Self-supporting Construction

The behold final stage amplifier BPA768 is a self-supporting aluminium construction. The big cooling bodies are load-bearing parts which are screwed together with other components by full profile groins. The aluminium central plate forms the basic framework together with the faceplate. Fitted on this is the main board with the signal processors. Left and right from that are the final stage functional blocks with their switched mode mains power mounted.

Easy to Disassemble

Despite of the compact construction this power amplifier can easily and fast be taken into pieces and assembled again. With a special set of cables it can even be operated in open condition, advisable, however, for trained staff only. This staff will greatly appreciate the clear construction, an advantage also for the customer.

The Switched Mode Power Supply

made it possible to keep the weight in acceptable limits. The behold BPA768 weights only 41kg to 45kg and can be transported relatively comfortable by two persons by means of two handles, housed elegantly and harmonically in the top and bottom cover.

Only three different circuit boards are existing. They are connected to each other by flat ribbon cables and respectively with 2.5mm² conductors in the power range.

The "music" is made in these three circuit boards. The structures are clear and considerable and in combination with a meaningful pairing of excellent new digital technique and new ways in the area of analog technique show a really well thought-out concept. It may not be found elsewhere.

BPA768-DSP:

The Signal Processors

to control the power conditioner with PFC and voltage transformation (ADSP21990) and the complete signal processing (ADSP21161) of one or more audio signals.

The Process Regulation

of processing the idle current with the ADSP21161 Signal Processor.

Digital Receiver

The Power Supply

for stand-by operation.

BPA768-FPA:

The Analogue Heart

of the behold BPA768. Digital data are fed to the four stereo D/A-Converter (4xAD1853). There they are changed filtered and pre amplified in a fully symmetrical circuit. Used for that are the most low- noise and also otherwise best operational amplifiers available today for analogue audio tasks (4xAD797).

The Transimpedance Amplifiers

The full symmetrical transimpedance amplifiers in the next step generate the voltage gain needed for the output. For good reason they are not traditional difference amplifiers.

The Output Buffer

The output currents are generated in a buffer stage with the voltage gain "1". A large number of high value capacitors are arranged here.

BPA768-PFC:

The Power Electronics

the power conditioner of the PFC and the full bridge voltage transformation of the switched mode mains power supply.

The Interference Suppression Filters

for "cleaning" of the DC-voltage combined with the generation of the auxiliary voltage for the analogue final stage.

The Protection Circuits

The parts handling the high power are equipped with autonomous discrete protection circuits ,i.e. independent from the processor. By that those components are protected completely independent.