The RMI Acouswitch IQ DI is a floor unit for acoustic players that packs most of an acoustic pedalboard into one box. Its maker describes it as an A/B-input switcher, a high-end preamp, a clean booster, a parametric EQ, an FX looper and a DI box1. It was conceived by Jacques Ruppert of Ruppert Musical Instruments, manufactured, assembled and tested in Germany, and is now listed as discontinued21.
The unit is built for players who switch between instruments, fight feedback on stage, and need a balanced signal for the mixing desk. Premier Guitar counted two channels, eight I/Os, nine knobs, three footswitches and two mini toggles on the front panel3.
Channel A and Channel B
The two inputs feed two different signal paths. Channel A carries the high-end preamp and a 3-band EQ designed specifically for acoustic instruments, with bass, semiparametric mids and treble controls1. Channel B has no preamp or EQ at all, keeping the signal pure and unprocessed1. That split lets a player run one guitar through the full EQ treatment while a second instrument, perhaps one with its own onboard preamp, passes through untouched.
The EQ's semiparametric mids sweep from 100 Hz to 6 kHz2, and the preamp offers up to +/- 15 dB of gain1. The maker's published measurements point to a clean signal path: distortion of 0.005%, a frequency range of 50 Hz (low cut filter) to 100 kHz (+/- 0.2 dB), a maximum level of 4.5 V RMS (about 15 dBU), and a signal-to-noise ratio of -92 dB at 1 kHz, 0 dBU (A weighted)1.
The controls and footswitches
Three footswitches sit on the front panel: MUTE, MIX LOOP/BOOST, and A/B1.
| Control | What it does |
|---|---|
| A/B footswitch | Toggles between input INST A and input INST B, and between channel A and channel B1 |
| MUTE footswitch | Mutes the LINE OUT and D.I. OUT for quiet tuning or stand-by1 |
| MIX LOOP/BOOST | Switches the effects loop; doubles as a boost when no effects are in the loop13 |
| Mix Control | Sets the effects ratio added to the original sound, from 0% dry to 100% wet2 |
| PAD button | Attenuates the output signal to match a mixing desk microphone input1 |
The MUTE function works alongside a dedicated TUNER OUT, which keeps the tuner out of the signal path and prevents potential sound losses1. Premier Guitar noted the loop arrangement in its review: the IQ has a serial effects loop and a switchable effects loop, and the loop switch doubles as a boost when nothing is plugged into the loop3.
The body contour control and feedback notch
The Body Contour Control is the unit's feedback fighter. Lehle describes it as two things in one: a narrow notch filter to reduce feedback, sweeping 45 Hz to 500 Hz, or a broad low to low-mid boost2. The BCL (Body Contour Level) knob sets how far it goes: -24 dB in notch filter mode or +18 dB in peaking mode, across that same 45 Hz to 500 Hz range1.
Premier Guitar's reviewer found it practical for exactly the situations it is aimed at:
"the body contour control, which is effectively a notch filter that works within the 45 to 500 Hz range..."3
For an acoustic player on a loud stage, that notch range covers the body resonance frequencies where an acoustic guitar most often feeds back231.
Power and connections
The Acouswitch IQ DI is flexible about power but hungry for current. It accepts any supply from 9 to 20 volts, AC or DC, with polarity not relevant, but the supply must deliver at least 150 mA2. Whatever comes in is internally rectified, filtered, stabilized and brought to 18V1.
The maker states the power consumption is too high for the unit to run satisfactorily on batteries1. Plan on a dedicated power supply, not a battery or a low-current daisy chain output.
The rear panel carries the full connection set: LINE OUT, TUNER OUT, SEND and RETURN for the serial loop, SEND and RETURN for the Mix Loop, and an XLR D.I. Out for the mixing desk1. Output impedance is 150 Ohm1.
The DI output is a studio-grade box with pad, pre/post and ground lift switches, and it includes a Lehle LTMZ transformer for galvanic isolation2. The maker states the transformer handles a frequency range from 20 Hz to 100 kHz (linear) and levels of up to 16 dBU, and that both the D.I. Out and the Line Out can handle that range1. Galvanic isolation breaks ground loops between the stage and the desk, a common source of hum with balanced DI connections.
The enclosure is described by the maker as extremely robust with protected controls2, and at 1,375g in a 16.2 by 22.0 cm footprint1 it is a substantial floor unit rather than a compact stompbox.
Videos
Jacques channel
Jacques channel
Jacques channel
Questions
Can the RMI Acouswitch IQ DI run on a battery?
No. The maker states the power consumption is too high for it to run satisfactorily on batteries. It needs an external power supply delivering 9 to 20 volts AC or DC and at least 150 mA, and the supplied voltage is internally rectified, filtered, stabilized and brought to 18V.
Can I use two acoustic guitars at once with the Acouswitch IQ DI?
Yes. It has two inputs, INST A and INST B, each with a 5 MOhm impedance, and an A/B footswitch that toggles between them. Channel A carries the preamp and EQ while Channel B passes the signal pure and unprocessed, so you can set up two instruments with different treatments.
Does the Acouswitch IQ DI work with piezo pickups?
Yes. Both inputs have a high input impedance of 5 MOhm, which the maker says makes the unit suitable for piezo pickups as well as magnetic and active pickups. The high impedance preserves the top end that piezo transducers can lose into a lower impedance input.
Is the RMI Acouswitch IQ DI discontinued?
Yes. Lehle, which now presents the RMI products, lists the Acouswitch IQ DI as discontinued on its product page. The unit was designed by Jacques Ruppert of Ruppert Musical Instruments and was manufactured, assembled and tested in Germany.
What transformer is in the Acouswitch DI out?
The DI output uses a Lehle LTMZ transformer for galvanic isolation. The maker states the transformer handles a frequency range from 20 Hz to 100 kHz (linear) and levels of up to 16 dBU, and that both the DI out and the line out can handle that range.
Sources (3)
- EN.indd, Ruppert Musical Instruments, 2023
- RMI ACOUSWITCH IQ DI (DISCONTINUED), Lehle GmbH
- Ruppert Musical Instruments Acouswitch IQ DI Review, Premier Guitar, 2013-04-15
