# JL Audio HD 900/5 sub channel problem



## pimpndahoz (Dec 11, 2011)

OK so my JL Audio HD 900/5 sub channel seems to be not working? I disconnected my sub box to Dynamat the trunk. When I reconnected it the next day the subs only played at half volume. I've made no changes to the system. The crossover in the amp is not being used. Gains are correct and double checked. Everything in the system is 3 weeks old. I DO have a remotel level control on that channel and it works properly. Anything else I should look at? Here's my equipment list....

Sony DMR
JL Audio 900/5
Focal KRX3's running passive in custom window enclosures
2 JL Audio 10's in a small sealed box, presenting 2 ohms
08 Honda Civic Si sedan

Thanks in advance....


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## UNBROKEN (Sep 25, 2009)

2nd one this week I've heard of.
Off topic...any pics of the front stage set-up?


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## pimpndahoz (Dec 11, 2011)

UNBROKEN said:


> 2nd one this week I've heard of.
> Off topic...any pics of the front stage set-up?


I can take some pics tomorrow, but you'll have to tell me how to post them. I'm old (38) and can barely use a computer, lol.


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## UNBROKEN (Sep 25, 2009)

I'm 3 years older than you...I'm the wrong guy to ask. LOL

I have the same set for a front stage though...always curious as to how others set theirs up.


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## Angrywhopper (Jan 20, 2010)

Use photobucket.com to post pictures.

Also weird that 2 people with the 900/5 having same issue this week.


Sent from my iPhone using Tapatalk


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## thomasluke (Jun 10, 2011)

I know this has made me real squirly of the pf the amp i was about to get. I mean 900 bucks.....


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## TypeR (Apr 28, 2011)

Any updates on this?
I just installed a HD 900/5 and the 4 speaker channels work great, but the sub channel has pathetic output. I'm running an Alpine 8" R supplying a 2 ohm load, which is within the JL RIPS impedance range of 1.5-4 ohms. I'm going to put a multimeter on it tomorrow to see where the gain is at, but the Massive Audio blade 1000 (500 watt rms) I had running the same sub was easily out performing the 900/5....help?


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## BuickGN (May 29, 2009)

TypeR said:


> Any updates on this?
> I just installed a HD 900/5 and the 4 speaker channels work great, but the sub channel has pathetic output. I'm running an Alpine 8" R supplying a 2 ohm load, which is within the JL RIPS impedance range of 1.5-4 ohms. I'm going to put a multimeter on it tomorrow to see where the gain is at, but the Massive Audio blade 1000 (500 watt rms) I had running the same sub was easily out performing the 900/5....help?


Is the input set on high or low?


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## adrenalinejunkie (Oct 17, 2010)

Nothing new...
I've read stories about the sub channel on this amp before. Sounds like a defective issue with these amp's. JL should have some sort of recall unless it's just user error...
Are you guys sure the Rca's are plugged in properly?


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## TypeR (Apr 28, 2011)

BuickGN said:


> Is the input set on high or low?


Input voltage set on low. I have read a few threads inluding yours about how a weak battery will mute the sub channel completely, but mine just sounds weak. I even started the car before turning on the stereo to make sure it wasn't a low startup voltage issue.

I'm quite confident in the installation because I was just changing out my old 4 channel +mono amps and replacing them with this. Same wiring/rca's - disconnect, reconnect. The rca's connections on the 900/5 are much tighter fitting than my previous amps, but I made sure they were pushed on far enough. The 4 speakers sound excellent, loads of crystal clear power, sub barely sounds like it's there...

This is my first purchase off this forum, so I'm hoping I didn't get sent a lemon. The guy I bought it from said he bought it used but never installed it. I want to troubleshoot this as best I can and ensure it has nothing to do with my installation/settings before I contact him though.


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## pimpndahoz (Dec 11, 2011)

The issue I had with mine was resolved. I swapped out the RCA's running to the sub channel, when I pulled the old ones out one of the center points that actually plugs in was BROKEN. Problem solved it was not an amp issue.


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## TypeR (Apr 28, 2011)

Wow, ok thanks for the tip. I've got some extra cables laying around so I'll start by switching out the sub channel RCA's. I'd be surprised if the sub RCA's are faulty because they are practically new, but now I'm hoping that they are broken!


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## BuickGN (May 29, 2009)

Let us know how you resolve the problem, I'm curious. After swapping the battery, mine has never acted up again. Before the battery I could make it fail on demand. But mine had no sub or it was perfect, no in between like yours so I'm sure it's not the same problem as you said.


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## Driven Audio Tony (Feb 14, 2011)

When you have low output it's always a good idea to test both the left & right input RCA to make sure they are working 100%. You can also plug an iPod into the amp and see what output is like then to check the output level vs your main source.

And yes, always check over all parts of the system - voltage, ground, input, speaker wire etc.


