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lukeamdman

Luke's Gjallarhorn/Othorn Discussion

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lukeamdman    154

A few recent SPL videos, and the addition of 21ipal drivers to my Othorns has caused some discussion recently.  I figured I'd stop hijacking threads and start one here.  

 

To start, some information on the components of my system.

 

Subwoofers:

 

(2) Gjallarhorns (loaded with LMS 5400 Ultras)

(2) Othorns (loaded with B&C 21-IPAL drivers)

 

L/R Mains:

 

Dual AE TD18H+ in 9.5cu.ft 25hz ported boxes, SEOS-24 w/BMS 4594ND

 

Center:

 

AE TD15M in a 4cu.ft 45hz ported box, SEOS-12 w/Denovo DNA-360

 

Surrounds:
 
(4) Radian 5210 in .60cu.ft angled boxes. Crossovers designed/built by Matt Grant (mtg90)
 

 

Amplifiers:

 

(2) Crest CC5500 (one bridged to each Ghorn)

SpeakerPower SP2-12000 (powering the Othorns in stereo)

Crest Pro-Lite 7.5 (quad AE TD18H+)

Lab Gruppen IPD 2400 (SEOS-24 w/BMS 4594ND)

Crest CC4000 (center)

Behringer iNuke NU4-6000 (surrounds)

 

Processor, EQ, and Blu-ray:

 

Marantz AV7005

MiniDSP 10x10HD

Oppo BDP-93

HTPC

 

Misc:

 

For measurement equipment, I have a calibrated UMIK-1 from Cross Spectrum Labs, and a SPL Lab USB meter.  

 

There are 6 circuits dedicated to the amp rack, and a 7th circuit also but that's shared with the room. The SpeakerPower amp is on a dedicated 240v 30A line, the Crest CC5500 amps are each on dedicated 30A 120v lines, and the Crest ProLite 7.5 is on a dedicated 20A 120v line. 

 

The room is in a basement on a concrete floor that measures roughly 23'x12.5' with 8ft ceilings.  The back wall behind the seating, as well as the right hand side wall are cinder block.  The other two walls have two layers of 5/8" drywall.

 

 

 

Here's how the subs are positioned behind the TV:

 

20140723_232422_zpsnzlaegzx.jpg

 

 

IMG_4694_zpsdd7dgzrj.jpg

 

Here's the back of the room.  Rear seating is on a riser:

 

20140721_142238_zpsry04scel.jpg

 

 

Here's the latest frequency response sweep at the main LP:

 

7-5%20response_zpsw00x75p7.jpg

 

 

 

Impedance of the 21-IPAL loaded in an Othorn:

 

21ipal%20impedance_zpsusaktkcx.png

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lukeamdman    154

Here's a video of the Edge of Tomorrow bass sweep.  The SPL meter is a SPL Lab USB meter, basically a Term Lab clone.  It can measure up to 183db and requires no calibration.  Very easy to use!

 

 

 

 

With the help of Bossobass, I recently got Spec Lab up and running.  Here's a waterfall at a typical "reference" level, where bass peaks are 115-120db:

 

spllab_zps6eec89fa.png

 

SL-EOT_zps09d1287d.png

 

 

I know Bosso has some feedback so I'll open the discussion here!

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Madaeel    64

Holy hell Luke!! Your ceiling isn't finished yet?? That must be loud as hell upstairs haha. I wonder how much you'll gain down low when you finish it too? Double drywall on the ceiling too?

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vxds11    44

You are the man! Thank you so much for this. Your space is coming along nicely. I remember seeing the old school carpet in the past. :P

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Bossobass Dave    241

Here's the animation from digital to your mic'd version:

 

49b9e82ea18748340a253145cb986e44.gif

 

You can clearly see the harmonic distortion (2HD only, 3HD is masked by the second fundamental of each fundamental tone) from the 20, 25 and 15 Hz hits. It's down around 2% 2HD, which is excellent, but typical of a multi-driver sealed system. Running the Raptor system 3 in my 3500 cubes showed 5.5% 2HD of the 20 Hz fundamental running the scene at +6dB over reference.

 

As Max mentioned in the other thread, the last multi-tone wherein 10 Hz is the fundamental, is the loudest of the 5 tones in the scene. In fact, looking at the waveform graph on the right side, you see that the effect ramps up in level as each next lower fundamental kicks in. So, the obvious intended effect was to ramp up the level as the fundamental decreased.

 

In the presentation from the horns, the effect ramps up to the 20 Hz fundamental and then decreases for the next 2, eliminating the 10 Hz fundamental altogether. It completely alters the intent of the creators of the effect to suit the end user's preference (or pocketbook, or laziness, or craving for higher SPL, etc ) This is the crux of the debate over the years. The difference is that now we have to tools to quantify each of the opposing opinions and this is a good example.

