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An alternative.. What about the neater brother of EP2500, the EUROPOWER EPX2000 from the upper class, it is class H ciruit with switching mode power supply quite promissing in delivering the fast burst of low frequency power. Is lighter too. I do not actually know but it looks 1 to 1 like the quality QSC amps but is cheaper.
Just checked the prices for EP2500 and EPX2000-they are the same 519.99$ from behringer online shop
 

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Elite Shackster
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I tend to lean to the side of Steve on the amp selection, based on what Ive read when researching on an amp for myself.

For one, PA amps are designed for long term high power use, so what we're throwing at them for the most part will be peanuts in comparison. Headroom is always a big bonus. Most of the features of a subs plate amp are bypassed. Usually phase is left one way or the other, and even if its not, the amps Audyssey can make up for that. We still have the option of gain on the amp, a phase swap is easy with a polarity swap, and powering a second sub should one wish to have a second really tips the VFM towards the PA amps. Even PEQ isnt of major concern with Audyssey, and I get consistently good results with Audyssey.
 

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Discussion Starter #44
Uh, why yes it is. :)
I didn't really doubt it, just wanted others to comment on it.

If 30W would do, why would anyone ever need 500W, let alone 1300W!? :yikes: Surely the additional power is never tapped into, and therefore is a complete waste.
 

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Elite Shackster
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IIRC, that is based on a measurement only 1 meter from the driver. There are other factors at play once the driver is in an enclosure, then the enclosure put inside a room. The sub design itself makes a difference too. Also if you add in a LTC in your amp then depending on how you design it, 100watts can blow the driver to bits.

1000 watts of power handling ability doesnt necessarily mean you need to put 1000watts into that driver. Its really a measure of what the driver can handle depending on your design, its not a must that you have to pump all that in. With DIY subs though, to make the builds easier and more predictable, we're keeping the design more simple. Large highly capable driver, in a sealed box, with plenty of power. Its the cheapest way for us to build, and get results beyond what we pay for.

I've spent around £800-£900 on my build (projected spend on completion) and some of the comments Ive had are that something similar from a commercial company would cost anywhere from 3k-5k. One person gave me a figure that whatever you buy generally actually costs 25% of that to produce.
 

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Moonfly said:
a phase swap is easy with a polarity swap
Yes, for 180 degrees, but you can also get much finer control than that. The subwoofer distance setting in your receiver or pre/pro adjusts the delay to the sub, so it can be used as a fine phase adjustment.

tyler durden said:
If 30W would do, why would anyone ever need 500W, let alone 1300W!? Surely the additional power is never tapped into, and therefore is a complete waste.
A doubling of clean power results in a 3db increase assuming the driver has more excursion to give. Dynamic bass peaks in both movies and music (mostly movies) can be very large, so while you may be ok floating along with 16 watts or less most of the time, when a dynamic scene comes along, and the power starts climbing into the hundreds of watts territory, you can't get another 3db unless the power doubles. Demands can easily go from 16 watts to 800 watts to 2000 watts and back down to 5 watts within a matter of seconds. It's best to have that capability on hand if possible, or else you squash your dynamic capability.


Is this statement really the case!?

Uh, why yes it is.
Actually the LFE channel requires 115db capability for reference playback - when you then add in the <80hz redirected bass from up to 7 channels, you really need a subwoofer system capable of ~118db over your intended range. A single sealed 15" definitely won't get you there, but I doubt you listen at reference. That capability is what you would ideally shoot for though.
 

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Elite Shackster
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Yes, for 180 degrees, but you can also get much finer control than that. The subwoofer distance setting in your receiver or pre/pro adjusts the delay to the sub, so it can be used as a fine phase adjustment.
Like I say, with the ability to implement Audyssey as well, the lack of variable phase really isnt a big issue for the DIY'er.
 

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Discussion Starter #49
Also, in my searches I always come across lots of car audio amps that have very high power ratings, is there a reason these are not used in home applications?
 

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Elite Shackster
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So, how much power can I use with that driver, in the planned enclosure?
I have modelled it already to handle 1000 watts, and give a QTC of .675. It exceeds xmax (but not xmech) by 1mm at 10hz when using maximum power.

