Applications
Where these amplifiers go
Eight installations, from a residence with speakers you cannot see to a floor plate with twenty-six of them — each one worked through as an actual channel and zone configuration rather than described in the abstract.
- Installations
- Eight
- Distribution
- Lo-Z and 70 / 100 V
- Power budget
- 500 W per chassis
How to read these
Every case below spends the same 500 W, because that is what the SD125.4 has. What changes between them is how the four outputs are arranged and where the speakers sit on them.
Ch 1 is one low-impedance output, up to 125 W into a 4 Ω to 16 Ω load. Ch 1/2 is a bridged pair driving one 70 V or 100 V line at up to 250 W, so the four outputs become two. Both arrangements can run at once in the same chassis, which is what most of these buildings actually want.
Power Share is not shown in these diagrams because it is not something an integrator lays out. The supply hands watts between the channels of a pair on demand, while the music plays — the numbers below are the design budget, not a set of allocations anyone types in.
These are worked examples rather than fixed products: arithmetic on the published specification, using tap values and speaker counts that a real install would use. Cable gauge, the constant-voltage wiring rule and the high-pass that keeps line transformers out of trouble are all on the technology page.
Speakers you were never meant to find
The case the rest of the category does not have: a house where every loudspeaker is either plastered into the wall, cut into stone outside or made of glass — and the amplifier is in a cupboard, which is the only piece of the system anyone is allowed to see.
Four rooms, four low-impedance outputs, nothing between the terminals and the drivers. Take the terrace outside and the arithmetic changes: bridge one pair into a 70 V line and the garden, the pool house and the terrace become one run of tapped speakers, while the two remaining outputs stay low-impedance indoors. Same chassis, no second amplifier, no transformer in the rack.
Four zones, low impedance
One residence · 4 Ω / 8 Ω
Great room Nakymatone invisible
4 speakers · 8 Ω
Kitchen & dining Nakymatone invisible
2 speakers · 8 Ω
Primary suite Nakymatone invisible
2 speakers · 8 Ω
Listening room Waterfall Audio glass
2 speakers · 4 Ω
Grounds on a 70 V line
One residence · Hi-Z outside, Lo-Z inside
Terrace, garden & pool house Architettura Sonora
8 speakers · 20 W taps · 160 W of 250 W
Great room Nakymatone invisible
4 speakers · 8 Ω
Kitchen & dining Nakymatone invisible
2 speakers · 8 Ω
Four rooms that are never at the same level
A small box with real power per channel is what a bar actually needs: the counter loud, the seating civil, the back room on its own, and the courtyard running whatever the weather allows.
Four low-impedance outputs cover it without a rack — the whole amplifier is half a rack unit wide and 2.8 kg, so it goes in the cupboard behind the till rather than into a cabinet somebody has to find space for.
Four zones, low impedance
One venue · 4 Ω / 8 Ω
Main bar
4 speakers · 8 Ω
Lounge seating
4 speakers · 8 Ω
Back room
2 speakers · 4 Ω
Courtyard Architettura Sonora
4 speakers · 8 Ω
A dining room and a bar are not the same room
Sound is part of the service, and the level a dining room wants is not the level the bar wants three metres away. The two need separate control, and the dining room usually needs more speakers at lower output rather than fewer at higher.
That is exactly what a constant-voltage line is for: a dozen ceiling speakers on 10 W taps across the dining room, spending 120 W of the pair's 250 W budget, while the bar and the private room stay on their own low-impedance outputs.
One 100 V line, two Lo-Z rooms
One restaurant · 100 V ceiling, 8 Ω rooms
Dining room
12 speakers · 10 W taps · 120 W of 250 W
Bar
4 speakers · 8 Ω
Private dining
2 speakers · 4 Ω
Sound branding, across a whole floor plate
Retail sound is matched to the store rather than to a room: cool and low across a furniture floor, denser and louder in a clothing shop. The demand varies enormously between one tenant and the next, and the speaker count is usually high while the power per speaker is low.
