Amp discharge on power down.
Bob in WI
Posts: 155
Trust this is the right section to post this in;
I'm no tech & I need some guidance here. I picked up a PS Audio amp that seems to work fine but it discharges on shutdown & I'm concerned about the long term effect on my speakers, esp the tweeters as the discharge can be crackles as well as assorted pops & whistles. So the seller gave me 4 resistors & said I can use these to absorb the sound. I have a speaker selector switch & I'm going to connect these resistors - (2) Dale DCS 1/2, 1 0 mu 1 %, 7028 & (2) marked the same except 7026. So if I put a 7026 & a 7028 on left & 1 of each on the right, will that absorb the discharge from a 200 wpc amp? Speaker set "A" will be normal speakers, speaker set "B" will be the resistors. I would switch to set "B" before powering down. Sorry to be long winded but I don't want to make a potential problem an actual problem. Additionally, is it normal for an amp to discharge on shutdown? I haven't noticed it ever before on any of my equipment. TIA
I'm no tech & I need some guidance here. I picked up a PS Audio amp that seems to work fine but it discharges on shutdown & I'm concerned about the long term effect on my speakers, esp the tweeters as the discharge can be crackles as well as assorted pops & whistles. So the seller gave me 4 resistors & said I can use these to absorb the sound. I have a speaker selector switch & I'm going to connect these resistors - (2) Dale DCS 1/2, 1 0 mu 1 %, 7028 & (2) marked the same except 7026. So if I put a 7026 & a 7028 on left & 1 of each on the right, will that absorb the discharge from a 200 wpc amp? Speaker set "A" will be normal speakers, speaker set "B" will be the resistors. I would switch to set "B" before powering down. Sorry to be long winded but I don't want to make a potential problem an actual problem. Additionally, is it normal for an amp to discharge on shutdown? I haven't noticed it ever before on any of my equipment. TIA
Post edited by Bob in WI on
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I have an ATI amp that does the same thing. It is my understanding that some amps are designed this way to eliminate thump when powering on. Since the output capacitors are drained they must charge up when powered on eliminating the thump. Some amps have relays that open on shutdown, eliminating the drainage through the speakers. In my case as long as I turn off the pre or source first I get a silent shutdown, but if I just shut off the amp it will continue to play music for about 10-15 seconds before it dies off, giving pops and clicks for the last 3 to 4 seconds.Oh, Listen here mister. We got no way of understandin' this world. But we got as much sense of this bird flyin in the sky. Now there is a lot that bird don't know, but it don't change the fact that the world is happening to him all the same. What I am tryin to say is, is that the course of your life, well its changing, and you don't even see it- Forest Bondurant
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Pre have "mute"?
Try muting it and then turn your amp off.
I always turn my pre off last.Testing
Testing
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Thanks for the suggestions. As the pre is upstream of the amp (from the speakers), it has no effect on this phenomena. source to pre to amp to speakers. The discharge is from the amp & it is connected directly to the speakers so I can't fix this by powering down or muting the pre. I tried. I'm thinking there may be a defective protect relay in the amp. I'll need to read up on the amp & confirm it has one.
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Thanks for the suggestions. As the pre is upstream of the amp (from the speakers), it has no effect on this phenomena. source to pre to amp to speakers. The discharge is from the amp & it is connected directly to the speakers so I can't fix this by powering down or muting the pre. I tried. I'm thinking there may be a defective protect relay in the amp. I'll need to read up on the amp & confirm it has one.
Just a thought, and not 100% sure, but if you have major problems shutting down your amp, you got problems..................Just saying.:redface:
Bleed resistor?
My thoughts are the pre is is whats causing any shutdown noise.
I have my doubts the actual amp is the cause.
I would do a DMM test to check the amplifier before making any short term decisions on the amp.
Could be, because the amp does not have NEAR as much gain as the preamp.
And again.I am not sure, just a thought, nothing else.
Hopefully someone with more "knowlege" than myself can chime in here!Testing
Testing
Testing -
Trust this is the right section to post this in;
I'm no tech & I need some guidance here. I picked up a PS Audio amp that seems to work fine but it discharges on shutdown & I'm concerned about the long term effect on my speakers, esp the tweeters as the discharge can be crackles as well as assorted pops & whistles. So the seller gave me 4 resistors & said I can use these to absorb the sound. I have a speaker selector switch & I'm going to connect these resistors - (2) Dale DCS 1/2, 1 0 mu 1 %, 7028 & (2) marked the same except 7026. So if I put a 7026 & a 7028 on left & 1 of each on the right, will that absorb the discharge from a 200 wpc amp? Speaker set "A" will be normal speakers, speaker set "B" will be the resistors. I would switch to set "B" before powering down. Sorry to be long winded but I don't want to make a potential problem an actual problem. Additionally, is it normal for an amp to discharge on shutdown? I haven't noticed it ever before on any of my equipment. TIAMain System: Denon DP-59L | Audio-Technica AT33EV | Marantz SA-11S2 | Classe DR-10 | Classe CA-300 | Classe RC-1 | PSB Stratus Gold i's | DIY Balanced AC Power Conditioner | Acoustic Zen and NeoTech cables | Oyaide and Furutech power connectors | Dedicated 20A isolated ground line.
