TXA-3004

75 x 4 @ 4 Ohm

150 x 4 @ 2 Ohm

300 x 2 @ 4 Ohm

Mpyre 65

150w rms @ 4 ohm

Seas neo

90w @ 4ohm

1 - 20 of 26 Posts

TXA-3004

75 x 4 @ 4 Ohm

150 x 4 @ 2 Ohm

300 x 2 @ 4 Ohm

Mpyre 65

150w rms @ 4 ohm

Seas neo

90w @ 4ohm

Joined

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5,752 Posts

You can't. If you are using one pair of speakers and they are 4 ohms, then you get 4 ohms. You can't wire them for 2 ohms unless you use both mids, but then you can't use that passive crossover since the crossover frequency changes drastically when you reduce the impedance by half by wiring the speakers in parallel, or if wired in series for 8 ohms.

TXA-3004

75 x 4 @ 4 Ohm

150 x 4 @ 2 Ohm

300 x 2 @ 4 Ohm

Mpyre 65

150w rms @ 4 ohm

Seas neo

90w @ 4ohm

I'd just use one set of mids.

Joined

·
2,544 Posts

You cannot do what you are asking. If you want 150w for your drivers, you need to buy a 150w x 4 amp. If you had a component set that was 2 ohm, then yes, you would have 150w and it would be noticeably louder, but 2 ohm components are very rare.

Joined

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5,752 Posts

if i run the speaker active i dont need it right?

Correct, you wouldn't need the passive crossover. Keep in mind though, if you plan on using both mids just to get the impedance down to two ohms, you are going about this the wrong way. I still recommend using just one set unless you have some plan for both sets, that's not just to load the amp down to two ohms.

Joined

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2,544 Posts

What is your goal? Do you just want this to be loud? If that's all you're after, go ahead and bridge two Mpyres to each channel (you will still need a processor to do this), but you realize that the amp's power is now split between two instead of one. The benefit is that you have twice the area, but each woofer is not getting twice the power.

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5,752 Posts

If the amps crossover goes high enough, you can go that route. Actually nothing would be bridged. You have 4 speakers and 4 channels.thanks for the quick reply so best way only one pair i can run them active with the amp crossover? one pair bridged to channel 1,2 and tweeters to 3, 4 ?

I just did some quick checking and it looks like the crossover only goes up to 250hz so you can't use the amps crossover.

You might try bridging the amp for two channels and using the passive crossover. If not that, you'll need a deck with a better crossover, or a separate electronic crossover.

Joined

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729 Posts

Each woofer is getting the same power, but the power is still doubled. Twice the surface area, twice the power is theoretically 6db increase. They will most definately get loud.

What is your goal? Do you just want this to be loud? If that's all you're after, go ahead and bridge two Mpyres to each channel (you will still need a processor to do this), but you realize that the amp's power is now split between two instead of one. The benefit is that you have twice the area, but each woofer is not getting twice the power.

I also agree with those that said you need an active crossover / signal processor. I think they are 100% right and you should ditch the passive crossover, it does you no good whatsoever in this situation.

Joined

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2,544 Posts

I didn't think it was anywhere nearEach woofer is getting the same power, but the power is still doubled. Twice the surface area, twice the power is theoretically 6db increase.

Joined

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729 Posts

I said theoretically, not real worldI didn't think it was anywhere neardoublethe sound just because you doubled the surface area. It will most definitely be louder, but I don't think it's a full 6dB. Can anyone confirm it? In real world scenarios I thought it was a lot less.

Also, I said 6db because 3db for double the power, 3db for double the surface area.

If he runs 75wrms on one speaker, compare it to 150wrms on two speakers - that's double the power

It's just a rule of thumb though it's not 100% accurate.

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5,752 Posts

6db sounds about right, at least on paper.I didn't think it was anywhere neardoublethe sound just because you doubled the surface area. It will most definitely be louder, but I don't think it's a full 6dB. Can anyone confirm it? In real world scenarios I thought it was a lot less.

I mean a speaker getting twice the power

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2,544 Posts

The rather convoluted formulas: http://www.termpro.com/articles/spkrz.html

Joined

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5,752 Posts

Each speaker is still getting 75 watts each, but if he used 2 drivers per side, he now have 150 watts per side, with twice as many drivers. 6 db more.

Let's just say one driver on 75 watts can 105 db.

1 driver @ 75 watts = 105db

2 drivers @ 75 watts = 108db

2 drivers at 150 watts = 111db.

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729 Posts

Huh? The point I am making is that you don't get 150 watts to each Mpyre. You get 150 watts from each channel which is then divided equally by the number of drivers you have (assuming they are equal impedence). The amp makes 150w per channel, but each driver is still only getting 75--you just have two of them. You don't get double the power (to each driver)anddouble the surface area.

The rather convoluted formulas: Series Vs. Parallel Wiring

I think you got confused - his amp doesn't do the same wattage at all impedence. If you half the impedence it puts out double power.

One speaker = 4 ohms, so you get 75wrms / channel

Two speakers = 2 ohms, so you get 150wrms / channel - this is effectively doubling the power

Joined

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2,544 Posts

TheI think you got confused - his amp doesn't do the same wattage at all impedence. If you half the impedence it puts out double power.

One speaker = 4 ohms, so you get 75wrms / channel

Two speakers = 2 ohms, so you get 150wrms / channel - this is effectively doubling the power

Many noobs have the impression that all speakers are going to now get double the power if you halve the impedance which would be crazy. The amp works twice as hard, but each individual speaker is still getting the same power--you just have more speakers now which naturally produces more sound.

Joined

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729 Posts

However, the total amount of power that is being generated is double, which increases output by roughly 3db (as said before, on paper)Theampis making 150w per channel, but it now must power two drivers with that same 150w. Each driver still gets the same power, you just have two of them. That's all I was saying.

Many noobs have the impression that all speakers are going to now get double the power if you halve the impedance which would be crazy. The amp works twice as hard, but the speakers are still getting the same power--you just have more speakers now.

That's in addition to the obvious 3db gain from double surface area.

Joined

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5,752 Posts

Theampis making 150w per channel, but it now must power two drivers with that same 150w instead of one at 4 ohms. Each driver still gets the same power, you just have two of them. That's all I was saying.

Many noobs have the impression that all speakers are going to now get double the power if you halve the impedance which would be crazy. The amp works twice as hard, but the speakers are still getting the same power--you just have more speakers now which naturally produces more sound.

Well I believe the whole debate started when it was stated that the increase in loudness from doubling the amount of speakers and power would be 6 db which it would be but you didn't think it would be.

So I take it we are all at least on the same page now as far that goes.

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