Burl Audio, whose B2 Bomber stereo A-D and D-A converters we reviewed back in November, have just released a multi-channel version, called the B80 Mothership.
Unusually for a converter, its construction is modular, and it can be configured in a number of different ways, according to the user’s requirements. The 4U chassis has 10 slots for converter modules, and the modules themselves are available in two-, four- and eight-channel versions, for both A-D and D-A conversion. This means you can load it up with cards to convert up to 80 channels of digital audio to analogue, or vice versa — or 40 channels each way, or any combination in between.
Like the B2 Bomber, each channel of A-D conversion is preceded in the signal path by a by a custom, Burl-manufactured BX1 transformer. The idea behind this arrangement is to ‘warm up’ audio as it’s being recorded, with the transformer introducing some subtle distortion and saturation, of the type you’d expect from a vintage console (or the input stages of some tape machines).
The D-A converters, on the other hand, have been designed to be more neutral, and these feature transformerless analogue stages, instead employing a proprietary Burl op-amp (a BOPA1). The converter chips for both the A-D and D-A converters are AKM models (5394s for the A-D converters, and 4399s for the D-As).
In addition to the 10 converter module slots, there’s another space on the right-hand side of the rack for a ‘motherboard’ (controller) card, of which there is currently one type, the BMB1. This features eight LEDs: one showing whether the unit is switched on, one indicating correct sync with other digital devices, and six that display the sample rate in use (the B80 will work at 44.1kHz, 48kHz, 88.2kHz, 96kHz, 176.4kHz and 192kHz). Below these is a rotary control, which allows you to select the B80’s clock source.
The BMB1’s rear panel hosts the power supply input, a USB socket, a word-clock input connector, two word-clock outputs, plus two DigiLink sockets. The USB socket allows you to use a connected computer to configure the B80 (it doesn’t offer audio-interface functionality). The word-clock sockets allow you to use the B80 as either clock master or slave in your studio. The two DigiLink connectors, meanwhile, let you connect the converter directly to an Avid Pro Tools HD Core or Accel card. The power comes from a separate 1U PSU, called the BP250, which provides 250W of power, and ±24V power rails.
For more information about the B80 Mothership’s technical performance, read our review of the B2 Bombers (www.soundonsound.com/sos/nov10/articles/burlb2.htm), in which we tested their identical converters’ performance. Alternatively check out the Burl Audio web site, below.
