junkyarddog

I know it seems like a novice question,I really appreaciate you takng the time to answer.

the amp is a 65w X 2 "power logic" *Coustic model. the speaker leads are aranged as follows : R+,R-,L-,L+ there are no instructions or indications to show the correct way to bridge this amp. I would like to use the amp to power two subs in parallel @ 4 ohms. it even says 65w X 2/150w mono (bridged) on the cover,so someone meant for this amp to be bridged. it's got to be one from each channel like it normally is,but I don't want to take any chances. thanks!





I did just as suggested,all I did was dsconnect both speakers and test a pair,didn't work,so I tried the R+ and the L-....worked!! at which point I twisted the +'s and -'s of each speaker wire together and bidged them happily ever after,assuming the amp is at 2 ohms mono,the speakers are also bridged at 2 ohms. with 150 watts. the sens. and gain are turned all the way down and it sounds fine. it is an AMP-360 model without it's own crossover,thankfully the HU, Alpine 7861 has it's own adj. crossover and sub level for the RCA's...perfect!

I also ran a 220 uF cap inline with the rear speakers, really helped keep the low bass away and cleared them up alot, I'll probably do the fronts soon to.

coalyard

JYD,

Hook the amp up to a signal source, play some music with the head unit set at about half volume. Using a multimeter set to AC volts (musical sine waves are AC, not DC), simply test the speaker outputs until you find the right pair for bridged operation. That should do it.

junkyarddog

thanks coalyard,I'm in NH as we speak. I knew I should've brought my multimeter! could it seriously harm the amp if I hook it up to the wrong two leads?

JamesC

iTrader: (5)

I know relatively little about automotive stereo; however, in a home version, it's my experience that an amp designed for bridging will have a simple switch to toggle between stereo and mono. You might check under the hood, so to speak.

JamesC

caleb

if there is a switch for bridging, it will be on the sides or on the bottom they never put it inside. As for hurting it by bridging wrong, i dont think its possible, all you will do is get the same as if it were running one channel unless you get the right ones, and then you would get the extra power!

JamesC

iTrader: (5)

Humm, as I mention, I'm new to car stereo, so please bare with me. In home applicatons, for bridging to occur, the amp must be specifically designed for it (bridging combines the two stereo channels (transfomers) internally, via a switch, into a single mono channel, usually the right one, for significantly more power). To bridge a home amp as suggested would be impossible.

JamesC

coalyard

JYD,

No it shouldn't hurt things, just make sure to have your source unit turned all the way down, and then go up slow. No sound, wrong combo. Most amps are heavily protected at the output taps anyway. It is always one channel positive, the other negative, BTW. Good luck, and enjoy beautiful NH:-)

redraif

Typically you run the + of one channel and the - of the other. I have a Coustic Power logic amp bridged running my 8in Boston. Thats how I did it. Mine never stated that it was designed for bridging, but it worked. It was made in 1992.

With other amps they will go into safe mode and not power up if you hook something up wrong. I would think it would be the same in this case.

JamesC

iTrader: (5)

Unless I'm way off base, and not to beat a dead horse here, bridging means linking two transformers for more power through one set of outputs, for example 65X2 in stereo going to 150X1 in mono. A postive from one channel and a negative from the other, I believe, still gives you 65X2 because the two transformers have not been linked internally (you might get sound, but not bridged power). I'm very curious, so should anyone have a manual, I'd certainly appreciate some specific information.

I just did a search, and indeed, if the amp is designed for bridging (and apparently sometimes when it's not), using the postitive/negative will work.

JamesC

junkyarddog

these guys are right,the amp will automatically switch to a single channle 2 ohm operation when the load (seaker coil) is placed across the + fom one side and the - of the other. the other two are left disconected. most car audio amps work this way,I've never seen any with a switch.