FAQ's will be added as questions are submitted to lubell_labs@wowway.com
Question: I am using Lubell swimming pool speaker (underwater). I am facing difficulty to water proof connection of cable through conduit hub. Is there any requirement of cable gland to fix in 1/2" conduit hub? --NM
Answer: Wet-niches designed for underwater luminaries / speakers have flooded conduit design by nature. It is for this reason that the opposite end of the conduit must be elevated above the pool's water line (as dictated by Local, National, and International Electrical Code -- 8" minimum typical) and terminated inside a junction box. If the pool is in a location not subject to freezing, then generally no additional precautions are required. If pool is in location subject to freezing, then conduit/hub area inside wet-niche is sealed with sealing compound (as prescribed by Local, National, International Electrical Code), and RV type anti-freeze is poured inside sealed conduit as secondary protection.
QUESTIONS ABOUT SUITABLE AMPLIFIERS:
Question: Can any amplifier be used to power the 9484 in wall pool speaker?
Answer: A "Class AB" amplifier rated up to 78 watts rms @ 8 ohms (25 Vrms) may be used to power one or two of the 9484-25V-*** underwater speaker kits, providing amplifier has UL or ETL listing label, and has a three prong power cord connected to a grounded GFCI power outlet per National Electrical Code. Each LL916 UW speaker / AC205B transformer box circuit presents a 16 ohm reactive (capacitive) load; Multiple circuits must be wired in parallel only, observing minimum impedance rating of amplifier. Commercial sound amplifiers having 25V output (NOT 70V output!) may be used -- allow 37.5 watts power consumption for each Lubell LL916-XXX speaker and AC205B transformer connected in parallel to the 25V line.
Example one: The USA version of the monaural Bosch PLE-1P120-US amplifier (Class AB) provides a 25V constant voltage speaker connection and 120 watt power rating, allowing connection of up to three paralleled Lubell 9484's (37.5W x 3 = 112.5 watts total), which does not exceed the amplifier's 120 watt rating, or the 9484's 25 Vrms maximum rating.
Example two: The USA version of the monaural Bosch PLE-1P240-US amplifier (Class AB) provides a 25V constant voltage speaker connection and 240 watt power rating, allowing connection of up to six paralleled Lubell 9484's (37.5W x 6 = 225 watts total), which does not exceed the amplifier's 240 watt rating, or the 9484's 25 Vrms maximum rating.
Example three: The stereo Samson Servo 200 amplifier (Class AB) is rated at 66 watts per channel @ 8 ohms ( 22.98 Vrms), allowing connection of either one 9484 (16 ohms) or two 9484's in parallel (8 ohms) to each channel of the amplifier. Although the amplifier is rated at 4 ohm minimum load, experience has shown that connecting more than four speakers to this amplifier can result in instability at certain frequency ranges.. so not recommended.
Question: Please can you advise me if we can connect 9484 in-wall UW speakers to Tesira 4175R amplifier or if not, do you have solution to do so?
Answer: The Tesira amplifier (Class D) is rated at 175 watts @ 8 ohms (37.42 Vrms) which greatly exceeds the 9484's 25 Vrms maximum rating, and would likely result in rapid burn out of the underwater speakers. Amplifier is also Class D (not recommended) with no mention of stability when driving reactive loads. We would not recommend using this amplifier!
REMOTE VOLUME CONTROL:
Question: Can an L-pad or autoformer volume control be installed between the speaker/transformer and the amplifier?
Answer: No. The Lubell underwater speaker is a reactive piezoelectric speaker providing a primarily capacitive load to the amplifier. Inserting a variable resistor or autoformer between the capacitive speaker and the amplifier will result in an alteration of the frequency response as the volume is changed. For this reason, use a remote volume control that changes line level signal to the amplifier.
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