Hi,
I took some pics of my bridge parallel amp and here it is: http://www.geocities.com/jojod818/index.html
JojoD
I took some pics of my bridge parallel amp and here it is: http://www.geocities.com/jojod818/index.html
JojoD
avenger,
Please bear with me on this but here it goes.
When I was building my bridge parallel, I was too lazy to include the dc servo but not that lazy in matching my components. The resistors for example are 5% tolerance! So I have to measure them carefully with a DMM, that is the reason why I bought a lot of them but they are very cheap. Even the 0.1ohms 5 watt resistors are 5% tolerance so I bought a lot. I then pick the ones with the closest values and used them in my non-inverted pcb for the 549 (see my website). I wired it up, and couple it to a DRV134 for the input. Guess what? the whole amp heats up with a load!
I then said to myself, maybe I need the servos after all
, but there was this basic circuit in AN1192 that uses dc blocking caps instead of servos. I desoldered one leg of the 1Kohm resistor (going to ground) and insert a small 22uf electrolytic and my problems were solved! 
No more heat dissipation without load, even with a load without volume.
I still can't believe that a single cap is all I need to clear that output. I tried it in a single 549, without the cap I measure 0.005V dc offset and with the cap I can barely measure a 0.001V. At a 20mV setting I can measure a 0.01mV dc offset which in my book is a very outstanding offset.
I urge you to try it, I never thought a chipamp in such a configuration can handle a lot of power before but now I have proven to myself that sometimes simple things can be good, and in a diyer's hand, can be better.
Best regards,
JojoD
Please bear with me on this but here it goes.
When I was building my bridge parallel, I was too lazy to include the dc servo but not that lazy in matching my components. The resistors for example are 5% tolerance! So I have to measure them carefully with a DMM, that is the reason why I bought a lot of them but they are very cheap. Even the 0.1ohms 5 watt resistors are 5% tolerance so I bought a lot. I then pick the ones with the closest values and used them in my non-inverted pcb for the 549 (see my website). I wired it up, and couple it to a DRV134 for the input. Guess what? the whole amp heats up with a load!
I then said to myself, maybe I need the servos after all
, but there was this basic circuit in AN1192 that uses dc blocking caps instead of servos. I desoldered one leg of the 1Kohm resistor (going to ground) and insert a small 22uf electrolytic and my problems were solved! No more heat dissipation without load, even with a load without volume.I still can't believe that a single cap is all I need to clear that output. I tried it in a single 549, without the cap I measure 0.005V dc offset and with the cap I can barely measure a 0.001V. At a 20mV setting I can measure a 0.01mV dc offset which in my book is a very outstanding offset.
I urge you to try it, I never thought a chipamp in such a configuration can handle a lot of power before but now I have proven to myself that sometimes simple things can be good, and in a diyer's hand, can be better.
Best regards,
JojoD
I use the drv134 for the input. Now, consider the schematic below, it's a non-inverting version from the datasheet. I build 2 pairs of this wherein each pair is in parallel. Now each pair gets their input from one of the drv134's output. Simple isn't it?
The 22uf cap that saved me a lot of headache was inserted between R1 and ground.
HTH,
JojoD
The 22uf cap that saved me a lot of headache was inserted between R1 and ground.
HTH,
JojoD
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JojoD818 said:
Will the LM4780 (60W Stereo IC) work just as well for this circuit? (Excepting the very small pin spacings.)
http://www.diyaudio.com/forums/showthread.php?postid=259365#post259365
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