Hsu VTF-3 HO REQ results....suggestions?

After much nashing of teeth and late nights I have managed to find the right memory for my PC, loaded up the REQ software and made all the physical connections. I am running the Hsu VTF-3 HO w/turbocharger through an Onkyo TX-SR573 receiver. Crossover is set at 80hz. My main listening room is approx. 15 ft by 22 ft w/vaulted ceilings - 3400 cubic ft. opening to the kitchen/dining area. I have the sub in the only corner available - a quotes far field placement relative to my seating position. This is all of about 10 ft. I have taken measurements with the sub in a nearfield position as well. Not much change, the lower end measures slightly worse than the graphs posted. I am using the digital Rat Shack Spl meter and I did load the calibration file. Soundcard calibration looked ok, I could not figure out the to perform the "left" soundcard check. Here is the soundcard calibration data and my best graph. Any ideas on how to bring up the low end? Obviously I can bring down the big peak if i go the BFD route.
Taking it a step at a time. Thanks for any suggestions,
Scott

[brucek]

Any ideas on how to bring up the low end?

Well, it's quite a large room and you're only using a 12" sub with a 350watt amplifier. The specs say it has a 20-25Hz extension. If you ignore the resonance around 40hz, you're not far off spec.

A corner will help, but there's not much you can do if that's how it measures. I would try equalizing the peak away and this will allow you to turn up the wholesale level somewhat to reveal more of the bottom end. A larger sub of course, would help with that room.

brucek

The VTF-3 HO has a 500 watt amplifier and with the turbocharger is supposed to be flat to 16hz. I was hoping I had forgotten a setting or two which would skew the results. Are there any room treatments short of installing doors which might improve the situation?
Scott

[fibreKid]

You "might" be able to get rid of that little dip around 70 by switching the phase to 180. Now I don't know where your mains are in relation to your sub, so it might have the desired results. It sure helped mine.

-john

[brucek]

The VTF-3 HO has a 500 watt amplifier and with the turbocharger is supposed to be flat to 16hz.

Yep, I admit I had never heard of this model.

I see why they call it a turbo..... :raped:




Well, either you have it in a really bad null in the room, or you're getting a very wide peak from ~20hz to 60Hz and if you cut that area it might have the extension you want.

Have you checked how it acts below 15Hz with REW to see how low it goes, or does it just continue to drop off.

brucek

[Wayne A. Pflughaupt]

My main listening room is approx. 15 ft by 22 ft w/vaulted ceilings - 3400 sq. ft. opening to the kitchen/dining area.

I assume you mean 3400 cu. ft, not sq. ft? If the kitchen and dining open to the HT room, you have to count all that space, too.

Are there any room treatments short of installing doors which might improve the situation?

Short of installing doors? No. Acoustical treatments aren’t going to “buy” extension. However, making the room smaller will.

Any ideas on how to bring up the low end? Obviously I can bring down the big peak if i go the BFD route.

The BFD can help the lower end, too. It wouldn’t take more than a few dB of boost to get you flat out to 20 Hz, which is pretty good in a big room with a single 12” sub.

Regards,
Wayne

John - The graph shown is sub only. The dip at 70 is pulled up when I have the mains added in the mix.
Brucek- I'll have to run another sweep to see what is happeming below 15hz.
Wayne - sorry, did miss the cubic in feet. Room is 15' x 22'. The sub is in the right front corner. The back right corner is angled in at a 45 degree angle due to a fireplace. Cuts a 7' x 12' chunk out. This is to my immediate right from my seating/measurement position. 9' ceiling pitched to 11' at the center. 6' wide opening to my immediate left, floor to ceiling for entry to the dining and kitchen area. The wall behind my seating position is open above 8' to the kitchen area. Funny if my room is too large for the sub to handle - the whole house is less than 1100 sq. ft. Thank you all for your comments.
Scott

[geekwithfamily]

Scott

I only have a VTF 2 and I get ample response to below 20 Hz in a 3200 cubic foot room. How do you have the sub set? Is it in max extension or max output mode? The 40 Hz hump looks like you're in max output mode which limits extension. Max extension mode gives you the flattest response (plus you need the ports plugged for extension mode as in the instructions (not sure how the turbo works))

Also could your AV processor be set to night time mode?

Speaker out from computer connnected to both left and right of CD input on the receiver. Night mode defaults to off and only works with Dolby Digital according to the manual. Sub amp switch is set to 16 hz w/ turbo - maximum extension mode. I am not sure what I should see but curve really did not change dramatically placing the sub nearfield, which placed it ajacent to the 6' wide opening to the dining area. Bottom fell off a little more and the upper end bounced a bit more.