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## adrenalinejunkie (Oct 17, 2010)

A bit off topic, but what cable are you guys using to plug in the IPod to the amp? It's not the one that has the head phone jack (3.5MM) on one end and the Rca's on other end is it?


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## Driven Audio Tony (Feb 14, 2011)

Yes those will work fine for testing. The advantage with that is you can adjust volume on the ipod quickly while testing.


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## adrenalinejunkie (Oct 17, 2010)

tdehnke said:


> Yes those will work fine for testing. The advantage with that is you can adjust volume on the ipod quickly while testing.



Ok, cool.
I thought that type would limit SQ, but then it's just for testing purposes and it makes sense to have a volume to have control. Thanks


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## rain27 (Jan 15, 2009)

TypeR said:


> Any updates on this?
> I just installed a HD 900/5 and the 4 speaker channels work great, but the sub channel has pathetic output. I'm running an Alpine 8" R supplying a 2 ohm load, which is within the JL RIPS impedance range of 1.5-4 ohms. I'm going to put a multimeter on it tomorrow to see where the gain is at, but the Massive Audio blade 1000 (500 watt rms) I had running the same sub was easily out performing the 900/5....help?


Where do you have your gain set?

I purchased one of these new and thought the same about the output out of the sub channel. 

I have a HD 750/1 as well, and with the gain at 10 o'clock it has great output. But when I put in a 900/5, I had to turn the gain up to about 2 or 3 o'clock to get good output from it. I thought this was odd given that it was only a 250 watt difference for the sub channel.


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## TypeR (Apr 28, 2011)

Well I went over all my sub related wiring and everything was good.
I'm starting to think it's mainly a level adjusting issue. My last setup had a wimpy 50x4 and 500x1 and I didn't even have the 4 speakers turned up really. The sub was getting more power at a lower volume. This 100x4 makes the speakers scream and almost drowns out my dinky 8"sub. 
I turned the gain all the way down for the 4 speakers and have my sub at 2o'clock and get decent sub output but the speakers are still insanely loud at 3/4 source volume! Just surprised I had to turn the sub gain up so high. The sub itself most likely has a lot to do with it. It seems like much cleaner bass with the 900/5 and the Massive blade had more of a "bass boost" sound which was a bit dirty, but loud. I'm putting in a 8W7 soon so hopefully that makes a bit of a difference.
I need to get a sine wave disc and set the sub level with a meter to do it properly.


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## adrenalinejunkie (Oct 17, 2010)

Check out this link:
Gain Settings
has instruction and some test tones you can download. Hope that helps.


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## TypeR (Apr 28, 2011)

Update - so funny story...when I installed the HD900/5, I turned off all the EQ settings/loudness as per the manual for properly setting the gains. Apparently this digital amp is WAY more sensitive to these settings on my deck than my last amps. Especially the sub channel. When I turned them back on, the sub was insanely loud. I had to turn my gain down from 3/4 to 1/2...and it's still louder than before. Long story short, I'm glad it was something stupid like that and not a problem with the sub channel. I still can't believe how much the sub channel was affected by one stupid setting on the deck....


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## BuickGN (May 29, 2009)

I also see large differences in sub output by small adjustments to the MS8's bass boost. On the old 1,000w amp the differences didn't seem so drastic. With the 900/5 just one click up on the MS8 makes an audible difference. I only run the gain at the 10o'clock position and it pushes the pair of 15s nicely but of course there are a ton of variables. I'm also running 16ga speaker wire to the subs, got to replace that soon.


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## luisc202 (Oct 29, 2013)

I am facing the same issue with my 900/5 and it happens when the car is off. I had this same amp in my Tundra and no issues when it was in the truck. I had 2 in the Tundra and swapped one out to the new Honda accord. So I am thinking it is my battery since I ran new OFC 0 Gauge from Knuconceptz to the amp.


I just didn't think a brand new cars battery would be the culprit.


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## luisc202 (Oct 29, 2013)

BuickGN said:


> Let us know how you resolve the problem, I'm curious. After swapping the battery, mine has never acted up again. Before the battery I could make it fail on demand. But mine had no sub or it was perfect, no in between like yours so I'm sure it's not the same problem as you said.


This solved my issue. New AGM battery coupled with Knuconceptz OFC 0 gauge and no more sub shut off.


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## joeyvaz (Jan 23, 2009)

I've experienced this as well, but I didn't think to check my battery. I park my car one day and all was fine. sub was playing normally. I go back to my car 8 hours later and I have no sub output. I thought it might be my new Parrot Asteroid, but I reset it back to factory and nothing changed. I'm going to test my battery tonight and see what the voltage looks like. 

I am also going to test the RCAs but I doubt it is that since they are new. I was going to add a mono Alpine amp for my sub, but now I'm wondering if it's my battery.


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