 

And, please everyone... no one is telling anyone else what to like or dislike. If the discussion goes there, the discussion becomes a din of nonsense. And, over the years, this is the straw man used... accusing me of dictating what people should like. I could not care less, honestly and truly, what anyone else, everyone else, the majority of the world's population, etc., likes or dislikes.

 

It's simply accuracy vs other.

 

The tradeoff for efficiency across one octave of bandwidth, which I've always maintained and was the subject of my rant that got this convo going, is box size and, in this case clearly shown by the data, loss of content in playback. My system nails the 10 Hz fundamental with <5% THD at +6dB over reference in 3500 cubes where horn, ported, passive radiator, bandpass, transmission line and any hybrid of the above alignments cannot.

 

From the first view of the YT vid at 136dB I was certain it was not without harmonics generated by the horns. There simply can't be 2-5% THD at 120dB but none at 136dB. This is why I prefer SpecLab over other measurement metrics. It shows everything, whether it's missing or there but shouldn't be there. It explains the total dBSPL number shown on a meter and goes a long way to explaining subjective comments from listeners.

 

I am assuming that this is a peak hold of the entire scene showing the 20 Hz fundamental being the loudest from your horns at the seat:

 

4b6cbb7120a9b4b651feee3270b7dc6d.png

 

Notes: Yes, the 10 Hz fundamental is missing, everything above 30 Hz is below the minimum threshold, but... and this is a big but, this little gadget can accurately measure the total dBSPL of any effect played back in-room to 10 Hz. Pretty freakin' awesome. No more "My sub hit XdB, UNCORRECTED".

 

So, what happens <10 Hz? It picks up nothing? It rolls off? Do you know these details or can you point us to where they may be found? Is the TermLab version better, does it go lower, or what is the difference, if any?

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lukeamdman    154

 

So, what happens <10 Hz? It picks up nothing? It rolls off? Do you know these details or can you point us to where they may be found? Is the TermLab version better, does it go lower, or what is the difference, if any?

 

The TermLab has a "NASA" mode where it can measure all the way down to 1hz.  

 

So far, the only downside I'm aware of to buying the cheaper SPL Lab version that I have, is the 10hz limitation.  The software doesn't even allow you view anything below 10hz, so I can't speak to it's behavior.

 

For me it was the difference in spending ~$650 vs $330.  Since my system wasn't designed for <10hz, I didn't see the need to pay the extra cash.   

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Bossobass Dave    241

Hey Luke, the scene, or one like it, with a full BW spread of frequencies, I'd love to see clocked is the scene in Star Trek where Spock goes to warp and Nero yells "Go after him!".

 

Curious to see how it clocks a much more transient effect.

 

I would also like to see what, if any, difference there is clocking with subs only vs subs+sats. Keith Yates saw a diff of around -9dB with subs only but that was outdoors.

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lukeamdman    154

Hey Luke, the scene, or one like it, with a full BW spread of frequencies, I'd love to see clocked is the scene in Star Trek where Spock goes to warp and Nero yells "Go after him!".

 

Curious to see how it clocks a much more transient effect.

 

I would also like to see what, if any, difference there is clocking with subs only vs subs+sats. Keith Yates saw a diff of around -9dB with subs only but that was outdoors.

 

Sure, I can measure that scene with the SPL Lab.  

 

From what I've seen so far, the transient response of the SPL Lab is poor.  Its "update interval" is only a few times a second.  

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Ricci    652

I'd often wondered about the "speed" of the TermLab. I figured it may not capture short instantaneous events and needs a second or so to capture. Burps in SPL vehicles are a little lengthier than a kick drum or door slam.

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lukeamdman    154

Hey Luke, the scene, or one like it, with a full BW spread of frequencies, I'd love to see clocked is the scene in Star Trek where Spock goes to warp and Nero yells "Go after him!".

 

Curious to see how it clocks a much more transient effect.

 

I would also like to see what, if any, difference there is clocking with subs only vs subs+sats. Keith Yates saw a diff of around -9dB with subs only but that was outdoors.

 

Yeah, SPL Lab doesn't do too well with quick transients.  

 

On that scene where the big ship goes to warp, REW is getting a peak of ~108db, and Spec Lab shows that peak at about ~28hz.

 

The SPL Lab will sometimes pick up a peak of 104db, while other times missing it entirely.  

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lukeamdman    154

There is a different mode called "AVG", and it updates twice a second rather than once a second like in SPL mode.  Is this mode it is capturing the transients in that Star Trek scene.  

 

The only downside is that in AVG mode, there isn't a "Peak Hold" option.  

