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MB 115/B

The MB 115/B building suggestion is a bass speaker for professional musicians. If fullrange musicians' speakers need boosting the bass department, you need bass speakers with a comparatively high level of efficiency. Bass reflex speakers have the advantage of a low limiting frequency, but this also means they need a large cone area with the large cabinet that this entails, in order to produce sufficient sound pressure. A completely uncompromising bass speaker should really be enormous. However, the MB 115/B makes use of a cleverly designed flare geometry, perfectly matched to the BGS 40 - 8 Ohm driver, to produce a relatively compact horn. A limiting frequency of 50 Hz is a perfectly respectable level for a musician coupled with an output level of 96 dB above 60 Hz under open-field conditions (no walls, no floor) at just 1 watt is an excellent starting point for extreme bass pressure. It must be taken into account that, positioned on the floor away from walls, this figure increases by 3 dB and near a corner by as much as 9 dB. We measured peak output levels of as much as 125 dB (above 60 Hz) under favourable conditions. And all that with the typical horn-like, bone-dry sound characteristics an experience for aficionados of solid-level, dynamic sound!

The horn sound develops in a vortex beginning in front of the diaphragm and moving outwards towards the opening. At the rear, the woofer acts on a small, enclosed compartment. This prevents the stroke in the low bass and subsonic ranges from becoming too extreme which prevents mechanical damage to the driver. The impedance curve retains a pleasingly high level throughout. This means that the booster is not overloaded and the voice coil does not overheat. Crucial points in the tough daily life of professional musicians.

Active separation is recommended. This allows the optimal position between separating frequency and slope rate to be found. As a cost-saving alternative, we have also developed a passive crossover. This system separates at 150 Hz and goes well with the top-of-the-range MB 208/H, if the recommended high-pass section is used ( refer to MB 208/H ).


Extract from HobbyHiFi

"Verdict: This combination of 208/H and 115/B provides excellent sound properties at hi-fi level, and with masses of dynamic power in reserve. Thanks to the high efficiency level, even a 100-watt amplifier will provide the enough power - calculations show that this would produce a maximum output of 113 db, even if a more powerful booster will make even more sense of both the satellites and the bass."

Technical Data
Component parts list
Additional Content
Rated power 500 W
Nominal impedance Z 8 Ohm
Übertragungsbereich (-10 dB) 50–400 Hz
Mittlerer Schalldruckpegel 96 dB (1 W/1 m)
Gehäuseprinzip Horn
Außenmaß Höhe 800 mm
Außenmaß Breite 480 mm
Außenmaß Tiefe 720 mm

Component parts list for 1 box

BGS 40 - 8 Ohm
1 pc.
ST 77
1 pc.
Special wood screws
5 x 30 mm
8 pc.
2 x 2,5 mm²
1 m

Frequency- and impedance response


Crossover for passive mode:
Universal circuit board
UP 35/3
1 Stückpc.
LR 6,8 mH
2 pc.
Elko spezial 82 µF
4 pc.

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