The only surviving World War II-era Royal Navy submarine, the Gosport-based HMS Alliance, recently underwent a £7 million restoration. As part of the refurbishment, over 50 speakers were fitted throughout the 218ft (66m) submarine to bring the retired vessel back to life as a historical attraction for the National Museum of the Royal Navy in Portsmouth.
Hampshire-based AV specialist DJW was responsible for the design, programming and installation of the soundscaping system. DJW project manager John Doe explains: “It was a very small, claustrophobic space to work in, which made getting equipment in and out, let alone installed, quite difficult.
“It was also tough finding enough nooks and crannies to hide 51 speakers throughout the sub. We wanted to make the experience as real as possible, so it was important to us to hide as much of the equipment as we could.”
The audio system is used to recreate scenarios that would have occurred during daily life on the submarine. For example, in an attack scenario, a deafening alarm rings through Visaton loudspeakers, accompanied by the frantic flashing of red emergency lights. “The Visaton speakers were used on six of the reanimated boat-wide radio speakers in the crew messes,” says Doe.
“In the end we used two types of speaker: the Tannoy Di5 and the Soundtube SM31-EZ,” Doe continues. “The Soundtube speaker is quite small but still gives a good sound and was easier to hide in the more difficult areas. We used about 20 Soundtube speakers and about 25 Tannoy Di 5 units, with the rest being made up of reused on board speakers that we refurbished.”
The audio is sourced from two Mac minis, with power for the speakers delivered by Audac DPA616 power amplifiers. Doe explains: “Audac DPA616 16-channel power amplifiers were used because there was a small space for the amplifiers and a lot of speaker channels.
“The multi-channel Mac audio is fed via FireWire cable to the 8 channel Motu DSP, which is linked by fibre optic cable to the 16-channel Ferrofish DSP to give 24 channels of audio distribution. There are now two Macs in the same configuration to give 48 channels of audio. The line outputs of the Motu and Ferrofish units are then fed into the amplifiers and then cabled out to each speaker.”
HMS Alliance is now open to the public following the grand opening of the submarine and a new section – also DJW-installed – of the National Museum of the Royal Navy.