Guest Anonymous Posted December 9, 2004 Share Posted December 9, 2004 I have been trying to read up on how to bridge these amps as well as connect everything so i know exactly what i need to buy. I want to bridge both of My NAD 2200's into mono and then use each for 1 ch basically from my understanding there is going to be a switch on the back that i turn to mono and then i connect only 1 analog interconnect from my pre-amp to the amp..... Then I will use both positive outputs on the back of the amp to the speaker is this right? it doesn't seem right, but that is what i just read, anyways I was wondering then do i need bi-wireable speakerwire or no? furthermore how many sets of analog interconnects will i need to set up just the amp and the pre-amp? Thanks Quote Link to comment Share on other sites More sharing options...
WMcD Posted December 9, 2004 Share Posted December 9, 2004 I don't know about your amps, but if they are not set up for it at the factory, it is not an easy project. Let's talk about the normal set up with two amps. You can use a Y splitter to feed the inputs. Then the two "hot" or "plus" leads at the outputs move their voltage the same. The plus peak of a sine wave at the input causes a plus output at both. Hooking a speaker across the plus outputs would result in nothing. This is because there would be no voltage difference. Hooking them in parallel doesn't help either because either one, in theory, give the same voltage anyway. Sometimes a stereo amp is set up for bridging at the output by the engineers. This means, as above, the speaker is connected or bridged across the plus outputs. But this only works if there is the appropriate circuitry with the switch and the amp is designed for the increase in power demanded. The switch is not connected to the output, but rather the input end. It combines the two inputs at the RCA inputs but then further, internally, inverts the input to one of the amps. A positive input signal results in a negative output on one amp. The result is that, at a peak positive input to the pair, bridged speaker "sees" a positive voltage at one terminal, and a negative at the other. So you have twice the voltage to the speaker. This results in 4 times the power of ONE channel . . . IF the amps can handle the load presented by the speaker. One thing which is going on is not obvious. Lets start with an 8 ohm resistor as simulating the speaker. And then we're going to re-imagine it as two 4 ohm resistors in series. There is junction or node between the two. In a non bridged situation, the speaker is connected between the one channel amp's "plus" and ground. It acts as an 8 ohm resistance. The amp is happy. The midpoint node goes to half the voltage from the hot output. Now, go to the bridged situation and keep the 4 ohm resistors in mind. Now, one end of the series is going positive and the other end is going negative. The node is at zero volts, which is to say "ground", or a virtual ground (meaning it looks like a ground). The result is that in the bridged configuation, either amp output "sees" a 4 ohm load (rather than 8 ohms). This is why I asked you to imagine the node. The node end (center in the series) of either 4 ohm resistor is attached to ground, or at least is at zero volts. Same thing. That can be a challenge to the power supply circuits which have limited current capacity. The effective 4 ohms is sucking out twice the current from each amp. You can do the math three way different ways, all resulting in the same result. One is to say that Power = V x V / R. The bridging gives us 2V of one amp (same R = 8) and the squaring results in 4 P. The other is to realize that either amp channel may be rated at 100 watts into 8 ohms and 200 watts into 4 ohms (again if the power supply can supply the current needed). So the bridging creates both the ganging of the amps and the decrease in load. If P = V x V / R, then letting R go half the original results in a doubling from each amp. The third is somewhat a restatement of the second. Each amp is working. Power = V x I. Now because of the lower R, I is multiplied by 2 in each amp output circuit. Overall, it is fair to say that amps set up for bridging are for just that with big power supplies, and two channel operation is an option, rather than the other way around. Best, Gil Quote Link to comment Share on other sites More sharing options...
tkot Posted December 10, 2004 Share Posted December 10, 2004 set the bridging switch to bridged, set the impedance switch to 8 ohms/ normal the input is the left pre/ in the positive speaker terminal is the left+ the negitive speaker terminal is the right+ you will need two rca's one for each left and right, from the preamp outs to the amp inputs(see above) check out my system profile i love my NAD stuff (almost as much as my KLIPSCH stuff!!!) jay Quote Link to comment Share on other sites More sharing options...
djk Posted December 10, 2004 Share Posted December 10, 2004 A bridged NAD 2200 will clip at about 720W into 8 ohms until the protection kicks in. What do you own that needs that kind of power? Quote Link to comment Share on other sites More sharing options...
tkot Posted December 10, 2004 Share Posted December 10, 2004 ---------------- On 12/10/2004 3:51:29 AM djk wrote: A bridged NAD 2200 will clip at about 720W into 8 ohms until the protection kicks in. What do you own that needs that kind of power? ---------------- haveing way to much power is a good thing!! the amps coast along and you have all the headroom you could ever want. and when and if you decide to crank it up you have less chance of blowing speakers if the amps are not out of power when the speakers are maxed out jay Quote Link to comment Share on other sites More sharing options...
j-malotky Posted December 10, 2004 Share Posted December 10, 2004 George Don't worry... When you pick up the amps, I will show you how to bridge them. It is very easy. I will also show you how to bypass the all the protection circuits and filters to make them sound even better. JM Quote Link to comment Share on other sites More sharing options...
tkot Posted December 10, 2004 Share Posted December 10, 2004 ---------------- On 12/10/2004 7:45:06 PM j-malotky wrote: George I will also show you how to bypass the all the protection circuits and filters to make them sound even better. JM ---------------- j's talking about the nad inputs. they have a "normal" in and a "lab"in the lab input workes great if you dont have a turntable or any vibration effected soarces, because it does bypass the infrasonic and other filters built into the normal inputs jay Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted December 10, 2004 Share Posted December 10, 2004 thanks guys, i havn't decided if i am going to bridge these amps, or if i am going to bi-amp/bi-wire, i have enough analog interconnects and 4 conducter speaker wire now to do whatever i desire.... i am looking forward to get this all set up and done, i have pretty much bought everything except my speakers and i have nothing in my hands... haha what a horrible feeling to have, but i right now i have a line on a pair of paradigm monitor 9's.... there not the klf 30's, but those are next to impossible to find... ohh well, once i get home and get this all set up it will be money i am sure..... Quote Link to comment Share on other sites More sharing options...
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