H All,
I thought you may be interested in the latest email I received from a company looking to use our 4B amplifier under conditions far outside the audiophile applications normally attributed to an audio amplifier. One area where our 2B's and 3B's have been used exclusively over many years is in all the airline flight simulaters produced by a company called CAE.
Other alternative uses- see below:
Sent: Friday, December 05, 2008 4:35 AM
To: jamestanner@bryston.com
Subject: Alternative applications for Bryston amplifiers?
Hi!
Your power amplifiers have a solid reputation of being very robust. The impressive technical specification makes you wonder if it is possible to use them for other applications than original intended. I would like to drive an echo sounder transducer around 70 kHz with a 4B SST in bridge mode.
The power bandwidth and slew rate seems OK and stability in loads above 4 ohm/all angles sounds promising. To my questions:
· As I understand it the amplifier output impedance at 70 kHz is mainly determined by the output filter (approx 0.8 ohm). The damping factor will of course be higher than in the audio band but that is acceptable. Will the output filter survive? The echo sounder signal has a duty cycle of less than 1%.
· Since the load consists of a piezo element it is likely that a voltage will be generated by the load and fed into the amplifier output. Will this damage the amplifier or will the diods D1 and D2 solve the problem?
· The amplifier is obviously designed for speaker loads (4-8 ohm). What about impedances in the range 20 to 100 ohm and phase angles -70 to +70 degrees.
· Any other issues of concern for this application?
Best Regards
Anders Eriksson
Sweden
ThyssenKrupp Marine Systems
Hi Anders;
Thanks for your recent inquiry. Bryston amplifiers have often been used in non-speaker and supersonic applications. 70KHz is within the 4B SST amplifier's power bandwidth. It will have no difficulty driving loads in that frequency range. The output filter will easily handle the current delivered into a 20-100 Ohm load at 70KHz, especially if the duty cycle is <100%. The output commutating diodes are designed to prevent reverse-biasing the output transistors, which could happen if flyback spikes are returned to the amplifier by inductive loading under certain circumstances. Capacitive loading won't do this, but Bryston amplifiers have been designed to run capacitive loading without difficulty. Reactive loading does display energy storage, increasing the heating in the output transistors, but in the case of impedances in the range you describe, at low duty cycles, there should be no issue with heat generation.
Bryston amplifiers have in the past been used for:
1. generating magnetic currents in buried coils
2. for geological exploration and mining,
3. for delivering supersonic pulses into the clouds for weather pattern prediction,
4. for generating sonar pulses by navy ships,
5. for directly driving the precessing motor for an observatory telescope,
and a number of other unusual or alternative applications with great success.
I am sure your requirements are well within the 4B SST's design capabilities. However, if modifications are required for any purpose, Bryston will be pleased to assist with any engineering that may be required. I hope the above is helpful, but please let me know if you have any other questions, and thank you for thinking of Bryston.
Sincerely,
Chris Russell
Bryston Ltd.