Home Theater: Toshiba D-VR5SU | Laptop #1 |Outlaw Audio OAW3 wireless audio system | Marantz SR-19 | Phase Linear 400 Series 2, modified | AudioSource 10.1 EQ (for subs) | Axiom M3 v3’s | Axiom VP150 | Optimus PRO-X55AVs | Dayton 12” powered subs (x2) | Belkin PureAV PF-60 line conditioner.
Party System: Laptop #2 | Audioquest Dragonfly USB DAC | Technics SU-A6 | Acurus A-250 | Radio Shack 15-band EQ | Pioneer SR-9 reverb | Cerwin Vega DX9's | Dayton 100° x 60° horns with titanium HF/MF compression drivers. -
PS Audio 200CX. Pre on or pre off makes no difference.
" Its audible, maybe annoying but harmless" ....my only concern is for the speakers. I've heard that distortion blows more speakers than volume & the sounds is bugger makes on power down sure aren't musical. But if its not abnormal for this amp, I'm all good with it. -
Seems odd to me. As I mentioned my amp dumps its stored energy thru the speakers but you cant hear unless I give it a signal to amplify. I can't imagine where those harmonics are being generated if not thru the input. Have you tried powering down with the interconnects disconnected from the amp? Perhaps the cables are picking up some emi/rfi. Or are you getting any ground loop hum in your system? My logic tells me the dc current should remain flat/silent unless its getting a signal from either input, ground, or emi/rfi. Im betting its not the amp its interference.Oh, Listen here mister. We got no way of understandin' this world. But we got as much sense of this bird flyin in the sky. Now there is a lot that bird don't know, but it don't change the fact that the world is happening to him all the same. What I am tryin to say is, is that the course of your life, well its changing, and you don't even see it- Forest Bondurant
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I can't say anything for certain but I've has 3 different pre's, & shut down the CD player before powering down the amp. The noises are not the same every time but tend to be a pop or thump followed by crackle or buzz sometimes for 10 seconds or more. Not usually hum, crosstalk, etc. The pre & turntable are grounded to the house wiring. I should prolly pick up new RCA jacks regardless, the one I have are pretty old (decades) altho they have been cleaned. I'm going to try with the input jacks disconnected next. That would surely eliminate or verify up stream sources.
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+1 on what pester mentioned about turning off the preamp last. I've always followed the sequence of shutting off all power amps before turning off the preamp. I've got a couple of Soundcraftsmen power amps and they absolutely have___ to be turned off first before turning off the preamp , if not I'll fry some circuitry in them!:eek: There's a way to rewire them so I don't have to worry about this every time,but I'm not savvy on doing the work.:question: I've noticed on my power amps when I power down the speakers will pop too, unless I use the speaker switch( A,B) to disconnect the signal to them.Obviously, I always mute the source on the preamp. It sounds like your PS Audio power amp may have a similar speaker selector switch to turn or off speaker set A or B or both?
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I bought a separate speaker selector switch for exactly that purpose. It gets installed tomorrow. I truly am not understanding how the pre that sits upstream on the amp - speaker connection can make any difference unless the source of the discharge is the pre itself & I'm fairly certain that is not the case. Regardless, its free to try so I will do that.
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Polkie2009 wrote: »+1 on what pester mentioned...
Freudian slip? :biggrin:Lumin X1 file player, Westminster Labs interconnect cable
Sony XA-5400ES SACD; Pass XP-22 pre; X600.5 amps
Magico S5 MKII Mcast Rose speakers; SPOD spikes
Shunyata Triton v3/Typhon QR on source, Denali 2000 (2) on amps
Shunyata Sigma XLR analog ICs, Sigma speaker cables
Shunyata Sigma HC (2), Sigma Analog, Sigma Digital, Z Anaconda (3) power cables
Mapleshade Samson V.3 four shelf solid maple rack, Micropoint brass footers
Three 20 amp circuits. -
LOL!!!! Good catch BlueFox ! Sorry about that Pepster, it was my slip up.
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B&K amps are famous for this. They do it while switching inputs too. I have been able to resolve this problem using a line conditioner on the amp. We use this guy, http://www.amazon.com/Panamax-M4300-PM-Outlet-Clean-Power/dp/B000SXWGDI/ref=sr_1_2?s=electronics&ie=UTF8&qid=1373056943&sr=1-2&keywords=panamax+4300. Panamax 4300. We use another trick too but I cant remember it. I will post it as soon as I do remember.B&W CM9Classé Sigma