hello everybody,
When I turn off my Luxman L-3, after 5 seconds the woofers get " sucked in ".
DC offset is 0mV on both channels but on turnoff it goes up to 12Volts on both channels. I 've been searching about the subject but the only solution I can find is placing a relay or putting a 1µF cap on the powerswitch. Shouldn't it be possible to solve this whitout changing the amp's design ? I can't imagine the Luxman was meant to suck the woofers in on turnoff.
I've been working on this amp(new transistors and a few caps) so maybe I did something wrong.
I saw the power supply caps discharge at different speed, one in 5 seconds the other in 2 minutes. Is this normal ?
thanks in advance
When I turn off my Luxman L-3, after 5 seconds the woofers get " sucked in ".
DC offset is 0mV on both channels but on turnoff it goes up to 12Volts on both channels. I 've been searching about the subject but the only solution I can find is placing a relay or putting a 1µF cap on the powerswitch. Shouldn't it be possible to solve this whitout changing the amp's design ? I can't imagine the Luxman was meant to suck the woofers in on turnoff.
I've been working on this amp(new transistors and a few caps) so maybe I did something wrong.
I saw the power supply caps discharge at different speed, one in 5 seconds the other in 2 minutes. Is this normal ?
thanks in advance
Attachments
A cap on the power switch will do nothing for this problem. It is inherent in the amp design and is due to what happens when the rail voltage falls below that required to maintain the current sources inside the amp.
A relay is the only way you can avoid it.
A relay is the only way you can avoid it.
I currently have an L-3 on the bench who behaves exactly as you describe except for the PSU caps.
Check the bleeder resistors across both caps.
Apart from that, 12V is present on both outputs after turn off (5sec.) and slowly decreases to 0 within about 15 seconds.
/Hugo
Check the bleeder resistors across both caps.
Apart from that, 12V is present on both outputs after turn off (5sec.) and slowly decreases to 0 within about 15 seconds.
/Hugo
Good to hear other L-3's are doing the same thing. Does it to the same thing to the woofers also ?
I'm using it with cheap speakers now but it doesn't look healthy, I'm afraid to use the amp on good speakers. Can 12Volts do any damage ? If it does I think I'll go looking for a relay.
I'm using it with cheap speakers now but it doesn't look healthy, I'm afraid to use the amp on good speakers. Can 12Volts do any damage ? If it does I think I'll go looking for a relay.
Woofers are moving backwards too but only very little. This depends on the type of woofer.
I wouldn’t consider it as dangerous but if you want to be sure, a relay is, as has been said, the only solution.
As for the caps, it wouldn't hurt the amp to replace them.
/Hugo
I wouldn’t consider it as dangerous but if you want to be sure, a relay is, as has been said, the only solution.
As for the caps, it wouldn't hurt the amp to replace them.
/Hugo
- Status
- Not open for further replies.