Please Help: Will This Audio System Work

[kingy_06]

Hey audio people,

just wondering, i am about to buy an Alpine head unit (two to choose from, either one with one pre out OR the other with three) a pair of Type R splits, an amp - either 75x4 or 100x4 (both 4ohm) and the reason for the post; a type s 12' single voice coil sub! Now can i run my splits and sub of the one amp ( say i use the 75x4) can i run 50 watt into each split and the rest into the sub(provided the amp lets me do this) will the songle voice coil sub take this? I dont know what a single voice coil sub is? Any help would be great!

Cheers,

Tyson

Edited November 17, 2006 by kingy_06

[Fixxxer]

Grab the head unit with 3 pairs of RCA outs, this will give you front, rear and a subwoofer RCA's and is a better choice anyways.

Yes, you can run the splits and the sub off one 4 channel amp. You would run the front RCA's fromt he head unit to the 4 x100W amp and run the splits of channels 1 & 2 of the amp. You would run the Subwoofer RCA's fromt he head unit to the amp and connect the sub to channels 3&4 of the amp (in Bridged mode).

You will need an amp that is bridgeable (practically all of them are these days) and will work at a 2-ohm load.

I gather the single voice coil Type S Sub is 4-ohms.

Fixxxer

[kingy_06]

i understand that i need an amp that is bridegable, though will the amp still run at 4 ohm when bridged cause the sub is a single coil 4-ohms!

[wolverine]

alpine HU's are a pain in the arse. (yes i have one)

too complicated on set up, too complicated in every day use.

look at other brands and be happy.

[DRAGTS]

It really depends what you want from your system.

I'm running a current spec Apline 9852i head unit. (only 1 pre out)

But try finding something else with full ipod control for the $$$$.

As far as sub set up, the best thing you can do is make sure your amp is 2ohm stable when bridged, then buy your self a dual 4 ohm, voice coil sub. This allows you to load it to 2 ohms.

I'm only running 1 amp for my whole system, it's a soundstream 4.480. It gives me 60 watts rms for the splits a solid 240 rms to run my 12 inch sub.

f you have any other questions let me know i've been installing this stuff for years.

Cheers

Edited November 17, 2006 by DRAGTS

[Fixxxer]

i understand that i need an amp that is bridegable, though will the amp still run at 4 ohm when bridged cause the sub is a single coil 4-ohms!

The sub will always be 4-ohm, but when you bridge two channels of a amp together, the amp will 'see' a 2 ohm load through both those channels.

So long as the amp is bridgeable, stick with the 4ohm sub as you indicated, it will work great.

Fixxxer

[mtopxsecret6]

The amp will see a 4 ohm load on both channels in bridged mode, as your running a 4 ohm load. it will only see a 2 ohm load if you load the amp with a 2ohm load. ie parrallel two 4 ohm subs or twin coils.

[Fry_33]

I've got s similar type setup to what you're after I think.

I have a Kenwood Deck (MP6029) with 3 pre outs, not the best deck but it'll do, eclipse are being recomended but quite a few people these days.

JL Audio Splits (50wrms) - running off amp channels 1 & 2

Rears (35wrms) - running off the deck, just for fill

Sub - Alpine 12" dual 2ohm voice coil - running off amp bridged to channels 3 & 4, seeing a 4ohm load.

The Amp is an Alpine MRP-F450, 4 x 70wrms @ 4ohm, Bridged 4ohms - 350W x 2

I ended up using a stainless steel bracket for the amp.

There's a pic of it in this thread somewhere.

http://www.skylinesaustralia.com/forums/in...34720&st=20

Use the search and you'll find a few others setups which are similar and give you ideas on what suits you best.

good luck

[Fixxxer]

The amp will see a 4 ohm load on both channels in bridged mode, as your running a 4 ohm load. it will only see a 2 ohm load if you load the amp with a 2ohm load. ie parrallel two 4 ohm subs or twin coils.

Bugger, I just wrote a whole lot of stuff and the computer lost it, so here is the short version.

The above advice is totally incorrect and I'm willing to put money on it (I need money, hehe). It is also why most people get caught out when their amp goes into protection mode or heats up so much it shuts down to protect itself. I have been in the car audio scene for well over 10 years now and have seen it happen many many times and have seen a lot of people ripped off by bad advice.

Just like paralleling coils on a subwoofer, bridgeing an amp will do the same internally. The amp will 'see' half the impedence of the sub. This is referred to as a 4-ohm MONO load (when 2 channels are bridged) or also known as 2-ohm STEREO load (i.e., the amp is 'seeing' a 2ohm load on both channels, even though the subwoofer is 4ohms).

