Amp ByPass How-To (*PICS*) - Page 2 - Nissan Sentra Forum - B15, B16 and B17 Sentra Forums
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post #16 of 29 Old 05-08-2004, 05:27 PM
87SENTRASE
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Oh, sorry, thanks. I cannot remove my deck. Thanks for the info. I just want to replace my speakers but I think nobody makes spacers for the front speakers yet?
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post #17 of 29 Old 05-08-2004, 07:12 PM
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Quote:
Originally posted by 03v-2
I was thinking, tap both the fronts and backs to the front leads
and subs to the rear leads.... (7500mp deck has sub control)
will this be too much load on the HU amp?
That will drop the impedence on the front channels to 2ohm

2ohm on a headunit = death

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post #18 of 29 Old 05-08-2004, 09:14 PM
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Quote:
Originally posted by 87SENTRASE
Oh, sorry, thanks. I cannot remove my deck. Thanks for the info. I just want to replace my speakers but I think nobody makes spacers for the front speakers yet?
1. People here on the forum make spacers for the front speaker. Do a search for "mdf AND spacer" either in the audio section or in the classifieds section.

2. I have no experience in using wirenuts, but I'd never use them unless I was forced to do so. And I'll never be forced to use them on stranded wire. As for a solid core wire.... I'd try to get a pair of 'U' clamps and bolt them together, but I wouldn't put wire nuts completely out of the question for that IF they would be guaranteed to not be moved/vibrated.
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post #19 of 29 Old 05-09-2004, 10:27 PM
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Quote:
Originally posted by 2001 SE #2
That will drop the impedence on the front channels to 2ohm

2ohm on a headunit = death
How about tapping both fronts and rears to the front output (deck) though series as opposed to parallel.
This'll up it to 8ohms, which should be ok right?

I just finished doing this, seems to sound ok!
I've got single 10inch hooked up to one of the rear leads as a sub. (I am assuming it will detect it as a sub and drop it down to 2ohms?)


Tech specs from manual:

Maximum power output ..... 50 W × 4
for subwoofer (70 W × 1 ch/2 Ω )
Load impedance ................. 4 Ω (4 – 8 Ω [2 Ω for 1 ch]
allowable)

Last edited by 03v-2; 05-09-2004 at 10:35 PM.
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post #20 of 29 Old 05-10-2004, 12:04 AM
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Wiring at 8ohm on a headunit would be horrible. Not that it would be bad for the headunit, just that each speaker would get about 3-4 watts before the headunit started clipping.

And the headunit can't detect that something is a sub and "drop it down to 2ohm", it doesn't work like that. The headunit puts out a voltage, the speaker attached to the headunit has a certain resistance, and depending on that resistance, a certain amount of current flows. The speaker decides the resistance, because it IS the resistance, the headunit/amp has no say in the matter.

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post #21 of 29 Old 05-10-2004, 12:56 AM
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Placenta - I have the Rockford Fosgate package and would like my system to sound a lot better but do not want to do a whole system swap due to it being leased. If I just buy a headunit and disconnect the amp, all my stock speakers would sound better even the 8" sub?

Is it a huge project to do all of this, I want to do the simplest thing for a good system upgrade.

Also, if this is all possible I was thinking in getting a good alpine HU, but not sure which one, any recommendations?

Thanks!
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post #22 of 29 Old 05-10-2004, 03:38 AM
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Quote:
Originally posted by 2001 SE #2
Wiring at 8ohm on a headunit would be horrible. Not that it would be bad for the headunit, just that each speaker would get about 3-4 watts before the headunit started clipping.

And the headunit can't detect that something is a sub and "drop it down to 2ohm", it doesn't work like that. The headunit puts out a voltage, the speaker attached to the headunit has a certain resistance, and depending on that resistance, a certain amount of current flows. The speaker decides the resistance, because it IS the resistance, the headunit/amp has no say in the matter.
clipping?

Also I meant that I am setting the rear sp to "sub" (HU has option for this) so that it sends out a 2 ohm load?

I am guessing that is what it means based on the 70 W x 1 ch/2 ohm thing for the sub...

Last edited by 03v-2; 05-10-2004 at 03:40 AM.
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post #23 of 29 Old 05-10-2004, 11:51 AM
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Quote:
Originally posted by 03v-2
clipping?

Also I meant that I am setting the rear sp to "sub" (HU has option for this) so that it sends out a 2 ohm load?

I am guessing that is what it means based on the 70 W x 1 ch/2 ohm thing for the sub...
Clipping is what happens when you pass the limits of an amp, in your case the built in amp in the headunit. A pure tone looks like a nice clean sine wave, as you turn up the volume this sine wave gets larger and larger. You can think of the rising and sinking voltage as a kid jumping on a bed in a room, as the volume/sine wave gets larger and larger, the kid jumps higher and higher. Well, there is a roof above the kid, and he can only jump so high, if he tries to pass that limit he smacks his head on the roof, it's the same thing when you try to turn the volume too high. The wave increases until it hits a wall and then it starts clipping off the top and bottom of the wave, distorting it. This is called clipping, and it's bad for the amp, speakers, and your sound quality.

