The BSM BM-Q Special is a treble booster from the German maker BSM, built to reproduce the silicon treble booster design Brian May switched to in Queen's mid-phase for more bite. It is inserted between the guitar and the amplifier, not into an effects loop, and with the guitar's volume control turned up to the maximum BSM says it produces a fat, biting and penetrating lead sound, minus any shrill characteristics1.
Specifications
| Specification | Value |
|---|---|
| Type | Treble booster1 |
| Designed for | Single coil pickups with standard coil inductance1 |
| Power | 9V battery1 |
| Current consumption | approx. 500 uA1 |
| Average output level | 10dBm1 |
| Maximum output voltage | 7V max when the strings are struck really hard1 |
| Placement | Between guitar and amplifier, not the FX loop1 |
Power draw and output level
The BM-Q Special is powered by a 9V battery, and its current consumption is around 500 microamps, a figure far below what most pedals draw1. Its average output level is 10dBm, and the maximum output voltage when the strings are struck really hard is 7V max1. Those output figures matter for players feeding an amp that is expected to supply the distortion: the pedal is designed to hit the front end of a tube amplifier hard, which is why BSM specifies placement before the amp rather than in a loop1.
The BM-Q Special is designed to sit between the guitar and the amplifier, not in an effects loop1. Its sound depends on driving the amp's front end, with the guitar's volume control turned up to the maximum1.
Brian May and the BM-Q Special
The pedal's lineage runs through Queen's own gear history. According to BSM, Brian May used the British Range Master germanium treble booster in his early days, then in Queen's mid-phase switched to a silicon treble booster design for more bite, which BSM now reproduces with the BM-Q1. Guitar World has noted that May's tonal trio of his Red Special guitar, a Vox AC30, and a treble booster has underpinned Queen's entire discography2.
Pickups and what it is voiced for
BSM states the BM-Q treble booster has been specifically designed for single coil pickups with a standard coil inductance, naming Fender, Rickenbacker, Burns and Gibson guitars as examples1. It is not a pedal aimed at humbucker players; within the BSM range, designs for other pickup types exist, such as the BSM RPA California II Special Booster, which BSM has described as a preamp/booster for fat single coil and double blade humbucker pickups.
The BM-Q Special and the BM-Q
The Special is one of two versions of the same circuit. BSM describes the relationship simply: the same unit fitted with a volume control is called the BM-Q1. Players who want to shape the boost level from the pedal itself would choose the BM-Q; the Special is the fixed-output version.
BSM's broader treble booster range covers several related designs, including the BSM HS-S Treble Booster, the BSM RM Treble Booster, the BSM RM Early Days Treble-Booster and the BSM DM-T Fat Treble Boost. For more on the effect type itself, see Boost Pedals.
Videos
Marco G. Di Marco
Questions
What is the difference between the BSM BM-Q and the BM-Q Special?
They are the same circuit. According to BSM, the BM-Q is the same unit fitted with a volume control, while the BM-Q Special is the version without it. Both are treble boosters intended to sit between the guitar and the amplifier, not in an effects loop, and both are built around the silicon treble booster design Brian May used in Queen's mid-phase.
Does the BSM BM-Q Special work with humbuckers?
BSM designed the BM-Q specifically for single coil pickups with standard coil inductance, naming Fender, Rickenbacker, Burns and Gibson guitars as examples. It is not pitched as a humbucker pedal, so players with medium or high output humbuckers would look elsewhere in the BSM range.
Who designed the BSM BM-Q Special?
The pedal was designed by Bernd C. Meiser, whom BSM's own product page calls the company's tech-head and mastermind. Meiser was the designer behind BSM's range of treble boosters and related pedals.
What battery does the BM-Q Special use?
The unit is powered by a 9V battery, according to BSM. Its current consumption is very low, around 500 microamps, which is far below what a typical pedal draws and well suited to battery power.
Why is the guitar volume kept maxed with this treble booster?
BSM describes the BM-Q's characteristic sound, a fat, biting and penetrating lead sound without shrillness, as occurring with the guitar's volume control turned up to the maximum. The pedal is voiced to be driven hard from the guitar, so rolling the guitar volume back changes what it delivers.
Sources (2)
- BM-Q Special Treble Booster, treblebooster.net, 2025
- Joe Bonamassa now owns Rory Gallagher's Number 1 Rangemaster, Guitar World, 2025-02-28
