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Concrete Speaker Design at Nottingham Trent University
Concrete is an amazing material that can be used in many applications (in addition to your garden path!). One great application that we came across in the last few weeks is a speaker enclosure that is being produced by students studying Product Design at Nottingham Trent University. An example of a finished speaker is shown below. We thought these looked really cool and decided that we would have to go along and see what was involved in creating them.

concrete_speaker_design_nottingham_trent_university_560_01

The casing is made by casting concrete in a mould to create the housing. A laser cut insert allow the speaker to be neatly mounted. The design is based around our Mono Amplifier Kit which the students soldered together themselves. The project was developed by Kerry Truman (@kerry_truman on Twitter) and Julian Robinson (@NTU_Concrete). These guys seem to be doing some great work and it is definitely worth following their Twitter accounts.

Creating the Concrete speaker housing

To make the housing a concrete mix was cast in a mould. Julian explained to the students how this is done. He started by explaining what goes into a typical basic concrete mix. To help with this he has produced a great hand-out which you can download here. concrete_speaker_design_nottingham_trent_university_560_02 The mix that the students were going to make was referred to as a ‘1-2-4’ mix. This meant they wound be mixing one part cement with two parts fine aggregate (sand) and four parts course aggregate. These materials were all neatly organised ready for the students. concrete_speaker_design_nottingham_trent_university_560_03 Before the students started their mixes Julian also highlighted any health and safety issues. All of the students wore face masks (for the dust) and safety glasses. Julian also explained that concreate is a caustic substance. This meant that if it got splashed on the skin it should be washed off. The caustic nature of concrete means that if it is left on the skin for long periods of time chemical burns can occur. Scales were used to measure out the required amounts of each material.

concrete_speaker_design_nottingham_trent_university_560_04 Water was then added to the mixture and all the parts were mixed together. Julian informed the students that the more water that is added to the mix the ‘weaker’ the finished concrete will be.

concrete_speaker_design_nottingham_trent_university_560_05 The completed concrete mix is then ready to add to a mould. The mould is made up of the outer mould and a ‘laser cut’ collapsible insert. concrete_speaker_design_nottingham_trent_university_560_06 The students have the choice of two types of outer mould. A metal mould that gives a smooth finish to the concrete. concrete_speaker_design_nottingham_trent_university_560_07 Or a Polystyrene mould that gives the final product a slightly more textured look. The Polystyrene moulds are much cheaper but can’t be reused. concrete_speaker_design_nottingham_trent_university_560_08 The students decided which type they preferred and then added their concrete mixture. concrete_speaker_design_nottingham_trent_university_560_09 A vibration plate was used to make sure the concrete mixture entirely filled the mould without any voids.

concrete_speaker_design_nottingham_trent_university_560_10 Once the concrete has set the parts can be removed from their moulds.

concrete_speaker_design_nottingham_trent_university_560_11 Building the amplifier circuits

As a separate task (in a slightly cleaner room) the students built one of our Mono Amplifier Kits. All of the students appeared to be competent at soldering and managed to build the kit in under an hour. concrete_speaker_design_nottingham_trent_university_560_12 concrete_speaker_design_nottingham_trent_university_560_13 They used the step by step instructions (available online) to guide them through the assembly process. concrete_speaker_design_nottingham_trent_university_560_14 Once they had finished building their amplifiers they gave them a quick test to make sure they were working.

Finishing off

All that is left is to mount the amplifier into the concrete housing. Unfortunately we didn’t get to see this as the students moulds were still in the process of setting. There were some examples that Kerry showed off. A laser cut Perspex insert was used to house the speaker in the front of the housing. These could be cut in any colour that you want. concrete_speaker_design_nottingham_trent_university_560_16 The rear of the speaker housing has plenty of space for the PCB and a 9V PP3 battery. concrete_speaker_design_nottingham_trent_university_560_17 There were also some other examples shapes that had been tried out. One of these is shown below (with the orange front). concrete_speaker_design_nottingham_trent_university_560_18 concrete_speaker_design_nottingham_trent_university_560_19 They appeared to have been moulded using a small Tupperware tub (or something similar). We certainly found the visit very interesting. The people over at Nottingham Trent University were very welcoming (for which we send our thanks) and hopefully we will get to see some of the other things they get up to. It is very interesting to see concrete used in this way. Maybe it will inspire you to try using it on one of your own projects. Kerry sent us a few completed project pictures below: 15796677940_5eeb5a2bb6_c   15364332143_ccce337252_c   15983943665_8b69ae493a_c   15983948215_9e43c64f43_c   15798223117_5d0f400b48_c   See more pictures on this Flickr page.

5 comments

Charles Clark

Charles Clark

Looks awesome!!! I was thinking about making a guitar amp out of granite if anyone has ideas for cutting stone. I've lived on Vinalhaven, Maine USA Island, It used to be a huge quarry supplier for like the licoln memorial…also Hurricane Island nearby which is used for the Outward Bound Program. -C

Rob Haywood

Rob Haywood

Sounds like a follow up project to me Peter! It might be worth asking Kerry Truman on Twitter.

Peter

Peter

Looks great but has anyone measured the acoustical performance of the concrete speaker? I vaguely recall that in days of yore it was possible to buy HiFi speakers made with concrete which were extremely high performance. I guess what this comes down to is do will build concrete loudspeakers because we can and they look different or because they represent improved performance of other materials (Design!!!!!)

Matt Hubert

Matt Hubert

No one might have even thought to use concrete for speaker. Your post gives detail overview on making concrete blocks for speaker. Thanks for sharing useful tips.

jorge

jorge

Very nice speaker proyect! im looking forward to build a wood speaker, but you made me reconsider other materials, and concrete looks awesome!

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