An example, and there are millions of others out there. My Kicker amp puts out 2x90WRMS @ 4ohms and 2x180WRMS @ 2ohms, if I bridge the channels it puts out 360WRMSx1 <--- 4ohm MONO load. As you can see, it makes the combined output of the single channels at 2-ohms, proving it is operating in a '2ohm STEREO mode' even though there is a 4ohm sub attached to it.

Ohh and Fry33, your 2_2ohm sub, when the coils are put in SERIES will indeed make a 4ohm sub, when you bridge the amp channels it will see a 2ohm load. So in essence you are running your front speakers off a single channel each (Ch1 and Ch2), they will show the amp a 40hm load (so they are getting 70Watts each), but Ch3 and Ch4 are operating at 2ohms.

Fixxxer

Edited November 19, 2006 by Fixxxer

[mtopxsecret6]

Ok, i have just finished some testing with my 2ohm internal resistant 2 channel mtx amp. I used a 4ohm speaker and 2ohm speaker for this test.

Test 1. Amp internal resistance = 2ohm. It saw this on both single channels. I then Bridged the channels and i still saw a 2 ohm load. I then tested the ohmage of the 4 ohm speaker and got 4 ohms. I then tested the 2 ohm speaker and got 2 ohms.

Test 2. running 4ohm speaker in both single and bridged mode.

I saw a 4 ohm load on the single channel with 25ampers being provided. Switched speaker to second channel and still saw a 4ohm load with 27ampers being provided.

-Now, 4ohm bridged.

This still saw a 4ohm load across the bridged channels, but, i now had 55ampers.

Test3. I now used the 2ohm speakers for the test.

First i ran the 2ohm speaker in single channel setup. I saw a load of 2ohm with 52ampers being provided. I did this for the second channel and saw still 2ohm and 55ampers being provided.

-Now, i used the 2ohm speaker in bridged mode. I saw a 2ohm load on the amp, and a 120ampers being provided.

Test4. I finished by checking the ohmage of the channels on the amp, 1st 2ohm, 2nd 2ohm. Then checked the ohm of bridged, 2ohm. Then i rechecked the 4 ohm speaker and got 4ohm. then i checked the 2 ohm speker and got 2ohm.

Is an amp providing an output ohmage? I dont understand how by bridging two channels together will drop from 4ohm to 2ohm. Fair enough they have an internal resistance, but it did not effect my results. I was led to believe that an amp wasnt providing an output ohmage, why add an external load that had any ohmage rating if it was? You can run any speaker off an amp, and depending on its internal resistance(ohms) depended on how efficient the amp could run. If you bridge two channels, you are doubling the current (ampers), but not halving the load(ohm's) the amp see's, mono or not.

[Fixxxer]

Hi MtopxSectret6,

Good testing, I have never tried this test proceedure or claim to know exactly how it all works internally in an amp, I only know what works in terms of matching subs to amps in real life practice applications and what I have researched/read in tech magazines.

I think you may be best to test power output as your testing doesn't seem to show what I am explaining. I look at it like I explained before, just like a dual voice coil sub, by paralleling the coils you get half the resistance (load), I look at it as if you are paralleling the resistance of the amps channels, hence half the resistance. This explains that on the vast majority of amps (that are stable at 2ohm), they will approximately double their output when bridged to a 4ohm (subwoofer) load, i.e., 2 x 90 WRMS @ 4ohm amp should make approximately 360 WRMS x 1 when bridged, it is not 2 x 90 = 180 WRMS x 1 @ 4ohm.

Some of the better amps have the facility to go into protection mode if it senses a 'load' that is not able to be run safely on the amp. I am unsure of how this is done internally to be honest.

Fixxxer

[mtopxsecret6]

I have power outputs included in my results. If you test your theory i would suggest that to gain what you are stating, its the actual load which is what is providing the efficency of the amp. Bridging the two channels doesnt halve the ohmage. It has the same ohmage, but double the power because you have two feeds in. iTs like firing hoses of water at the same tree, you have twice the volume, but not half the effort.

[mtopxsecret6]

Either way, it will be asy to set it up how he wants and it will sound great!

[Fixxxer]

Like I said, I don't know exactly how it all works electrically internally in the amp, but what you're saying is that firing the 2 hoses at the tree will give you double the volume of water, say 2 x 90 L.... =180 L but it doesn't explain the quadrupling of the 'volume of water' i.e., power, that most amps will make when run in 'bridged' mode, i.e., those 2 x 90 L hoses will make 360 L x 1. This is undeniable and proven in real life a million times over.

Anyways, I think we have started our own thread..... I would recommend that he stick with what he had planned.

Fixxxer