Cerwin Vega Microphone T 680 User Manual

Vega T-680 Series  
UHF PRO-PLUS Wireless Microphone  
Owner's Manual  
T-689  
T-682  
T-687  
T-688  
 
Wireless-Microphones  
3
1
2
Unlatch cover and insert a 9-volt battery.  
Slide 9-volt battery into compartment with the plus  
“+” terminal as shown above. Slide cover back  
on.  
Turn the transmitter Power “P” on and  
Microphone “M” on by sliding the switches  
toward the dots.  
3
4
In the area covered by the wireless system,  
verify the receiver is receiving by observing  
its indicators (see receiver instructions for  
details).  
With a small screwdriver, adjust transmitter  
mic level so the receiver's “AUDIO LEVEL”  
LED flashes only when speaking very loudly.  
If it flashes frequently, turn it counterclockwise. If  
it doesn't flash at all, turn it clockwise.  
5
6
Adjust mixer/preamp/amplifier to its normal  
setting. Speak into mic. If necessary, adjust  
receiver's audio output level until wireless system  
volume matches wired system volume (see  
receiver instructions for details).  
“Walk” the coverage area to check for  
problems. If there is a problem, check mic  
batteries (fresh?); ensure antennas aren't  
touching each other or any metal objects. Path  
between transmitter and receiver must be clear  
for proper operation.  
 
4
T-680 Series  
Compatibility  
T-680 Series mics are designed to work with Vega's Model 662 Series receivers. T-  
680s are not necessarily compatible with other receivers, especially if not purchased  
together.  
System receivers must use DYNEX®III audio processing and use precisely the same  
frequencies as the transmitters. The transmitters are not compatible with other  
manufacturers' receivers.  
T-680 Series mics work in the 494 to 608 MHz and 614 to 806 MHz UHF range. The  
exact frequency is marked on the data label inside the transmitter's battery  
compartment. If the transmitter and receiver frequencies are not precisely the same,  
the frequency of one of the units must be changed. It's advisable to return both units  
to the factory or authorized service location when changing frequencies, to ensure  
the best results. Because of the very high performance of these units and the  
specialized test equipment required to adjust them properly, users should not try to  
change frequency themselves.  
If two or more systems are used at the same location, proper frequency selection and  
spacing are required to avoid possible interference.  
Vega offers a free frequency-coordination service for purchasers of its equipment.  
Frequencies are selected by computer to avoid any possible interference from other  
wireless systems and broadcast stations. To take advantage of this free service,  
contact the Vega factory or your local sales representative (phone number on last  
page of this manual).  
The T-680 Series professional handheld transmitters are self-contained units and  
require only a battery and a compatible receiver for operation. Individual models in  
the T-680 Series each use different types of microphone elements, leading to some  
differences in physical appearance between the various models. However, all  
transmitters in this series are functionally equivalent, and the operation instructions  
below and other information in this manual are applicable to all models.  
Because of the acoustic characteristics of the various types of microphone elements,  
individual models in this series may sound significantly different from other models.  
These differences are entirely due to the microphone element; all models offer  
identical performance, otherwise.  
 
Wireless-Microphones  
5
Operating Instructions  
(1) Verify that the associated wireless-microphone receiver is on the exact same  
frequency as the T-680 Series transmitter to be used.  
(2) Set up, adjust, and connect the receiver as described in its instruction manual.  
(3) Verify that the transmitter's battery is fresh.  
(4) Turn on the transmitter via the switch on the bottom (toward the dot). The LED  
indicator should flash briefly upon turn-on; this indicates that the battery is installed  
properly.  
NOTE: The LED does not provide an indication of battery condition. If there is any  
question as to the condition of the battery, it should be replaced prior to use of the  
transmitter.  
(5) Turn “on” the microphone in the transmitter via the switch on the bottom of the  
unit (toward the dot). Make an initial adjustment of the microphone gain control of  
about one-quarter turn from the minimum (fully counterclockwise) position.  
(6) With the receiver and transmitter on, the “SQUELCH” indicators on the receiver  
should be illuminated. Observe the RF-level meter (or bargraph) on the receiver. If  
the meter does not read well above midscale when the transmitter is within a clear  
50-foot radius of the receiver, difficulties are indicated (refer to section “In Case of  
Difficulty”).  
(7) Speak into the microphone at normal voice level. The audio meter on the  
associated receiver should indicate audio on voice peaks, and the audio should be  
audible on the associated monitoring equipment. The audio may also be monitored  
on headphones plugged into the receiver “monitor” jack.  
(8) Adjust the transmitter audio gain control, if necessary. When speaking or singing  
very loudly, the LED on the transmitter should flash “on” only on the very loudest  
voice peaks. This indicates that the transmitter is reaching the point where soft gain  
compression is occurring in the microphone preamplifier. If the system is correctly  
set up, the compression point will be reached only rarely.  
Internal adjustments are not required for normal operation. Only qualified  
experienced technicians should open the case. Unauthorized adjustments or repairs  
inside the equipment case can void your warranty and cause unnecessary repair cost.  
If you feel that internal adjustments or repairs are needed, we recommend you  
contact the factory or your nearest authorized service center.  
(10) “Walk” the coverage area to ensure that there are no areas of poor coverage.  
Signal “dropouts” (little or no signal in small areas) show up as a flickering of the  
“SQUELCH” indicator on the receiver and a brief “fizzing” sound in the audio (which  
may or may not be followed by a silent period due to squelched audio). The audio may  
be conveniently monitored with headphones plugged into the front-panel  
“MONITOR” jack on the receiver. If there is an area where a “dropout” occurs, the  
receiving antenna(s) can usually be repositioned to eliminate the problem. Frequently,  
a change of just a few inches in location will completely solve the problem.  
 
