BTB MMSR 3 KNOB V/B/T/MSw USING 3 POTS & JACK
The BTB-MMSR 3 Knob, including Mid Sweep, has been designed with characteristics very similar to the original MM Stingray© 2 Band EQ, but is not a copy of the original circuit. The original used a single op-amp chip (single amplifier stage in the form of a chip) for both bass and treble circuits, whereas this unit utilises a more modern dual op-amp chip (two amplifiers stages in a chip). The bass and treble are stacked which allows inclusion of a mid sweep, along with original MM style bass and treble on a 3 knob plate. When the mid boost/cut is centred, its effect is neutral and the EQ is purely late 70s MM style.
This unit is supplied fully wired, including 1 single pot, 2 stacked pots, knobs, jack and battery clip, which may be spliced into an existing battery box, as would be available, in most cases.
· Single Knob - VOLUME
· Stack Knob - Late 70s MM style BASS / TREBLE / Pull for BRIGHT (Bright is similar to Sabre© bright toggle, but has a little more boost)
· Stack Knob - MID / MID FREQUENCY SWEEP (Mid Sweep 01 unit)
POWER REQUIREMENTS: 9-18V, 2.5mA
BASS & TREBLE CONTROLS
The design of the 2 band EQ in the early Stingray© basses is unusual in that it does not follow the types of topologies around which the majority of equalisers are designed. It would seem that Leo Fender designed it to create a particular sound rather than follow any conventions, such as symmetrical EQ curves. Consequently the figures shown may appear unusual to those familiar with such specifications. In fact it's not easy to portray what this EQ does with a few numbers, but in any case some figures, based around a flat response input signal, are quoted as reference points.
NOTE: Like the original Bass/Treble EQ, this circuit does not have a flat response when the controls are set midway. This unit is not designed as a clinical tool, where what goes in, comes out at some reference setting. However, the Mid Sweep circuit does have a neutral setting in order to preserve the original feel of the Bass & Treble EQ.
TREBLE (+20dB / -16dB @ 10 kHz)
The upper knob controls the treble. There is more boost than cut, giving rise the characteristic 'sizzle' associated with the Stingray© style of EQ.
BRIGHT (+6dB @ 7kHz)
Pull the Treble knob for the Bright setting.
BASS (+14dB / -7dB @ 40Hz)
The lower ring bass control has a little more boost than the original. The boost curve continues to rise towards the lower frequencies, without flattening out at any frequency within the normal bass guitar range. Conversly the cut characteristic is shelving, having an essentially flat response from 30 - 100Hz, when fully cut.
MID LEVEL & FREQUENCY
BOOST/CUT (+/-12dB) The upper knob sets the amount of Mid boost or cut at frequencies according to the setting of the Frequency knob. The midway indent is the 'flat' setting.
FREQUENCY (100Hz - 1kHz or 200Hz - 2kHz)
The lower outer ring sets the continuously variable Mid frequencies for boost or cut. DIL switches on the circuit board allow low or high ranges to be set. Both switch sections should be set to ON for the Low Range and both set to OFF for the High Range.
Sets the level from the bass and treble section of the preamp feeding the mid section. This means that the pickup feeds the preamp directly, allowing the best possible transfer of signal, and full interraction of the pickup with the preamp. Since the mid section is after the volume control, it feeds the jack directly with a low impedance output.