Subwoofer LFE AC Voltage Range

[rickvj]

I have done a ton of Google searches for this and can't find a answer. I have a 250W Dayton
replacement plate amp on my 12" JBL sub and I am not getting any volume out of it at all. If I set my home theater receiver to play Sirius BPM pounding club music my sub used to shake wine glasses off the wine rack in the kitchen. Now if I turn the gain all the way up I barely feel a vibration on the subwoofer surface. My plate amp is well under it's 5 year warranty and they said they will readily replace it but I want to be sure it is not the LFE output from the receiver so I want to check the voltage output from the LFE RCA subwoofer output on the receiver but I can't find for the life of me what the voltage range should be from that output. I know that audio is AC and when I check the voltage at half volume on a heavy bass groove I get a range from .20VAC - .50VAC from the LFE. Any thoughts or advice? Pretty sure it's the plate amp but I want to be sure. The receiver is a 100W x 5.1 home theater receiver.

 

[TLS Guy]

I have done a ton of Google searches for this and can't find a answer. I have a 250W Dayton
replacement plate amp on my 12" JBL sub and I am not getting any volume out of it at all. If I set my home theater receiver to play Sirius BPM pounding club music my sub used to shake wine glasses off the wine rack in the kitchen. Now if I turn the gain all the way up I barely feel a vibration on the subwoofer surface. My plate amp is well under it's 5 year warranty and they said they will readily replace it but I want to be sure it is not the LFE output from the receiver so I want to check the voltage output from the LFE RCA subwoofer output on the receiver but I can't find for the life of me what the voltage range should be from that output. I know that audio is AC and when I check the voltage at half volume on a heavy bass groove I get a range from .20VAC - .50VAC from the LFE. Any thoughts or advice? Pretty sure it's the plate amp but I want to be sure. The receiver is a 100W x 5.1 home theater receiver.

You don't say what model the sub is. The voltage from your receiver sounds right to me.

I suspect your problem is that the JBL amp has an Eq and frequency response specific to that sub and the Dayton does not.

It often does not work to change the model of a plate amp.

I suspect you need an exact replacement amp or a new sub.

The other possibility is that the sub driver's voice coil was fried when the old amp failed by sending DC off set though the driver.

JBL subs have had a lot of issues. Probably time for a new sub.

 

[highfigh]

I have done a ton of Google searches for this and can't find a answer. I have a 250W Dayton
replacement plate amp on my 12" JBL sub and I am not getting any volume out of it at all. If I set my home theater receiver to play Sirius BPM pounding club music my sub used to shake wine glasses off the wine rack in the kitchen. Now if I turn the gain all the way up I barely feel a vibration on the subwoofer surface. My plate amp is well under it's 5 year warranty and they said they will readily replace it but I want to be sure it is not the LFE output from the receiver so I want to check the voltage output from the LFE RCA subwoofer output on the receiver but I can't find for the life of me what the voltage range should be from that output. I know that audio is AC and when I check the voltage at half volume on a heavy bass groove I get a range from .20VAC - .50VAC from the LFE. Any thoughts or advice? Pretty sure it's the plate amp but I want to be sure. The receiver is a 100W x 5.1 home theater receiver.

Decrease the level control to minimum on the sub amp and connect a short cable to the LFE input, then touch the tip of the plug with your finger. Raise the input level control and listen for hum- if it never becomes audible, try the other jack, after rotating the level control to minimum. If it never becomes loud, call Parts Express.

Do you have a smart phone and a mini-RCA cable? Connect that and try it- that should be a suitable substitute for the signal from the AVR.

Check the crossover frequency- if it isn't set at the highest position, change that and see if it corrects the problem. Your AVR should set the needed frequency- the control on the sub amp is really for the times when you might use the high level inputs.

 

[j_garcia]

You replaced the amp, but did you verify that the driver itself was not also damaged when the sub failed necessitating the replacement of the amp? Regardless, I agree with TLS, it is time to retire that sub.

 

[rickvj]

You don't say what model the sub is. The voltage from your receiver sounds right to me.

I suspect your problem is that the JBL amp has an Eq and frequency response specific to that sub and the Dayton does not.

It often does not work to change the model of a plate amp.

I suspect you need an exact replacement amp or a new sub.

The other possibility is that the sub driver's voice coil was fried when the old amp failed by sending DC off set though the driver.

JBL subs have had a lot of issues. Probably time for a new sub.

The JBL Sub is a PSW D112 250W and the original OEM plate amp was faulty and out of warranty. I put in the Dayton replacement amp a year and a half ago and it worked awesome until a couple weeks ago. With the gain turned all the way up I can feel the speaker vibrate slightly but not enough to generate any sound. During normal use the gain was never even half way up. The actual sub driver is a beast and I am sure it has nothing wrong with it otherwise it would make an off sounding noise like a rattle or scratching blown sound. The plate amp is matched for the driver's power handling and I am sure I never got it loud enough to do any damage to the driver. All other electronics/amp except for the new Dayton have been removed from the sub enclosure so it's just been the driver and the Dayton in the box. If you say the power output from the receiver sounds right, you have confirmed my suspicion that the plate amp is at fault. The warranty has 3-1/2 years left on it and Parts Express will replace it in 7 days, the 13.5 pound shipping cost is what sucks though!!!

 

[rickvj]

You replaced the amp, but did you verify that the driver itself was not also damaged when the sub failed necessitating the replacement of the amp? Regardless, I agree with TLS, it is time to retire that sub.

Yes, I removed the old OEM plate amp a year and a half ago and custom fit the Dayton plate amp and it worked awesome until a couple weeks ago. That JBL sub driver is a beast and I am sure I never put enough through it to blow it. There is no adverse sound indication that it is blown - ie. scratching, rattling etc. It vibrates slightly and clean but not enough to make it pound like it's supposed to. One of the last replies told me that the voltage output from the receiver LFE sounded right so I am suspecting the amp failed and like I said it is well under warranty.

 

[j_garcia]

It does sound like the amp failed then. The JBL drivers are fine, it was the amps they had issues with.