ID12v3 x JL XD700/5 low output issues

[wanton789 10+ year member]

Hi all,

Just hooked up my Image Dynamics 12" v3 D4. Have it sealed in a 1.25 cu ft box. Have it on the sub channel of a JL XD700/5. Have the dual voice coils wired parallel so it's 2 ohms (JL XD700/5 should give 300 W RMS @ 2 ohms).

I can barely hear it. I know a signal is getting through, I can put my hand on it and feel it.

Tried turning up the gain slightly on the amp, but the difference is negligible. I even got the yellow overcurrent protection light after about 2 turns (I think even less than 2... it was no more than 3 turns).

I picked up some Hybrid Audio Unity's but don't even have em on the JL amp yet (wanted to wire to HU just so I could see the diff). The sub is the only thing wired to the amp.

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Any immediate ideas pop into your head? Could use some troubleshooting advice here.

Thanks in advance.

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[neo_styles 10+ year member]

Out of phase? Try reversing the + and - wires on the amp.

 

[wanton789 10+ year member]

P.S. My HU is a Kenwood BT952

 

[neo_styles 10+ year member]

I'm leaning towards your sub being wired out of phase. Also check your crossover points on both the head unit and amplifier. You should be running one or the other, not both. For starters, don't bother with the subsonic filter (leave all the way CCW). Just mess with the LPF until you're around 60-80Hz. Check Sub volume on the HU as well.

 

[wanton789 10+ year member]

I just switched it, same result. I was pretty careful with wiring the whole way through. I don't think I wired it out of phase. I'll have to double check my connection all the way through tomorrow.

I have my LPF on the amp @ about 60 Hz right now. LPF on HU is off. I left my HU gain at 0, amp gain is slightly above 0. (I should be getting something even with the gains at 0, right?)

I will have to mess around more with EQing tomorrow also.

I even tried turning fronts and rears down as far as my HU would let me and still couldn't really tell. I can feel the bass from my stock speakers more than I can from my sub, so something is up... I was running back and checking the sub all the time while I was messing with it.

Tried turning the gain up on my HU for the sub... even maxed it... nothing. I went back there to feel it and it had a very slight increase.

 

[neo_styles 10+ year member]

Could be bad RCAs or, worst case, bum sub channel on the amp. If your amp isn't new, you could try opening the casing to check the capactors to make sure nothing blew.

 

[neo_styles 10+ year member]

Do you have a multimeter btw? It really helps when adjusting your amp gains. Find a 40Hz -5db test tone and play that at 3/4 volume while adjusting your gain (sub disconnected for this step, obviously). Using ohm's law, you can figure out what voltage you should be seeing to get the right output to your sub.

 

[wanton789 10+ year member]

Could be bad RCAs

I did make the RCAs. I beep checked the shield and signal on each of them after I was done making them though. 16 gauge speaker wire.

or, worst case, bum sub channel on the amp.

I did get it off CL. Luckily I know where this guy's office is...

 

[neo_styles 10+ year member]

You can't fault the seller, though. He may not have known. I just bought a MB Quart from a local CL ad that turned out to have a blown cap. He was willing to fix the problem, but had no clue that it was an issue.

 

[wanton789 10+ year member]

Ok. Thanks for the advice.

I'll check the Vout of my subwoofer channel tomorrow.

 

[wanton789 10+ year member]

Just in general, with all (HU and amp) gains at zero, the sub should at least knock a decent amount. Yes or no? Of course depends on wattage required / delivered.

With the ID12v4 asking for 50-400 watts RMS and the JL amp theoretically giving 300 watts RMS, it should slap pretty decent at 0 gain, correct or incorrect?

 

[zako 10+ year member]

12 inch sub on 300watts of power should give you some tangible bass impact IMO.

First thing, I'd check that crossovers are not interfering with subwoofer application. First, you don't need the subsonic high pass filter, so either turn it off or set it to the lowest setting. Next make sure your low pass for subwoofer is not too low (try to turn it off, or set at the maximum for testing).

Next, try to set amplifier gain by the DMM method (see the tutorials posted on this web site). Get a DMM, set it to AC voltage mode. Turn off all crossovers on the stereo and the amplifier. Play a 0dB test tone somewhere in the bass region (like 40-50Hz) with the volume knob at the normal listening level or a bit higher. Turn up gain starting from the lowest level until you get a 25V reading. Leave subwoofer gain at that level and then listen to normal music. If you amplifier doesn't put out 25volt reading, specially with subwoofer connected, something is wrong with it IMO.

 

[wanton789 10+ year member]

This morning I tested it out real quick before I had to leave for work.

With the gain maxed out (no sub connected):

- LPF off I was able to get ~31 volts out.

- LPF @ 60 Hz, I was only able to get ~21 volts out.

Previously, when I had the sub connected the night before, I barely turned the gain up and got an overcurrent protection. I was not testing with my multimeter to see what the Vout was at this point. I will need to do this tonight.

 

[wanton789 10+ year member]

With the sub connected, I can't turn the gain up past ~3 volts out. I'll hear the sub start to make some awful noise (clipping?) and so I stop.

Measuring the VAC across the two signal pins of the RCAs, I read 00.1 V. This is supposed to be 4 V from my headunit (that's what 4V preamp means right?). Maybe this isn't the correct way to measure this though.

What is weird also, is when I am near the ~3 V with the sub connected, the over current light may flicker on and off. This is without me adjusting the gain or the volume.. with it just sitting there on the 50 Hz tone.

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So what is the issue here, my sub channel is broke? Or my headunit doesn't give a strong enough signal to begin with?

Thanks in advance again.

 

[neo_styles 10+ year member]

You should be setting your gains without the sub connected. Then connect the sub and leave it well enough alone.

Are you getting that 0.01v on each RCA )pin to ground or outer metal surface) individually or measured together? If so, I'm thinking it could be bad RCAs. Could have been a bad solder joint or loose connection. RCAs could have fallen off your HU too.