Hello,
I am having an issue with my Jl 1000/1.
The amp has very low output.
With a 2.5Vrms signal in I get ~6Vrms out (At max gain).
There is no distortion just very low output.
Idle current is ~2.8A and there are no error lights on the amp. It starts up normally with only the green light illuminated.
I've cleaned all of the pre amp switches and removed the preamp board to reseat. Neither seems to help this problem.
Any help would be greatly appreciated.
Thanks,
Steve
I am having an issue with my Jl 1000/1.
The amp has very low output.
With a 2.5Vrms signal in I get ~6Vrms out (At max gain).
There is no distortion just very low output.
Idle current is ~2.8A and there are no error lights on the amp. It starts up normally with only the green light illuminated.
I've cleaned all of the pre amp switches and removed the preamp board to reseat. Neither seems to help this problem.
Any help would be greatly appreciated.
Thanks,
Steve
I've never seen it in the 1000 but I've seen the muting transistor fail in the 500. It would be something to check if you're sure all pots and switches are clean and you have the input level set to low voltage.
Have you removed the aluminum cover to expose the board?
Have you removed the aluminum cover to expose the board?
I gave the switches and pots a pretty thorough cleaning with 99% isopropyl alcohol. Toggling all of the switches does not get the output level to return even intermittently.
The board is completely removed from the amp chassis on my bench currently. Just the output heatsinks are left attached.
Be very careful when handling the amp. If you don't keep the board perfectly perpendicular to the heatsink, it can bend the legs of the transistors and cause various problems when you try to reassemble the amp.
Q511 is a J111 transistor. Remove it to see if the level returns.
Q511 is a J111 transistor. Remove it to see if the level returns.
Thank you for the warning.
I removed Q511 amp is the same as before. Working with very low output level.
I removed Q511 amp is the same as before. Working with very low output level.
I'm currently playing music through the amp with the LPF off. I believe it has a natural LPF at 250 Hz.
Before when I was probing I input a 2.5Vrms 80Hz sine wave when I measured output of 6Vrms.
Output sounds perfectly clean. I haven't looked at the output with a scope. I don't have an isolated scope.
Before when I was probing I input a 2.5Vrms 80Hz sine wave when I measured output of 6Vrms.
Output sounds perfectly clean. I haven't looked at the output with a scope. I don't have an isolated scope.
You don't have to have an isolated scope. You can either use differential mode or simply probe the two speaker terminals individually.
Does the high/low input switch work as expected?
Does the high/low input switch work as expected?
That's a good point. I forgot about using differential mode on two channels.
The high/low switch works. You hear the output level drop about 50% in the high position.
The high/low switch works. You hear the output level drop about 50% in the high position.
There is another J111 near the PS driver transformers, is that possibly part of the muting circuit?
Hi Perry,
I found the source of the problem I believe. I used a different source for the signal. I used a cell phone with a 3.5mm jack and the gain is completely normal. The minimum gain setting is probably 3x as loud as the original source at max gain.
The original source is a Schiit Modi3 DAC. I might try the source on my other 1000/1 to see if there is any issue at all with this amp.
I found the source of the problem I believe. I used a different source for the signal. I used a cell phone with a 3.5mm jack and the gain is completely normal. The minimum gain setting is probably 3x as loud as the original source at max gain.
The original source is a Schiit Modi3 DAC. I might try the source on my other 1000/1 to see if there is any issue at all with this amp.
That should have been my first question. Some JL amps (and others) have problems with signal sources that don't have a grounded shield.
Thank you so much for all of the help.
The issue is definately my source. I tried my other 1000/1 and the signal level is exactly the same.
The issue is definately my source. I tried my other 1000/1 and the signal level is exactly the same.