Congratulations on your purchase of the LBR-100 Lead Bass Rhythm Isolator.


Take a minute to inspect the contents of this box.


You should find:

1)         LBR-100 Lead Bass Rhythm Isolator

2)         120 volt, 60 Hz AC power adapter, 9 VDC, 500 ma, positive inside terminal, negative sleeve

3)         Registration Card

4)         Warranty Information

5)         This manual


We have made this manual as short as possible so that it is practical for someone to read it carefully and thoroughly. Please take the time to do this now and feel free to follow the instructions with your unit as you read through the manual.


Note: Cabling

The line in and line out jacks  take a 3.5 mm stereo miniplug .


Setting up your LBR-100 

Hook up a stereo line level output from a CD player, tape player or stereo to the input jack of the LBR-100. Hookup the line level output from the LBR-100 to a stereo input of your stereo or powered speakers.


Power can be supplied from either a 9 VDC battery placed inside the unit or from the supplied power adapter. See instructions at  the end of the manual before putting in the 9VDC battery. The ON/OFF switch is located on the rear of the unit.


Singers wanting to produce backgrounds may want to skip to the end of the manual and use the recommended setup for vocal and lead elimination.


Getting Started

Set the leftmost knob to CENTER , the leftmost switch to BAL , the middle knob so the pointer is pointing at FREQ, the rightmost switch to BY  and the rightmost switch turned to it's furthest counterclockwise position.


This is the neutral setting for the LBR-100. If you play music through the unit in this state, it will appear at the output unchanged.


Signal Path through the unit.

The LBR-100 consists of two separate sub units, the spatial filter and the frequency filter. Sound travels into the spatial filter and then through the

frequency filter and then to the output of the LBR-100. With one exception, the leftmost knob and switch effect the spatial filter and the rightmost two knobs and one switch are part of the frequency filter.


What is a spatial filter?


The whole point of the stereo recording format is to give a sense that the band is in front of you, with all the various instruments at different places spatially.  For example, usually the singer in a band will appear be in front of the band in the center. If you put on headphones and listen to a stereo recording, you'll  most likely notice that it sounds like the singer is in front of you with the other  members to the left or right side in varying degrees.


The spatial filler then allows you to filter the music based on this spatial property of stereo music. Thus this spatial filter will not work with an old fashioned mono recording  .




The simplest kind of spatial filter is the traditional left/right balance often found on stereo systems.


When the leftmost switch is in the BAL position, the leftmost knob acts as a stereo balance control.


By leaving the knob pointer pointing straight up, the left/right balance is as originally on the recording.


By turning the knob to the left, the output of the spatial filter is more heavily weighted towards the left channel, Similarly by turning the knob to the right, the output of the spatial filter is more heavily weighted towards the right channel.


When using this device to transcribe, sometimes a particular instrument may be eliminated or brought to the forefront by simply adjusting the balance control. Similarly, some play-along records require a stereo balance control so the device can be used for that application too.


Cancel (Vocal or Lead Elimination)


Sometimes one desires to eliminate some particular musician in the recording so that you may replace that person . For example, a singer might wish to sing along with the recording and want the singers voice on the recording to go away.


This function is called stereo cancellation because some point on the stereo line of left to right is cancelled (remember that each instrument appears to the ear to exist somewhere in the left to right line in front of you).


Some simple units in the past have had this function with the only point that can be cancelled being the center of the stereo line. This is called "center cancel" and will work in a limited way on stereo pop recordings where you want to cancel the lead player or vocalist since they are usually in the center.


When the left most switch is set the CAN, the left most knob is the stereo cancellation control.


When the cancellation control is in the CENTER position, then stereo center cancellation is in effect.


On a stereo pop recording this should have the effect of removing the vocal or lead instrument. It will not do this 100% usually because of  various reasons, the most common being the presence of stereo reverb in the recording. How well the cancellation works will depend on the recording but in any case, the amount of the lead or vocals should be greatly diminished and if you play or sing on top of it, you shouldn’t be able to hear the original vocal.


This function is also useful for someone wishing to figure out the background parts in a recording. By eliminating the lead or vocal, it's easier to hear the rest.


However, many times the instrument you want to eliminate is not in the center, but rather to the left or right.


