why o why doesn't this work ? Balanced 549

SpaBlauw · 25th January 2004, 08:21 PM

I tried this idea to drive the balanced output of my Roland E660 in a gainclone. Used chips are OPA549. No bad smell, no DC on the output but also no sound

They are powered with 2 12v batteries wich gives a -12 and +12 rail. Also there's a 0,1 µF cap over the 2 rails.

Even when i connect just one on a unbalanced output still nothing.

The only thing i hear is a slight *pop* in the speakers when I power the 549's.

Matttcattt · 25th January 2004, 11:44 PM

i asume you mean the OPA549? what have you connected the current limiting and Vref pins to? there will be no output unless the are both set. the easiest way to do this is to connect them both to ground. this will set the current limit to maximum (10A).

have fun.

SpaBlauw · 26th January 2004, 02:15 PM

both are connected to the ground, wich in this case is the plus and minus from each batterie. -12 gnd +12

runebivrin · 26th January 2004, 02:30 PM

Is the ground of output from the Roland connected to anything? Quite often balanced outputs are created without a transformer, and since your input is transformerless, you really need to connect the grounds together.

Rune

SpaBlauw · 26th January 2004, 02:44 PM

yup, those are connected to the ground as well.

mmm, i was fiddeling a bit. Now i got his very hard sounding clipping music true the speakers. Well not music, more static/hum on the beat of the song.

carlosfm · 26th January 2004, 03:29 PM

Excuse me, maby I need a cold beer, but is that a balanced GC?
Two IGCs?

Matttcattt · 26th January 2004, 04:23 PM

Quote:

Originally posted by SpaBlauw
both are connected to the ground, wich in this case is the plus and minus from each batterie. -12 gnd +12

yes.

sorry to hear about the hum. i cant really help more, as i dont know anything about balanced inputs/outputs.

SpaBlauw · 26th January 2004, 04:52 PM

I just red the datasheet over again, in wich stated that ref. pin must be als low as the negative voltage if V- is used. So in my case -12. Sadly enough I don't have anymore samples avaible so this project has to wait.

@carlosfm, actually this is a bridgeclone. But you can call it a balanced amplifier since you use the - in / + in to drive it.

Mad_K · 26th January 2004, 05:08 PM

What have you done with the E/S pin? (It shouldn't be connected to anything when REF and ILIM is at GND)

As long as you have a psu voltage above +/- 4V, you can connect REF and ILIM to GND.

SpaBlauw · 26th January 2004, 05:18 PM

E/S pin is cut off

25th January 2004, 08:21 PM	#1
SpaBlauw diyAudio Member Join Date: Apr 2003 Location: Genk / Belgium	why o why doesn't this work ? Balanced 549 I tried this idea to drive the balanced output of my Roland E660 in a gainclone. Used chips are OPA549. No bad smell, no DC on the output but also no sound They are powered with 2 12v batteries wich gives a -12 and +12 rail. Also there's a 0,1 µF cap over the 2 rails. Even when i connect just one on a unbalanced output still nothing. The only thing i hear is a slight pop in the speakers when I power the 549's.

25th January 2004, 11:44 PM	#2
Matttcattt diyAudio Member Join Date: Feb 2003 Location: Bristol	i asume you mean the OPA549? what have you connected the current limiting and Vref pins to? there will be no output unless the are both set. the easiest way to do this is to connect them both to ground. this will set the current limit to maximum (10A). have fun. __________________ If it aint broke, don't fix it. If it is broke, fix it. If you can't fix it, take it apart and see how it "worked".

26th January 2004, 02:30 PM	#4
runebivrin diyAudio Member Join Date: Jul 2003 Location: Huddinge, Sweden	Is the ground of output from the Roland connected to anything? Quite often balanced outputs are created without a transformer, and since your input is transformerless, you really need to connect the grounds together. Rune __________________ Do wizards use spell checkers?

26th January 2004, 05:08 PM	#9
Mad_K diyAudio Member Join Date: Sep 2002 Location: Norway	What have you done with the E/S pin? (It shouldn't be connected to anything when REF and ILIM is at GND) As long as you have a psu voltage above +/- 4V, you can connect REF and ILIM to GND. __________________ Mads K

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26th January 2004, 02:15 PM	#3
SpaBlauw diyAudio Member Join Date: Apr 2003 Location: Genk / Belgium	both are connected to the ground, wich in this case is the plus and minus from each batterie. -12 gnd +12

26th January 2004, 02:44 PM	#5
SpaBlauw diyAudio Member Join Date: Apr 2003 Location: Genk / Belgium	yup, those are connected to the ground as well. mmm, i was fiddeling a bit. Now i got his very hard sounding clipping music true the speakers. Well not music, more static/hum on the beat of the song.

26th January 2004, 03:29 PM	#6
carlosfm Banned Join Date: Mar 2003 Location: Lisbon, Portugal	Excuse me, maby I need a cold beer, but is that a balanced GC? Two IGCs?

26th January 2004, 04:52 PM	#8
SpaBlauw diyAudio Member Join Date: Apr 2003 Location: Genk / Belgium	I just red the datasheet over again, in wich stated that ref. pin must be als low as the negative voltage if V- is used. So in my case -12. Sadly enough I don't have anymore samples avaible so this project has to wait. @carlosfm, actually this is a bridgeclone. But you can call it a balanced amplifier since you use the - in / + in to drive it.

26th January 2004, 05:18 PM	#10
SpaBlauw diyAudio Member Join Date: Apr 2003 Location: Genk / Belgium	E/S pin is cut off

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