Amp owners manual is wrong?
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=64469
Printed Date: May 14, 2024 at 7:13 PM
Topic: Amp owners manual is wrong?
Posted By: johnlarkin
Subject: Amp owners manual is wrong?
Date Posted: October 16, 2005 at 7:52 AM
It says to bridge the speakers for using a single subwoofer. I agree. It says to run both RCA cords from head unit to amp. I agree. It says to put the amp in stereo mode. I disagree. I am only using one subwoofer. Here is the diagram in the manual with my personal notes in color. Am I right? I hope you can read this attachment. -------------
Replies:
Posted By: johnlarkin
Date Posted: October 16, 2005 at 7:53 AM
That was awful! Moderator, please remove this pic. 
Posted By: speedwayaudio1
Date Posted: October 16, 2005 at 9:13 AM
Well the best I can tell from that awful pic is they are talking about tri-mode. a left and right full range set up then bridge a mono ch for the sub. the sub would use a inline crossover. Thats just a guess from what I can see.
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Big Dave
Posted By: 04MDX4SQ
Date Posted: October 16, 2005 at 9:21 AM
Well, with the diagram being unintelligable, I would say it is possible the reason they would say to put the amp in stereo mode has to do with the inputs. Some amps when put in mono mode will only use the left or right RCA for signal, while stereo mode will use both. The amp may then turn the left and right signal into a mono signal when it is hooked up in a mono bridged configuration.
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04 MDX - Clarion DRZ9255 / MB Quart QAA4250 / MB Quart QSD216 / Orion Concept 97.2 / JL Audio 10w6v2
91 GMC Syclone - Delco tape deck
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Posted By: johnlarkin
Date Posted: October 16, 2005 at 9:43 AM
That's possible. Thanks for the replies. Sorry about the pic.
Posted By: DYohn
Date Posted: October 16, 2005 at 9:45 AM
What is the make.model of the amplifier? ------------- Support the12volt.com
Posted By: johnlarkin
Date Posted: October 16, 2005 at 10:52 AM
Sony EXM-302: 30 stereo or 90 mono, both 4 ohm settings driving a JL Audio 8W0-4ohm. I have another problem too. In the same configuration (just like the manual, both RCAs plugged in - set to stereo - sub bridged) I put an inductor inline with the positive speaker wire, 5.6mH for roughly 110Hz lowpass filter. Couldn't get much more than a whisper from the sub so I kept cranking up the head unit subwoofer control, ending at max (+15) and it smoked the inductor (literally - it's now black). No damage anywhere else seemingly, amp still on. I have two more inductors - never buy just one. The inductors seem small like something for a circuit board, maybe 1/4" diameter copper wound barrel with a lead out of each end no thicker than a paperclip. I would like to use the amp in mono so I can get more watts to the sub. Just a little new and confused. I am only looking for bass to fill in the sound, not for annoying my neighbors. The other half of the install went great! 4-channel amp up front works fine. Thanks for removing my goofy pic.
Posted By: DYohn
Date Posted: October 16, 2005 at 1:26 PM
OK, yes you seem to have the amp set up correctly. Make sure you have your gain set properly. Assuming your sub is 4-ohms and you want a 110Hz low-pass passive filter, you'll need to use an inductor capable of handling the power output from the amplifier, so it needs to be rated for at least 100 watts. I recomend going for a coil that is over-rated, something like this would work and give you a 1st order LP crossover at about 125Hz. ------------- Support the12volt.com
Posted By: johnlarkin
Date Posted: October 16, 2005 at 1:58 PM
Wow, a 15 oz. inductor? These teenie ones I bought might weigh 1/10 oz. Thanks DYohn, I just figured my problem out. The frikkin subwoofer preout in my head unit (Alpine CDA-9847) handles the subwoofer crossover; I had no idea until I did a little Googling. The manual does not state this specifically but I just hooked it up straight to the sub and it is playing fine. I still would like to know at what frequency it low passes; must have been double-resisting the sub. The amp never got hot so I guess it's extreme duty tested now. Thanks alot; I'm gonna stop fooling with this and enjoy it.
Posted By: DYohn
Date Posted: October 16, 2005 at 2:21 PM
Cool deal. re: passive crossover components. Inductors and capacitors must be rated to handle full system power or they will, as you discovered, fry. Never try to scrimp on crossover parts. in many cases, a good passive crossover will cost as much as or more than the speakers it is connected to. You didn't say what HU you use, but most have variable subwoofer crossover points. Check your owner's manual. ------------- Support the12volt.com
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