6
T-680 Series  
Antennas  
The receiver antenna may be the most important single component in a wireless-  
microphone system. However, this is the item most often overlooked in setting up a  
system, and is frequently the cause of quite unnecessary problems. Proper placement  
of the receiving antenna(s) is vitally important in any wireless-microphone system.  
A whip antenna connected directly to the wireless receiver is adequate for many  
installations. This type of antenna is provided with the R-662 Series receivers. When  
the distance between the receiver and the transmitter is 100 to 200 feet (30-60 m) or  
less, and there is a clear, unobstructed line-of-sight path between the receiver and the  
transmitter, good results can usually be obtained.  
Optional Antennas  
If you wish to have the receiver in a location which does not have a clear line-of-  
sight path to the transmitter, another type of antenna will be needed. Vega offers  
magnet-mount 1/4-wave-whip and “ground-plane” antennas with an attached 15-  
foot (4.6-m) cable, which may be used for this purpose. Two such antennas are  
required for use with diversity receivers.  
Other types of antennas may be needed for unusual applications, such as operating at  
extreme ranges of 500 feet (150 m) or more. Vega offers a high-gain log-periodic  
antenna that covers the complete operating-frequency range of the R-662 receiver.  
UHF TV antennas (with appropriate matching transformers) are often used for this  
purpose. A wide-bandwidth “corner reflector” antenna works well in this  
application.  
 
Wireless-Microphones  
UHF communications antennas are also sometimes used for specialized  
7
requirements. However, such antennas are usually narrow band and must be  
modified to function properly in the 494 to 608 MHz and 614 to 806 MHz ranges.  
Contact the Vega factory or your sales representative for assistance in selecting  
antennas for unusual applications.  
Antenna Placement  
No matter what type of antenna is used, care must be used in positioning and  
mounting. In all cases, a clear and unobstructed line-of-sight path between the  
receiving antenna and the transmitter is required. The receiving antenna may be  
concealed behind fabric, thin plastic, acoustic tile, and thin plywood without  
significantly affecting performance. However, close proximity to metallic objects  
such as furniture, lighting fixtures, scaffolding, electrical cables, metal structural  
members, aluminum window frames, and equipment cabinets must be avoided.  
Whip and dipole antennas require at least a 5-inch (0.13-m) minimum spacing from  
metal surfaces. Other types of antennas may require greater spacings. The radiation  
pattern of these antennas is much larger than the antenna itself. Consequently, even  
objects well off to one side of the line-of-sight path can distort the antenna pattern,  
affecting performance. Also often overlooked are the effects of using metal brackets  
for physical mounting of the receiving antenna. Vega's magnetic-mount and ground-  
plane antennas are designed to mount on a flat metal plate and on an antenna mast,  
respectively, but many types of antennas are not. The manufacturer's  
recommendations should be followed when using Yagis and other types of  
specialized antennas.  
The use of long cables connecting the antenna to the receiver is strongly  
discouraged. At UHF frequencies, the signal loss in the cable rapidly builds up and  
can seriously degrade operating range.  
 
