24 dB/Octave 2/3-Way Linkwitz DC on output after power cut

Calebay · 5th August 2005, 08:55 AM

Hello

i build this 24 dB/Octave 2/3-Way Linkwitz from http://sound.westhost.com/project09.htm

i made it 3 way and i have changed all opamp for OPA627
it seems to be working just fine. but then today i acidently pulled the AC plug, from the filter while the amp was still on. 1 sec. later! a Bad sound! and smoke! from my new Neo3PDR

so i disconecntet the amp and mesured no DC on output when power on. but when i turn it off for 1-2 sec. 1-1.5volt DC on all output

How can i cure this??

sajti · 5th August 2005, 09:00 AM

Apply mute circuit on the end, with relay, or muting transistor. Another solution, to use stronger powersupply to keep the circuit up, untill your powermaplifier switch off.
And last but not least: Use coupling capacitor on the output of the filter

sajti

Calebay · 5th August 2005, 09:15 AM

hmm but is it normal this DC after i cut the power?

Jan Dupont · 5th August 2005, 09:20 AM

The DC could be caused by that the pos. and neg. supply fall at different speed

Calebay · 5th August 2005, 09:32 AM

they drop at the same speed very close on my scope.

its fisrt after the supply voltage has dropped below 2volt. then i get the DC on the output

sajti · 5th August 2005, 09:44 AM

Quote:

Originally posted by Calebay
hmm but is it normal this DC after i cut the power?

Unfortunately yes. Most of the manufacturers use muting circuits on the output, to cut the DC during the ON/OFF period.

sajti

sajti · 5th August 2005, 09:46 AM

Quote:

Originally posted by Calebay
they drop at the same speed very close on my scope.

its fisrt after the supply voltage has dropped below 2volt. then i get the DC on the output

Just add series capacitor (1-10uF), and parallel resistor (100-200k) to the output, and You will never see this problem any more....

Sajti

Calebay · 5th August 2005, 11:17 AM

okay did not know that

ill better put some capacitors in there then

tnx for the help

Calebay · 1st October 2005, 07:15 PM

Hello

I’m back whit a new problem, worse i think.

My crossover has been working fine for a I think ½ a yeah. But just 5 minutes ago while playing music. A LOUD, VERY LOUD horrible sound, I don’t believe my speakers can get any louder than that. Very nasty sound I believe it was between 60-3000Hz. it was only in the one channel, I ran over and turned it off. When I turned I back on it was gone. What can cause this? A bad solder join? Or a bad cap? Glad the speaker id not blow.

Hope someone can help

Jan Dupont · 2nd October 2005, 04:59 AM

Sounds to me like a bad solder joint.......
Maybe a Gnd connection?

5th August 2005, 08:55 AM	#1
Calebay diyAudio Member Join Date: Jul 2003 Location: Denmark	24 dB/Octave 2/3-Way Linkwitz DC on output after power cut Hello i build this 24 dB/Octave 2/3-Way Linkwitz from http://sound.westhost.com/project09.htm i made it 3 way and i have changed all opamp for OPA627 it seems to be working just fine. but then today i acidently pulled the AC plug, from the filter while the amp was still on. 1 sec. later! a Bad sound! and smoke! from my new Neo3PDR so i disconecntet the amp and mesured no DC on output when power on. but when i turn it off for 1-2 sec. 1-1.5volt DC on all output How can i cure this??

5th August 2005, 09:20 AM	#4
Jan Dupont diyAudio Member Join Date: Apr 2003 Location: Copenhagen, Denmark	The DC could be caused by that the pos. and neg. supply fall at different speed __________________ Free Schematic and Service Manual downloads www.audio-circuit.dk, Company: www.dupont-audio.com, Joint venture: www.DupontMantra.com

2nd October 2005, 04:59 AM	#10
Jan Dupont diyAudio Member Join Date: Apr 2003 Location: Copenhagen, Denmark	Sounds to me like a bad solder joint....... Maybe a Gnd connection? __________________ Free Schematic and Service Manual downloads www.audio-circuit.dk, Company: www.dupont-audio.com, Joint venture: www.DupontMantra.com

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5th August 2005, 09:00 AM	#2
sajti diyAudio Member Join Date: Apr 2003 Location: Vác, Hungary	Apply mute circuit on the end, with relay, or muting transistor. Another solution, to use stronger powersupply to keep the circuit up, untill your powermaplifier switch off. And last but not least: Use coupling capacitor on the output of the filter sajti

5th August 2005, 09:15 AM	#3
Calebay diyAudio Member Join Date: Jul 2003 Location: Denmark	hmm but is it normal this DC after i cut the power?

5th August 2005, 09:32 AM	#5
Calebay diyAudio Member Join Date: Jul 2003 Location: Denmark	they drop at the same speed very close on my scope. its fisrt after the supply voltage has dropped below 2volt. then i get the DC on the output

5th August 2005, 11:17 AM	#8
Calebay diyAudio Member Join Date: Jul 2003 Location: Denmark	okay did not know that ill better put some capacitors in there then tnx for the help

1st October 2005, 07:15 PM	#9
Calebay diyAudio Member Join Date: Jul 2003 Location: Denmark	Hello I’m back whit a new problem, worse i think. My crossover has been working fine for a I think ½ a yeah. But just 5 minutes ago while playing music. A LOUD, VERY LOUD horrible sound, I don’t believe my speakers can get any louder than that. Very nasty sound I believe it was between 60-3000Hz. it was only in the one channel, I ran over and turned it off. When I turned I back on it was gone. What can cause this? A bad solder join? Or a bad cap? Glad the speaker id not blow. Hope someone can help

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