XT32 Results as Tested with REW

[gadgtfreek]

 

...so I can probably work out the sub dip at 22hz with it.

 

That looks like a room mode at 22 Hz.  What are the dimensions of your room and where did you place your microphone relative to the subwoofer(s)?

 

You can usually see if there is a room mode issue by looking at the group delay plot in REW--if GD is high at the frequency area of interest, you're probably looking at room mode or speaker placement.

 

Are you running an upsweep from REW and using that to drive your system, or are you using a CD to generate a drive signal?

 

Chris

 

I used the REW and my laptop as the up sweep generator.

 

I am going to have to do more reading on null's and room modes, etc... I am a newbie at this for sure. The subs are on both sides of the tv stand, by the fronts and the measurement was taken at the MLP about 10.5 feet away.

 

I probably will not attack anything further until I get both subs changed out and see what I am dealing with too, so I have some time to research the problem. The subs are where they are too, I cannot move them anywhere else.

[gadgtfreek]

Run after the new sub was put in. The sub response from 10-80 is better with one rythmik and one hsu, vs two hsu's. makes me wonder what it will be like when I get the second rythmik. it digs to 12hz.

 

Edited June 5, 2015 by gadgtfreek

[etc6849]

ChrisA is very knowledgeable, you're definitely on the right track with him involved.

 

I'm sure you know this, but frequency response is only a small part of having a great sounding system.  I listened to ChrisA and this thread, adding lots of bass traps and treatments, and my system is now the best I've heard.

Edited June 7, 2015 by etc6849

[gadgtfreek]

http://gikacoustics.co.uk/what-are-room-modes/

 

Found that. I need to do the calculations tonight or tomorrow and see what it tells me.

 

Below is the formula for calculating all room modes, not just the axials.
F = c/2 * sqrt(p^2/L^2 + q^2/W^2 + r^2/H^2)

F= Frequency
c = speed of sound (1130 feet per second or 344 meters per second)
sqrt = Square Root
^2 = squared
L = Length of Room
W = Width of Room
H = Height of Room

[Chris A]

If you open up REW and look to the right-most button at the top within the window, there is a button labeled "Room Sim".  Click on that and you'll see a box that allow you to put in your room dimensions and your listening position.  Under the "Speaker Controls" expandable window, you can check off having a left and right front speakers, and up to four subs.  Then you can position those subs and fronts within the graphic window at the bottom left, making sure to check the "Show Elevation View" box to set the height above the floor for your loudspeakers and listening position.

 

When you finish inputting those values, then you can grab the listening position or any of the loudspeaker positions and move them around while looking at the FR window at the top right.  This will show you interactively how your loudspeaker positions and sub placements affect the frequency response at the listening position for all frequencies up to about 200 Hz (i.e., the "sparse room mode region"). 

 

Voila!

 

Chris

Edited June 7, 2015 by Chris A

[gadgtfreek]

If you open up REW and look to the right-most button at the top within the window, there is a button labeled "Room Sim".  Click on that and you'll see a box that allow you to put in your room dimensions and your listening position.  Under the "Speaker Controls" expandable window, you can check off having a left and right front speakers, and up to four subs.  Then you can position those subs and fronts within the graphic window at the bottom left, making sure to check the "Show Elevation View" box to set the height above the floor for your loudspeakers and listening position.

 

When you finish inputting those values, then you can grab the listening position or any of the loudspeaker positions and move them around while looking at the FR window at the top right.  This will show you interactively how your loudspeaker positions and sub placements affect the frequency response at the listening position for all frequencies up to about 200 Hz (i.e., the "sparse room mode region"). 

 

Voila!

 

Chris

Freaking sweet!!!

 

I admit I havent had time between work, learning REW basics and getting my laptop setup to play with more than the measure and SPL features. I may send another donation REW's way, the software really is cool.

 

On that note, I went ahead and ordered a verified CM140 SPL meter from Cross Spectrum. I am seeing some odd issues using the Umik 1 as an spl meter, and when comparing the Umik 1 numbers to the SPL meter I have, my ears tell me the SPL meter is giving a better level result. I have no choice but to level match after XT32 completes because the 64ii adjustment bottoms out at -12db. So, it is very important that I can accuracy match the subs and speakers to 75db at reference volume on my preamp. The CM140 is good for 31.5hz to 8khz and the -30 and -40dbfs tones on the blu-ray I have are 30hz to 2khz pink noise.

 

I spoke with Herb at cross spectrum about this yesterday, and I gotta go with the recommendation from the guy who went to MIT and is engineer.

