DanCan81

I need help figuring this out. I bought an entire system from Dennis at DD mods and he will not return my phone call for the life of him. Here's what I got:

2011 Grand Sport 3LT
-Pioneer 4200 NEX
-Focal Auditors (front and rear)
-JL 10" TW3 dual voice coil 4 OHM sub

• power range: 100-400 watts RMS
• peak power handling: 800 watts
• frequency response: 24-200 Hz
• sensitivity: 82.1 dB
• sealed box volume: 0.519 cubic feet

-Kenwood Exelon 801/5 amp

• 5-channel car amplifier
• 50 watts RMS x 4 + 500 watts x 1 at 2 ohms

-DD Mods custom .570 cuft rear partition box

Everything was hooked up without issue, the ground beside the passenger pillar works perfectly and I'm not getting any whine/hum/buzz from the speakers. What I do have a problem with though is that JL 10 is not pushing like it should.

For the life of me, I cannot figure out why my $300 sub and $350 amplifier cannot rattle these windows. My wife has a $160 Rockford Fosgate P300-10 in her little Scion and it makes your ears bleed turned all the way up. When I turn mine up all I get is a flat sounding bass.

With my sub being dual voice coil it's running the amp 500watts @2ohm load. Is this too much power causing it to sound flat? The sub only needs a hair over .5 cuft and the box is .57. Do I need a bigger box? Is this normal for corvettes to not produce decent bass due to limited cabin air space ?

AMP settings for sub channel
:-LPF 80hz
-input sensitivity 3.5
-bass boost 2

daverulz

First I would check that the sub is wired in parallel correctly, check the polarity the wires going to each coil at the sub and the amp. If you've got one backwards you'll effectively be cancelling out the signal and it will sound very underwhelming.

After you verify the wiring is correct, I would start turning the input sensitivity up on the sub channel. Do this by setting the volume to your maximum listening level, then slowly turn the input sensitivity up until it is either a) loud enough, or b) you hear distortion.

You also might want to adjust the high pass filter (hpf) on your fronts and rears to around the 80hz the sub is crossed at...this is not to help with your subwoofer problem, but there is no reason to have the small speakers try to reproduce subwoofer frequencies.

Edit: It's actually hard to tell with that type of potentiometer for the controls do you have the HPF set to 50 or to 125? Also input sensitivity on inputs A and B, are they set to 4 or 0.5? You might have to look at your gain structure overall to remedy the situation, It looks like maybe you have high gain on the full range speakers and low gain on the sub channel.

Here's a good tutorial on setting gains: http://www.diymobileaudio.com/forum/...wer-usage.html

DanCan81

- HPF is set to 125
- A/B/sub inputs are set to 4
-head unit is 4v

so should I back down my input sensitivity? If so on what to what?

Homer3D

Check the wiring on the sub. Since it is a DVC 4ohm, if you wired it is parallel you will get a 2 ohm load. But if you wired it in series you would end up with an 8 ohm load. Make sure it is positive to positive/negative to negative between the 2 voice coils and then positive to positive/negative to negative from the sub to the amp. If you have a multimeter you can also test the ohm load.

Next, Pioneer 4200 NEX has a 13 band EQ with LPF/HPF. Set the EQ to flat and disable the LPF/HPF. This way you know you are sending full signal to the amp as it might be possible you are sending the wrong frequencies to the sub channel.

Side topic. That amp doesn't look new. Not saying that the amp is bad but could be suspect if this is a used/refurb amp. Did you just get the amp because it looks like it has a few miles on it.

racebum

you have a shallow mount ten in half a cubic foot. output will be similar to an 8" with more midbass.

that's not a window rattling combo.

1st did you set your gains correctly with a volt meter? 2nd is the sub wired in parallel? both voice coils should be ++ and -- tied together

if you did the power is there. you can eq up 40hz 3db and see if it helps. that's about the end of it. personally i hate shallow mount small box subs. they just don't perform.

when it comes to low frequency and output there is no getting around box size. airspace is a requirement

daverulz

first check the wiring. Make sure the coils are in parallel and nothing is crossed in terms of polarity. If you have it wired so that the coils cancel each other there is nothing you can set on the amp to fix it.

Another good point made above...make sure the head units crossovers are all set to full range...or the amps are all set to full range and use the head units. No matter what, you should only be using one set of crossovers, either the head unit's or the amplifier's, not both.

I would start over with your gains. This is how I do it.

1. Set the crossovers either on the amps or the head unit but not both
2. Set the gains counter clockwise to the lowest setting on the amplifier
3. Turn the head unit up to the maximum level before clipping, usually about 75 or 80% of the volume
4. Slowly turn up the gain on the front speakers until they a) are too loud or b) start to distort
5. then back it down a little bit
6. do the same thing for the rear speakers
7. do the same for the subwoofer
8. then level match the fronts/rears/sub only by turning gains down

The markings on the gain may be a little counter intuitive at first. The higher the number, the lower the sensitivity. So at 4v, you actually have the gain barely cracked open on the amplifier. Because it is expecting a hot signal and is therefore attenuating the signal that comes in. Head units, much like amplifiers can (for lack of a better term) lie about the preamp output. This is why you need to use specialized equipment, or your ears to adjust gains, and not to just go by the specs of the head unit and the numbers written on the amp. I would also say that you're leaving power on the table if you use a voltmeter, just use your ears if you don't have access to an oscilloscope. Also keep in mind that some clipping of the signal is perfectly acceptable, especially on a sub.

