How can I make an orion 2150 gx bridgeable?

[spooney]

I just bought an orion 280gx off from a guy on craigslist. He kept telling me it was bridgeable and I just kinda nodded my head and agreed even though I knew they weren't bridgeable without the module......or so I thought. I got the amp home and started checking it out and it is indeed bridgeable. Somebody went inside of this thing and piggy backed an opamp on top of another one and added a few resistors and a cap. Here are some pics of the work(sorry they are not the best quality) :







I've seen the bridging plug that Perry designed for these amplifiers and it would do what I'm looking for but it would be nice if I could make my 2150 gx work like this 280. Is it even possible? Here is a pic of the input section of my 2150gx :



I imagine if I could trace the circuit good enough and see how they did it that it would work but I may be totally missing something. It would definitely be harder to accomplish inside the amp that in the plug though.Does anyone have any input on this?

[1moreamp]

You have gmail...

Please see U3 on the details, I think a simple + - reverse on any second stage op-amp will grant your bridging request...Lets talk soon if you have any questions...C

[spooney]

in the pic above of my 2150 gx which ones are the second stage op amps? the ones closest to the rca/din inputs or the ones closer to the mpsu07/57's

[0ldSch00lf00l]

Perry has something on his site too: Operational Amplifiers

Here is the circuit he has on his site: http://www.bcae1.com/images/swfs/bridgingmodule.swf

ETA: Oops, reading > me.

[I Am An Idiot]

The power supply section of the above diagram can be eliminated. The amp has + and - 15 volts in the din plug. Perry also has a diagram for a module that will fit inside a 5 pin male din plug. It consists of an op amp and 2 caps and a resistor or 2.

[djQUAN]

I've done that before.





I converted that amp that used a single RCA input with a bridge/stereo switch to a 3 way bridge capable amp.

I simply made an op amp inverter circuit and inserted it somewhere in the input stage right after the RCA. piggy-backing the op amp onto an existing opamp serves as a mounting and gets the supply from the existing op amp rails.

[1moreamp]

Originally Posted by spooney

in the pic above of my 2150 gx which ones are the second stage op amps? the ones closest to the rca/din inputs or the ones closer to the mpsu07/57's

The last op-amps near the MPSu's should work nicely. It did on the Orion pic I sent you. Remember that the input op-amp is a buffer and variable gain control in most amps so its not the best choice to reverse the input on, and the last one to the input of each channel is a fixed gain output buffer in most cases so it presents the most stable place to do signal phase inversions with out adding piggy backed op-amps. Anything in between is usually crossover filtering or tone controls which need buffering just to keep them stable....

Everybody has a sound solution for this issue you posted about, I just try to KISS by simple phase inversion on the most stable op-amp in the chain just before the main amp input diff pairs should do nicely...In this case the op-amp is the input of the main amp channel so it should be all good, Just swap the non inverting and inverting inputs to the op-amp on the bridging channel only and VIOLA ! she should be done...

Oh also remember to reverse the speaker connections internally on the mod channel also so the internal mod will not confuse or confound others and the output phase will be matching for stereo operation...Then you will be just like the factory did on all these older amps....hope this helps...C

[djQUAN]

Originally Posted by 1moreamp

The last op-amps near the MPSu's should work nicely. It did on the Orion pic I sent you. Remember that the input op-amp is a buffer and variable gain control in most amps so its not the best choice to reverse the input on, and the last one to the input of each channel is a fixed gain output buffer in most cases so it presents the most stable place to do signal phase inversions with out adding piggy backed op-amps. Anything in between is usually crossover filtering or tone controls which need buffering just to keep them stable....

Everybody has a sound solution for this issue you posted about, I just try to KISS by simple phase inversion on the most stable op-amp in the chain just before the main amp input diff pairs should do nicely...In this case the op-amp is the input of the main amp channel so it should be all good, Just swap the non inverting and inverting inputs to the op-amp on the bridging channel only and VIOLA ! she should be done...

Oh also remember to reverse the speaker connections internally on the mod channel also so the internal mod will not confuse or confound others and the output phase will be matching for stereo operation...Then you will be just like the factory did on all these older amps....hope this helps...C

sorry, but it might not work. because if you reverse the input pins to the op amps, you will connect the feedback resistor to the non inverting input of the op amp.

if you reverse the inputs of the entire op amp circuit instead (before the input resistors), gain calculation is different for buffers and inverters so a resistor change is necessary.

[Perry Babin]

Since I don't have a 280GX, I can't try this but if it works, it's a simple modification. This is using part of a schematic from a 225G2 amp.

http://www.bcae1.com/temp/orion280gx...bridging01.swf

[I Am An Idiot]

Circut for Bridging Orion GX amps?