Blown Fi 15" Q

[BigCProductions99 21]

Define Gain, Relative Power Of The Amp, Or Bass Boost?

Because I Was Thinking An SSD 18" D2 With Copper Coil And BP Options With A JL Audio T1000.1 TMA Mono With A Kenwood eXcelon KDC-X692 (4 Volt Preamp Output.) And I Do Not Want To Blow This Beast Of A Sub.

[lee 2]

[nick_19 1]

Can someone make that picture about 1/325345435 the size it is now?

[chad.SQ 0]

Can someone make that picture about 1/325345435 the size it is now?

yes

[Joeys91 0]

So this has nothing to do with the hifonics amp being overrated and "crappy" like everyone says (i have a hifonics amp and it wrecks). It's actually because the amp is too strong? Which is a good thing because that means it isnt overrated...

[KU40 173]

No, it doesn't mean that. The amp is rated for 1600 watts. The sub- 1000. Even if the amp only did half of its rated power, 800 watts, a hard clip could double that, back to 1600, and still blow the sub.

[ackslaxrichard 0]

How overrated are we talking? If the Hifonics says its putting out 1600 rms what is it actually putting out?

[NDMstang65 403]

IF they are overrated they arent THAT overrated. I hear if you have the newer amps with the "80" fuses they put out pretty close...i have my Hifonics 1606D powering my Fi Q 15 to the MAXX. And i have my gain set to 3/4 to avoid clipping, but its still putting out AT LEast 1000 watts instead of 1200 at 3/4 gain

You don't get "1000" watts at whatever gain..and 1200 at another..

How much power you produce is dictated by the volume knob, the output voltage that your headunit puts out should match the input voltage (gain pot) on the amplifier..

So if you have a 4 volt deck, your gain should be much lower than on a 1 volt deck.

[BKOLFO4 29]

And i have my gain set to 3/4 to avoid clipping

Man, bring up an old thread and then make that statement. Did you read anything above? Did you understand???

You can make an amp clip with the gain set at 1/8 if I have a strong enough input signal. It is not a volume control or output limiter. It determines what input voltage is required to achieve maximum output.

In my own personal vehicles, I keep the gain set so I can maximize output well below full power of the headunit is achieved. I then install an inline controller on the RCA's. Now if I am playing a song with weak bass, or just feel like HEAVY bass, I can just adjust the inline controller.

The way I see it, the main problem with Hifonics is not the amp itself, it is that 90% of the people buy them are looking for the lowest cost maximum performance system. Those two things normally do not go together. The user ultimately tries to get more out of the amp than it was made for and kills it.

Brian

[Joeys91 0]

Now I am totally lost.. i had the complete wrong idea sorry. Where can i go to find out how to set my gains properly?

Edited May 5, 2009 by Joeys91

[BKOLFO4 29]

The perfect amplifier takes a signal on the input and produces that same signal but amplified.

Let's say I built an amp that took a 1 volt input signal and amplified it to 60 volts on the outputs.

That is great, but what happens to the guy with the radio that has 4 volt preouts? He has 4 speakers connected to the radio's power outputs and the amp connected to his RCA's. He turns the volume to 1/4 way up - his speakers are getting 1/4 power, but his amp output is maxed.

how do I fix that problem? I add a setting on my amplifer design that allows the user to adjust what voltage is required on the input to achieve the 60 volts on the output. A normal amp may give you 0.5 - 10 volts as a range. If I set it at 0.5, then when there is 0.5 volts on the input, there will be 60 volts on the output. Set it at 10 volts, there will be 60 volts on the output when there is 10 volts on the input.

Most of the time, you have a good approximation with the radio's rated output and the numbers on the amps gain setting, but:

Sometimes the headunit does not produce what it is rated.

Sometimes they do more than rated.

The numbers on the amps are not perfect (tolerances - I have 6 amps in my van - none of them are set the same to get the outputs to all match).

Not all amps actually have a linear output changes as you change impedances. If an amp does 600 watts at 2 ohms and only 800 watts at 1 ohm, there will be a difference in the gain settings depending on the load impedance connected to the amp.

Some amps (like the Kicker I just installed in my Silverado) do not even have numbers on the gain setting (just says min - max).

The list of variables goes on. . .

The best way to set the gains would be to use an O-scope and look for the output actually being clipped.

Most people just use a True RMS DMM and look at the amp's output voltage using a 50 Hz test tone. You know the amps rated power and impedance, so you can calculate the maximum voltage you should see on the outputs. Sometimes even this is off due to the actual impedance of the subs in the box playing a 50 Hz tone, but once again it is a great starting point.

Some of us can set the gain by ear and then know how to tell when the system is being stress. If you can do this, it really does not matter where it is set, since you will not go past the limits of the system

Brian

[Joeys91 0]

Some of us can set the gain by ear and then know how to tell when the system is being stress. If you can do this, it really does not matter where it is set, since you will not go past the limits of the system

Would this be the same as Raising the volume on your HU to your regular listening volume then adjusting the gains on the amp to avoid distortion? someone told me to do that and that's what i did.

[BKOLFO4 29]

And then do you play it with any of the headunit setting higher than they were when you set the gain or play a song with more bass than the one you were playing while you set it???

It is hard to hear distortion in a trunk setup. . .

[KU40 173]

And then do you play it with any of the headunit setting higher than they were when you set the gain or play a song with more bass than the one you were playing while you set it???

It is hard to hear distortion in a trunk setup. . .

I find the best way to hear distortion in a trunk is to have it playing at the level you think is the maximum, then open the trunk and take about 10 steps backwards and listen. It's easier to hear distortion from a ways away.