[gadgtfreek]

Looks like the left sub is the issue. I input all the heights for the front and left speaker, the two subs, the distance for all them, the room measurements and the MLP data.

 

When I highlighted each sub, the sub to the right was fine, but the sub to the left just drops off the chart under after it makes that 24hz bump. If I put the subs back to where they were on the outside of the fronts, instead of inside, the right sub is still fine and the left sub peaks up the match the "main" graph very closely. I wonder if I should not move my fronts back inside as it seems the farther spread out sub 1 is on the left the better under 30hz.

 

Left sub inside

 

Right sub inside

 

Left outside

 

Rigtht outside

[wvu80]

Knowing my upgraditis I am sure I will end up with a mini dsp...

 

Well, good, we are all pulling for you.  

 

The first step towards dealing with an audio addiction is to acknowledge you have a problem. 

Edited June 8, 2015 by wvu80

[Chris A]

Looks like the left sub is the issue. I input all the heights for the front and left speaker, the two subs, the distance for all them, the room measurements and the MLP data.

 

When I highlighted each sub, the sub to the right was fine, but the sub to the left just drops off the chart under after it makes that 24hz bump. If I put the subs back to where they were on the outside of the fronts, instead of inside, the right sub is still fine and the left sub peaks up the match the "main" graph very closely. I wonder if I should not move my fronts back inside as it seems the farther spread out sub 1 is on the left the better under 30hz.

 

Left sub inside

 

Right sub inside

 

Left outside

 

Right outside

 

Too bad you can't turn the whole setup 90 degrees to the right - then I believe all your problems will disappear and you will be rewarded with much better front and sub coverage.

 

I've always learned to put both subs in corners, and you actually have the option of doing this in your present setup by moving the left sub to the right rear corner--but only if you're crossing low enough to your fronts.  I recommend crossing below 60 Hz in order to eliminate the localization of the subs' output by the listeners.

 

If you have more than two subs, then you can begin to "fill in the holes" in LF room coverage by placing the extra subs at wall midpoints, etc.  There is a lot written on this subject, but note that PWK was the original proponent of placing the lowest-frequency loudspeakers in the corners.  The reasons you will see in the Room Sim utility within REW, especially as you move the listening position around a bit after placing the subs in corners.  When I say "place the sub in the corner", I'm recommending that you place them within 12 inches of the room corner itself. 

 

Try it within REW Room Simulator to see if it works.  Then you try in your room for real to verify that the simulator is telling you the truth.

[gadgtfreek]

And the room is even worse than it looks.

 

To the left of sub one (from the MLP) there is a small hallway to a bedroom and a bathroom. So they sub can only move to the left so far. On on the other side of that opening is a fireplace. The 13ft wall on the left is actually a window and back door...

 

Now, the 13 foot wall on the right is not actually a wall. It is open into a dining on the wall the subs are on, and the wall the MLP is on it curves into a kitchen. Instead of being a true rectangle, it is a "T". That 4200 cuft measurement doesnt include this whole other area, so the are actually no corners at the front with the subs.

 

I have some more testing to do, in where I want to run the Rythmik sub in all 6 modes with XT32 off and by itself, to see the freq resp of each. I then want to do all three modes of the VTF15 by itself to see if either have a mode that is similar to each other in result. I figure this is the best way to pair modes from two different branded subs. It'll be awhile before I get the next Rythmik.

 

i was also told to run sub sweeps to 250hz (LFE crossover up high in XT32) to get an idea where the speakers and subs overlap well for proper setting of the crossover. I have a good feeling the RF7ii's would do fine at 60hz but I need to do some more testing.

[derrickdj1]

Running the RF 7's as small, I run the sub sweeps to 200 and don't worry about LFE.  I use 1/6 smoothing and adjust the graph for 10-20 Hz up to 200 Hz.  It is much easier to see what is going on this way.  As Chris said, a couple more subs will give the room the best FR possible.  Each room can only get so good and we have to live with it.    A MiniDSP will give you the ability to make a few boosts and cuts as needed.

 

As a general rule, I don't like using more than 3 PEQ changes.  If more are needed, the location of the subs and seating may need to be looked at.

[gadgtfreek]

Did some more testing today. I set the Rythmik up in 1 port open, low damp mode and 14hz, and the Hsu in max extension 1 port mode. And then set them up in their 2 ports mode.

 

The red is of course both of them in 1 port open calibrated by XT32. This mode really digs deep and when the sweep ramps up from REW the 1 port open mode starts rattling stuff early. I also have a BAS test tone CD, and with the 16hz tone the 2 ports mode is quiet as a mouse, the 1 port mode not so much.They are very similar until you hit 20hz.