[brucek]

You appear to have done everything correct in REW and in your measurements. I don't really know what to think. We haven't had this situation before.

Does the very low end appear to be weak in reality, and it's only the graphed response that shows it poor?

Have you tried your sub in a small room as a test to see if it then produces good extension - (bedroom)?

Have you considered perhaps there is a problem with your meter. Could you borrow another one to test that out?

brucek

I have spent the last few days working on answers to the questions poised by Wayne, brucek and GWF. From my answers I obviously should have been better prepared before posting my initial results. I acquired an analog SPL meter and verified my digital is producing correct results. Good news there. If y'all figured out I am in uncharted territory you are correct. This is my first sub and system. I do not have friends with HTS so I have no real basis for comparison. Wayne and GWF pushed me to accurately measure the true volume of the rooms.
Here is a layout of the room:

Ouch, 4700 cubic feet. The kitchen ceiling slopes from 8 ft to 13 ft. The living space slopes from 9 ft to 11 ft and back down to 10 ft. There is a pot shelf over the entry reducing the ceiling height to 8 ft. and the 5 ft straight wall behind the chair location is open to the kitchen above 8 ft.
From my readings in various forums I was certain the one corner of the living space was "the" location for the sub. Here is my original graph down to 10 hz in the corner:

I decided to go sub crawling after brucek stated "haven't had this situation before" . I tried locations between the chair and the fireplace, On the hearth of the fireplace, in the entry, to the right side of the couch and ended up as shown in the sketch, to the right side of the components' rack. Driver towards the wall about 5 inches away.
Here is that graph:

I am thinking this one is at least workable with the BFD.
Thanks for slogging through this if your still with me. Maybe this will help someone else break out of a corner
Thanks for all the help, Scott

[brucek]

I do not have friends with HTS so I have no real basis for comparison.

Welcome to the club. My friends usual response to anything I say about HT is, "You spent that much on a single CD player? Are you nuts?"............... I don't tell them what my speakers cost.....:raped:

4700 cubic feet. The kitchen ceiling slopes from 8 ft to 13 ft. The living space slopes from 9 ft to 11 ft and back down to 10 ft. There is a pot shelf over the entry reducing the ceiling height to 8 ft. and the 5 ft straight wall behind the chair location is open to the kitchen above 8 ft.

Wow, no rule-of-thumb standard practices for subwoofer placement can be used with a room setup like that. It's a very large area to use a 12" sub in (turbo or not). It also has difficult ceilings creating any number of unpredictable resonances. Trial and error is the way to find an optimum placement - and you did that..

I would say you did very well by finding a spot that would produce the response you have shown in the last graph. I would raise the overall level of the sub (at the sub amplifier) by about 5dB to 8dB and then do some cutting with the BFD. Something like I have shown below......




brucek

Well, I have a jumping off point I am having a hard time wrapping my head around all the graph is displaying. No matter where I establish sub calibration, my lower freq. sub output level will always be/graph low? This is due to my room size and boosting the sub 5-8 db is compensation? Given I do not have a BFD (yet), I could set the sub "hot" +5db to +8db with, say pink noise, to balance spl with the remainder of the system? Is this why I have plenty of overall volume but not the "pressurized chest" condition I read about but do not feel? Any suggestions on room treatments or is size reduction the only option? Would heavy curtains across my openings help or do I need solid barriers like walls and doors?
Good news is I have plenty of volume left on the sub. About 1/3 open. Thanks for the tutoring
Scott

[brucek]

Given I do not have a BFD (yet), I could set the sub "hot" +5db to +8db with, say pink noise, to balance spl with the remainder of the system?

No, my 'red line' suggestion only holds true to compensate for the loss of level you'll realize if you used BFD cut filters to reduce all the peaks above the red line. It is the accepted method of not adding 'filters with gain'. We simply cut where needed at the BFD (within reason) and compensate by adding wholesale gain with the sub.

Is this why I have plenty of overall volume but not the "pressurized chest" condition I read about but do not feel?

No, that's a result of a very large space being driven with a single 12" driver. It simply takes a lot of driver and a lot of power to pressurize a room that size.

Any suggestions on room treatments or is size reduction the only option?

Neither seems realistic to me. The only option is to use a couple very large subs with 15" drivers or subs with multiple 12" drivers driven with fairly large power amplifiers..

You've gained by relocating the sub you have. Maybe add a BFD (which you'll ultimitely need), and do some equalizing. Then see where you feel you're at.........

brucek

[Wayne A. Pflughaupt]

I decided to go sub crawling after brucek stated "haven't had this situation before" . I tried locations between the chair and the fireplace, On the hearth of the fireplace, in the entry, to the right side of the couch and ended up as shown in the sketch, to the right side of the components' rack. Driver towards the wall about 5 inches away.