8
T-680 Series  
In Case of Difficulty  
The majority of difficulties with Vega wireless mics are not due to equipment  
failure. Vega equipment is fully tested before leaving the factory. In most instances,  
problems are due to equipment application.  
The following paragraphs describe the most commonly encountered application  
problems. If you are having difficulties with Vega equipment, please review this  
information and take any necessary corrective action prior to returning the  
equipment for repair.  
Most users of Vega equipment enjoy years of troublefree operation. However, as  
with all electronic devices, problems might be encountered eventually. If you  
experience difficulty with your Vega wireless microphone within the first year of  
operation, it will be repaired under warranty (see below). Service for older units may  
also be obtained from Vega; contact the factory or your sales representative for  
information.  
General  
Contact the Vega factory or your sales representative prior to returning equipment  
for repair. Often, the problem can be resolved by phone, avoiding downtime for  
unnecessary returns. However, should repairs be necessary, Vega will promptly  
correct the problem and return the unit. Return both the transmitter and the receiver,  
to allow us to perform a complete checkout and test of the entire system. This can be  
especially helpful for elusive or intermittent problems  
Battery  
The most common problems with wireless-microphone systems are those related to  
the batteries. Vega recommends that only new, fresh Duracell MN1604 or  
“Eveready” Energizer No. 522 alkaline batteries be used. No other batteries tested by  
Vega provide equal life and reliability. Other batteries might work, but battery life  
probably will be short and current inadequate.  
Rechargeable batteries (“ni-cads”) are not recommended for use with T-680  
transmitters. Their limited capacity does not provide adequate operating time.  
Exhausted batteries will cause numerous problems, including distortion, audible  
squeals and howls, poor range, and off-frequency operation. It is strongly  
recommended that the battery be checked prior to each use, and that it be replaced if  
there is any question about its condition. It is also good practice to try replacing the  
battery with a fresh unit in the event of any sort of problem with the system, because  
a low battery might affect system operation in subtle ways.  
Battery contacts must be clean and unbroken. Attempted forced reverse insertion of  
a battery is practically impossible, but the attempt will often damage the battery  
contacts. Some “9-volt” batteries sold are larger (or smaller) than standard and either  
might fail to work or might damage the contacts when inserted. Damage to the  
contacts usually requires a return to the factory or authorized service center.  
 
Wireless-Microphones  
Interference  
9
Vega wireless-microphone systems have been specifically designed to reject  
interference. However, interfering signals might fall directly on the receiver  
frequency, making it impossible to avoid problems completely. As mentioned  
above, this can be a particular problem if the receiver audio is left open when the  
transmitter is turned off.  
Problems with RF noise sources (fluorescent lights, digital effects generators,  
industrial equipment, etc.) are quite rare. However, defective fluorescent lighting  
fixtures can generate astonishing amounts of RF energy. Usually, repairing the  
fixture will cure the problem, because normally functioning fixtures almost never  
cause trouble. Some digital audio and video signal-processing equipment and effects  
generators also can generate substantial amounts of broadband noise. When this  
situation exists, nothing can be done to the wireless equipment to correct the problem  
that will not seriously degrade performance. The receive antennas should be  
positioned away from these sources of RF noise to minimize the effect of this  
interference. Fortunately, this type of problem is surprisingly rare.  
A more serious problem is selection of wireless-microphone operating frequencies,  
which are inherently subject to interference due to intermodulation. Fortunately, a  
proper initial selection or changing frequencies will almost always correct any such  
problem.  
Vega offers a free computerized frequency-selection service to purchasers of our  
equipment. If the frequency of other wireless equipment to be used in a given area is  
known, interference-free frequencies can be chosen. However, if equipment is added  
later without frequency coordination, it is likely that an interference problem will  
exist. Should this occur, contact the Vega factory or your sales representative for  
assistance. Many individuals believe that only a few wireless systems may be used in  
an area. This is incorrect, because installations with a dozen or more wireless  
systems are not uncommon. However, careful frequency coordination is essential.  
Common Sources of Interference  
 
