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Discussion Starter #1 (Edited)
Hi Folks,
I've been reading this forum avidly since the begining of this year. In building a new HT/Rec Room in our new home, I had the challenge of having to put all speakers in-wall. I have a 7.1 setup in a room that is approx 18'x25'. I have a 120" screen with a Pani projector. I went with Klipsch R-5800-W in wall's all around and for the price I paid for them, I am very happy with their performance.

The biggest challenge and the one which I started reading this forum for was the In-Wall subwoofer. Almost all "brand name" in wall sub systems were $1000+ and almost all of them had only a single 8" or 10" speaker. I have an interest/inclination in the electronics and speaker side and my brother is a master wood worker so together we set out to build a DIY in wall sub.

When all was said and done, we ended up with a 5.6 cuft sealed box built in-wall and fasted well so there would not be any vibrations. The box has 2 Shiva-X woofers and is powered by a EP2500.

My impressions over the last 2-3 months is that this setup get's LOUD. So loud at times that your insides start feeling funny. Reaching high SPL's is absolutely no problem for this setup especially with music. HT however was another matter. I have a little 10" Def Tech sub and I could tell by ear that this little guy was reaching lower than the in-walls. So back to the Shack I came to figure out what was going on. This is when I started reading about REW and it's magical ability to See what I was hearing.

Below are my REW graphs. I've done two measurements. One is the Dual Shiva's running and the other is with one of the Shiva's unplugged. (Simulate a passive radiator?) As you can see, my low end sucks. Any suggestions would be greatly appreciated.

Sound Card Calibration:
sound card.jpg


I should also note, since this unit is already in-wall, I cannot move it. I options to correct this room are:
1. Remove 1 Shiva and seal up the opening so the 5.6 cuft box has just one Shiva in it.
2. Add a passive Radiator
3. Try and EQ the dual setup

Also, I have just purchased a SMS-1 from these forums. I should be getting it in on Thr. This should help with the EQ.
 

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wadesi,

Good job with REW. Your response for a sealed sub looks pretty typical with a smooth roll-off at the lower end. It will likely need an LT boost. You also have a typical modal resonance around 60Hz.

I'm going to move your thread to the DIY subwoofer section as you'll get far better advice there on solving your problems.

brucek
 

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Looks like a little EQ would solve your problem. A nice wide boost to the low end and a notch to tame that hump at 60 hz. Cross it over at 80Hz and you should see a big improvement.
 

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Discussion Starter #5
Your dual Shiva-X's in 5.6 cu ft will perform better the a single sealed, single PR'ed or ported. Hopefully the SMS-1 will help solve the problem.
That's what I'm hoping. My biggest concern is in that 20hz range. I'm lacking response there now. Will the SMS-1 be able to boost the bottom end a bit?
 

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Wow, you guys have more confidence than I do that EQ will help this situation. I mean, 25 Hz is at least 18 dB down from the average level of the rest of the sub range (~80 dB). 20 Hz is off the chart. Don't you think it would be better to get a driver(s) that would work better with the enclosure?

Regards,
Wayne
 

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Discussion Starter #8
Hey Wayne,
Do you think it's a enclosure volume issue? Does the Shiva need more room to breath? Or is not the best driver for this use? FYI, this room is 90% HT and 10% music. The lack of a low end response is why I've started this thread. I'm open to suggestions.
 

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get a driver(s) that would work better with the enclosure?
But Wayne, it's in a sealed box. It looks exactly like any sealed box with a typical QTC of .707, does it not?

Come on - where are the sub gurus around here.....

brucek
 

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Yeah, thanks Mike, that's what I thought.

It would seem that if someone had an IB, that you wouldn't go to the trouble to build a sealed box around it, since an IB is essentially a big sealed box.

Wouldn't it be better to go to an SLLT design to get extension?

brucek
 

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But Wayne, it's in a sealed box. It looks exactly like any sealed box with a typical QTC of .707, does it not?

Come on - where are the sub gurus around here.....
LOL - Well, I'm certainly not one of those, I don't know QTC from XTC! I only have my own experience with Shivas to draw on (not the X model), and I got usable extension down to 25 Hz with a 2-cu. ft. box.



