bridging

[Thom]

I'm playing with a DH 200 as a sub amp. I see that they have a special board for bridging. Is their any reason that I cant just use a couple of op amps to put left and right input signals out of phase befor the amp and then take the signal from the two hot outputs as in normal bridged configuration. Or is there somewhere inside I can swap leads without smoke (I'm thinking probably not on that one). Also how are these these things. When I used to run 120's I always had a
spare. It seamed bullet proof till it felt like sneezing. Also I dug a crown DC300 out of my closet that had been in a piece of oem something and has no level controls and I dont really recognize the boards from what I see on the net. Sound familiar to anybody? Not really asking anybody to leave the couch or anything unless you remember something. I'm real fuzzy on this but when you put a signal on a non inverting input of an op amp, if you don't load it, don't you get an inverted signal at the inverting input. Protoboard time.

Thanks

[Chas]

If your soldering hand is getting twitchy, have a look at some SSM chips. They have some balanced to unbalanced and unbalanced to balanced devices.

[louped garouv]

don't know if it is the same circuit, but the bridging circuit schematic for the DH500 amplifier is posted here...

http://www.audioheritage.org/vbulletin/showpost.php?p=119196&postcount=1

[Thom]

Thanks I saw that, lots of parts. don't see why an op ampwouldn't work fine. Seems there ought to be a couple of wires that could be swapped in the unit to throw one side out of phase but doesn't seem like they would have used that circuit if it was that easy. Thank you though. parts are cheap for some reason perf board isnt.

[Hoerninger]

... lots of parts. don't see why an op ampwouldn't work fine.
Hafler is presenting a discret opamp design with a complete symmetrical differential input configuration. This gives sonical advantages.

The amplification is simply -1. Nothing may be omitted.
___________
Peter

[Chas]

Thanks I saw that, lots of parts. don't see why an op ampwouldn't work fine. Seems there ought to be a couple of wires that could be swapped in the unit to throw one side out of phase but doesn't seem like they would have used that circuit if it was that easy. Thank you though. parts are cheap for some reason perf board isnt.


For low frequency use, an opamp in an inverting mode should be fine. Watch out for DC offset, you should AC couple the output to isolate it from the amp input.

Opamps also have pretty wicked turn on/off thumps too, make sure it powers up first before you flip the power amp on. Or make sure the power amp is off before shutting down your circuit.