10  
T-680 Series  
Receiver Noise  
Vega wireless microphone receivers are designed to be extremely sensitive.  
Although high-performance squelch circuits are provided, it is not unusual for the  
receiver squelch to open and let through audio noise when the transmitter is off. This  
is usually due to spurious outputs from two-way radio transmitters, adjacent-channel  
leakage from TV transmitters, and, in some cases, RF noise from digital equipment  
such as audio and video effects generators, computers, and other industrial  
equipment that might be located near the antennas. When the wireless transmitter is  
“on,” this noise is suppressed and rarely causes any difficulties. However, if the  
audio channel is left “open” with the transmitter “off,” loud blasts of noise might  
occur. For this reason, it is advisable to “fade” the receiver audio when the  
transmitter is not in use. Changing the placement of the antennas and, in some  
extreme cases, changing the operating frequency might be necessary to minimize  
these problems.  
Antennas/Cables  
As noted in the section on antennas above, antenna placement and mounting are  
vitally important. Blocking the antenna with metallic objects reduces the signal level  
and might cut off the signal entirely (pattern “nulls”). If there is a coverage problem,  
try moving the receiving antenna, particularly if there are nearby metallic materials.  
Vega FaxBack  
Information including more detailed procedures, schematics, and other Vega  
products is available 24 hours per day from Vega's FaxBack system. Simply call  
(626) 444-2017 or 800-274-2017, then follow the voice instructions.  
Warranty (Limited)  
All Vega PRO PLUS wireless products are guaranteed against malfunction due to  
defects in materials and workmanship for one year, beginning at the date of original  
purchase. If such a malfunction occurs, the product will be repaired or replaced (at our  
option) without charge during the one-year period, if delivered to the Vega factory.  
Warranty does not extend to damage due to improper repairs, finish or appearance items,  
malfunction due to abuse or operation under other than the specified conditions, nor to  
incidental or consequential damages. Some states do not allow the exclusion or  
limitation of incidental or consequential damages, so the above limitation may not apply  
to you. This warranty gives the customer specific legal rights, and there may be other  
rights which vary from state to state.  
Vega authorized service centers enable Vega to give customers immediate service  
on repairs. These service centers are fully qualified and equipped to handle the  
servicing of Vega equipment, and turnaround time is excellent. To obtain the address  
of your nearest authorized warranty service center, contact your dealer or the factory.  
If you should require service, pack the equipment carefully and return it to the  
factory service center or the nearest authorized service center.  
 
Wireless-Microphones  
11  
Important:  
Be sure the exact return address and a description of the symptoms are enclosed  
inside the package with your equipment.  
It's also advisable to return the transmitter and receiver for a full system performance  
test when practical.  
Factory Service Center:  
Vega  
9900 E. Baldwin Place  
El Monte, CA 91731-2294  
(626) 442-0782  
Claims  
No liability will be accepted for damages directly or indirectly arising from the use  
of our materials or from any other causes. Our liability shall be expressly limited to  
replacement or repair of defective materials.  
 
12  
T-680 Series  
T-680 Series Transmitter Specifications  
494-608, 614-806 MHz  
Direct FM, crystal controlled, 180KF3E; 75-kHz maximum deviation  
±0.002%  
150 mW, nominal or 40 mW nominal, depending on version  
40 dB below carrier, minimum; typically 50 to 55 dB below carrier  
DYNEX®III  
At maximum gain typically 112 dB SPL for onset of compression; maximum  
acoustic input: 143 dB SPL  
Power on/off, microphone on/off, microphone gain  
Audio compression  
Per FCC requirements; “soft” compressor action, 25 dB range; typically system  
distortion is less than 0.4% at 25 dB compression  
Patented* Internal dipole  
9-V alkaline, Duracell MN1604 recommended  
Varies by model, from 9.85 in (25 cm) to 10.75 in (27.3 cm)  
Varies by model, from 9 oz (256 g) to 13.5 oz (385 g), including battery  
UHF PRO PLUS System Specifications  
with R-662A or R-662B receivers  
1,700 ft under good conditions; 500 ft or more under typical conditions with  
standard whip antennas  
Depends upon microphone element and electronics; 90 Hz to 15 kHz, ±1.5 dB, 120  
Hz to 12 kHz, ±0.75 dB (units include highpass filter to minimize handling noise;  
extended low-frequency response available on special order)  
<0.25%, 400 Hz, nominal input level  
<0.25% (SMPTE 60/7,000 Hz, 4:1)  
Microphone off: 101 dB (flat), minimum; 108 dB typical, A-weighted. Microphone  
on: varies by element type and gain setting, typically over 100 dB (A-weighted) at  
normal gain settings.  
Varies by element type and gain setting; typically over 100 dB; over 125 dB with  
gain adjustment  
Patent #4,344,184 issued August 10, 1982  
9900 East Baldwin Place • El Monte, California 91731-2294  
Telephone: (626) 442-0782 • Toll-Free: 800-877-1771  
Fax: (626) 444-1342 • CompuServe: 73513,1417  
FaxBack: (626) 444-2017 • Toll-Free FaxBack: 800-274-2017  
Printed in U.S.A.  
©April 2000 Vega  
 

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