The Lehle RMI Classic Boost, sold in its manual as the Lehle RMI Basswitch Classic Boost, is a compact bass preamp that combines the boost circuit from Lehle's BASSWITCH IQ DI with a 3-band EQ voiced for vintage basses1. Lehle designed it with classic passive P, JJ and PJ basses in mind, and the manual, written by Ruppert Musical Instruments of Schouweiler, Luxembourg, describes it as a high-end bass preamp and booster gently voiced for passive P, JJ and PJ type basses2.
The pedal is discontinued: Lehle's product page lists it as such, so it is now found only on the used market1. When Bass Musician Magazine reviewed it in July 2016, it sold for $2593.
What it does and who it is for
Lehle positions the Classic Boost as a booster with an adjustable EQ, and its primary application, per the manual, is exactly that: a boost pedal with EQ shaping built in2. The maker lists three ways to use it:
- As a stand-alone booster1
- Teamed with the BASSWITCH IQ DI for more options1
- As a compact preamp in front of an active monitor or bass cab1
The signal path starts from a discrete JFET input stage, and Lehle claims a dynamic range of over 110 dB with very little noise1. The input accepts both active and passive instruments, so while the EQ voicing was aimed at passive P and J style basses, active basses can be connected without issue2. The output is intended for a bass amp, power amplifier or active monitor2.
Controls and EQ
The gain control adjusts the volume of the pedal, boosting or cutting the signal, with a neutral position at 12 o'clock2. Overall gain adjustment spans +/-15 dB1.
The 3-band EQ is where the Classic Boost differs from Lehle's Clean Boost. The treble control combines a passive high-frequency reduction with an active high-frequency boost, so it can either roll off top end or push it1. The bass control offers +15/-11 dB at 45 Hz as a peaking filter2.
| Control | What it does |
|---|---|
| GAIN | Adjusts volume, boosts or cuts the signal, neutral at 12 o'clock2 |
| Bass | +15/-11 dB at 45 Hz, peaking2 |
| Treble | Passive high-frequency reduction combined with an active high-frequency boost1 |
Bass Musician Magazine's reviewer Jake Wolf found the EQ gave the pedal more shape than the Clean Boost, writing3:
"Where this pedal differs from the Clean Boost, is that it has a little more shape to its tone profile, which again is designed to complement passive or traditional style basses."3
He also found it worked well with Fender style instruments:
"I felt that it helped pocket the sound of my P bass even more effectively than the Clean Boost."3
Power and switching
The Classic Boost works internally at 18V but is content with any external supply between 9 and 15V, AC or DC1. The manual specifies a minimum of 60 mA and notes that the polarity of the supply is not relevant: either alternating or direct current sources can be used2. Internally the supply is rectified, filtered and stabilized up to 18V2.
The Classic Boost cannot run on batteries. The manual states its power consumption is too high to run it satisfactorily on batteries, so an external supply is required2.
Switching is handled by Lehle True Sound Technology, which uses exclusively gold-plated contact relays and/or gold-plated switches rather than a true bypass arrangement2. Lehle describes the construction as extremely robust, with protected controls and an indestructible switching mechanism1. Maximum output level is 15 dBu with a 12V power supply2.
Questions
Is the Lehle RMI Classic Boost still made?
No. Lehle lists the RMI Classic Boost as discontinued on its product page, so it is no longer in production. It appears on the used market, and its original selling price was $259 when reviewed in 2016.
Can the RMI Classic Boost be used without a DI box?
Yes. Lehle describes it as usable as a stand-alone booster or as a compact preamp in front of an active monitor or bass cab, with an output designed for a bass amp, power amplifier or active monitor. It can also be teamed with the BASSWITCH IQ DI for more options.
Does the RMI Classic Boost work with active basses?
Yes. The manual states the input is designed to accept active and passive instruments. Lehle says the EQ voicing was designed with classic passive P, JJ and PJ basses in mind, but active basses can be connected.
Does the RMI Classic Boost use relay switching?
Yes. Lehle True Sound Technology switches exclusively through gold-plated contact relays and/or gold-plated switches rather than true bypass, which Lehle describes as an indestructible switching mechanism.
Can the RMI Classic Boost run on AC power?
Yes. It accepts 9 to 15V from either AC or DC supplies, and the polarity of the connector is not relevant. It cannot run on batteries, since its power consumption is too high for satisfactory battery operation.
Sources (3)
- RMI CLASSIC BOOST (DISCONTINUED), Lehle GmbH
- Lehle-RMI-Basswitch-Classic-Boost_Manual_EN.pdf, Ruppert Musical Instruments, 2023
- RMI Sonic Spark, Clean Boost, and Classic Boost Reviews, Bass Musician Magazine, 2016-07-17
