Introduction to H-BUS

Concept

The H-BUS digital interface has been invented by Hoontech with the presentation of the SoundTrack Digital Audio 4ch/16ch soundcards [1] back in 1998. The goal was to create a flexible interface for multichannel digital audio transfers to create affordable professional audio solutions with virtually unlimited connection and expansion possibilites. H-BUS has the following specifications:

There are of course also other digital multichannel interfaces on the market such as ADAT by Alesis, TDIF by Tascam, R-BUS by Roland or mLAN by Yamaha (and others). These interfaces however either do not have the flexibility that was originally intended for the SoundTrack Digital Audio 4ch/16ch [1] (e.g. no transfer of MIDI signals is possible, the max. samplerate is just 48kHz, max. 2 devices can be connected simultaneously) or the implementation would have been too expensive. Some of these other interfaces also did not exist when H-BUS was first presented.

The most important aspect of H-BUS is the cost-effective implementation on the hardware (which was the main goal). This allows Hoontech / ST Audio to develop affordable multichannel recording solutions with very good price/value and many expansion options.

Every external H-BUS device has a DATA IN and DATA OUT connector. This makes it possible to use several devices at the same time. Just connect the H-BUS interface (like the DSP24 PCI card) with the first external device (using one of the DATA connectors) and then connect the second one via the still available second DATA connector of the first device. This creates a bus connection from the interface card until the last device in the chain. To address the different external units, every one gets a unique number that can be selected on the hardware (usually by DIP-switches).

Compatibility

The usage of H-BUS on our audiocards (like the DSP24 and DSP24 MK II) of course means that they are not directly compatible with other famous multichannel audio interfaces. It is our experience that many users do not need this compatibilty in most situations. When one of our H-BUS compatible interface cards are used, the combination with our external rackmountable extensions such as the ADC&DAC2000, ADC III, DAC III or DM III (which are all part of the second generation of external H-BUS options) provide a cost effective solution for pro and home studio users.

Of course this does not mean that H-BUS is incompatible with other digital multichannel audio interfaces. The DS2000 provides ADAT I/O and TDIF I/O and can be connected later when needed. Still H-BUS keeps the advantages over these interfaces: you are still able to transfer MIDI signals over the same cables and you can connect several I/O interfaces to your PC at the same time without changing the cabling - just change settings inside the application software (such as External Links [2]) that works as a virtual patchbay when needed.

Future

ST Audio will also develop H-BUS compatible devices in the future. This will make it possible to exchange the interface card and add or exchange or external boxes when a new generation will be available. This means that you do not have to buy a complete new product when new technology becomes available and you want to take advantage of it. Just add or exchange the necesary part when wanted/needed and keep everything else.

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last updated: 09/23/2001 author: Claus Riethmüller