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Discussion Starter #1
Well I've decided I'm gonna try a Behringer EP-2500 amp when I give the Tumult/LT a try. My question is about the subsonic filter or HPF in the amp.


The specs say the -3db point is 5hz. Will I be OK with that, or would it be a good idea to include the input buffer/HP filter in my LT?


I'm gonna see about that Bassis but it seems like once set it's not something I'm gonna change(except to show it off to someone) and even though I haven't priced out building an LT circuit yet I doubt it'll cost more than $50.


Thanks again
 

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I'm not sure if this is what you're asking, but the 2500 has a 5Hz rumble filter built in that can not be disabled.
 

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Quote:
The specs say the -3db point is 5hz. Will I be OK with that, or would it be a good idea to include the input buffer/HP filter in my LT?
Depends on what your excursion looks like. You can use box size to control that, and let it roll off second-order till it hits that filter at 5Hz. With a single driver/limited Vd, that's what I'd do. Here's a related article that might help choosing Vb:

http://www.rythmikaudio.com/sealed.htm


Bossobass might also have some very useful input here also.


Quote:
I'm gonna see about that Bassis but it seems like once set it's not something I'm gonna change(except to show it off to someone) and even though I haven't priced out building an LT circuit yet I doubt it'll cost more than $50.
I think the variability of the Bassis implementation mainly comes into play when trying to achieve a specific in-room response, you can play with it until it's right. Problem with the fixed circuit is that you've got to guess at what it'll do in-room...and it won't look like the nice curve the spreadsheet spits out. Of course, if changing out the components on the PCB is no big deal for you, then that's an equally "variable", and cheaper, solution.
 

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I have an EP2500 and like it very much. It is a stout amp and is basically a QSC Copy. I use a seperate Subsonic (high pass) filter on my Behringer Ultragraph Pro GEQ. I have it set at about 12 hz. My response drops off steeply at around 14Hz anyway.


Using the filter will give you more headroom on passages that have content that low. It is very easy to clip an amp trying to reproduce a sub 10hz signal.


Is it NEEDED? No. As long as your driver can handle it.


-Eli
 

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It also has selectable 30hz and 50hz high pass roll-off filters. Watch out because when the dip switch is off (default) that filter is actually on.


I couldn't understand why I was clipping the heck out of this amp and it was only giving like 100db. You would think that OFF meant the filter was OFF. The diagram on the back of the amp is correct, but I didn't notice when I first set it up.


After I figured it out and changed the setting I was very impressed with the performance. The fan is pretty loud though, I'm gonna have to mod it for sure.
 

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Discussion Starter #6
Thanks for all the quick replies.


Cecaa850 yeah that's what I was wondering about. I just wasn't sure if the filter was set to such a low frequency that I'd need to add/build a high pass/subsonic filter so I didn't chance damaging my sub. In a sense the low frequency it's at is nice since you can add your own high pass filter and tailor it to what you want. My current amp(Kiega 1000w plate amp) has a fixed 18hz high pass filter and it's not defeatable so it's not gonna work well when I add the Linkwitz Transform circuit(not to mention it doesn't have enough power).


Eli I would defiantly add a high pass filter(or something) if I was building a reflex box since every graph I've done in Unibox with that type design showed serious over excursion below the tuning point.


Johnm_10 that's good to know because I'd probably do the same thing. I've also read about the fan noise but I don't mind switching out the fan with a quieter one. If that's still not enough I can build a new tv stand with doors so it's not audible.


Jack thanks for the link. I've been working on the wife to let me build an IB and I think I'm getting pretty close to getting the OK. I just keep showing her some of the huge enclosures(multiple in some cases) and then picks of the IB's :D . If I do get to go that route I don't think I'd use the Bassis(never know though) but I'm sure i could sell it.


I can't wait to see the price on that new Ascendant 18". I'm know the amp I'm getting is WAAAY to much power but depending on the voice coil configuration of the speaker I might not have to much trouble running 2 of them in an IB. If the IB ends up a no go then a second amp and 2 18"s(since I'll have the BASSIS) might be fun. Just depends on the price of the 18"s and what my Tumult will sell for.
 

