Raven Labs True Blue EQ Owner's Manual
A novel approach to equalizers, the Raven LabsTrue Blue EQ is basically a 5 band semi-parametric designed to “enhance the essence” of your sound, while maintaining the basic characteristics. It is the ideal choice for dialing in “your sound”, mastering a mix, correcting room acoustics, and equalizing “hot” or “dead” spots on an instrument.
Boost or cut is achieved by adding or subtracting the original signal to itself in a parallel arrangement. Most EQ’s use active series circuits that can muddy the signal, cause phase shifting, and other undesired anomolies. The bandwidths in the boost mode were chosen for “musicality”, and are a function of frequency. The bandwidths in the cut mode are narrower, creating more of a notch filter affect. This allows the user to better pinpoint a problem area without drastically altering the true sound. Hence the name, “true blue”. You will notice the difference the first time you use it!
The unit can be powered with two 9 volt batteries, or a custom A/C adapter. Under normal use, new batteries can last up to 80 hours provided the unit is turned off after each use.
When using the True Blue EQ, first decide the best location in the signal path of your system. If used with a musical instrument, such as a guitar or bass, it should be placed either in the Effects Loop of your amplifier, or between the preamplifier and power amplifier. Since the input impedance of the True Blue EQ is relatively low (40K ohms), you should not plug your instrument directly into the EQ. This could cause a loss of highs with a magnetic pickup, or loss of lows with a piezo type pickup. Keyboards, or other musical instruments with on-board preamps or buffers can be inserted directly into the True Blue. If in doubt, always check with the manufacturer of your instrument. In all other applications, use as you would any other equalizer.
Always use good quality shielded patch cords of minimum length. Try to avoid placing the EQ near a large power supply or transformer (such as found in a power amplifier). If you are getting a humm or buzz, try relocating the unit to a more friendly area.
Each of the 5 bands of equalization has two functions: the Level control; and Frequency control. The LEVEL control on the LEFT adjusts the desired amount of cut or boost. The FREQUENCY knob on the RIGHT sets the area of sound (frequency) to be adjusted (by the Level function). No sound alteration will occur with the Level control set at the “0” or 12 o’clock “flat position, The chart below should help you find the area you desire to be enhanced, or may be having trouble with- such as a dead spot or feedback.
To get used to how the Level and Frequency functions work, try playing a chord on an instrument or listening to some pre-recorded music. As you do, boost or cut one of the Level controls to near maximum. Then rotate or “sweep” the Frequency function next to it. Each band will give you a different range of coloration. The more you get used to each band and it’s properties, the easier you will find the area you wish to address. Again, also notice that with the Level at “0”, no sound changes will occur when sweeping the associated Frequency knob.
It should be noted that pushing in the EQ IN/OUT switch (red LED lit) is the same as having all Level controls set to flat. This function is an easy way to A/B the sound you have selected.
The following is a general equalization curve and adjustment to try as a starting point for enhancing your sound. Remember however, that when using a musical instrument, what may sound good solo, may not work in the “mix”.
1. After you have installed the True Blue EQ in your system, activate the EQ IN/OUT switch in the “out” position.
2. Adjust the 5 bands as follows:
Band 1: Level at +7 dB (3 o’clock), Frequency at 80 Hz (about 1 o’clock)
Band 2: Level at -6 dB (9 o’clock), Frequency at 200 Hz (approx. 11 o’clock)
Band 3: Level at -6dB (9 o’clock), Frequency at 800 Hz (around 1 o’clock)
Band 4: Level at -6 dB (9 o’clock), Frequency at 2KHz (about 11 o’clock)
Band 5: Level at +6 dB (3 o’clock), Frequency at 5KHz (about 10 o’clock)
3. While listening to a chord played on your instrument or some pre-recorded music, activate the EQ by engaging the IN/OUT Switch to the “in” position (green LED).
After listening, you may find this “curve” pleasing or maybe a little thin. Moving the Level controls from one extreme to the other (cut or boost), should help you find a curve that is more suited to your ear or instrument.
On each band, the Level control cuts or boosts the frequency set by the Frequency control to it’s right. The Level function will boost up to +15 dB and cut at least -15 dB. In some cases, if all the tolerances are exact, a greater cut than -15 dB can occur. Remember that the bandwidth, or “Q” in the cut mode is less than that in the boost position.
The numbered frequencies surrounding the Frequency control are to be used as a guideline. To find the exact frequency you are searching for, start at the approximate position, then rotate the knob left or right to find that “sweet” spot.
EQ IN/OUT Switch
Activating this feature takes the 5 bands of EQ out of the signal path. This is indicated by the red LED lighting. The EQ is in the circuit when the green LED is lit.
Power ON/OFF Switch
To turn on your True Blue EQ, push this switch in. This will be indicated by the green LED lighting. If the EQ IN/OUT switch is activated, the red LED will light. The power is off when neither LED is lit.
Balanced Input and Output jacks are provided on the True Blue EQ. Wiring is as follows: Tip = +, Ring = -, Sleeve = ground. These jacks should only be used with feeds to or from balanced inputs or outputs. Phantom power applied to the Balanced output jack will not cause any harm to the unit. Both the Balanced and Unbalanced output jacks can be used simultaneously as they are completely independent. However, only one of the input jacks can be used at any given time.
Input impedance of the Balanced and Unbalanced Input jacks is 40 K ohms. Output impedance of the Balanced and Unbalanced Output jacks is 100 ohms.
Unbalanced TS Input and Output Jacks
Use these jacks in any unbalanced situation such as that of a mixer or musical instrument amplifier. As stated above, both the Balanced and Unbalanced outputs can be used at the same time. This means that you could send a feed to an onstage monitor using the Unbalanced ouput, and send a signal to the “house” using the Balanced output jack.
Dual 9 Volt Battery Holder
Easy external battery access and installation is provided using this feature. Be sure and check the polarity of your batteries before installing them. Plus is on the left, minus on the right. If, after installing batteries, your unit does not turn on, turn off immediately and check the polarity of both batteries. Clamping diodes protect the internal circuitry and will cause batteries installed incorrectly to get warm.
A/C Adapter IN/OUT Jacks
When using a Raven A/C adapter, plug the adapter into the adapter IN jack on your True Blue EQ, and then into the wall outlet. Thisprevents momentarily shorting the adapter to ground during the insertion process.
One Raven adapter will power several other Raven products. To power another unit,run a stereo mini jack cord from the A/C Out jack to the A/C In jack of the secondproduct. Since the output from the adapter is a DC voltage, no humm induction should occur to other units in the vicinity of these patch cords. The output from the adapter is +/- nine volts. Wiring is as follows: tip = -, ring = +, sleeve = ground. Always unplug the adapter from the wall after each use.
Rack Mounting
An 8-32 threaded stud in provided on the bottom of your unit to aid in mounting to a rack shelf, etc. Use an 8-32 machine screw no longer than 1 1/2 inches. Leave the rubber feet attached as they can act as a “shock absorber”.
Low: 30Hz to 100Hz
Low Mid: 100Hz to 300Hz
Mid: 30Hz to 1kHz
Treble: 1kHz to 3kHz
Ultra High: 3kHz to 10kHz
Input Z : 40 K ohms
Output Z : 100 ohms;
Distortion: .002% @ 1kHz
Noise: -90 dbV (IHF unweighted)
Max Input Level : 2V RMS (+6dbV)
Max Output : 6V RMS
Frequency Response: -3dB @ <10Hz to 63kHz
Size: 6.7” W x 2.26” H x 6” D
Weight: 3 lbs.
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