Boston Acoustics PRI665CV, PRI85SUBCV, PRI685CV owner manual Adjusting the Transformer Tap Switch

Adjusting the Transformer Tap Switch

The switch on the front of the speaker frame selects the secondary transformer tap that supplies the signal to the speaker. It serves to control the distribution of the amplifier power to the various speakers and cor- respondingly can be used to balance the relative output of the speakers. The switch has setting for power levels of 4, 8, 16, 32 and 64 watts. There is also a “DirX” bypass setting should you want to connect the speakers to a conventional amplifier at some point in the future. (The PRi85Sub has a slightly different group of setting. See the information on the following page.)

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To determine the proper tap settings, follow the directions in the Speaker Spacing section on page 6 of this manual. These instructions provide the initial setting of all speakers in the system. After installing the system, verify that the SPL and balance between the speakers is correct. If not, adjust the tap setting for each speaker.

Keep in mind the power available from the amplifier. The total of the power level selected with the switch set- tings, plus a 20% “transformer loss factor” will tell you if the amplifier has enough power for the configuration. For example, say you have 6 speaker on a given amplifier channel, three with the transformer set to 16 watts and three set at 32 watts. The calculation would be:

[(3 x 16) + (3 x 32)] x 1.2 = 172 watts

As long as you have that much power available then you can drive the combined speakers properly. It you set all six of the speakers to the 32 watt setting then you would need 230 watts:

(6 x 32) x 1.2 = 230

Once you are satisfied with the transformer switch settings press the speaker grilles into place to complete the installation.

Listening Levels and Power Handling

The listed power recommendations assume you will operate your system in a way that will not produce distor- tion. Even very rugged speakers can be damaged by a relatively low power amplifier if it is producing distortion.

If the sound is harsh or gritty turn down the volume. Prolonged or repeated operation of your speaker with a distorted signal from the amplifier can cause damage that is not covered by the warranty.

Additional Information on the PRi85Sub

The PRi85Sub in-ceiling subwoofer has a built-in passive crossover. The 8, 16, and 32 watt settings of the transformer then route the signal through the crossover. The “DirX” setting bypasses the transformer should you want to connect the speaker to a conventional amplifier at some point in the future. This setting still passes the signal through the crossover so it should be used if speaker is receiving a full range signal.

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