Amp size for Altec 9845A

[Virtue]

Greetings. I'm having a gathering in my back yard and I'm going to rent a power amp to drive a pair of 9845A monotors. Anyone have an idea how powerful I can go without harm to the speakers? The manual says 50 watts continuous. Thanks.

[CONVERGENCE]

The 806 driver is rated at 15 watts and the 416 probaly 75 watts. You could be safe with a 100 watt amp since you need head room and the impedance is 16 ohms.

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[Virtue]

Could I go more watts and be resonably safe. Would hate to be underpowered being it's going to be outside. Thanks again.

[CONVERGENCE]

You could go 150 watts ;the 806 phargms might snap. If they do :GPA has better ones at 35 watts were the leads inside are not bent.

I've heard them inside and they are pretty aw some.

Don't go beyond 200 watts though. If you feel you need more SPL :Then what you need is more speakers not more wattage.

When I used Altecs Outside first I never used small format drivers ,the A-5
were my favorite . Depending on the crowd I added more A-5.

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[Rolf]

You can use the most powerful amps in the world, just listen to the sound, and turn the volume down if it starts to sound distorted.

[CONVERGENCE]

You can use the most powerful amps in the world, just listen to the sound, and turn the volume down if it starts to sound distorted.


Here is the rule of thumb by JBL for Amp power.

How do I choose the right amplifier power for my speaker system?

Ideally you should pick an amplifier that can deliver power equal to twice the speaker's continuous IEC power rating. This means that a speaker with a "nominal impedance" of 8 ohms and a continuous IEC power rating of 350 watts will require an amplifier that can produce 700 watts into an 8 ohm load. For a stereo pair of speakers, the amplifier should be rated at 700 watts per channel into 8 ohms.
A quality professional loudspeaker can handle transient peaks in excess of its rated power if the amplifier can deliver those peaks without distortion. Using an amp with some extra "headroom" will help assure that only clean, undistorted power gets to your speakers. Some professional amplifiers are designed so they have additional headroom. These amps can cleanly reproduce transient peaks that exceed the amplifier's rated power. In this case select a model with an output power rating equal to the continuous IEC power rating of the speaker. Consult the amplifier manufacturer or owner's manual to learn more.
In some applications, such as critical listening in a studio environment, it is important to maintain peak transient capability. For these applications, use an amplifier that can deliver 6db (or four times as much) more power than the continuous IEC power rating.
If budget restraints or legacy equipment force you to use an amplifier with less power, extreme care should be taken to see that the amplifier is not driven into clipping. It may surprise you to learn that low power can result in damage to your speaker or system. Download our Danger: Low Power (http://www.jblpro.com/pub/technote/lowpower.pdf) tech note for more information.http://www.jblpro.com/pages/general_faq.htm

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