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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.
I’m 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. I’ve 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, I’m wondering if this amp would not be suitable for this purpose. |
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#2
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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. > > I’m 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. > > I’ve 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, I’m 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. |
#3
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John Williamson wrote:
---------------------- > > > 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. > ** Fraid your math is waaaaay off. Power = "I squared R" or I = sq.rt P/R So 6.12Arms or 8.6A peak. > Your amp is rated to supply up to 15 Amps into a bridged mono 8 ohm load. ** No way: I = sq.rt P/R 110/8 = 13.75 so I = 3.7A rms ...... Phil |
#4
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On Thursday, November 21, 2019 at 2:31:11 PM UTC-6, John Williamson wrote:
> 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. > NHT SW2: 10" woofer in vented enclosure. Frequency response: 21Hz-350Hz, ±3dB direct in. Crossover: 130Hz (passive version, built-in). Sensitivity: 89dB (2.83V at 1m), 200W maximum. Impedance: 8 ohms nominal, 6.2 ohms minimum. I'm going to go ahead and configure the amp (which does NOT have a beefy power supply) for mono mode and try it out. |
#5
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Bob Simon > wrote:
> >I=E2=80=99ve read that some applications require high current. Due to its = >light weight, I doubt this amp can source a lot of current. Does a subwoof= >er require a lot of current? If so, I=E2=80=99m wondering if this amp woul= >d not be suitable for this purpose. Try it. Does it clip? Does it overheat? If not, go with it. The D-75A is not exactly the best sounding amplifier of all time, but putting it on a subwoofer is likely to avoid most of the sound issues with it, and that NHT subwoofer isn't a very demanding load. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
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