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Post by Darren on Jul 18, 2006 6:49:44 GMT -7
Chrisbee,
You say you are running stereo on the EP2500 at 8 ohms a channel... why don't you run them 4ohms bridged mono? You'll get tons more headroom and can crank the bass to match whatever level those IB15's will tolerate. Turn the signal way down though to start.
Right now with 8 ohms per channel you are only giving each driver 225 watts. If you were to bridge the amp mono you'd be giving each driver 600 watts. You should be able to manage whatever level of bass you can stand or the drivers can handle.
With my 4 RL-P15's and only 225 watts per channel with my smaller EP1500 I can surpass the output of my AV15 box sub which is quite good in itself. I've measured 114db in the listening position and have more room to go. I totally know what you are referring too though when you compare the two. The box sub hits hard but it is not nearly as defined, it misses much of the detail. The IB catches the detail, has no bloating at all (part of what is perceived as bass with the box sub but is really coloration), and it is very crisp.
I think you just need to wire 4ohms bridged mono and crank up the bass to whatever level works for you. You should have more than enough headroom with that amp and those drivers.
I'll be upgrading my amp though so I'll be getting about 325 watts per driver in the end.
Oh, have you tried messing around with different house curves? You should be able to mimic the properties of the box sub that you desire and have several different BFD settings for different listening.
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Post by jagman on Jul 18, 2006 9:27:14 GMT -7
Thomas,
I agree with you on all accounts. Will turning the gain on the amp all the way up increase distortion or hiss? My concern with the amp is that with the volume 80% up, the amp still doesn't seem to be working all that hard. My concern is that even when maxed, it still will be loafing along no where near to clipping. That leads me to the conclusion that the signal it receives isn't high enough. Don't get me wrong, I don't want it to clip, but I would like it to get 80% there. I'll finish the room treatments, get the EQ, take more measurements, and then put in a house curve. Hopefully that will be enough. If the amp still isn't working hard, I'll have to get a line level booster. The idea of getting a bigger amp is good, but if this one isn't fully used, then a bigger one won't be fully used, either, and then I'd still have the same problem. hopefull maxing what I already have will be enough.
We'll see what helps... thanks for the imput.
EDIT: I've been thinking over your comment about the response being that of a lossy or leaky room. There is an opening in the front left corner about the size of a door. It opens up to a 8500 cubic foot two story living/dining room... and that room opens up to a 6500 cubic foot kitchen/family room. I was hoping to not have to install a door, but it now seems like I must do that (solid core). The other factor is that there is 57 square feet of windows in the HT/music room. I would assume that is also contributing to the leakage. How much do you think thick, heavy curtains would help?
Finishing room treatments, installing a solid core door and thick curtains, taking SPL measurements, adding an EQ and generating a house curve, taking more SPL measurements... not to mention the possibility of needing a line level booster or even a new bigger amp and then taking more SPL measuremtns and redoing the house curve. I have a lot of work ahead of me... at least I'm reasonably happy with what I already have. What I have now is nght and day better than what I had before. We are a crazy group of people, that much is sure.
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Post by jagman on Jul 18, 2006 10:28:53 GMT -7
Darren...
I think you nailed it on the head regarding rewiring the IB. It would take little effort to do that, and the there would be no doubt the subs would move a lot more. It would also be much easier to play them louder while not having to have the mains too loud.
Chrisbee... you have one more possibe tweak... go for it! Sure, the amp would work a little harder, but it should be able to handle 4 Ohms mono. You probably won't have to turn the gain up nearly as high, too, so I'm sure it would work. Don't get depressed just yet!
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Post by chrisbee on Jul 18, 2006 15:28:56 GMT -7
Thankyou for the suggestion. Nothing to lose by trying it bridged. Except finally having to build that opposed driver manifold to take the extra loads. Anything to keep the little women happy.
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Post by jagman on Jul 18, 2006 16:02:33 GMT -7
You are in an odd position with the misses wanting a larger HT system... then again a woman wanting a quick driver with more displacement that has a large... eh hmm Xmax... isn't anything new.
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Post by ThomasW on Jul 18, 2006 16:30:32 GMT -7
Except finally having to build that opposed driver manifold to take the extra loads. Anything to keep the little women happy. And putting a louvered back with openings equal to the combined Vd of the drivers....
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Post by chrisbee on Jul 19, 2006 4:59:31 GMT -7
That was well below the belt Thomas! It was done purely as a protective measure against my drivers getting sunburnt. It runs well over 100F out there despite white curtains covering the whole area inside the glass. I've been seriously thinking about fitting large, permanent wooden louvres outside the glass. High ventilation might help get a chimney effect going if it draws in cool air at the bottom through the lower opening windows. External louvres would have to be very strong to cope with our winter storms. (but that's another forum)
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Post by chrisbee on Jul 19, 2006 5:00:50 GMT -7
You are in an odd position with the misses wanting a larger HT system... then again a woman wanting a quick driver with more displacement that has a large... eh hmm Xmax... isn't anything new. ;D
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Post by ThomasW on Jul 19, 2006 8:40:51 GMT -7
That was well below the belt Thomas! It was done purely as a protective measure against my drivers getting sunburnt. It runs well over 100F out there despite white curtains covering the whole area inside the glass. I understand the situation. I'm just saying that Sd shouldn't be the criteria, Vd is what you should use. Also I recommend using something other than metal unless you have a method for damping it's vibrations.