Baseline Response


Here is what the modeling shows. Yellow is what he has, green would be if he ported a single Shiva-X.
Your modeling shows 25 Hz to be only about 7-8 dB down from 50 Hz. Obviously a far cry from what subnoob is seeing.

The first thing to check is to see if the 30 hz high pass filter is engaged on the EP2500.
That crossed my mind, too - glad you brought it up. I wouldn't be surprised to find that the HPF is engaged.

Regards,
Wayne

 

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Yeah, thanks Mike, that's what I thought.

It would seem that if someone had an IB, that you wouldn't go to the trouble to build a sealed box around it, since an IB is essentially a big sealed box.

Wouldn't it be better to go to an SLLT design to get extension?

brucek
His box size is by no means big for dual Shiva-X setup. I don't think IB was an option for him. An LLT would definitely have more extension, but that would depend on the amount of space that is available.
 

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Discussion Starter #14
Ok, so who has two thumbs and is a big IDIOT :hide: That would be me. Even though I know i've checked the settings a couple of times I thought I would download the online manual for my EP2500 and give it another check. The On/Off writing on the back of the EP is not the same as what was in the manual. The back of my EP says Left/On and Right/Off. This does not jive with what the settings should be according to the Manual. So I've basically been running this setup for the last 6 months with the HPF set at 30 Hz. I know I'm a big dumby and if you could feel the sinking feeling in my stomach when I compared the manual switches to what I had behind my unit you would feel pitty on me.

So here are my Correct measurements. These look much more in line to what things are supposed to look like. NOW from this point I'm sure the SMS can help smooth things out.

Blue is the Single Shiva-X whith the other one unplugged. Green is with both running.

updated measure.jpg
 

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Discussion Starter #15
Here is what the modeling shows. Yellow is what he has, green would be if he ported a single Shiva-X. The first thing to check is to see if the 30 hz high pass filter is engaged on the EP2500.
Thanks Mike, You hit it right on the Dot...:T
 

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Discussion Starter #19
Thanks Mike, It sounds Great! Sorry it took me a while to reply but last night is the first real "session" I've had in my theater since correcting my settings. Although I'm not sure if it "sounds" great is correct. It sounds about the same, more like it "feels" great is more appropriate. It always sounded good, now I have that low rumble feeling that I've been missing.

My SMS-1 is coming in today! I'm hoping that it will help me level out that peak around 60hz which from all I've read is very common in DIY subs. I'll post an updated REW after the Velodyne has had a chance to equalize the sub. Are there any other points of correction in my graph? I've been reading that you really can't EQ the dips so i'm not sure there is much I can do about the dip around 27hz. Any suggestions would be helpfull.

Ok, I'm a tweaker at heart like many of you here and I still have issues with my sub even though they are really only my issues as most people can't tell the difference. Due to factors out of my control the only place to put the sub in the wall (not my choice) was directly in middle of one of the side walls. This also happens to be a direct shot to where the side of my head is from the optimal listening position. One problem I'm having is that there is a really annoying "Mid" dialog coming out of the sub. I can see how that woud be normal when the sub is placed really close to the fronts and the mids blend into the front stage. I however am cringing every time I watch a movie because I have vocals coming out of the center (Highs) and the side of the room (Mids) at the same time. This is true on all movie audio tracks. Once again 90% of the people watching movies in my theater can't tell but it's like running your nails against a chalkboard for me. I havn't yet tried moving my seating position which is an option. I can move up 2-3ft and have the sub slightly behind me instead of directly to the side. I will try that this weekend. Any other thoughts? Do I need a Low Pass Filter? Am I going to cut out all the "Mids" in my room if I do that? The frequency of dialog does help give a richer sound but since it's coming from a different location than the front I'm getting dialog from two different directions. Are there any settings on the SMS that can help with this?

Thanks alot again for all your help in advance. You guys are real troopers for putting up with all our self induced problems.
 

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Discussion Starter #20
FYI, In case you were wondering. My H/K AVR-254 has some of the worst EQ options I have ever come across. My sub crossover options are Present, 10", 12", 15". I've tried all these options and my ears can't tell the difference between them at all. I suppose I could do a REW graph at each of these options if it would help...
 
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