Is my wiring correct? (Amplifier and Subwoofers)

[Kroze]

I want to bridge my subwoofers and run them in parallel mode and wonder if this is the correct way to do it. If so, does this mean that i'm running the amp at 2ohms instead of 4ohms?

 

[kornphlake]

Assuming your amp is bridgeable your wiring is correct. The nominal impedance with 2 subs in parallel will be 2 ohms, is your amp 2 ohm stable?

 

[jtvang125]

I'm assuming this a car amp. Besides a few high current competition models most will not handle a bridged 2 ohm load. In the case of mono-block subwoofer amps they can usually handle a wider range of resistance, 4-2 ohms and some will even do 1 ohm.

 

[Kroze]

Yes this is for a car.

The subs are MTX jackhammer single voice coil rated @ 100-200watts rms

Amp is MTX 405 5 channels amp.
http://store.mtx.com/caraudio/archive/thunder405.cfm

Birth sheet said it put out over 400rms @ 2ohms on the subwoofer channel.

For some reason the sub is not hitting as hard even though the new amp (mtx 405) is putting more power out than the old amp i used.

Is this a symptom of poor grounding (I used a different grounding point when i install this new amp) ? If my new amp is putting out more power, shouldn't the subs hit harder? Yes I've adjusted the gain, equalizer, and freq but to no avail.

 

[SithSolo1]

http://www.the12volt.com/caraudio/woofer_configurations.asp?Q=2&I=41#results

You can change the speaker amount and number of coils/ohms in the Subwoofer Wizard section on the right near the top.

Also I find it odd that the page lists the RMS output bridged to 2 ohms at 200w, Dynamic 300w yet the birth sheet is saying its RMS is 100w higher than the peak Dynamic. Not saying its wrong, just odd.


Other things that come to mind:

Assuming the box and woofers are the same, doubling the power only gets you ~3 more Db.
Could also be your battery is not supplying the amp enough juice.

 

[Kroze]

About the amp putting more power than advertised, MTX historically underrate their amplifiers for competition purposes (back in the days when bean counters and marketing doesn't dictate how the company should run)

You can count on any older style MTX amp to put out nearly double the amount of power it listed/advertised. The birth sheet accompanying it always verify this along with numerous people at audio competitions.

I don't know why it doesn't sound any louder or cleaner with the added juice. Maybe the amp is defective? I'm going to try and switch it out with a different amp to see if the results are any different....

But could it also be poor grounding?

 

[Howard]

Adjust the input gain.

 

[herm0016]

for bridging many amps the extra positive and negative poles are wired together or there is some sort of dip switch or similar. maybe check your wiring for that amp?

try adjusting the crossover too.

 

[kornphlake]

Grounding could be a problem, ground wires are typically short so the gage of the wire is most often overkill for the application assuming you grounded to the frame, what size is your ground wire? The power wire might be undersized which could be audible, what is the length and gauge of the power wire?

A multi channel amp may not have large enough caps to sustain maximum output across all channels simultaneously. A monoblock amp would be the best solution for a high decibel system.

Just to be certain you only changed the amp right, not the drivers? Different drivers have different sensitivities.

 

[Kroze]

Thanks for the help guys, found out my old amp was putting out more power than the new one. No wonder why it didn't sound any louder.

And just to update, I removed the 5 channels amp and replaced it with 2 separate amps. a 4 channel amp to power the speakers and a 2 channel amp to power the subs.

Just to give you guys an idea, this is my MTX 304 amp's birth sheet. As you can see, the actual output is way above the advertised spec. On top of that, it's only at 12.5 volts. All cars today are running on 14 volts so you can bet that the power output this amp push out is nearly 100rms per channel. This is a lot higher than the "rated" 37.5 rms/channel.