Two bridged pairs give two independent constant-voltage lines from one chassis — the sales floor on one, fitting rooms and the entrance on the other, sixteen and ten speakers respectively, each line spending well under the 250 W it has available. Headroom on a line is not waste; it is the next six speakers the tenant adds.
Two 100 V lines
One store · constant voltage throughout
Sales floor Gray Sound
16 speakers · 10 W taps · 160 W of 250 W
Fitting rooms & entrance
10 speakers · 10 W taps · 100 W of 250 W
A yoga room and a spin studio, from one box
No other vertical asks a single amplifier for this range. A spin class wants everything the channel has; the yoga room next door wants almost nothing; the weights floor and the cardio deck sit somewhere in between and change through the day.
Four low-impedance outputs, four levels, and the reason this works from one chassis rather than two is that the demand is never simultaneous — the studio takes its headroom in bursts and the pair it belongs to hands the power across automatically while the music plays.
Four zones, low impedance
One club · 4 Ω / 8 Ω
Studio — spin & HIIT
4 speakers · 8 Ω
Weights floor
4 speakers · 8 Ω
Cardio deck
4 speakers · 8 Ω
Yoga & stretch
2 speakers · 4 Ω
Long runs, many rooms, one budget
Hotels and campuses have the same shape of problem: auditoriums, theatres, dining halls and a lot of meeting rooms, spread over distances that make low-impedance wiring impractical. What they need is complete flexibility in where the available power ends up.
Two constant-voltage lines carry it — front of house on one, the conference and teaching floor on the other. Cable length is the constraint that bites on a site this size, and the published gauge and run-length figures are on the technology page.
Two 100 V lines
One site · constant voltage throughout
Lobby, corridors & restaurant
16 speakers · 10 W taps · 160 W of 250 W
Auditorium & meeting rooms
10 speakers · 15 W taps · 150 W of 250 W
Open plan, boardroom, cafeteria
The corporate estate is several different jobs in one building: masking and background across open-plan desks, speech in the boardroom, and something with more level in the cafeteria and the warehouse.
A sixteen-speaker line on 5 W taps spends 80 W across the office floor — deliberately quiet, deliberately even — while the two remaining low-impedance outputs run the boardroom and the break area at whatever level those rooms need.
One 100 V line, two Lo-Z rooms
One floor · 100 V open plan, 8 Ω rooms
Open-plan office Gray Sound
16 speakers · 5 W taps · 80 W of 250 W
Boardroom
4 speakers · 8 Ω
Cafeteria & breakout
4 speakers · 8 Ω
Speech, first and last
A house of worship needs the voice carried reliably and intelligibly over a large distributed area with a lot of specialised speakers on it — which is a demand for quality at moderate power rather than for maximum output.
Twelve speakers on a 100 V line cover the nave at 15 W each, 180 W of the pair's budget; the narthex and the hall stay on low-impedance outputs so a service can carry through to the overflow space without the main run being touched.
One 100 V line, two Lo-Z areas
One building · 100 V nave, 8 Ω rooms
Nave
12 speakers · 15 W taps · 180 W of 250 W
Narthex & hall
4 speakers · 8 Ω
Chapel & offices
2 speakers · 4 Ω
Across all eight
500 W that moves
The supply shares its output automatically across each pair of channels, so a zone that briefly asks for more than its continuous rating gets it from a partner that is asking for less. Nothing to configure.
Both modes, same box
Output mode is set per output in the amplifier's own interface — no transformer in the rack, no separate high-impedance amplifier, and no reason a building has to pick one topology throughout.
Set up from a browser
The amplifier hosts its own web interface over a built-in wireless access point. Levels, zones, filters and limiters are set from a laptop or a phone on site, without a separate adapter and without joining the building's network.
Half a rack unit
44 × 220 × 319 mm and 2.8 kg, with optional rack and wall/desktop kits — so the equipment cupboard in a café and the comms room in a hotel take the same amplifier.
Specifying one of these
The SD125.4 page carries the full specification, the connector list and the mounting hardware; the technology page has the wiring and cable references behind every configuration above. For a system that does not look like any of the eight, talk to us.