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Discussion Starter #1
So my 900/5 has a problem, I'm assuming if I decide to stay in the hobby I'm going to need a different amp.

The problem: It comes on and plays just fine for as long as the car is running. Once you shut the amp off, the sub channel will not come back on unless it sits for 10 minutes. The other channels work fine. I've played it loud for a long time and the sub channel works fine, it will not shut down once it's on.

I figured I would make sure there's not a simple quick fix before junking this thing.
 

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Sell it, I'll buy it and try to repair it myself.
 

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We knew you couldn't stay away.:p:D
 

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So my 900/5 has a problem, I'm assuming if I decide to stay in the hobby I'm going to need a different amp.

The problem: It comes on and plays just fine for as long as the car is running. Once you shut the amp off, the sub channel will not come back on unless it sits for 10 minutes. The other channels work fine. I've played it loud for a long time and the sub channel works fine, it will not shut down once it's on.

I figured I would make sure there's not a simple quick fix before junking this thing.
And the MS8 can't be the problem because you have tried swapping RCA's when this has happened....right???
 

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Discussion Starter #5
And the MS8 can't be the problem because you have tried swapping RCA's when this has happened....right???
Yep. While doing the pink noise right after the input setup there was no sound from the sub channel so I ran the "sub" RCA into the center channel and the MS8 was definitely doing it's job. Today, if I did not purposely turn the car off and right back on I would not have known there's a problem. It worked fine for the 90 minute round trip to work and back. I know how these things work though. Eventually it's going to not work even after sitting overnight once in a while then it's going to become most of the time until it fails altogether.

Just saw the other thread with the same problem as well. Hopefully this does not become a regular problem.
 

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Sounds like a cooling problem to me. If your pushing the sub harder then it was designed for, the voice coil will get extremely hot. Now as long as you are still using the sub it is being cooled by movement, but you let it sit for a couple minutes and it overheats and causes a protection circuit on the sub channel to turn off that channel until the coil cools down.

Have you made certain your not overpowering your sub or overddriving the amp? What sub are you using and how is it wired?

The amp could be about to die, or the sub itself could cause the same thing you are describing.
 

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Discussion Starter #7
Sounds like a cooling problem to me. If your pushing the sub harder then it was designed for, the voice coil will get extremely hot. Now as long as you are still using the sub it is being cooled by movement, but you let it sit for a couple minutes and it overheats and causes a protection circuit on the sub channel to turn off that channel until the coil cools down.

Have you made certain your not overpowering your sub or overddriving the amp? What sub are you using and how is it wired?

The amp could be about to die, or the sub itself could cause the same thing you are describing.

I've got 500w available to a pair of subs that can take 500w each and I doubt they see 100w in normal use. I can start the car first thing in the morning, subs work. Shut the car off after 5 seconds of running and restart and the subs don't work. Once the subs are on I can pound them for 45 minutes at a time and no problems. Amp barely gets warm to the touch.
 

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Look at this as an opportunity to try new amps and not as a problem! Send the JL to be repaired and sell it! Get some real SQ amps! The classifieds are overflowing with options lately!

Sent from my DROIDX using Tapatalk
 

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Look at this as an opportunity to try new amps and not as a problem! Send the JL to be repaired and sell it! Get some real SQ amps! The classifieds are overflowing with options lately!

Sent from my DROIDX using Tapatalk
A real SQ amp? I thought the JL HD were SQ.
 

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Not bad I must admit, but, there are some higher resolution examples out there lately! With the front stage he has I would try some different amps, but to each his own!

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You missed an important part of my questons...
What subs (exact model, SVC/DVC) are you running and how did you wire them?

Anything below 1.5 OHMS will cause trouble for that amp.

The mono subwoofer channel will deliver its full 500W output into any impedance between 1.5-4Ω.
The operation of the R.I.P.S. circuitry is
entirely automatic and adjusts itself every time the
amplifier is turned on. There are no user controls
to configure. The system operates through
multiple stages of impedance optimization,
choosing the stage most appropriate to the actual
impedance of the speakers you connect to it.
http://a248.e.akamai.net/pix.crutchfield.com/Manuals/136/136HD9005.PDF

Page 15, what color is the panel indicator when the subs don't work?
 

