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Discussion Starter · #1 ·
-Long time reader here, finally a member!

Wondering on how much power is enough and what would be too much. I have a small HT room about 230sq feet and need to replace my current powered sub with something with a little (read LOT) more punch and rumble. I have a RE XXX 18" sub waiting for a project, however I'm not sure what do for an amp or what amount of wattage I need to fill my small room. The sub can handle 2k watts - but I think that would be a little overkill and over budget. I am experienced in box fabrication and will probably be doing a simple ported enclosure. Any help would be great!

Thanks.
 

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Re: Sub amp wattage

Welcome KB!

If the sub can handle 2 KW after being inserted in the enclosure, so shoot for at least 2KW. Can you do a modeling with WinISD/Unibox?

The EP-2500 is a great candidate!
 

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Re: Sub amp wattage

Which XXX do you have? The old style or the new 2006 and up? It's a big difference between the 2.
 

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Discussion Starter · #4 ·
Re: Sub amp wattage

XXX is an older unit... 2004-5

Ahmed - I like to use Bassbox Pro. By Harris Tech

WinISD works great too.
 

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Re: Sub amp wattage

If I may ask, does the XXX series work well for HT use? Isn't it designed for automotive use? I'm curious because I was looking at that series of drivers also and have read various opinions about using automotive speakers for HT usage.

Thank you.

Bob
 

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Discussion Starter · #6 ·
Re: Sub amp wattage

Good Question - I would be interested in getting opinions on that car use vs HT use... I do see a lot of people on here using subs that were originally sold as car audio units.

I would think that it would be based on the LFE optimization on a HT sub where an automotive unit would be for music? Either way with an 18" it should be able to hit pretty low.

Any one have opinions or personal experience on the Car Audio for HT post?
Any more votes for amps????
 

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Re: Sub amp wattage

XXX is an older unit... 2004-5

Ahmed - I like to use Bassbox Pro. By Harris Tech

WinISD works great too.
Cool. They both should work fine for HT, but they need very different box requirements.

Do you have the specs for your 18?
 

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Re: Sub amp wattage

As far as amps are concerned...How much do you want to spend? The EP2500 is the starting point basically. They are $299 some places.

There is a Crown XS1200 on Ebay buy it now for $500(this is a killer deal). The next major step up in amps from an EP2500 is the $650-$800 range. You would be looking at these:
Crest CC4000 new
Crown CE4000 used
Crown XS1200 used
QSC PLX3602 used
QSC PLX3402 used
QSC MX3000A used (good luck)

Also a good sub is a good sub. It really doesn't matter if it is a car audio sub or a HT DIY sub driver.
Tumult, Avalanche, 13W7, RLP's, XXX's, IXL's, TC Sounds subs, and 0v2's are all first and foremost car subs that work beautifully for HT. If it models well then roll with it.

Just stay away from the SPL drivers with short throw and high FS's. They won't work so well in HT. You want long throw and a decently low FS for HT.
 

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Re: Sub amp wattage

Thanks, Josh. I thought car subs would be designed to utilize more of the cabin gain in an automobile and wasn't sure how it would do in a larger room.

Bob
 

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Re: Sub amp wattage

You are right Bob. There are some duds out there that you would not want to use for sure. Anything with a 38hz Fs and 12mm xmax isn't going to cut the mustard for serious HT. Also some of the car subs are optomized for really small boxes or a peaky response for all out SPL. When in doubt plug the TSP's in your modeling program of choice:T.
 

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Discussion Starter · #11 · (Edited)
Re: Sub amp wattage

I need to dig up the TS numbers - All that I can find ae the newer models. This thing has been sitting around for the past few years - since I finally have a well isolated HT room I have the oppertunity to pull off some good sound without getting divorce papers.

Thanks for all the input - I guess I'll give it the wattage!

PS the xmax of the re xxx is 54mm one-way I believe and the FS is about 15hz?
 

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Re: Sub amp wattage

Either way with an 18" it should be able to hit pretty low.
Not necessarily. It depends on its design. The T/S parameters tell you if it will or not.
 

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Re: Sub amp wattage

Yeah, right... Xmax also comes to mind when it's about low frequency.
But don't they belong to T/S parameters? :neener:

I was only addressing that size only is not the ultimate factor that will determine LF behavior...Remember PA speakers, they're not necessarily small :)
 

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Discussion Starter · #15 ·
Re: Sub amp wattage

PA's tend to be horn drivers?... I'm just playing devils advocate at this point. I totally agree with you. I was looking for an education not objecting to your statement by any means.
 

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Re: Sub amp wattage

Many of them do but not all.
 

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Re: Sub amp wattage

I know a lot of people use the EP-2500 and other similar amps for their subs but I noticed that these amps spec out at 20Hz to 20KHz and was wondering how they perform on the low end (below 20Hz). Do they really provide full rated power at those low frequencies? Also, wouldn't it be better to get a sub designed for just the low end that a sub uses? I don't know the design issues but it seems like designing for a range of frequencies that are not used is wasted money. Are there such amps available (low end only)? :scratch: :huh:

I may be way off base here since there are a LOT of people using these amps and don't report any problems.

Thanks again.

Bob
 

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Re: Sub amp wattage

It doesn't matter a lot if the amp will produce the entire range or not. What really matters is the power output. Since it is only fed with LF, it will only reproduce LF.

Of course there are class D switching amps that are limited (by the technology) to about 200 Hz if I am not mistaken. They are also more efficient (80% instead of 50 for class AB). They are used for subwoofer duties only and are more expensive.

I'll add that a 1000 W class D amp will have the same output as a 1000 W class A/B amp if both are used to feed a sub. So it won't matter a lot if the amp can produce a broader FR than required (as the case of the EP2500).
I don't think using class AB or class H amps for subs duties is "a waist of money", bandwidth limited amps are more expensive.

Amps are pretty linear down to at least 10 Hz, but generally they won't be able to output the same Wattage as they can output at 1 Khz.
 

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Re: Sub amp wattage

Ahmed:

Since it is only fed with LF, it will only reproduce LF.
I understand that but I would imagine designing circuits to cover the full spectrum would require using components that don't need to be there.


Amps are pretty linear down to at least 10 Hz, but generally they won't be able to output the same Wattage as they can output at 1 Khz.
If the amp is losing wattage down low and the driver response is sloping downward, it sounds like the curve in programs like WinISD might be off a bit in the low end unless they take into account the decreased power. Yes?

In any case, thank you for trying to clear it up for me but I must admit, the more I look into DIY, the more confusing it gets.

Bob
 

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Re: Sub amp wattage

PS the xmax of the re xxx is 54mm one-way I believe and the FS is about 15hz?
That's the XMAx for the newest models only. I believe the earlier version was between 30 and 33mm xmax. I couldn't seem to dig up the TSP's on the 05 model.
 
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