Competitors may use the program material of their choice while competing.
The program material being played may originate from any type of source unit that has been specifically designed to play music. This includes cassette decks, CD players and changers, DVD players and changers, VCR's and VCP's, MP3 units, AM/FM/Satellite radio tuners, smartphones, tablets, etc.
Both wired and wireless connections between the source unit and the sound system are permitted. This includes RCA cables, Fiber-Optic cables, Bluetooth, WiFi, etc.
The program material may consist of music, test tones, or any other type of recorded audio signal.
The program media may be from a commercial source (such as a CD you purchase) or a custom, homemade recording.
Competitors must use the dB Jams Vol 22 competition CD (or a digital copy of the CD) at all multi-point events. If an event takes place prior to the release of the official CD, then the previous year's CD may be used in the interim.
In the Stock division, competitors are limited to playing frequencies between 20 and 50 Hz in the Street Stock classes and between 20 and 60 Hz in the Pro Stock classes.
In the Super Street division, competitors are limited to playing frequencies between 20 and 50 Hz in the Super Street X class and between 20 and 80 Hz in the remaining classes.
In the Extreme division competitors are limited to playing frequencies between 20 and 80 Hz.
If a competitor's highest SPL is achieved at a frequency outside of the specified range, then that competitor's score will be recorded as zero. If the violation occurs during the qualifying rounds, the competitor may be granted a retry at the sole discretion of the head judge. If the violation occurs during the elimination rounds, the competitor will be eliminated from the competition, regardless of the competitor's score.
Adjustments to the sound system may be made while the vehicle is being metered as long as no other applicable rules are violated during the adjustment process.
The contestant's vehicle may be running while in the judging lanes as long as the following conditions apply:
Operation of the vehicle or sound system must not endanger the judge, competitor, spectators, or any real or personal property on the premises.
The vehicle's parking brake must be set.
The wheels must be chocked.
The hood must be closed.
The maximum engine idle speed must not exceed 2000 RPM.
A remote "engine kill switch" must be easily accessible from outside of the vehicle for those competitors that are bolting (clamping, strapping, etc.) the doors of the vehicle closed while in the judging lanes.
It is the competitor's responsibility to comply with the conditions listed above. Competitors found to be in violation of one or more of these conditions may be eliminated from the competition.
The contestant must be outside of the vehicle while the vehicle is being metered and all doors, windows, and other openings to the vehicle must remain closed during this time.
Exception - Contestants who elect to remain inside of the vehicle during metering must meet the following requirements:
The contestant is defined as the sole operator of the sound system (not a teammate.)
The contestant must sit in the driver's seat and may not lean across the centerline of the vehicle. Additional passengers are prohibited.
The contestant must wear adequate hearing protection at all times. Removal of the hearing protection while inside of the vehicle will result in a zero score.
The contestant must sign a dBDRA entry form that includes a waiver stating that the contestant understands that "exposure to high sound pressure levels may result in temporary or permanent hearing loss".
It is the contestant's responsibility to take adequate safety precautions when operating the sound system at high sound pressure levels.
When the SPL metering process begins, contestants will have 30 seconds to achieve their highest Sound Pressure Level (SPL). The SPL metering equipment will record and save each competitor's high score during this 30 second judging interval.
Contestants may not open their vehicle during the metering process. If a contestant opens his or her vehicle while being metered, the competitor's score shall be nullified. If the violation occurs during the qualification rounds, the competitor may be granted a retry at the discretion of the head judge. If the violation occurs during the elimination rounds, the competitor in violation shall forfeit the round.