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Ricci said:
if that makes any sense at all
It makes all the sense in the world.

You don't know what it is like until you have experienced it, even if you think you do. The difference is extended low end FR with much cleaner headroom. That low end bass energy will make its way right through your body and just ravage your room.
 

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Hey Steven,
I think I understand what you are saying. Sounds like you are describing the way it feels when the sound pressure decays. Like the bass hits you and then you hear it slightly delayed?
Yes and no. I don't hear the sound after I feel it anymore except of a corner in my room that needs treating, but in a sence of how long the sound is I feel a different decay and different sensation. I sit on a concrete floor so most of the tactile response has to do with the couch I sit on, or if I am on the couch with the riser. The very low frequencies (low for my subwoofers) make me feel like my hair is standing up, but it is not like a breeze. I have tried placing a candle in front of one of subwoofers and playing a movie with cannon fire, and the candle would not start to move very much until I would measure over 100dB next to it. None of the candle movement and SPL movement was audible on the video recording I made with camera. It did however make the sound on my camera stop and start recording with some loud clacking noises. I know that very low frequencies are moving air but I don't seem to get any feelings of having a breeze. The frequencies all feel very solid to me but not having to do with any particular direction unless they are lasting for a very long time. It may be something to do with the longest distance in my room. It looks like you are describing the feeling of the wave itself which being such a long length wave that there is seemingly no begining or end, but instead of it feeling heavy or lifting one out of the seat, it is pressing forward. That is interesting thank you.
 

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Discussion Starter · #23 ·
Ricci, you can relax. I had the Re XXX info stored where the Maelstrom X was labeled. Two different and distinct specie. As they say, "My Bad".
But let me correctly enter the RE XXX info into WinISD and play with it for a couple days. It does look interesting.
I"M ALWAYS RELAXED:rant:!!! JK.:R

If you were modeling a Maelstrom X that would explain things. :yes:
 

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Discussion Starter · #24 ·
I took a bunch of measurements last night of both subs and I'll try to get some of it posted up later tonight. Spent about 6hrs on it yesterday and I still have a bit to go. There were some interesting findings (to me). A lot of what I got was expected, some was not expected and there was one thing that has me stumped.
 

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I'd be interested to see the WT3 measurement differences of the XXX driver parameters, if any, when placed in the Sealed vs Ported.

1) WT3 measurements free air (you said you had some)
2) WT3 measurements in sealed
3) WT3 measurements in ported
 

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Discussion Starter · #26 ·
Phil,
The parameters once they are in the box are heavily affected by the box. It's mostly for determining the impedance and box resonance or tuning in the case of ported cabs.
 

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Discussion Starter · #27 · (Edited)
Ok. Let's start off with the basic FR graphs at about 100db or so.I've removed the Rane PE17 that I had in the line because I determined it's not needed for HPF protection with the ported cab and it's robbing me of a few db's down low I'm zooming in as much as is reasonable on most of these graphs to better represent the differences. The only differences in between when the sealed and ported measurements are taken, is the switching of the cabs. Did the sealed measurements, unplugged it, dragged it out of the way, rolled the ported one in place, plugged it in and repeat measurements. All gains and settings the same.

There will be no smoothing or prettification on any of these graphs



Ported




This is to show the effect that the Rane PE17 was having on the bottom end with the ported cab. The more rolled off one is the one including the Rane.




Here is the basic sealed FR without the Rane.



This is showing the effect of the Rane on the sealed cabinet's lower end. Again you can see that the removal of the PE17 helped the low end out a bit.




This is an alternative FR measurement for the sealed cab that I took when playing around with the orientation of it in the same spot.

MUCH better :eek:. It really pulled my big 70-100hz suck-out back up. Still a nasty 95hz pit, but if I were to use the sealed cab dedicatedly in this room I would place it like this for sure. This is one advantage for the sealed cab. There will be no fooling with placement with my Behemoth ported wall.







And here is the sealed and ported FR's together from the same position and orientation as much as can be possible with large kitchen appliance sized enclosures.
 

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Discussion Starter · #28 ·
Ok. Here is something that is curious and I'm having a hard time reconciling it. All of the volume was controlled through REW for these tests and I started at a baseline of -39db for the FR sweeps and power compression tests. I run the tests, etc. etc. no biggie. I switch to the ported cab and the baseline FR sweep is 5 or 6db louder than the sealed cab's at the exact same -39db setting:confused:. This trend continues as the volume increases. Here is a graph to illustrate this.

This is with the sweep level at -39db for both cabinets. I repeat the same settings. Notice how much louder the ported cab is.





Now. I immediately think that something is wired wrong or whatever with one of the cabs. Maybe one of the drivers has the vc's in parallel and the other's are in series? Maybe one of the drivers is a dual 1ohm instead of dual 2ohm? Negative on all that because I've already taken impedance measurements of both cabs with the WFT3 and they both show a DCR of roughly 4.5ohm and match up well with the simulations. I can post these if needed.

