Is this safe for OPA2134?

Thunau · 12th February 2004, 08:25 PM

I built a 3 way crossover using ESP boards. I'm using OPA2134s. They have a rather nasty way of powering down, by dumping a sizeable near DC swing on the outputs. I was going to install a normally closed relay across the signal and ground on the outputs and power it from the 5V output of my switching PS. When I power up it will open the contacts and let the signal flow to the amp. When I power down it will close and the DC swing will dump to ground. Is it safe for the output buffer opams? There are 110 Ohm resistors on the outputs used to prevent oscilation.

PMA · 12th February 2004, 08:51 PM

Output short-circuit is unlimited in duration, but this is an overcurrent, not short circuit. Probably nothing wrong will happen, but ...
I would prefer NO contact with delayed ON function (NE555 timer e.g.).

5th element · 12th February 2004, 09:18 PM

?? Just powerdown your poweramps before you turn off the active. And visa versa, power up the active xover before the power amps. This is all I do and I avoid and nasties.

Thunau · 13th February 2004, 02:27 AM

That's what I have been doing all along, but it takes about 40 seconds for the caps in the amp to discharge when there is no music playing. I just wanted to make a more elegant solution than standing there waiting for the amp to power down before flipping the power switch on the crossover.

tool49 · 13th February 2004, 03:51 AM

This might sound silly, but why not just always leave the crossover on? These thing should have a quiescent current of a few mA at a few volts... not likely to get your electricity bill any higher....

Or perhaps use a relay on the amps to shut them off as soon as you remove power from them.

Sébastien

mskeete · 13th February 2004, 08:43 AM

Use a relay as you first suggested but changed the output resistors to 680 ohms

Vix · 13th February 2004, 08:53 AM

I had the same problem. I solved it in a "silly way". I leave the crossover powered on all the time, except when I leave home for longer periods. Since the transformer is small, I don't think it will make a difference on your electricity bill:-)
Regards
Vix

12th February 2004, 08:25 PM	#1
Thunau diyAudio Member Join Date: Mar 2001 Location: PA USA	Is this safe for OPA2134? I built a 3 way crossover using ESP boards. I'm using OPA2134s. They have a rather nasty way of powering down, by dumping a sizeable near DC swing on the outputs. I was going to install a normally closed relay across the signal and ground on the outputs and power it from the 5V output of my switching PS. When I power up it will open the contacts and let the signal flow to the amp. When I power down it will close and the DC swing will dump to ground. Is it safe for the output buffer opams? There are 110 Ohm resistors on the outputs used to prevent oscilation. __________________ "Most people just say what they know, the wise ones know just what to say."

12th February 2004, 09:18 PM	#3
5th element diyAudio Member Join Date: Oct 2002 Location: England	?? Just powerdown your poweramps before you turn off the active. And visa versa, power up the active xover before the power amps. This is all I do and I avoid and nasties. __________________ What the hell are you screamin' for? Every five minutes there's a bomb or somethin'! I'm leavin! bzzzz! Droggon Attack!

13th February 2004, 02:27 AM	#4
Thunau diyAudio Member Join Date: Mar 2001 Location: PA USA	That's what I have been doing all along, but it takes about 40 seconds for the caps in the amp to discharge when there is no music playing. I just wanted to make a more elegant solution than standing there waiting for the amp to power down before flipping the power switch on the crossover. __________________ "Most people just say what they know, the wise ones know just what to say."

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12th February 2004, 08:51 PM	#2
PMA diyAudio Member Join Date: Apr 2002 Location: Prague, Kitakyushu, Fukuoka	Output short-circuit is unlimited in duration, but this is an overcurrent, not short circuit. Probably nothing wrong will happen, but ... I would prefer NO contact with delayed ON function (NE555 timer e.g.).

13th February 2004, 03:51 AM	#5
tool49 diyAudio Member Join Date: Apr 2003 Location: Montreal	This might sound silly, but why not just always leave the crossover on? These thing should have a quiescent current of a few mA at a few volts... not likely to get your electricity bill any higher.... Or perhaps use a relay on the amps to shut them off as soon as you remove power from them. Sébastien

13th February 2004, 08:43 AM	#6
mskeete diyAudio Member Join Date: Oct 2003 Location: London	Use a relay as you first suggested but changed the output resistors to 680 ohms

13th February 2004, 08:53 AM	#7
Vix diyAudio Member Join Date: Nov 2003 Location: Somewhere on Planet Earth	I had the same problem. I solved it in a "silly way". I leave the crossover powered on all the time, except when I leave home for longer periods. Since the transformer is small, I don't think it will make a difference on your electricity bill:-) Regards Vix

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