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Quote:
Jack thanks for the link. I've been working on the wife to let me build an IB and I think I'm getting pretty close to getting the OK. I just keep showing her some of the huge enclosures(multiple in some cases) and then picks of the IB's . If I do get to go that route I don't think I'd use the Bassis(never know though) but I'm sure i could sell it.
Actually, that links argues against IB, at least in cases where Vd isn't "unlimited".
 

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FWIW....


I did the fan resistor mod on mine. I measured it the other night. With the mic 4"s away from the front grill of the amp, it will not register a reading on my meter. (so its something below 50 db)


With the mic as close to the front grill as possible without touching it it will read 53 db.


It is inaudible to me unless my ear is right next to it. I checked the temp last night after watching The Island at -0 with no breaks. It was slightly warm to the touch....just barely warmer than room temp.


The two mods I have made to this amp are the fan mod and I pulled the control board out and covered the "signal" LEDs with electrical tape and reinstalled them. The "signal" LEDs were very annoying to me ans serve no purpose. After these 2 things were done I am very happy with the amp. It is built nice, sounds nice, and has good power. IMO, it is a nice step up from the crown XLS series that I was using. The insides of the 2 are like apples and oranges.


-Eli
 

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Discussion Starter #9
Jack yeah I read that link but I'd still like to try an IB. I just mentioned the IB because I'm pretty sure you have an IB setup. I'm not sure if I'll end up getting to do it but I'd sure like to.


Eli thanks for that info. Makes me feel a lot more comfortable about buying that amp. I'd been trying to get a used Crown K2 but for the price they go for I could get 2 EP-2500's and a BFD.
 

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Quote:
Jack yeah I read that link but I'd still like to try an IB. I just mentioned the IB because I'm pretty sure you have an IB setup. I'm not sure if I'll end up getting to do it but I'd sure like to.
I'd certainly never discourage anyone doing it if you can, I think it's the best way to go.
 

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Originally Posted by fraDcat
Eli thanks for that info. Makes me feel a lot more comfortable about buying that amp. I'd been trying to get a used Crown K2 but for the price they go for I could get 2 EP-2500's and a BFD.
Crowns K1 and K2s are EXCELLENT amps...but they are $$$$$. On the budget side of things I am convinced the EPs are some of the best. Used QSCs are a good bet as well.


-Eli
 

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Quote:
Originally Posted by TJEli
FWIW....


I did the fan resistor mod on mine. I measured it the other night. With the mic 4"s away from the front grill of the amp, it will not register a reading on my meter. (so its something below 50 db)


With the mic as close to the front grill as possible without touching it it will read 53 db.


It is inaudible to me unless my ear is right next to it. I checked the temp last night after watching The Island at -0 with no breaks. It was slightly warm to the touch....just barely warmer than room temp.


The two mods I have made to this amp are the fan mod and I pulled the control board out and covered the "signal" LEDs with electrical tape and reinstalled them. The "signal" LEDs were very annoying to me ans serve no purpose. After these 2 things were done I am very happy with the amp. It is built nice, sounds nice, and has good power. IMO, it is a nice step up from the crown XLS series that I was using. The insides of the 2 are like apples and oranges.


-Eli
Anyone know a good link to this mod? Would it be better to just find a quieter fan?
 

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Quote:
Originally Posted by fraDcat
The specs say the -3db point is 5hz. Will I be OK with that, or would it be a good idea to include the input buffer/HP filter in my LT?


The -3 db @ 5 Hz the frequency response. The amplifier offers two switches

( -3 dB @ 50 & 30 Hz) which may or may not be helpful pending on what you

are using it for.


It may be wiser, to use your own HP Filter pending on your sub requirements.


If you don't have an electronic crossover, it may be time to purchase one.

That way you can select the starting and ending point of the sub frequencies.


This would be much better than relying on a fixed on and off switch.


Good Luck!
 
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