What i discovered in my LLT build - Page 2 - Home Theater Forum and Systems - HomeTheaterShack.com

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post #11 of 47 Old 04-23-07, 04:05 PM
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Re: What i discovered in my LLT build

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blaser wrote: View Post
If you make a simulation you will find the Xmax is exceeded, but if bottoming out is related to Xmech, so not very sure it is bottoming.

Blaser
And even that simulation is assuming the EP2500 is capable of that much power output down load given that load.

Quote:
how much do you think the EP2500 realistically puts out into two ohms?

Check out this post by Thylantr: http://www.avsforum.com/avs-vb/showt...&#post10333605

Quote:
You can guess on what 2 ohm/ch or 4 ohm bridge mode power is. Since this is an
amplifier based on a conventional power supply, don't expect power to double
when impedance is cut in half. I would estimate ~1800W RMS bridged
mode @ 4 ohms only if your AC line is a constant 117VAC, but this won't happen in
reality. If you did an RMS test on that amp, expect AC line sag. I'd probably
estimate 1200w - 1400w as the real power offered by EP2500 using 1% THD+N,
20hz sine wave test, less than the advertised 2400w.

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post #12 of 47 Old 04-23-07, 04:39 PM
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Re: What i discovered in my LLT build

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ccdoggy wrote: View Post
really? hmmm, well i have experienced the normal clipping in a klipsch 10" sub, would that be considered soft clipping?
Most commercial subs (also Klipsch) have very aggressive output limiters which prevents the amp from going into hard clipping. A pro amp will make a whole different kind of noise when it clips.

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The clip limiter was not on the 2500, so was that my main problem i was getting the horrific metal sound?
Those little lights are not good indicators. One can have the clipping sound before they lit.

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I cannot estimate the actual excursion during that point as i was directly in front of it and hurriedly dashing to turn it down.
When you get a chance, raise the volume slowly (1 dB steps) and play the same scene over and over. Monitor the driver excursion at the same time. I'm not sure but I'm assuming that driver has well over 30 mm of Xmech (+60 mm peak to peak). No way 1000 watts or so is able to use all that excursion unless you are under the tuning frequency (which you are not).

Dual 1 ohm coils are a difficult load for any pro amp. You will definitely need a better amp than EP2500. Before that I'd try running both channels at 1 ohm load.
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post #13 of 47 Old 04-23-07, 05:14 PM Thread Starter
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Re: What i discovered in my LLT build

the amp will not support a 1 ohm load, not that i have tried.

27mm of Xmax, no listing of Xmech.

After reading up it looks like the amp is not putting out enough power to get close to the Xmech what ever it might be. hmmm... going to look into seeing how much it would cost to make the sub into a dual 2, for a 4 ohm load to bridge it.
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post #14 of 47 Old 04-23-07, 05:23 PM
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Re: What i discovered in my LLT build

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ccdoggy wrote: View Post
the amp will not support a 1 ohm load, not that i have tried.
Yes, I know it doesn't "support" it. I'd would still try it.

Quote:
27mm of Xmax, no listing of Xmech.
Usually Xmech is quite a bit more than Xmax. I'd guess 35-40mm.

Quote:
After reading up it looks like the amp is not putting out enough power to get close to the Xmech what ever it might be. hmmm... going to look into seeing how much it would cost to make the sub into a dual 2, for a 4 ohm load to bridge it.
That would certainly make your amp choice easier.
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post #15 of 47 Old 04-23-07, 05:26 PM Thread Starter
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Re: What i discovered in my LLT build

well rewiring for a one ohm load would be tough, could i just bridge it into the 2Ohm load? would that not be doing basically the same thing?

P.S. Thanks allot for you're help!

I am currently playing at moderate levels with it bridged at 2 ohms just to see how it handles it before i put it through its paces later tomorrow or so.
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post #16 of 47 Old 04-23-07, 05:31 PM
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Re: What i discovered in my LLT build

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ccdoggy wrote: View Post
well rewiring for a one ohm load would be tough, could i just bridge it into the 2Ohm load? would that not be doing basically the same thing?
Yes.

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P.S. Thanks allot for you're help!
You are welcome.
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post #17 of 47 Old 04-23-07, 07:05 PM
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Re: What i discovered in my LLT build

Hey ccdoggy!! what size port did you use???

What are the dimensions on the box??



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post #18 of 47 Old 04-23-07, 08:06 PM
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Re: What i discovered in my LLT build

The Q15 appears to use the 12-spoke Venezuelan basket, good for about 35-36mm of Xmech.

If you don't have a BFD for your sub, get one fast!
If you don't have REW, get it now!
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post #19 of 47 Old 04-23-07, 09:24 PM Thread Starter
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Re: What i discovered in my LLT build

the box is ~27" x 27" x 3 feet. its is a 6" port ~27" long with a flare on both ends to 9", with a right angle in the middle to fit in the box.

I played some rock for about 3 hours straight with allot of bass and the amp dident get warm so tomorrow shall be stress testing and seeing what it can and cant do.

Thanks for the info Exocer!
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post #20 of 47 Old 04-24-07, 06:49 PM Thread Starter
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Re: What i discovered in my LLT build

alright, so I did some master and commander scene tests with the FI Q on a single channel and bridged at 2Ohms.

I do get a little bit more excursion before it has trouble, so it does look like a lack of power issue, although everyone i talk to says thats way more then enough. I guess i am just bass hungry and want to optimize everything.

I have a Eclipse TI from my car (sealed) that i am thinking might work well having it on the other channel as some support and strength.

However i also think one of my main problems is voltage drop as every time it hits the lamp next to me dimms a good amount. I dot have the setup very good at all with my arcam, cd player, and the EP2500 all on the same outlet.
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