help me tune my jl 1000/1v2 amp please

[swizz977 10+ year member]

well the guy from jl said ill get more signal and better voltage on the low setting

 

[swizz977 10+ year member]

he also said the low is for aftermarket hu n the high is for stock idk man u call him

 

[TheUnderFighter 10+ year member]

Ok, well I have read the manual, and as ridiculous as this sounds, the guy from JL is wrong. Now for the last time, I will tell you, your input needs to be on HIGH, and I am going to take one more attempt to explain to you why.

LOW INPUT: is for 200mv-2v inputs.

HIGH INPUT: is for 800mv-8v inputs.

Now your HU is feeding 5v signals, which even if it is not a true rating, it may be, what? 3.5-4v? So even assume your HU is only putting out 4v. You tell me, using simple logic, where your signal falls into? The low input, or the high input?

You have 4 volts, do you fit between 200mv-2v, or 800mv-8v?

You need to be on the high input. Otherwise, you will be feeding your subwoofer an exceptionally strong, and clipped (very bad) signal. If you want to run it on low input your subwoofer will fry. If you don't care about the lifespan of your subwoofer, then run it at low input. Just know, low input is the wrong setting for your amplifier for your subwoofer.

 

[swizz977 10+ year member]

this is my head unit

Amplifier KD-R900

Maximum Power Output 50W x 4

Continuous Power Output (RMS) (CEA-2006 Compliant) 20W RMS x 4CH at 4 ohms and no more than 1.0% THD + N

MOS-FET Amplifier Yes

Audio DAC

TI/Burr-Brown 24-bit DAC Yes

Source-Specific Volume Control Yes

Volume Attenuator Yes

Loudness Control Yes (3 patterns)

Balance/Fader Control Yes

EQ

3-Band Parametric iEQ Yes

LPF/HPF Cross Over Yes

HPF Yes

Max. Amp Gain Switcher Yes

Amp Defeat Switch Yes

Front AUX Input Yes

Line Output Terminals (Pair) 2 Pairs (Gold-Plated)

Subwoofer Output with Level/Frequency Control Yes (Gold-Plated)

Load Impedance 4 ohms (4 - 8 ohms allowable)

Line Output Level 5.0V

Line Output Impedance 1 kohms

Subwoofer Output Level 5.0V

 

[swizz977 10+ year member]

this is step 8 on how to set ur gains

Increase the input sensitivity control until the desired voltage (determined in Step 5) is delivered. If multiple subwoofer amps are being used, set each one to the same exact voltage and you have also level matched them. If excessive voltage

is read with the control at minimum (full counterclockwise), switch the “Input Voltage” to “High” and re-adjust.

i can get the desired voltage on low so

 

[TheUnderFighter 10+ year member]

Do what you want man. If you wanna crank the gain up to 90% to get that power on low input, do it. You'll likely fry your amp in the process, but that's fine. If you want it set properly, Just read back to what every single person has told you what to do.

 

[>>SQL<< 10+ year member]

This is why I stopped posting in this thread.

So many people just want to hear that what they want to do is the right way.

OP is not looking for the right answer, just confirmation that he knows best.

 

[bread0710 10+ year member]

This is why I stopped posting in this thread.
So many people just want to hear that what they want to do is the right way.

OP is not looking for the right answer, just confirmation that he knows best.

and when he frys his sub or blows his amp he will come back asking why =]

 

[bread0710 10+ year member]

dbl post =/

 

[southernboom88 10+ year member]

uhhh all i did was read the entire owners manual and it gives you every bit of advice on tuning the amp.

 

[swizz977 10+ year member]

actually if you read wat i wrote when its on low my gain is like 30 percent on high its like 80 percent

 

[Z1NONLY 10+ year member]

One more time....

Theoretically they should both sound identical if they are both set to the same voltage.
However the potential to "overdrive" the amp's input and induce clipping should be less with the amp set to "high".

 

[swizz977 10+ year member]

even if the gain is almost all the way up on high and very low at low?!

 

[Z1NONLY 10+ year member]

Yes. As I said, if you are at your target voltage, you are at your target voltage. (Regardless of which input scale you are on.)

On the "low" scale, a single degree adjustment makes a much larger difference in the amp's output than on the "high" scale.

It's not set in stone that you are going to blow your amp on the low scale. It's just that the chances of doing so are greater on the low scale.

The primary question is your target voltage. If you are sure you are at or below the proper voltage, great.

For someone with your understanding of car audio, I recommend the "safer" high scale. If you want to use the "low" scale, that tops out at 2 volts, with your 5v preout deck (and you are 100% sure you are at the proper voltage), go ahead.

It's your stuff.

 

[vaiboy 10+ year member]

Do what you want man. If you wanna crank the gain up to 90% to get that power on low input, do it. You'll likely fry your amp in the process, but that's fine. If you want it set properly, Just read back to what every single person has told you what to do.

You have that reversed, he said the gain is at ~80-90% on "High". That is because with his current volume, EQ, and loud settings there's no way that head unit is outputting 4-5V. The JL rep is correct, the "High" setting was designed for speaker level signals to eliminate the need for a LOC. That head unit probably won't do over 4V without the volume at 100%, the EQ at +12dB, and loud on. In reality with his current settings the outputs are probably at less than 1.5V, that is why the gain needs to be at ~30-40% in "Low". As long as he keeps his current setting there won't be a problem running the amp in "Low".

OP if you want to know what voltage the head unit really outputs, you could play a 50-60Hz test tone and probe the preouts with a DMM set to VAC.