 

 

One other thing I wanna do is set the fronts and center xover to 40hz and see how they roll off down low. 

Edited June 9, 2015 by gadgtfreek

[K5SS]

Nice to see another Rythmik fan on this site!

[gadgtfreek]

Nice to see another Rythmik fan on this site!

 

I am impressed. For one, Hsu, SVS and Rythmik are well designed offering you several tuning modes, instead of just a port and "deal with the results". Not that it is a bad thing, but by all reports one port plugged for max extension means LESS output. And they test that way in a field, or whatever. However, in my room, one port plugged digs deeper and is louder than 2 ports, but room gain comes in here I guess. Which is why I am glad I spent $100 getting into REW, for simply testing sub modes. You really do not know what the best mode is until you can test, or have someone test for you.

 

I knew the FV15HP would have more power, but the numbers I have seen by just replacing one Hsu at 12, 16 and 20hz has been pretty cool, and I cannot wait to get the other. Let me be straight though, the VTF15MK1's have served me well and gave outstanding bass for a few years. I'm just getting more into it and making the next step. A lot of what held the VTF15MK1 back (driver is not as well built as the SVS and Rythmik models and the amp is underpowered) has been changed with the MK2. Which is why I had to decide to get two of those or the Rythmiks. When I decided to go dual 15"s a few years ago, my ranking was FV15HP, PB13 ultra and then VTF15. I went with dual VTF's because of budget, so this go around I decided to go with the guys I wanted the first time. IMO, SVS is gonna be in a pickle with the new VTF output/pricing and the new dual 18" from PSA and its output/pricing.

Edited June 11, 2015 by gadgtfreek

[derrickdj1]

I am glad you like the new subs.  just remeber Hoffman's Iron Law:  bass efficiency, extension and enclosure.  You can get two but, nobody can have all three when it comes to sub design and build.  In other words, there is always a compromise.

[gadgtfreek]

I wish you could get more bass from little enclosures LOL.

 

That is where they FV15HP and VTFMK1 are similar and different. Size is right there, granted the FV15HP is a little smaller which is NICE, but the quality build of the woofer and twice the power gives it the muscle.

 

Also looks better IMO. I like the ports are covered up (dog toys and dust), and the matte finish is better than my VTF15's finish for marks and fingerprints.

[derrickdj1]

I know a lot of people talk about extension but, a comparable vented sub will smoke a sealed down to around 15 Hz by around 10 db, WoW, that's a lot.  Unless you are in a small cubby hole, there is not enough room gain to catch the vented sub.  The power used for extension cuts a lot of 15 to around 40 Hz output that is just as tactile.  Most likely more tactile since more power will go into the 15-40 Hz area and not strain the driver or amp as much.

Edited June 12, 2015 by derrickdj1

[gadgtfreek]

Using the BAS cd with test tones that Hsu sends you, this is the reference volume differences between dual VTF's in max extension mode to one VTF15 in max ext + the FV15HP in 1 port open, 14hz, low damp.

 

Test tone---VTF's db---Mixed Subs 1 port---Mixed subs 2 ports

16hz---85.8---92.5---82.7
20hz---85.1---93.2---90.2
25hz---84.4---91.4---92
31.5hz---88.5---94.5---92.9
40hz---92.5---96.5---94
50hz---94.6---97.8---94.4
63hz---96.2---97.5---94.2
80hz---98---97.9---97.1
100---98.4---100.7---95.1

In bayformers 1, there is a deep bass hit near the end of the movie on the highway fight scene, right after the MRAP decepticon runs thru the middle of the bus and destroys it:

107.3db---109.2db---108.7

In the city battle at the end, when iron hide flips over the lady sitting in the street, there is another good bass drop

108.3---111.7---110.3

Measure at the MLP with a Galaxy CM140 meter

Edited June 12, 2015 by gadgtfreek

[gadgtfreek]

I am going to do one final shot of graphs tomorrow. Try out some compression sweeps with both subs in 2 ports open mode before I move them both back to one port open mode (that will be where they are left), and then do some compression sweeps again.

[gadgtfreek]

What do you guys think about these 3 graphs and the concept of crossing the mains and center at 60 and not 80?

 

80hz xover

 

60hz

 

40hz

 

I think they look well in that 50-70hz range. The red is a sub measurement on a couple of them. They look like the extend down under 50hz without issue in the 40h setting. XT32 of course sets the mains at large and the center small and 40hz, which I then change them to 80hz and small.

Edited June 12, 2015 by gadgtfreek