Setting The Limit

[James R]

Ok I've read and re-read everthing i could find here on mathmatically setting limiters and setting by voltage
This will be for 2 Titans 48's loaded with 3015's on 1 amp
Mathematically speaking I came up with this:

Amp Output 1400 @ 4 ohms 74.83 volts 39.70 gain
Driver Power 375 @ 5 ohms 43.30 volts 34.94 gain
approx limiter setting -4.75

I read using a sine wave 100Hz can be done also, is a RMS volt meter a must for this method?

Thank You,
Jim

[Bill Fitzmaurice]

To be safe don't feed a 3015LF more than 60 volts. Paralled on the same channel it will still be 60 volts no matter how many you have. 100 Hz sine is as good as any method, and an RMS meter is more accurate.

[James R]

Thank you Bill, that's what I needed can't wait to try the 2 out saturday

Edit: Another question though, if you use a sine wave and set the voltage across the terminals could you theroetically check the input voltage to the amp.
And monitor it that way also and how much of a difference in readings would the RMS meter be to a standard meter?

Thanks
Jim

[wallywally]

Thank you Bill, that's what I needed can't wait to try the 2 out saturday

Edit: Another question though, if you use a sine wave and set the voltage across the terminals could you theroetically check the input voltage to the amp.
And monitor it that way also and how much of a difference in readings would the RMS meter be to a standard meter?

Thanks
Jim

Yes. Input voltage is what gets limited when using an external limiter.
The meter must be RMS or the reading @ 100hz won't be accurate. Most modern DVOM's are RMS meters.

[jeffbabcock]

A cheap meter won't be accurate, but it won't be unusable either. Just allow for a slight margin of error and you'll be fine. I saw a comparison somewhere once and the difference between the RMS meter was noticeable but not a show stopper.

Make sure to use a sine wave and not pink noise. You don't need any speaker load connected to the amp, connect the meter right into the binding posts. You also don't need to use 100hz. I'd just use 1K, that seems to be a common frequency for amp ratings.

[James R]

Thank you Bill, that's what I needed can't wait to try the 2 out saturday

Edit: Another question though, if you use a sine wave and set the voltage across the terminals could you theroetically check the input voltage to the amp.
And monitor it that way also and how much of a difference in readings would the RMS meter be to a standard meter?

Thanks
Jim

Yes. Input voltage is what gets limited when using an external limiter.
The meter must be RMS or the reading @ 100hz won't be accurate. Most modern DVOM's are RMS meters.

I have a new Digital Voltmeter, what I was referring to about the input voltage say for example it was 5 volts at the input of the amp that produced the
100 watts I wanted. Couldn't you tap in during the performance to double check that you are maintaining the proper input voltage.
just an idea is all

thanks

[Tom]

Couldn't you tap in during the performance to double check that you are maintaining the proper input voltage.

Sure - if the performer is "Mr. Pink Noise" or "Ms. Sine Wave"

What value would this reading have for a band or DJ playing actual music?

[wallywally]

I have a new Digital Voltmeter, what I was referring to about the input voltage say for example it was 5 volts at the input of the amp that produced the
100 watts I wanted. Couldn't you tap in during the performance to double check that you are maintaining the proper input voltage.
just an idea is all

thanks

With music the values are all over the place. But will never exceed your limiter setting. In theory you could tap the input and monitor, but, it would involve converting values etc...IMO not worth the time. You can get a better result by connecting your meter in parallel (most amps have banana connectors that work well for this) and leaving it connected. Again monitoring voltage with music as the source is all but impossible the values change much too fast.

[LelandCrooks]

Couldn't you tap in during the performance to double check that you are maintaining the proper input voltage.
just an idea is all

thanks

They're called vu-meters. Run the mixer or source so the desired output to get your amp to voltage just bumps 3 -5 db. I did it at +5db, just for an extra margin of safety.

[James R]

DOH ok you got me,but I know that I was aww beans nevermind lol way too much thinking and working

[James R]

Ok I haven't seen this mentioned anywhere here, so I'll put it out there. If using a sine wave with your drive rack wouldn't it be
better to use a sine wave at the crossover frequency that the Titan is crossed at? This is my minimal thinking here, if your trying to get say 60 volts at the amp running it through
the crossover. Isn't the voltage going to be higher at a 100hz with a 100Hz sine wave compared to a 1k sine wave at that same point?

[Tim A]

Ok I haven't seen this mentioned anywhere here, so I'll put it out there. If using a sine wave with your drive rack wouldn't it be
better to use a sine wave at the crossover frequency that the Titan is crossed at? This is my minimal thinking here, if your trying to get say 60 volts at the amp running it through
the crossover. Isn't the voltage going to be higher at a 100hz with a 100Hz sine wave compared to a 1k sine wave at that same point?

The sub won't see anything with a 1k sine wave if put through a crossover. Here's a quote from another thread:

If the back of the amp has a banana plug measure directly from there. Failing that, make a "test" cable with speakon at one end and banana at the other, as WB described.

Find or make a source CD that has a single frequency tone. I use 100Hz for subs and 1kHz for tops. Send that signal through your full chain - including the limiter and amp. Measure the output using the test cable. Set the gain structure of the whole system, and then use the limiter to back the signal off to your desired maximum output.

--Stan Graves

[James R]

Ok I haven't seen this mentioned anywhere here, so I'll put it out there. If using a sine wave with your drive rack wouldn't it be
better to use a sine wave at the crossover frequency that the Titan is crossed at? This is my minimal thinking here, if your trying to get say 60 volts at the amp running it through
the crossover. Isn't the voltage going to be higher at a 100hz with a 100Hz sine wave compared to a 1k sine wave at that same point?

The sub won't see anything with a 1k sine wave if put through a crossover. Here's a quote from another thread:

If the back of the amp has a banana plug measure directly from there. Failing that, make a "test" cable with speakon at one end and banana at the other, as WB described.

Find or make a source CD that has a single frequency tone. I use 100Hz for subs and 1kHz for tops. Send that signal through your full chain - including the limiter and amp. Measure the output using the test cable. Set the gain structure of the whole system, and then use the limiter to back the signal off to your desired maximum output.

--Stan Graves

Tim that is exactly what I thought , but i remember reading this reply

A cheap meter won't be accurate, but it won't be unusable either. Just allow for a slight margin of error and you'll be fine. I saw a comparison somewhere once and the difference between the RMS meter was noticeable but not a show stopper.

Make sure to use a sine wave and not pink noise. You don't need any speaker load connected to the amp, connect the meter right into the binding posts. You also don't need to use 100hz. I'd just use 1K, that seems to be a common frequency for amp ratings.

I was just second guessing myself