­ond or­der noise shaping

Trans­parency

The SFC2 is Bit-trans­par­ent with a con­ver­sion ra­tio of 1:1