My next thought is...Ok. Maybe since the front baffle of the ported sub is like 18sq ft :p it is getting some efficiency gains from that...but 5db? That seems excessive. So then I'm thinking what if I'm getting a db or 2 off of the huge face of the ported sub and I'm loseing a bit of efficiency with the sealed cab due to it being overstuffed with 10 pillows and that combined is where this huge discrepancy is coming from? Perhaps the huge amount of airspace in the ported cab really is providing extra sensitivity? This is not the case either. If that was happening then the ported sub would maintain this advantage all the way up until the system limits, at least above 40hz, where things are essentially on equal terms between the 2. It does not. :eek::confused:.

So from there I start thinking about the amp. Perhaps something is happening there. But this doesn't lead anywhere either from my thinking. At the settings that I was using the ported cab and CE4000 combo would only tolerate a sweep level setting in REW of about -23db. After this the amp and driver were both giving signs. Now with the sealed sub at the same -23db level it handled it fine with no signs of stress at all from either the amp or driver, but it was just like the graph above with the sealed about 6db lower than the ported sub through the 30hz and up range and is obviously being pushed much less hard. With the sealed cab things weren't stressed until -16db. 7db hotter. Which coincidentally puts the 30hz and up output right in line with where it should be in comparison to the ported sub.

I cannot figure out why there would be a 6db difference in gain between the 2 but it's there. For some reason it is exactly like I've increased the volume to the CE4000 by 6db when I switch to the ported cab. A level that causes the amp to clip in the upper bass results in levels that are within a db or so of where they should be according to sims and common sense, but the output levels from REW that produce this are 6db different from each other. I'm stumped. Other than determining the cause of it for knowledge's sake, it really doesn't matter much. If anyone has any ideas on the cause spit them out.

Next up power compression tests.
 

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I don't have the answer but I remember reading another guy having the same experience with REW.
The sealed box graph without the Rane, when you were "playing around with the orientation" looked excellent.
Why did the sealed graph response change when you ran both at the same time?
 

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I assume you're using PPN or other similar test signal to set levels? Have you thought about picking a frequency, say, 60Hz, and setting both boxes to 75dB at that level, then running your sweeps? This might change your seeming discrepancy in levels, as the ported and sealed may be responding to the PPN differently.

I don't know, but I remember someone else using a specific frequency as a reference when testing 2 different subs. Couldn't hurt to try.
 

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Discussion Starter · #31 ·
Phil,
I'm trying to match the ported and sealed positions to each other, so that the room effects each the same way and they can be compared directly as much as possible. This is why there's no EQ either.If I change the positioning of the sealed to the better responding position this negates a lot of what I'm trying to do. As the room is a bigger factor then than it already was.

Tenzip,

These are the same model of driver in 2 different cabs. They are using everything else the same. This is to determine what the cabs are doing to the driver response and eliminate as much else as possible. I set the sealed cab with PN and that's it for both cabs you just move them and plug the Neurik Speakon cable into each from there.
 

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Great work. I really appreciate you taking the time to document your subjective impressions with objective measurements. This is more water in the bucket that goes to show that a LLT design offers more balanced and accurate performance - if Ricci is somehow able to take THD measurements, we'll see how significantly cleaner the LLT is as well.

Ricci, you've posted compression graphs elsewhere, I'm assuming those will make their way to this thread as well? They go a long way to show just how much more the LLT offers. One of these subs is reference capable all the way down to 10hz with no EQ - impressive.
 

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Discussion Starter · #33 · (Edited)
I'm workin on it Steve. I haven't had a chance to get everything done that I wanted to yet. It's a lot of work putting all this stuff together with some form of coherency. :whew:.
The THD tests results will be up soon. I've got to organize everything and get the graphs ready to post.
 

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Discussion Starter · #34 ·
I may try to switch the drivers in the sealed with one of the other 3, but I'm not going to take the driver out of the ported cab. I have had more than just this one driver in the sealed cab already. I can't think of a reasonable way to take out the one in the ported cab without damaging the finish and I'm worried about stripping something out. I just don't want to mess with that.

I'm nearly 100% sure that the vc's are not wired out of phase and I would think that if they were there might be some audible effects of that. Plus if the coils were fighting each other I'm not so sure that the driver would be very happy with having 2KW or more dumped into it. I've been running it the way that it is for weeks now and it sounds fine and has no obvious problems that I can tell.

The driver is NOT the limiting factor above 25hz at-least in either cab. There is no doubt about this. It is not like the amp has a bunch of power in reserve running the ported cab. The amp will go into heavy clipping or shutdown altogether if I push it hard enough with either enclosure. It also does not appear as if the amp has enough juice to mechanically damage the drivers in either cab. This is not to say that it is not capable of pushing the bejeezus out of them but it is not as if I have to be careful with things for fear of damaging something.

The vc's are wired in series on both cabinets and I'm using the same Neutrik Speakon cable wired for bridge for both cabs. The polarity of the 2 drivers being different is a possibility maybe, but I wouldn't expect that to have this large of an impact either. With being a split coil design maybe it matters whether you wire to the top coil or bottom coil first?:confused: I don't know.








