oldmako Posted May 1, 2009 Share Posted May 1, 2009 The latest in my amp saga..... So the Phase Linear 400 dinosaur shows up last week and is in gorgeous shape. The lights on one of the VU meters are out....bummer. Other than that, it's perfectly quiet (at least to my ears) and makes my CFs sound great. It's got a ton o' thump. I have it's AC cord plugged into the back of my receiver. I am using it for a preamp until can scrape up the ching for a more suitable unit. Here's the rub.....when I shut it down, it makes a fairly loud, rather bizarre noise. I can't tell if it's coming out of one channel or both. I had to run to the airport and won't get home for several days to troubleshoot further. The noise is as follows.... BEEeeeeeeoooowwwwwwwzzziiPPP! How does a neophyte MOron like myownself determine whether or not this is harmful to my speakers? If it's just annoying than I can live with it. But, it's fairly loud and abrupt. Ahhh the perils of used gear! BEOzip out. Quote Link to comment Share on other sites More sharing options...
russ69 Posted May 1, 2009 Share Posted May 1, 2009 Yeah the ole Flame 400 will discharge on power off. I don't remember any noises other than a slight thump at the end but it shouldn't be too loud. Try it with the preamp turned on, no volume and then with the preamp off. One way might work better than the other. It's not uncommon for some amps to do this. Thanx, Russ Quote Link to comment Share on other sites More sharing options...
thebes Posted May 2, 2009 Share Posted May 2, 2009 Probably needs a capacitor across the leads at the on/off switch. Have no idea what value to use etc. Makes sure volumne is down before you kill the switch. Quote Link to comment Share on other sites More sharing options...
oldmako Posted May 2, 2009 Author Share Posted May 2, 2009 I have tried it with the volume down and it makes no difference. As it is pluged into the Switched outlet on the back of the preamp it naturally follows that switch. I suppose I could just leave it plugged in (on) to another outlet and minimize the noise, but I'm not too crazy about leaving electrical stuff on when it;s not in use, and or when I leave my domo. As long as it's not doing damage to the speaks then I can easily live with it. I have had less powerful amps make noises at shut down as well, but with 200 watts this thing really makes a racket. But man does it sound good when in use! I can only imagine what some nice tube gear must sound like. Someday.... Thanks for the input. Quote Link to comment Share on other sites More sharing options...
thebes Posted May 2, 2009 Share Posted May 2, 2009 Don't have much in the way of technical chops but that doesn't sound right to me. I would supsect that there could/might be a bleeding resistor that's gone bad or something along that line. Also, these seem to be very sensitive to using the right fuses, so do a google (you'll find a thread here and on DIYAudio) about this. Also, have you tried pluggin and unplugging directly from the wall. Maybe your switched circuit on the preamp is funky. Quote Link to comment Share on other sites More sharing options...
oldmako Posted May 2, 2009 Author Share Posted May 2, 2009 Thanks Thebes, I've tried very little because it showed up at my place right before I had to leave town for a week. I hope to get home late tomorrow and I'll try plugging it directly into the wall. I also noticed that when I rotate the volume knob excessively that the peace lilly on the floor in front of the right speaker flips this way and that like there's an open window.....and the grills on both speakers pulsate. This set up could wake the dead. Frustrated a bit, but smiling none the less. I'll check the fuses and do some more googling. Quote Link to comment Share on other sites More sharing options...
russ69 Posted May 2, 2009 Share Posted May 2, 2009 As Thebes said, don't use the switched outlet. Plug the amp into the wall and try it as I suggested. One of those ways will be the more quiet. 1. pre off then unplug amp 2. pre on then unplug amp. Thanx, Russ Quote Link to comment Share on other sites More sharing options...
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