Edit: Your A/B/Sub are not all set to 4. A/B are set to 4 and Sub is set to .5 . Look at the flat spot on the potentiometer, not just the direction the slot is pointing. Turn them all counterclockwise as far as they go, and then turn them clockwise from there to set the gains for each as i described above.

racebum

yea....that's not really a good way to do things


is a video with a quick explanation on how to properly set gains

you can get away with doing what you say with a good ear but it's not optimized and with multiple channels you will never get them all equal

the only thing wrong with this video is with low level you only bring the deck to 3/4 volume or a hair under as to not clip the pre amp. you want rated power at 3/4 volume

daverulz

Another thought, where is the sub level set on the head unit?

daverulz

Disagree. It is a very good way to do things. If you know what distortion sounds like it works quite well. The voltmeter method is not useful for setting gains because it does not account for any variables in the amplifier's output, nor the variables in the impedance of the speaker you are using. Have you ever looked at the impedance curve for a speaker? It's just that, a curve, not a straight line. It leaves output on the table. Manufacturer's tell people to do it this way for a couple of reasons: it's safe, most people have a multimeter (Even if it is not a true RMS unit) and it gives people piece of mind. That doesn't make it the best way to set gains. The fact of the matter is that the human ear is VERY sensitive and very capable of getting this right.

As far as your argument about "not being optimized with multiple channels and never getting them equal", that would only be an issue if you were trying to balance left/right. Front/Rear/Sub levels are pretty much NEVER equal in a system that is set up right.

Not trying too start a war, but I've been around this stuff long enough, and tried every method. By ear is the fastest, easiest, and most accurate (without actually looking at the wave form on an o-scope) method.

Please do not take this in any way that I am attacking you or anyone who uses the voltmeter or any other method of setting gains. This is what I've learned from many years of experience not only in car audio, but professional audio as well. And the fact of the matter is, once you understand what distortion sounds like, it's very easy for the lay person to do this.

racebum

the variables don't honestly matter because the whole point of a meter is to get all channels equal and putting out a given power at a given frequency. without this you can have one channel set one place. another somewhere else and another somewhere else. this means you have underpowered and overdriven channels. when you set ac volts you don't even have speakers connected. it's all about equalizing the channels and getting them to all produce what they should when the volume is at a certain place

unless someone has a scope voltage is the next best thing to getting output voltage correct. a VERY small flick of the gain is the difference between 40 and 50v ac output for a sub and you aren't going to hear distortion in a sub until it really ramps up

voltage also clues you in to what your amp is actually producing since it directly correlates to wattage. having channels out of balance can also make setting time delay impossible as you won't have even outputs between left and right / front and back or at least front and back if the amp does not have separate L/R gains

you can use the fader and or level gain on the deck to fine tune. you could also do it with the gains but again with voltage, so much easier. if you want 75w at 4ohms that's 17.3v ac, if the rear needs to be lower you can drop that to 15-16v which is such a small fraction of adjustment you would absolutely never be able to do that by ear. it's barely a tap of the screwdriver

back in the 90s setting gains by ear was common and really, i'm pretty good at it but never do anymore simply because it wreaks havoc with setting the DSP and time delay. https://www.dynaudio.com/dynaudio-ac...fi-in-your-car

dynaudio has a great few videos and one of them is with how they deal with in car reflections. long story short it's timing. which again requires predictable output

daverulz

Alright, but I still disagree. This has been battled over on DIYMA a hundred times. There's no reason at all that I need to know that my amp is producing x voltage because that number really means nothing. Knowing that I am putting out x volts or watts or whatever has ZERO bearing on level setting with DSP. I have never experienced a problem with tuning a car that had the gains first set by ear, and then adjusted on the DSP that wasn't easily resolved. What I do need to know is if my amp is clipping, and I can tell that with my ears or with an o-scope. If I can't hear the clipping, it really doesn't matter. When I tune, typically amp gains are between 0 and half, and I use the processor to set the level exactly where it should be. Room EQ Wizard and a 100 dollar (or less) mic makes pretty easy work of getting time alignment and EQ where they should be.

In my experience, if he has passive components (or coaxials) in the front and the back, and is not using time alignment or EQ. He wants the sub to balance with the front and rear speakers. Quickest way to do that is to set the gains by ear.

So we disagree, it doesn't really mean that either approach is wrong or bad. So the OP can choose what he wants to do. And I think we shouldn't turn this into a pissing match so lets move on.

Also back on that topic, the JL should have no problem getting pretty loud on 500 watts. So something is wrong. But in terms of the comparison to your wife's rockford 10. If you want to look at numbers:

My guess is that enclosure uses something like one of Rockford's Prime R2D2/4 subs, which is 87 db efficient, and it gives it 300 watts RMS

You have a sub that is 82 db efficient, and you are giving it 500 watts RMS

The relationship of power applied to output in decibels is a logarithmic curve. For every 3db of output more you want, you have to double amplifier power. If you want it to sound twice as loud, or a 10db increase, you need 10x the power.

So, it should be no surprise that in a perfect environment her sub is louder than your sub. She has basically 5db of output for free over your sub with 1 watt (or however they're measuring it). Your 200 extra watts, are not enough to make up for that efficiency deficiency (lol, that wasn't even on purpose)

Now, small cars have a lot of cabin gain. So you can probably make up for some of that efficiency with that built in boost. I haven't measured my 'Vette's cabin gain yet, but it's fairly easy to do with a db meter and some tones, or REW as I mentioned earlier.

Again though, you should be getting satisfying bass, so something is wrong and once you find that it should be easy to resolve.

• Make sure the sub is wired right
• Check the crossovers on the head unit
• Set the balance and fader to 0 on the head unit
• Set the sub level to ~75%
• Set your gains using whatever method you want to
• Level match the fronts/rears with the sub so it sounds to your liking.

DanCan81

TorchRedFred

I didn't know this old thread was a "For Sale" thread.