WFT3 impedance trace for the sealed cab





ported
 

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Discussion Starter · #35 ·
Here are the power compression tests for the sealed cabinet and ported cabinet. These are the 1M size full 21.8sec sine sweep in REW from 0-100hz with the mic at the listening position which is a little over 4 meters away from the drivers. The tone starts low and goes high. I would think that this is actually rougher than the descending tests that start at the higher freq's and go lower because the increased excursion at the lowest freq's will cool a driver better, while with the excursion decreasing as the freq's increase would decrease the air cooling in the driver motor. I started at a nominal level and increased the drive level by 3db for each sweep until there was clear distress from either the drivers or amplifier. After which I tried increasing the level by 1db at a time to determine whether it was worth going any further. This was done back to back repeatedly and sometimes multiple sweeps had to be done at the same level to get a good reading, so by the time that the loudest level sweeps were done the drivers vc's should've been well heated;).




This is the sealed cabinet. The first sweep is at -33 and the level was increased by 3db each sweep until -18db. The final one, which was only increased by 2db, is at -16db.






This is the ported set of measurements. The first sweep is at -39 and the level was increased by 3db each sweep until -24db. The final sweep was at -23db. As you can see the port is compressing heavily in the final 3 sweeps. Apparently even the crazy 10" sonotube based port system is not enough to handle this driver:(. There are huge amounts of air coming out of this thing! Guess I should've used a 12"er.




This is the 2 overlaid at the lowest sweep level. -33db for sealed and -39db for ported



This is the maximum sweep level attained for each overlaid on top of each other. The ported has been increased 16db to -23db and the sealed has been increased by 17db to -16db.
 

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The vc's are wired in series on both cabinets and I'm using the same Neutrik Speakon cable wired for bridge for both cabs. The polarity of the 2 drivers being different is a possibility maybe, but I wouldn't expect that to have this large of an impact either. With being a split coil design maybe it matters whether you wire to the top coil or bottom coil first?:confused: I don't know.
This is an AC signal, so you're backward half the time anyway. I cannot imagine any way in which this could make a difference to a coil of wire, at least at the frequencies in question. When you get to rf and microwaves, everything turns surreal.

In any case, it's easy to check, just use a battery across the terminals to assure the cone moves in the same direction on both boxes.

If you had the coils wired opposing, you'd have a heater, not sound.

Something else is causing your discrepancy, I suspect.
 

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Discussion Starter · #37 ·
Sorry for the delay. I had a few things come up. Here are the THD numbers for the sealed and ported cabs in room at the listening position.



63hz ported, 2.274% THD, 115.3db




63hz sealed, 6.217% THD, 116db




50hz ported 1.853%THD, 115.6db




50hz sealed, 2.2% THD, 116db




40hz ported, 3.315%THD, 114.9db




40hz sealed, 8.032% THD, 112.2db




31.5hz ported, 3.237%THD, 116db




31.5hz sealed, 10.588% THD, 118.2db




25hz ported, 5.707%THD, 118db




25hz sealed, 8.314% THD, 117.8 db
 

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Discussion Starter · #38 ·
Here is the good stuff. 20hz and below:)


20hz ported, 10%THD cap, 10.5% THD, 115.4db




20hz sealed, 10% THD cap, 9.377% THD, 115.6db




20hz ported, no THD cap, 23.936% THD, 119.3db





16hz ported, 10% THD cap, 10.691% THD, 111.1db





16hz sealed, 10% THD cap, 9.417% THD, 106.3db




16hz ported, no THD cap, 24.3% THD, 118.8db




16hz sealed, no THD cap, 22.764%THD, 112.2db




12.5hz ported, 5.757% THD, 119.8db




12.5hz sealed, no THD cap, 32.149% THD, 109.5db



12.5hz sealed, 10% THD cap, 10.941% THD, 102.9db




10hz ported, 10% THD cap, 10.3% THD, 113.8db





10hz sealed, 10% THD cap, 10.388% THD, 105.3db





10hz ported, no THD cap, 24.365% THD, 116.8db





10hz sealed, no THD cap, 32.149% THD, 109.2db
 

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Discussion Starter · #39 ·
There appears to be a trend toward a wee bit higher distortion in the sealed box at freq's above 25hz. The 40hz reading is a bit high for the sealed box because there was a dip in it's response that the ported cab did not exhibit as much of. Seems like things are about where they should be. I'm happy that both subs remain at 10%THD or way below until the 20hz test. It's no surprise that the ported sub dominates at 10hz and 12.5hz which are right in the tuneing range. I actually stopped the 12.5hz test because I was starting to worry about the structural integrity of the house. There was probably a bit left at 10hz too but with distortion hitting 20% levels I didn't feel like there was a need to push it further. I feel like the sealed sub did well since it is smaller less well built and all that. With peak output of probably 110db at the listening position at 10hz, albeit with high THD levels, I'm happy. When I get all 4 drivers running sealed that will add 12db across the board. Should be retardedly capable below 20hz.:)
 

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Ricci, I think that the gain in output in the vented cabinet can be attributed to the impedance, and air spring. The impedance in box is higher in the vented cabinet, and the air spring is weaker. The amplifier will be more linear and able to produce more voltage into the load. It would be interesting to actually measure the voltage across the terminals on both, running a sweep with the same settings.
 
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