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lukeamdman    154

Holy hell Luke!! Your ceiling isn't finished yet?? That must be loud as hell upstairs haha. I wonder how much you'll gain down low when you finish it too? Double drywall on the ceiling too?

 

The kitchen and laundry room are directly acbove, so lots and plumbing, gas, and electrical lines I might need access to in the future.  I'm doing a suspended ceiling with black fiberglass ceiling tiles.  They made by Certainteed, called "Theater Black f".  

 

You are the man! Thank you so much for this. Your space is coming along nicely. I remember seeing the old school carpet in the past. :P

 

Ah yes, who could forgot the wood paneling walls and orange shag carpet!

 

IMG_0132.jpg

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Madaeel    64

Yah I blocked all that in haha. I'm not gonna be the one to tear out the drywall and patch it anyway. :D No choice to keep as much bass from escaping the room as possible.

 

If you don't put DD on the ceiling aren't you defeating the purpose of doing the other walls though?  Any wall not decoupled or done with DD will just be the weak link and allow the sound to travel through it. It's a pita but it does make a difference. Even the seals around the doors made a difference in my room. Every little bit helps. You only hear/feel the bass in my upstairs but with subs like the Raptors, Othorns, and Gjallarhorn that's to be expected. Still it would be much worse without it. All my bro has is an eD A7s-450 sub and it sounds as loud upstairs as it does downstairs.

 

Anywho room looks good man. AT screen?

 

 

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lukeamdman    154

Yah I blocked all that in haha. I'm not gonna be the one to tear out the drywall and patch it anyway. :D No choice to keep as much bass from escaping the room as possible.

 

If you don't put DD on the ceiling aren't you defeating the purpose of doing the other walls though?  Any wall not decoupled or done with DD will just be the weak link and allow the sound to travel through it. It's a pita but it does make a difference. Even the seals around the doors made a difference in my room. Every little bit helps. You only hear/feel the bass in my upstairs but with subs like the Raptors, Othorns, and Gjallarhorn that's to be expected. Still it would be much worse without it. All my bro has is an eD A7s-450 sub and it sounds as loud upstairs as it does downstairs.

 

Anywho room looks good man. AT screen?

 

I know it sounds strange, but the doubling of 5/8" drywall was more for structural stability than sound absorption.  The left-hand wall in my theater is a supporting wall, and it would move around .75" peak-to-peak during <20hz material...Adding all that drywall must have lowered the resonant frequency by a good bit, because it doesn't move much anymore.  There's obviously still a lot of vibration, but at least you can't see it move visually just by looking at it from the seats  :D

 

I did stuff the floor joists above with R19 denim, but that was more for the acoustics in the room and to keep the noise of people walking across the wood floor above from being so loud in the theater room.  

 

I've been in dedicated theater rooms where no expense was spared, and the house was pretty much built around the theater room.  Even then, and with FAR less firepower than I have, I wasn't completely impressed.  The ULF still came through and the floor upstairs would still vibrate.  

 

Don't get me wrong, it was still a million times better than my theater, but I don't have the space, head clearance, or funds for such an endeavor.  

 

My room is only 12.5ft wide, just barely enough for the door to open and to be able to walk around the other side of the couch on the front row to get to the back row.  The ceilings are 7'10", and 6'10" under the soffits with the ceiling complete.  That means if you're standing on the riser and you're 6'5" or taller, you'll probably hit your head on the soffit...

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MKtheater    48

I did not use double drywall.  I used 3/4 drywall sandwiched in between two layers or an inch of sound board for every wall including the ceiling.  I filled all the gaps with fluffy insulation.  The bass still escapes no matter what.  The only way it would not is if you had concrete ceilings and doors.  My doors are cheap but with soundboard on them which makes them heavier but the bass still gets through.  Just too much bass! I get yelled at all the time now with the new system and without 5 star movies!

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Madaeel    64

Oh ok. Makes sense. Yah I know for ULF not much you can do. I would be curious to see the difference without GG and clips because I'm starting to think it didn't help much. Mass does for sure but I think I coulda saved a couple bucks on the GG and clips. 

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lukeamdman    154

Nice job my man ;)

 

Thanks!

 

+1. Looks good Luke. Should be able to turn it up a little more. :)

 

The amount of treble that makes it out of the room was dramatically reduced.  Bass...not so much, but that was expected.  

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Madaeel    64

Funny thing is it's the highs that are most annoying anyway. Jazzy will sit upstairs and watch a show or movie and not be bothered by a movie at reference downstairs. The bass hits are annoying no doubt, but except for a handfull of movies it's a small percentage of the time. Now the highs would be annoying if you could hear them all the time. Like some loud obnoxious idiot in the other room won't stfu.

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