Introduction•

Thank you for your purchase of a high-quality Groove Tubes
microphone. Taking a few moments to understand your microphone
will help to insure years of exceptional service.

••Unpacking
The container for your microphone was carefully packed forshipping. Please also retain this packaging for transportation in theunlikely event that you need to return the product to the factory forservice. If your box does not include the following items, pleasecontact your dealer immediately:••

Always keep the power supply (if applicable) away from moisture
as well.
Never disassemble the mic, except to exchange capsules asprescribed on the GT33 and GT44. There are no user
serviceable parts inside. In particular, never touch the golddiaphragm, as this would ruin the mic.
Always use top quality cables in order to avoid shorts that may
damage the microphone electronics.
Avoid temperature extremes above 95˚F and below 50˚F. When
moving the microphone between outdoor and indoor
environments, allow the microphone to acclimate to room
temperature before connection and use in order to avoid
condensation on the diaphragm.
Never attempt to change the tube on the GT 44, GT66 or GT67 orModel 1B. Please contact technical support if this is necessary.

GT33 / 55 / 57 / Model 1B-FET
1) Groove Tubes microphone1) hard case1) hard mountGT44 / 66 / 67 / Model 1B1) Groove Tubes microphone
1) GT PSM1 power supply
1) 25-foot, 6-pin soft audio cable1) AC power cable1) hard mount
1) shock mount
1) hard case
Important: Please fill out and mail your warranty card
immediately so that we may provide you with optimal support foryour microphone.

Care of Your Groove Tubes Microphone
Here are a few tips on proper care of your new microphone:•••••Never subject the mic to physical shock.
Always use the recommended shock mount.
After each use, always wipe the mic exterior down with a soft
dry cloth and return the mic to its case or your mic locker. This
helps to prevent damage from dust and shock.
In the event that your mic needs more extensive cleaning, lightly
wet a soft cloth with water or a household-cleaning agent andclean the metal exterior of the mic, wiping it completely drywhen finished. Never spray a cleaning agent on the microphoneitself, as the moisture can damage the unit.
Avoid subjecting the mic to any kind of moisture, such as rain or
singing in the shower. (Avoiding saliva is another good reason touse a windscreen in vocal applications.)

Connections and Phantom Power
Groove Tubes microphones output a balanced, low impedance
signal. As such they require the additional signal boost gained fromconnection to mic-level inputs of a preamp or mixer channel. Aswith all condenser microphones, your Groove Tubes condenserrequires power in order to operate.
GT33 / 55 / 57 / Model 1B-FET
If you have a GT33, GT55, GT57 or Model 1B-FET, you willneed to connect the mic via XLR to a preamp or mixer channel
strip that supplies +48-volt phantom power. (Phantom powershares the same XLR cable as the audio from the microphone).
In order to avoid loud pops that can damage components likespeakers and microphones, always perform the following in theorder presented:
1. Turn the gain on your preamp and/or mixer down.
2. Make sure that phantom power is disengaged.
3. Connect the microphone via a high-quality XLR cable.
4. Engage phantom power.
5. Turn up the gain on your preamp and/or mixer.
Reverse this procedure when disconnecting the microphone.

3. Make sure that the PSM1 power supply is turned off.
4. Connect the mic to the PSM1 power supply using theincluded 25-foot, 6-pin cable.
5. Connect the output of the PSM1 power supply to yourpreamp or mixer channel via XLR.
6. Turn the PSM1 power supply on.
7. Turn on the phantom power on your mixer if you are usingother mics that require phantom power and your mixer only
has a global phantom power on/off switch.
8. Turn up the gain on your preamp and/or mixer.
Reverse this procedure when disconnecting the microphone.

Polar Pattern Switch
The polar pattern of a microphone describes the sensitivity tosound at various angles. All Groove Tubes microphones offer a
cardioid polar pattern. The GT57 and GT67 have a switch formultiple polar patterns:• Cardioid Pattern
Cardioid is the most universal polar pattern found in microphones.
This is because the back of the microphone rejects sound,allowing the engineer to isolate the signal source from otherperformance elements or background noise.
• Super-cardioid Pattern
Super-cardioid pattern exhibits an extremely narrow sensitivity
window for very sonically focused recording. Super-cardioid isgreat for zeroing in on that perfect sweet spot for instruments suchas piano or drum. This pattern is also ideal for live recording
sessions where isolation is important, including minimizing bleed
between a vocalist and their own instrument.
• OmniOmnidirectional pattern picks up sounds without directional
discrimination. Use omni to capture room resonance, yielding amore open sound compared to the more “beamy” quality ofcardioid. It’s great for vocal groups, Foley sound effects, andrealistic acoustic instruments. Omni is also less sensitive to theproximity of a vocalist to the microphone.

GT44 / 66 / 67 / Model 1B• Figure 8

If you have a GT44, GT66, GT67 or Model 1B, the included PSM1
power supply provides the required power to the microphone. (Whileno external phantom power is required, the presence of phantom
power will not harm the microphone or power supply.) In order toavoid loud pops that can damage components like speakers andmicrophones, always perform the following in the order presented:

The figure-8, or bidirectional, pattern is excellent for capturing aduet or interview with a single mic. The –40dB side rejection spec
also makes it great for isolating an instrument like a snare fromthe rest of a drum kit. Figure 8 is also one of the key components
to M/S (mid-side) miking—a technique for recording stereo thatmany pros utilize exclusively.

1. Turn the gain on your preamp and/or mixer all down.
2. Make sure that phantom power is disengaged.

(Continued on reverse...)

The GT33 and GT44 are designed to accomodate interchangeablecapsules. They come standard wth cardioid capsules, with
optional supercardioid and omni capsule available seperately. Tochange capsules, simply unscrew the top of the microphone body.
Next unscrew the capsule itself and place it in a safe container.
Screw the new capsule in, then screw the top of the microphone
body back in place.

Sensitivity Pad
All Groove Tubes microphones, except the Model 1B and Model
1B-FET, feature a switch to engage a pad which reduces thesensitivity of the mic (-10dB on the GT 55, GT57, GT66 andGT67, and -15dB on the GT33 and GT44). These are useful toprevent overloading the microphone electronics or your preamp
when recording an extremely loud sound source such as closemiked guitar amps or kick drums. Engage this switch when you
must set your preamp input unreasonably low and/or hear
distortion. Otherwise, it is recommended that the pad remain
disengaged in order to benefit from the best signal-to-noise ratio.

Roll-off Filter
All Groove Tubes microphones, except the Model 1B and Model
1B-FET, feature a switch to roll off frequencies below 75Hz. Thisis useful in reducing or eliminating low frequency noise such as
floor rumbles, mic stand noise and passing trucks, etc.. It can also
be used to help eliminate the proximity effect present when using
cardioid patterns. (The proximity effect describes thephenomenon of increased bass emphasis or “boomy” soundquality as the sound source gets closer to the microphone.)

ServiceIn the event that your microphone appears to be malfunctioning,you may phone our technical support department. Should yourmicrophone need repair, our support staff will issue you a Return
Authorization number required in order to the return the unit.
M-Audio Technical Support
M-Audio
45 E. St. Joseph St.
Arcadia, CA 91006
626-445-8495
techsupt@m-audio.com

G T 3 3 / G T 4 4 / G T 5 5 / G T 5 7 / G T 6 6 / G T 6 7 / Model 1B / Model 1B-FET

Changing Capsules (GT33 and GT44 only)