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Discussion Starter #12
You missed an important part of my questons...
What subs (exact model, SVC/DVC) are you running and how did you wire them?

Anything below 1.5 OHMS will cause trouble for that amp.





http://a248.e.akamai.net/pix.crutchfield.com/Manuals/136/136HD9005.PDF

Page 15, what color is the panel indicator when the subs don't work?

It's always stayed green. Subs are in the sig, 4 ohm SVC wired in parallel. Everything has worked flawlessly since the installation a few months ago. Amp comes on regardless of temp, it's a time based failure.
 

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Not bad I must admit, but, there are some higher resolution examples out there lately! With the front stage he has I would try some different amps, but to each his own!

Sent from my DROIDX using Tapatalk
May I inquire as to what amp are you referring to as far as better quality? You can pm me if this offends anyone.
 

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Sounds like you have a bad amp. That JL amp is typically bullet-proof. JL has always taken care of me. Give them a call and see what they can do. The alternative, of course, you could make a play for some higher end amps, Mosconi, Audison, etc.
 

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Sounds like you have a bad amp. That JL amp is typically bullet-proof. JL has always taken care of me. Give them a call and see what they can do. The alternative, of course, you could make a play for some higher end amps, Mosconi, Audison, etc.
He didn't buy from an authorized dealer.


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Discussion Starter #16
He didn't buy from an authorized dealer.


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Yep, there are two items in my build that were not bought new and this amp is one of them.

To those that suggested upgrading, I would have gone with a higher end amp but after listening to the Interfire, Leviathan, McIntosh, JL6450, and now the HDs without hearing a difference I put more emphasis on power, size, and efficiency. If I was convinced there was an improvement to be had I would consider something else. I'm not completely closed off to the idea of a different/better amp improving SQ but so far I have not seen it with different amps on either extreme.
 

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We've seen this in rare instances in our early runs of the HD line. Essentially what happens is that when the battery in the vehicle drops to extremely low voltages during start-up, it throws the RLC board on the amplifier into a spin, the board mutes the output of the amp, and you get no output from whatever channels the RLC is controlling. On the HD900/5, the RLC only controls the subwoofer channel. That's why the rest of the amp continues to work fine.

Any later revision will never exhibit the problem, but even on the original HD amplifiers, good startup voltage should keep it from happening. In the two cases I've dealt with, replacing the battery in the vehicle eliminated the problem.
 

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I know a Good tech in Las Vegas, he is really good, and not super expensive....

Fixed my Brax Amp for $47 + return shipping costs.
 

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Discussion Starter #19
We've seen this in rare instances in our early runs of the HD line. Essentially what happens is that when the battery in the vehicle drops to extremely low voltages during start-up, it throws the RLC board on the amplifier into a spin, the board mutes the output of the amp, and you get no output from whatever channels the RLC is controlling. On the HD900/5, the RLC only controls the subwoofer channel. That's why the rest of the amp continues to work fine.

Any later revision will never exhibit the problem, but even on the original HD amplifiers, good startup voltage should keep it from happening. In the two cases I've dealt with, replacing the battery in the vehicle eliminated the problem.

That's great info! I'm replacing the battery this Friday. I think I have two problems.... The battery just doesn't have the power it used to since it was run completely dead a couple times due to the dome light being left on.

Second is my drive to work is only 3-5 minutes each way. I try not to use the defrost or seat heaters but I still have to take it on a drive once a week to charge up the battery or it gets slow to start.

Last night I was listening with the engine off. I went straight into "start" from acc without turning it off first. Maybe this is the combination that's causing the problem. I lost the sub channel during the startup but after turning the engine off for about 45 seconds and restarting the subs were fine again.

So I guess the lesson here is to go from off to start, not acc to start and make sure the battery is up to the task. The more I think about it, every time that I can think of that the problem has occured was when I had the amp running already and started the car.

Thanks for the info, you saved me a ton of trouble.
 

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BuickGN, I am glad to hear that is a simple fix for your problem. I know that sometimes the simplist things are what cause us the most frustration. When you swap batteries, let us know your findings please. My best goes out to you.
 
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