Oh the Math!

[unclecuz]

When calculating power/voltage requirements/limits for T39 w/3012lf, use 10 ohms (8 ohm speaker)? In parallel (2,3,4)?

When calculating power/voltage requirements/limits for DR280 w/piezo and DII 2512, use 8 ohms? In parallel (2,3,4)?

References appreciated.

Thanks,

James

[Frankie G]

Just plug the numbers into the calculator as they need to be, such as the exact ohm rating for the speaker, and whatever the plans say the the max power is, and hit the calculate button.

http://www.sengpielaudio.com/calculator-ohm.htm

[Bill Fitzmaurice]

When calculating power/voltage requirements/limits for T39 w/3012lf

Perchance read the plans?

[Sydney]

When calculating

I guess I would strongly recommend that you get as accurate a measurement as possible of the real load. Even if it is only a DCR measurement of the entire load loop that attaches to the amp output terminals ( including connector and wiring ).
A true impedance sweep would be best.

Syd

[unclecuz]

I have read the plans.

So 60V is the max for any quantity of paralleled 3012LF's down to the amp's recommended minumum impedance?

JM

[Bill Fitzmaurice]

I have read the plans.

So 60V is the max for any quantity of paralleled 3012LF's down to the amp's recommended minumum impedance?

JM

With paralleled drivers or cabs voltage is the same across each load, so the voltage limit that applies to one applies to all.
T39 plans, page 28.

[unclecuz]

Sorry. Thanks.

JM

[djeccentric]

do don't want to hijack this thread but i have a question i believe is along the same lines. i wanted to understand better amp output ratings and how they relate to different configurations of speakers. so if i am understanding how the output ratings works you have amps and volts and the amp is capable of outputting so many volts and that is constant no matter what the load and then it is heavy duty enough to handle so many amps which is dictated by the ohm load of various speaker configurations at a given voltage. so then no matter how many drivers in parellel you have each is getting the same volts and draw however many amps they draw. where i am confused is the watts. for example my amp can do 650@8ohm 1100@4 and 1400@2 per channel so if i had 8 ohm cabs the wattage per cab would be 650 devided by 1 cab(650 per cab), 1100 by 2 (550per cab) and 1400 by 4 (350 per cab). is this right or am i way off. this concerns me because my titan 48's are 450 max so i could max out 2 per channel but not 4. i am not sure if running 8 maxed out titan 48's is realistic but i like the idea of the headroom.

[Gregory East]

Headroom is pretty moot for subs as the limit voltage is the peak limit.

Running 2 amp loads at max power is generally not recommended. Not many amps can do that. You might try 3 per channel at 2.6 ohm.

Also beware that what the amp is rated at may be a lot less than it can put out when driven into distortion and clipping. You need limiting.

I don't know how the 2ohm rating comes about either. It would appear the max voltage does depend on the load after all. Or the amp reduces voltage by itself to avoid frying.