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DI box hire — active and passive
A DI box sits between an instrument and the mixing desk. It takes the unbalanced jack signal from a guitar, bass, keyboard or laptop and turns it into a balanced XLR line that can run the length of a hall without picking up hum. We hire both kinds — passive boxes that need no power at all, and active boxes that run from the desk's phantom power — at £2 per day each, dry hire or with a technician. Tell us what is being plugged in and we will send the right ones.
Every input on a mixing desk really wants a balanced signal, and instruments do not give one. A guitar, a keyboard or a laptop headphone socket puts out an unbalanced signal on a jack lead, and unbalanced signals collect hum and buzz as the cable gets longer. A DI box — direct injection — does the conversion. Instrument jack in, balanced XLR out, and the XLR line will run thirty metres to the back of a hall and arrive clean. Most boxes add two useful extras: a link jack that passes the signal straight on to the player's own amplifier, and a ground lift switch that breaks the earth loop behind most steady mains hum.
A passive DI is a transformer in a tough metal box. There is nothing to power and nothing to switch on, which is why it is the default for sources with a healthy output of their own: keyboards, active basses, electronic drum kits, DJ mixers, laptops and backing-track players. For the keyboard in a musical pit or the laptop running a dance show, passive is almost always the answer.
An active DI has a small preamplifier inside, which gives it a far higher input impedance. That matters for instruments with no electronics of their own — a passive electric bass, a guitar plugged straight in from its pickups, an acoustic with a pickup but no onboard preamp. Into a passive box those sources can sound thin and quiet; the active box keeps their level and tone intact. The preamplifier needs power, and it normally takes it as 48V phantom power sent up the XLR by the mixing desk — the same +48V button you would press for a condenser microphone. If your desk has no phantom power, say so when you book and we will supply active units running on fresh batteries instead. Phantom power does a passive box no harm, so a mixed rig on one desk is fine.
There is no rigging and no mains involved. The boxes sit on the stage floor by the player, get plugged in at the soundcheck and are then forgotten about until the get-out. Tell us what is being plugged in, instrument by instrument, and we will make up the right set — stereo pairs for keyboards and playback, actives for the acoustic guitars — with as many boxes as the show needs. For a big band night, tell us what is plugging in and we will supply enough for all of it.
One box on this page is not a DI. Interspace build the PCBB3 for a single awkward source: a computer. It takes the unbalanced output of a laptop or a desktop, balances it for the run to the mixer, and eliminates the hum that a machine sitting on the mains earth otherwise puts into the PA. If the buzz arrives the moment the laptop goes on charge, that is the fault it is built for. It hires at £4 a day.
What you get
Good for
What you need to know
- What it does
- Converts the unbalanced jack output of an instrument, keyboard or laptop into a balanced XLR signal that can run a long way to the mixer without collecting hum.
- Phantom power
- Passive boxes need no power at all. Active boxes run from the 48V phantom power on your mixing desk, or from a battery if your desk has none — tell us which when you book.
- Connections
- Quarter-inch jack in, a link jack out to the player's own amp, and balanced XLR out to the desk or stage box.
- Where it goes
- On the stage floor next to the player, or under the keyboard. A small metal box with no mains lead and nothing to rig.
- Who runs it
- Nobody, once it is plugged in and checked at the soundcheck. If there is hum, flick the ground lift switch; otherwise leave it alone.
Hire rates
Choose the one you need. The photo and price follow your choice.
Rates are per day and exclude VAT. A longer hire costs less per day — tell us your dates and we will price the period exactly. Ask us about delivery and hiring with a technician.
Check availability
See whether this is free for your dates. This is an indication from our current bookings, not a reservation.
Full technical specification (8)
| Type | DI (direct injection) box — active and passive units available |
|---|---|
| Input | Unbalanced 6.35mm jack, for instrument or line-level sources |
| Link output | Second 6.35mm jack passing the input straight on to the player's own amplifier |
| Output | Balanced XLR at microphone level, into any mixer or stage box |
| Power, passive units | None — a transformer does the conversion |
| Power, active units | 48V phantom power from the mixing desk, or an internal battery |
| Switches | Ground lift for curing mains hum; an attenuator pad on most units for very hot sources |
| Mains | No mains connection at either kind of box |
Common questions
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The rule of thumb is the opposite of the source. Anything with its own power — a keyboard, laptop, electronic drum kit, DJ mixer or active bass — goes into a passive box. Anything without — a passive electric bass, a guitar straight from its pickups, an acoustic with no onboard preamp — wants an active box. If you are not sure, tell us what is being plugged in and we will send the right one. The price is the same either way.
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It is 48 volts the mixing desk sends back up the microphone cable, and it is what powers an active DI. Look for a button marked +48V or P48 on the desk, either per channel or as one global switch; almost every modern mixer has it. Running the active box from phantom means no battery to die mid-show. Passive boxes ignore phantom entirely, so it is safe to leave on across a mixed rig. If your desk has none, we will send battery-powered units instead.
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Over a short lead into a spare stereo input, yes. But headphone outputs are unbalanced, so over a long run to the desk they pick up hum, and one minijack carries two channels that the desk wants on two separate inputs. A minijack lead into a pair of DI boxes is the reliable way: clean stereo on two XLR lines, however far away the desk is.
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Yes. The box sits between the instrument and the amp: instrument into the input, link jack on to the amp as normal, XLR to the desk. The amp behaves exactly as it always has and the player hears no difference, while the desk gets its own clean feed to mix and balance.
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Usually. The balanced XLR line refuses most interference on the way to the desk, and the ground lift switch on the box breaks the earth loop that causes steady mains hum — try it in both positions and keep the quiet one. If the hum survives that and the source is a computer, the Interspace PCBB3 balance box on this page is built for exactly that fault. Otherwise the cause is normally upstream, often lighting dimmers or the instrument itself; tell us the symptoms and we will help you chase it.
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Talk to us
Tell us the venue, the dates and what the show needs, and we will confirm availability.
Call 0333 404 0621, email [email protected], or send us the details of your production.
Related: Theatre production · Dance shows · Live events · Venue support · Production toolkit