Soundbox

Soundbox ideas as they stand. See Soundbox2 for older ideas.

Budget

Between £350 and £700

Large expenditures to come:

• batteries
• metal, wheels, etc. for cart
• boxes
• busbars and power cables
• power conversion/protection circuit(s)

Components

Storage

Box(es) for large items

• Waterproof - box can be closed and protect against weather/elements
  • https://cpc.farnell.com/c/electrical-lighting/enclosures-racks-accessories/ip67-enclosuress

• Wooden space dividers? - to keep batteries separate from amplifier and player equipment.

• Heatsink - to dissipate waste heat energy from the equipment in the box - milled aluminium
  • https://www.tosave.com/p/100418mm-Aluminum-Heat-Sink-Cooling-Heatsink-Kit-for-LED-Power-IC-Transistor-72933.html

Box for player

Main box needs to be open for large items. A small box therefore to hold both a Raspberry PI, a mobile phone, an space to charge/connect at least two other mobile phones.

Rain cover for box

A firm cover for the large box that stands off the edges to allow airflow but that is wider than the plan size.

If the amp/etc is running hot, the box can be run with the lid open.

Equipment

Power supply

Server power supply setup producing 24V or 48V

Batteries

SPIM08HP:

• https://www.ebay.co.uk/itm/42-SPIM08HP-3-7V-8AH-LITHIUM-POLYMER-BATTERIES-25C-200A-SUPER-CELLS-24V-36V-48V-/202508210597

Busbar

• Copper? - expensive, better conductivity
• Steel? - some variety. cheaper, more corrosive, could be sealed

Power conversion

• Buck converter
  • From 48V to near enough 14.8V for the amplifier.
  • From 48V to 5V 2A USB for the Raspberry PI.

Power protection

• Voltage tester / power output regulator

Cuts off bellow a certain voltage. Alarm sound? [1]. Part time checking; [2]

• Fuse / polyfuse / circuit breaker

Surge protection? Generator failure or lightning?

Ground loop isolation for when connected to a generator?

Amplifier

AudioControl LC-6.1200. 125 watts RMS x 6 at 4 ohms (200 watts RMS x 6 at 2 ohms). 400 watts RMS x 3 bridged at 4 ohms (4-ohm stable in bridged mode). Dimensions: 12″W (304mm) x 8.0″D (232mm) x 2.1″H (53.3mm).

Speakers

• Tannoy 623
  • Recommended amplifier power: 10-90W. 90W RMS?? 150W peak??
  • Dimensions: 409x237x219mm
  • Sensitivity: 87dB, 88dB at 2.83V at 1m
  • Nominal impedance: 8 Ohm
  • Frequency response: 55 - 30.000Hz
  • Crossover frequency: 4Khz

[3], Manual [4].

• Subwoofer enclosure and driver to be sorted at a later date.

Music player

• Raspberry Pi

Software stack to be decided.

Basic infrared control?

WiFi for when power is not an issue.

HDMI DAC for multi channel would be neat.

FM transmitter

For satellite speakers.

• Transmitter - either basic 50nW, or more advanced (1W TX).

• Aerial

Lighting

• LED lighting - so things can be operated in the dark, and so things can look good

Transport

Cart

Bespoke. Welded aluminium.

Boxes can be bungee chorded to the cart.

Projection of sound from speakers on the cart is an engineering challenge given cart will change between stationary and roving.

Notes

Power

to redo

• Amp - 1200W = 200W * 6 channels at 2 Ohm:
  • 125 Watts @ 4 Ohm ("With a 8 ohm speaker, maximum power = 50 watts"???)
  • 200 Watts @ 2 Ohm ("With a 8 ohm speaker, maximum power = 63 watts"???)
  • Min: two tannoys @ 120W
  • Future: above plus sub @ 200W = 320W

• FM:
  • 12-15V DC Regulated 650mA max = @ 12V 7.8W
  • Stereo: Power supply or battery over 11-16V DC

• RaspberryPi
  • Raspberry Pi 3 B Baseline
    • Idle 260 mA (1.4W)
    • ab -n 100 -c 10 (uncached) 480 mA (2.4W)
    • 400% CPU load (stress --cpu 4) 730 mA (3.7W)

Dimensions

• Amp
  • Width: 304mm (12″)
  • Depth: 232mm (8.0″)
  • Height: 53mm (2.1″)

• Speakers
  • Height: 409mm
  • Depth: 237mm
  • Width: 219mm