If you want, I can reduce box size by ten litres, raise the QTC to .707 and the driver just touches xmax at full power at 10hz. Ive modelled it base on the sound of my sub which gives excellent mid bass sound quality and a good balance of depth. I know you have a good in room response as well which will play into your hands and give very good in room response below 20 hz (the Monoliths tuning point) and probably decent performance down to 10hz.

Also, in my searches I always come across lots of car audio amps that have very high power ratings, is there a reason these are not used in home applications?
Yes, they run of 12v car power.
 

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Discussion Starter #51
I have modelled it already to handle 1000 watts, and give a QTC of .675. It exceeds xmax (but not xmech) by 1mm at 10hz when using maximum power.

If you want, I can reduce box size by ten litres, raise the QTC to .707 and the driver just touches xmax at full power at 10hz. Ive modelled it base on the sound of my sub which gives excellent mid bass sound quality and a good balance of depth. I know you have a good in room response as well which will play into your hands and give very good in room response below 20 hz (the Monoliths tuning point) and probably decent performance down to 10hz.
That's gone right over my head I'm afraid. (I have no idea what xmech or xmax are) although I do understand about a smaller box, and that is something I am interested in if it wont noticeably effect the range.

Yes, they run of 12v car power.
12v could be supplied through a computer power supply if it was worth it.
 

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Elite Shackster
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That's gone right over my head I'm afraid. (I have no idea what xmech or xmax are) although I do understand about a smaller box, and that is something I am interested in if it wont noticeably effect the range.
Xmax is the limit of driver movement before serious distortion starts to occur. Xmech is the physical limit of driver excursion before it will bottom out. You need to consider both when modelling a sub. Basically Ive modelled it so the driver can use its max power without over driving, and I have one sat in my room that proves it, and is running now. It does this all naturally without the need for filters etc. I can reduce the box size a little, but theres a good chance it will affect the low end sound of the sub and give a feeling its just lacking depth a little bit.

12v could be supplied through a computer power supply if it was worth it.
I couldnt comment on that, Ive never considered it.
 

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Discussion Starter #54
Okay, so does the amp need to be able to produce 1000w to use the driver to its full capacity in the planned enclosure?
 

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Elite Shackster
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I wouldn't worry about just slightly exceeding xmax in a simulation. That's assuming a continuous sine wave, not actual material, and as you mentioned, xmax as opposed to xmech. Should be fine.
Ive tested mine with material from the likes of Cloverfield on BR at reference level, and it doesnt bottom out :T
 

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Elite Shackster
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Okay, so does the amp need to be able to produce 1000w to use the driver to its full capacity in the planned enclosure?
Without additional filters/eq, and cost, yes it does really. Half the power will give a 3db drop in capability. Also consider what I told you about adding a second sub one day if you want to. Should you fall for the charms of heavenly bass, the O-audio amp would probably stop you doing it based on cost.

A Behringer amp would give you the room for expansion.
 

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Discussion Starter #57
Just listening to the Monolith which has a 300W amp and 12" driver, I doubt whether I would ever need anything to go louder.

I am leaning towards the plate amp for cosmetic reasons, what kind of dB output would I be looking at for one of the 500w plate amps that are on offer?
 

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Elite Shackster
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Remember what they told you about amp power vs output. For every extra 3db of output you need to double the power. So halving the power will give you a 3db drop on maximum available spl. Around 108db max in room @ 20hz.

On the Monolith, almost all manufacturer plate amps use some form of built in eq to shape the response of the sub/amp and alter what it does. We cant do that without adding in other devices. The cheapest being the BFD at around £50 second hand. Using REW though it basically gives you an auto EQ solution for under £100, which is less than half the price of the cheapest one on the market currently.
 

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Elite Shackster
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Yep, thats pretty much it, and 102db is what the Monolith is rated at. You actually can get upto 6db more than that with room gain, but how much you get isnt known until you get your sub going in there.

Of course, I cant build the sub without the plate amp. I could build one and run it off my amp for you to listen too, but your wont quite perform the same as it wont be as loud. Then modify the cabinet once your plate amp arrives.
 
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