BillFitzmaurice.info

The 3012LF datasheet says "450W / 900W Music Program". Which of these is closer to an RMS value for choosing an amplifier?

slade8200 wrote:The 3012LF datasheet says "450W / 900W Music Program". Which of these is closer to an RMS value for choosing an amplifier?

Chose the amp based on the voltage that the driver can take in a specific type of enclosure. The voltage is listed in the plans.

So the displacement limit for a 3012LF is 300W, is this not as easy as choosing a 300W @ 8ohm amp (even though it's around 10ohms because of the horn)?

slade8200 wrote:So the displacement limit for a 3012LF is 300W, is this not as easy as choosing a 300W @ 8ohm amp (even though it's around 10ohms because of the horn)?

I'm guessing that you don't have the plans....you haven't said which cabinet you are building. The voltage limit is different for Titans vs. Tubas.

For a 3012LF, I'd make sure to have at least 500 watts at 8 ohms to ensure some headroom....even though it will be limited below that amount. I run mine in T39s at 56 volts.

If you have the plans, read 'em closely. The section at the end usually is where the voltage limits are.

I'd have to check but I'm pretty sure in t39 a 3012lf takes all of the 450w when highpassed 45hz, but you won't notice any loss of headroom doing your limiting at 50v rather than 60v. If you're running into the limiter all the time with no headroom, you need more cabs.

Looking at amps, 4 ohm and 900w per channel will suffice. Any more is spare capacity so you aren't running flat out. Bonus points for 2ohm capability.

I do have the plans. This voltage level-monitoring is a little new to me. I've done lots of audio setups in living rooms, home theater, car, etc. and we've never done voltage monitoring, we just make sure the audio does not clip and ruin the speakers (have enough power to avoid under-driving). I guess it's something special about these folded horns that makes concern for voltage more important, yes? But even with that, you are really only concerned with power levels at a certain impedance, in this case, from the plans it looks like you add about 2 ohms due to the folded horn configuration. So if I have an 8 ohm speaker (now becomes 10 ohm), and the speaker is rated at 450W, then we really have a 10 ohm speaker now. Since the power rating goes down as the impedance goes up for a given amp, we'd like to see at least about 500W (something greater than 450W) @ 8 ohms (really it could be about 300W since it could be bridged for 600W since I only have one speaker), yes?

Where am I going wrong?

When you guys are saying "I run mine at 56V" or whatever... is this the max level when the volume is as high as you'd crank it?

slade8200 wrote: I guess it's something special about these folded horns that makes concern for voltage more important, yes?

You can't hear the driver distort in the horn. That means you might end up with a blown driver because of over-powering.

slade8200 wrote:
When you guys are saying "I run mine at 56V" or whatever... is this the max level when the volume is as high as you'd crank it?

There should be a limiter in front of the amp. Read this http://billfitzmaurice.info/forum/viewt ... amps+unity

slade8200 wrote:we've never done voltage monitoring,

Voltage is the only thing you can monitor. You can't monitor power.

we just make sure the audio does not clip and ruin the speakers (have enough power to avoid under-driving).

There's no such thing as under powering.

I guess it's something special about these folded horns that makes concern for voltage more important, yes?

No.

So if I have an 8 ohm speaker (now becomes 10 ohm), and the speaker is rated at 450W, then we really have a 10 ohm speaker now. Since the power rating goes down as the impedance goes up for a given amp, we'd like to see at least about 500W (something greater than 450W) @ 8 ohms (really it could be about 300W since it could be bridged for 600W since I only have one speaker), yes?

No. Impedance is not a constant value, and the driver power rating only says how much it is designed to handle before the voice coil melts.
Read the FAQs. They at least scratch the surface of all the things you should know but won't find in owners manuals.

You know what I mean by under-powering, inducing clipping by having an input signal that the amp can't handle. I know impedance varies thru the freq range. I have read the FAQs. I was looking for specific answers to specific questions.

What are some common limiters people use?

Where am I going wrong?

When you guys are saying "I run mine at 56V" or whatever... is this the max level when the volume is as high as you'd crank ?

The limit is where Bill has determined the optimum low end response can be achieved without smashing or cooking the driver. Mostly it's an excursion problem.

You can crank it as much as you like, the point is the limiter won't let you wreck drivers. To get the best dynamic sound is down to each operator to control gains to avoid clipping and or running into the limiter.

Underpowering is a myth. Don't use the word in a serious sentence. You will find yourself tilting at windmills very quickly in trying to explain yourself.

slade8200 wrote:You know what I mean by under-powering, inducing clipping by having an input signal that the amp can't handle.

Of course I know what you mean. Under-powering is still a myth. Clipping can hurt tweeters, and occasional midranges, never woofers. Read the FAQ.

What are a couple reputable brands of limiters?

Limiters don't get used much by forum members as the bang for buck factor is very low. We need crossover and eq for the horns so a processor like dcx2496 or driverackPA is the goto device. Everything in one unit.

So if I clip my subwoofers constantly even non stop at times its fine? I have two Peavey IPR 3000's and 4 Peavey Lowriders 800/1600/3200
Wrms/Program/Peak

Clipping in the amp you mean? That'll be way too much power for the lowriders. Even if it isn't it would sound lousy.

Square waves of themselves are harmless.