And again, your headunit can't just say "I'm going to run at 2ohm now". 2ohms is a resistance, the headunit has nothing to do with what resistance is attached to it. The speaker is the resistance, it determines what the resistance is because it's just a property of the speaker. If you attach a 4ohm sub to the headunit then it will run at 4ohm, if you attach a 2ohm sub then it will run at 2ohm, if you attach a 1ohm sub then it will run at 1ohm (until it blows).

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Last edited by 2001 SE #2; 05-10-2004 at 11:54 AM.
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post #24 of 29 Old 05-10-2004, 12:26 PM
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So this bypass was done in order to retain the stock wiring after the addition of an aftermarket HU? The RF amp is supposedly 300W. Will most HU amplifiers be better than the RF amp? And how is the quality of the stock speakers?

Which wires do the sub run off of?

Is there any use for the RF amp after it's bypassed? Could it be bridged to run a sub?

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Last edited by Spec V Boi; 05-10-2004 at 12:28 PM.
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post #25 of 29 Old 05-10-2004, 01:11 PM Thread Starter
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Quote:
As for the OEM amp, I don't really know. But as for the MAX wattage of the OEM speakers, it's something like this:
Front door: 25W x 2 = 50W
Tweeter: 5W x 2 = 10W
Rear deck: 45W x 2 = 90W
Rear sub: 150W

So the 300W advertised by Nissan. But remeber thoses are the MAX values and the like the sub is RMS rated at 35W if I remember right!
This is what Laurent told me... I removed my RF amp since I also removed my stock sub (I am running 2 Fosgate DVC's)...

*edit* The harness that goes to the stock sub is seperate from the wiring of the speakers, I suppose you could leave the power to the amp (2 White w/ Red Line wires, 2 Black wires, and the Pink remote wire) and leave the sub harness plugged in... Not sure how it would sound, but it will work.

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Last edited by AEM Spec V; 05-10-2004 at 01:20 PM.
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post #26 of 29 Old 05-10-2004, 05:31 PM
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Quote:
Originally posted by 2001 SE #2
Clipping is what happens when you pass the limits of an amp, in your case the built in amp in the headunit. A pure tone looks like a nice clean sine wave, as you turn up the volume this sine wave gets larger and larger. You can think of the rising and sinking voltage as a kid jumping on a bed in a room, as the volume/sine wave gets larger and larger, the kid jumps higher and higher. Well, there is a roof above the kid, and he can only jump so high, if he tries to pass that limit he smacks his head on the roof, it's the same thing when you try to turn the volume too high. The wave increases until it hits a wall and then it starts clipping off the top and bottom of the wave, distorting it. This is called clipping, and it's bad for the amp, speakers, and your sound quality.

And again, your headunit can't just say "I'm going to run at 2ohm now". 2ohms is a resistance, the headunit has nothing to do with what resistance is attached to it. The speaker is the resistance, it determines what the resistance is because it's just a property of the speaker. If you attach a 4ohm sub to the headunit then it will run at 4ohm, if you attach a 2ohm sub then it will run at 2ohm, if you attach a 1ohm sub then it will run at 1ohm (until it blows).

I c I c...
Well I don't hear any clipping even at loud volumes so it should be ok.

So if my HU can handle 2 ohms, that means I could run another sub in parallel to the same lead?

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post #27 of 29 Old 05-10-2004, 09:22 PM
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You did it

And great post will detailed pictures!

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post #28 of 29 Old 05-10-2004, 10:43 PM
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Quote:
Originally posted by Spec V Boi
So this bypass was done in order to retain the stock wiring after the addition of an aftermarket HU? The RF amp is supposedly 300W. Will most HU amplifiers be better than the RF amp? And how is the quality of the stock speakers?

Which wires do the sub run off of?

Is there any use for the RF amp after it's bypassed? Could it be bridged to run a sub?
no no, the RF amp isn't 300W, the RF system is 300W. The way Nissan rates the power on their sound systems is rediculous, what they do is take the peak (not rms) power that each speaker can handle, add them all together, and that's their power rating. It has nothing to do with how much power is actually being fed to the speakers.

And yes, most aftermarket heads will be much better than the RF head/amp setup. And the quality of the stock speakers is bad

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post #29 of 29 Old 10-17-2018, 01:23 AM
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Thank you very much for the wiring pin out for the amp. I just picked up an 02 spec v and didn't realize the audio situation in it. Basically the amp is shot. I was thinking about testing each wire, now I shouldn't have to! For some reason the images say they are blocked in original post. Is this because I am such a new user? Thanks I'll post more after project.
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