In this case you turn the cancellation control to the left or right until you hear the instrument diminished to a maximum degree.


Cancel and the Bass


What happens on a pop recording if two instruments are at the identical place on the left/right stereo line?


The answer is that you will cancel them both.


This is not usually  a problem except for the fact that on a stereo pop recording, frequently the singer or lead instrument and the bass player are both in the center.


So then if you cancel the vocalist, you'll also cancel the bass player.


If you are just using the LBR-100 to figure out the piano or rhythm guitar track then you won't mind because the more that gets taken out, the better.


However if you are a singer and want to use the LBR-100 to create a background, you aren't going to like that.


To solve this problem we have a way to add the bass player back in.


This is done by setting the leftmost switch to CAN+LO .


The LO refers to the frequency filter. You must set the frequency knob to only allow the bass to  pass . However the FILTER switch must be set to BY (See the filter unit description for how to do this). You can adjust the amount of bass added back in by using the LO PASS GAIN knob.


Frequency Filter Unit


Music can be filtered based on the frequency of the sound.


When one is trying to isolate individual instruments, this will work with limited success, depending on the instrument.


This is because the instruments overlap in their frequency range and because sounds have overtones which make even a low frequency instrument have a diminished component in the higher ranges.


The one exception to this is the bass which is there all by itself (except for the bass drum possibly) in the low frequency range.


In general the frequency filter unit will be applied directly to the output of the spatial filter . (The one exception to this is when the leftmost switch is set to CAN+LO which will be explained separately later).


There are two kinds of  frequency filters that can be applied to the sound, the low pass filter and the high pass filter. (Only one may be used at a time).


The low pass filter will only allow sound below a given frequency to pass through the unit and the high pass filter will only allow sound above a given frequency to pass through the filter.


No filter is perfect but on this unit, the low pass filter is fairly close to a brick wall (I.e. sound above the given frequency will be completely filtered out). This allows near perfect isolation of the bass player.


The high pass filter is good but not nearly as sharp as the low pass filter.


The middle knob is the frequency control and can be set at any frequency between 100hz and 1Khz.


The filter switch determines whether the frequency filter is in low (LO), bypass (BY) or high (HI).


When in bypass, the frequency filter is bypassed and not applied to the output of the spatial filter.


The most common use of the low pass filter is to isolate the bass player. By setting the frequency low enough, you should only hear the bass.


Similarly, if the bass player wants to play along with a recording, you can use the high pass filter and set the frequency very high in order to eliminate the bass. Note though that the bass player may also be eliminated in the CAN mode of stereo cancel or with the stereo balance control. The right choice depends on the recording.


Low Pass Gain (LO PASS GAIN)


This knob will control the amount of gain applied to the low pass filter. This knob should be left in the leftmost counterclockwise position when the low pass filter is not being used , otherwise some audio clipping may occur in some instances.




When using the CAN+LO function on the leftmost switch,  the LBR-100 will produce the sum of:


1) The spatial cancellation filter and

2) The low pass filter.


By setting the low pass filter frequency low enough, it will only allow the bass player to pass through and this is how the bass is added back when it is accidentally removed during cancellation of the singer or lead instrument.


The Filter switch should be in the BY position.


Recommended settings for singers (or lead players) producing backgrounds


Leftmost knob in center, leftmost switch on CAN+LO, frequency knob completely counterclockwise to the left, filter switch on BY and the LO PASS GAIN knob adjusted to taste.


Putting in the battery

Unplug the unit from the power adapter before performing this function.Otherwise electrical shock could result. The two screws on the bottom of the  unit should be removed. The top will come off and  you will see the battery  holder. Be careful when inserting the battery into the batter holder as the battery holder is part of the circuit board. Try not to get your fingers on the circuit board.





Features include:

·         Stereo Left/Right Control

·         Stereo Balance/Cancel/Cancel+Low Pass Select Switch

·         Filter Frequency Control

·         Low Pass/Bypass/High Pass Filter Select Switch

·         Low Pass Gain Control



Stereo Line input (3.5 mm stereo miniplug)



Stereo line output (3.5 mm stereo miniplug)


Power:  9 VDC, 500 ma, positive inside terminal, negative sleeve or 9VDC battery.