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Post by ThomasW on Jul 19, 2006 11:18:27 GMT -7
If you haven't already I would check the settings on the back of the EP2500. If the 30Hz or 50Hz filter is enabled the low output could be suffering... We don't need to reinvent the wheel here. Chris has output to 14Hz per his plots. If he wants to post plots comparing the IB to the SVS; we can identify what the differences are, and whether or not it's possible to EQ the IB to sound like the SVS.
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Post by chrisbee on Jul 20, 2006 5:27:43 GMT -7
Thomas At great personal risk I have just tested the SVS without a safety net. Just for you! ;D First image is the SVS 16-46PCI without speakers No eq. @ 8 feet Second image is my IB + speakers + BFD + house curve @ 8 feet. I think you will agree the SVS is a hard act to follow.
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Post by ThomasW on Jul 20, 2006 7:30:40 GMT -7
I think you will agree the SVS is a hard act to follow. It's pretty obvious what's needed to make the IB sound like the SVS. And doing that would take about 2 minutes to accomplish using your equalizer.
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Post by chrisbee on Jul 20, 2006 7:41:04 GMT -7
Now don't be such a tease Thomas. I'm already using +16dB at 20Hz on the BFD. So I'm already scraping the bottom of the barrel!
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Post by Darren on Jul 20, 2006 8:34:17 GMT -7
Chrisbee,
I believe what you need to do is increase the gain on the sub and then use much less gain in the 20Hz filter to accomplish what you currently have or go beyond to match the SVS... bridging mono should give you the headroom to accomplish that.
Just a theory, give it a shot and see if it helps.
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Post by chrisbee on Jul 20, 2006 9:53:14 GMT -7
Thanks Darren I wonder what happened to Thomas? I hope he didn't choke on his meusli?
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Post by ThomasW on Jul 20, 2006 10:59:41 GMT -7
Now don't be such a tease Thomas. I'm already using +16dB at 20Hz on the BFD. So I'm already scraping the bottom of the barrel! Look if the amp isn't clipping and the BFD isn't clipping then use more EQ if for some reason you actually want to duplicate the sound of the SVS. The SVS is tuned to 16Hz and even 8' away you're getting boost from the corner loading at the tuning frequency but.... You've got significantly more the Vd with the 4-15"s than the single 12" in the SVS so.... There's no reason the IB can't literally lay waste to the SVS given the differences in Vd (the obvious analogy here is a V8 motor vs a 4 cylinder) You can dial in boost at 21Hz, 22Hz, 23Hz, or whatever, that will impact the output at 16Hz. You can also pull down frequencies higher than 16Hz with shelving filters.
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Post by chrisbee on Jul 20, 2006 12:20:10 GMT -7
I bow to your knowledge of the BFD, Thomas. I had no idea this was possible. Nor can I readily see how this will help? I have just wired the EP2500 for 4 Ohms bridged. Not easy, as the terminals won't take a decent thicknesses of bare copper wire. So I'm gathering pairs of cables into cheap moulded terminal blocks and running a single speaker cable to the Behringer. Now my wife is watching gardening on TV so I can't wind it up and there's no bass on this programme to play with! Aaarrrggh!
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Post by Darren on Jul 20, 2006 12:26:39 GMT -7
Be sure and double check your load before firing it up. Measure across the wires to be sure it is 4 ohms...if you mess up you don't want to short the amp!
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Post by ThomasW on Jul 20, 2006 12:48:44 GMT -7
I had no idea this was possible. Nor can I readily see how this will help? I don't remember all the T/S parameters for the IB15", but even if the driver in the SVS is a high excursion unit ( I don't think it is), your IB certainly has no less than 3 times more swept volume than the 12". So unless you're power limited by the output from amp or something else goofy is going on, your IB has the ability to easily humble the SVS. There are all kinds of ways to recreate the curve of the SVS. I don't have REQW installed on this particular PC so I can't walk you through it step by step..... But try some cut filters in the 80Hz range with a double octave width. Watch the REQW curve while lowering the frequency of that particular filter and see what it does. You can play with a myrid of filters in the abstract. Once you have something that looks good on the PC screen, dial that into the BFD using a different preset number than your usual one. Sometimes going much higher in frequency helps as well. I think BruceK has a stock filter setting he uses, it's something weird like 300Hz or 500Hz. It flattens lots of stuff below the actual setting.
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Post by chrisbee on Jul 20, 2006 12:48:48 GMT -7
Thanks for the warning.
I checked wiith a 4.5 volt battery before connecting to the amp and everything seemed okay.
I'll just check with the meter though. Just to make sure.
It's okay. 3.5 Ohms is near enough.
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