[John Williamson]

On 21/11/2019 18:02, Bob Simon wrote:
I have some spare audio components and plan to modify a stereo system for biamp operation to add a subwoofer. The room is 22 x 24 and the existing amp and speakers are Adcom GFA-545 II driving Polk 10s (re-coned). I have available a Rane AC22 crossover, a second amp and an NHT passive subwoofer.

Im thinking about using a Crown D-75A (which can be set up to operate in bridged-mono mode) to drive the sub. Here are the specs:
Dual mode (both channels driven):
55 watts into 4 ohms.
40 watts into 8 ohms.
25 watts into 16 ohms.
Bridge-Mono mode:
110 watts into 8 ohms.
80 watts into 16 ohms.

Ive read that some applications require high current. Due to its light weight, I doubt this amp can source a lot of current. Does a subwoofer require a lot of current? If so, Im wondering if this amp would not be suitable for this purpose.

What power is the speaker rated at? I used to have a subwoofer that was
rated at 300 watts RMS, 1200 watts peak. At 8 ohms, that is just under
40 amps RMS at rated power, 150 amps at peak.

The situation is actually a lot more complicated, as speaker impedances
are reactive, depend to a degree on cabinet design and vary with frequency.

Your amp is rated to supply up to 15 Amps into a bridged mono 8 ohm load.

--
Tciao for Now!

John.