Here is that graph:

Aamzing. It’s not often you see improved performance with the sb out of a corner. I just confirmed it again here at my place. I would have expected that open hallway right next to the sub to annihilate extension. But - the graphs don’t lie!

Any suggestions on room treatments or is size reduction the only option?

What low frequency treatments primarily do is reduce ringing (a.k.a. long decay times), similar to what carpet and heavy curtains do to high frequencies. They can’t improve SPL or extension.

Regards,
Wayne

I was very surprised to see the results with the sub adjacent to the hallway. I may attempt to run more sweeps with the doorway temporarily closed off.

I just confirmed it again here at my place.

Wayne, Are you saying you are seeing a better curve with your sub moved out of a corner?
A couple more questions, please. The Hsu comes with rubber doughnut style feet. My room is carpet over concrete. Would spiking the sub through to the concrete produce any improvements? And is it possible I am losing the very low end due to the lower end receiver I am using (Onkyo TX-SR573). I'll shut up now until I have completed my BFD assignments from brucek
Thanks, Scott

[Wayne A. Pflughaupt]

Hi Scott,

Wayne, Are you saying you are seeing a better curve with your sub moved out of a corner?

Sorry to be so vague. No, I’ve typically seen the best results with the sub in a corner, and I saw it again a week or two ago when I moved my subs to a corner. They had been in front of a wet bar that’s between two boundaries and near an open staircase.

Here’s the unequalized response I had at the wet bar.

As you can see, it fell like a brick below 35 Hz or so. That was the reading from the sofa with the mic in my left hand. When I put the mic in my right hand that deep null moved from about 28 Hz up to 35 Hz! Even with aggressive equalizing, I couldn’t get anything below 30 Hz.

Here’s the unequalized response I got after moving the sub to the front corner. As you can see, extension improved to about 24 Hz, and the deep null is gone.

Here’s response with equalization.

We had planned to install the subs in a custom cabinet recessed under the wet bar, all nice and out of site. Needless to say, we’re re-thinking that now. I guess I’m really lucky we haven’t had the funds to complete that project yet – I’d sure be hatin’ life right about now, having blown all that money on substandard performance! Aside from improved performance, I've really enjoyed the seamless blend of having the sub up front with the main speakers. I know, bass isn't supposed to be easily localized, but I could always tell it was coming from the side.

I came across this crude graph I made several years ago with 1/6-octave sine waves using the same subs, experimenting with various locations in our master bedroom, which measured 12’ x 16’. The graph on the right is corner placement. The one on the left is with the sub half-way on the 16’ wall, facing into the room (black) and turned to face the 12’ wall (pink).

As you can see, with the mid-way placement output is obliterated. Overall, response is so bad it's beyond equalization. I took other readings as well, adding a second sub in a corner catty-cornered from the one mid-wall, with both subs in corners catty-cornered, and with both subs in the two front corners. Only the latter got anything resembling decent response, but even that wasn't as good as both subs in the same corner.

A couple more questions, please. The Hsu comes with rubber doughnut style feet. My room is carpet over concrete. Would spiking the sub through to the concrete produce any improvements?

My understanding is that spikes help tighten the bass, due to solid coupling with the floor below. It won’t do anything for extension or output.

And is it possible I am losing the very low end due to the lower end receiver I am using (Onkyo TX-SR573).

I’d be surprised, but you never know. You could always try bypassing the Onkyo and going direct to the sub and see what happens.

Regards,
Wayne

Thought I would provide my latest graphs which I think look much better. Have not had the time to tweak it beyond this. More importantly, Wow! Even I can hear the difference! Yeah, I was skeptical. I thought I had bass before! Here is the curve without the mains:

Here is with mains:


The shown results required 9 filters, 5 below 80 hz, 4 above. Largest adjustment applied was -21 db at 158 hz.
I did try blocking the doorway to the right of the sub position. Actually made the curve worse.
Ended up -13 db on my receiver to prevent clipping on the BFD (1124). Not a problem except the sub's auto sensing does not kick in until the volume is quite high. Changed to using "on" or "off" mode. I am also experiencing a very small hum from the sub with no signal. I guess I will try the cheater plugs to see if it can be eliminated. Also need to see if I can find some threads on how to balance the mains into the setup. Guess that is about all I can pass along.Possibly someone else will find this helpful.

[brucek]

Ended up -13 db on my receiver to prevent clipping on the BFD (1124)

With that much attenuation, have you tried using the switch setting on the rear of the BFD that sets the operating level from -10dBV to +4dBu? Sounds like you would have enough level from your processor to drive it using that setting.

Also need to see if I can find some threads on how to balance the mains into the setup.

Just use the built in test tones in your processor.

brucek