Huge drop in DB above 55HZ

J

Jamesrxx951

Enthusiast
I have a pair of HSU VTF-2 subs. The room is 20X21 with 8'8" ceilings. All drywall room. Marantz 6013 receiver with single subwoofer output. Mini DSP 2X4HD and Audessey turned off. I have been playing with delays, inverted etc and i just cannot get a higher output above 55hz unless i have my front towers plugged in. But i have my subvcrossover set to 250 and all speakers set to small and 80hz. Not sure if i am a candidate for 4 subs but i have tried to place my subs in various locations that i can do in there. The theater section is offset to the side because i have a kitchenette/bar area to the right of theater side. Not sure if i can attach the REW graph to this or not but i am not sure what direction to go right now. Trying to read as much as i can but as a beginner i seem to be getting overwhelmed.
 
S

shadyJ

Speaker of the House
Have you tried moving the subs around, if you have other places for them? If the bass just goes away and stays away above 55 Hz, there may be some kind of low-pass filter in effect somewhere in the system. I would take the MiniDSP out of the equation for now. I would measure each sub with everything in the system at default settings to rule out some kind of electronic filter. Make sure the subs have the same phase setting. It may be a room mode, of course. You should show your measurements, it will give us a better idea of the culprit.
 
J

Jamesrxx951

Enthusiast
Have you tried moving the subs around, if you have other places for them? If the bass just goes away and stays away above 55 Hz, there may be some kind of low-pass filter in effect somewhere in the system. I would take the MiniDSP out of the equation for now. I would measure each sub with everything in the system at default settings to rule out some kind of electronic filter. Make sure the subs have the same phase setting. It may be a room mode, of course. You should show your measurements, it will give us a better idea of the culprit.

I bought the MiniDSP in hopes of fixing the drop. It didnt make any difference. I did try a bunch of different locations that i have available but to no avail. I also thought of some filter but so far i cannot find anything left in the Maratnz menu. Do you have suggestion to show my measurements? I have it saved in REW but i cannot figure out how to post it here.
 
TLS Guy

TLS Guy

Audioholic Slumlord
You have your answer. Plug in your main speakers. What you are seeing is port reinforcement plus probably some room gain, especially if your room is on the small side.

Subs are for that last two and a bit octaves at most. Set you crossover to 60 Hz and let your other speakers do the rest.

Sub over expectation is common as is misuse of subs.
Major myth around here. If you have a massive over sized sub and puny speakers everything will me marvelous. Wrong, wrong and wrong again!. The power of music lies especially between 80 Hz and 600 Hz, and actually right up to 2.5 Khz at least before power demand drops away. That is where you need the power band response. In recent years that seems to have been forgotten. That is a total disaster and train crash.

I have come to the conclusion that not paying attention to the power band response of speakers is by far and away the biggest current oversight in audio and one of the greatest impediments to realistic reproduction.
 
William Lemmerhirt

William Lemmerhirt

Audioholic Ninja
On the graph screen, click on the “camera” icon. “Save as” etc. then upload to AH from your files.
 
S

shadyJ

Speaker of the House
I would say try running the subs without the Marantz. Take a response sweep using something other than the Marantz to send the signal. It looks like it could be a room mode, but you have to be sure, so we need to eliminate the Marantz as the source of the problem.
 
SwedishChef

SwedishChef

Audioholic Intern
One possibility is that the Hsu are set to internal crossover, rather than external. And that the internal is is set for something like 50hz. That could happen if the crossover knob was ignored because it wasn't being used, and a switch got bumped from ext to int.
 
everettT

everettT

Audioholic Ninja
I'd contact them, also I'd like to see a straight 85db sweep if you could.
 
S

shadyJ

Speaker of the House
Thanks William L.
The room mode calculator shows lots of modes for room dimension where you are seeing that null region. To be sure this is the case, take measurements from different areas of your room, and see if this changes. The solution may be that you might need to move your listening position. There are also some acoustic treatments that can help with this, but they tend to be pretty large.
 
highfigh

highfigh

Audioholic Overlord
I would say try running the subs without the Marantz. Take a response sweep using something other than the Marantz to send the signal. It looks like it could be a room mode, but you have to be sure, so we need to eliminate the Marantz as the source of the problem.
Really? You want to blame the Marantz for this?
 
highfigh

highfigh

Audioholic Overlord
I bought the MiniDSP in hopes of fixing the drop. It didnt make any difference. I did try a bunch of different locations that i have available but to no avail. I also thought of some filter but so far i cannot find anything left in the Maratnz menu. Do you have suggestion to show my measurements? I have it saved in REW but i cannot figure out how to post it here.
You can't equalize your way out of the room's dimensional effects. What you're seeing is the result of the interaction between the woofers and the room's dimensions- 21' has a mode at 53.8 Hz and 20' has one at 56.5 Hz, assuming the speed of sound is 1130 ft/second. to find the first mode, divide the speed of sound by the dimension (lower case c is used to denote that in the formula) and do the same for c/2, 2/4, 2c, 4c, etc.

If you have a few bucks for experimenting, get some Owens Corning 703, fasten two pieces together and wrap them in muslin (any fabric store will have it and it's cheap), then put the panels in the corners of the room. You'll need to stack them two high- watch REW as you do this and you'll be able to see the difference in real time.

I hated the sound in my living room until I did this and now, I don't even think about acoustical problems or constantly fiddle with anything- I use no equalization in my system.
 
highfigh

highfigh

Audioholic Overlord
The room mode calculator shows lots of modes for room dimension where you are seeing that null region. To be sure this is the case, take measurements from different areas of your room, and see if this changes. The solution may be that you might need to move your listening position. There are also some acoustic treatments that can help with this, but they tend to be pretty large.
Great link.
 
S

shadyJ

Speaker of the House
Really? You want to blame the Marantz for this?
Yes, this is clearly Marantz's fault. Marantz has repeatedly shown disdain and disregard for social norms, as well as a near total lack of respect for civil decorum. Marantz's corruption is well-known. Consider the mountain of documented misbehavior that has been made public, and then consider that is only the stuff we know of. I can scarcely believe that you are defending Marantz. Is there nothing so monstrous that they do that you would stop being an apologist for their reign of terror? ;)
 
highfigh

highfigh

Audioholic Overlord
Yes, this is clearly Marantz's fault. Marantz has repeatedly shown disdain and disregard for social norms, as well as a near total lack of respect for civil decorum. Marantz's corruption is well-known. Consider the mountain of documented misbehavior that has been made public, and then consider that is only the stuff we know of. I can scarcely believe that you are defending Marantz. Is there nothing so monstrous that they do that you would stop being an apologist for their reign of terror? ;)
Those bastiges! 'Dis is fargin' war!
 
ryanosaur

ryanosaur

Audioholic Ninja
Yes, this is clearly Marantz's fault. Marantz has repeatedly shown disdain and disregard for social norms, as well as a near total lack of respect for civil decorum. Marantz's corruption is well-known. Consider the mountain of documented misbehavior that has been made public, and then consider that is only the stuff we know of. I can scarcely believe that you are defending Marantz. Is there nothing so monstrous that they do that you would stop being an apologist for their reign of terror? ;)
Free the woofer! Free the woofer! Free the woofer!
 
J

Jamesrxx951

Enthusiast
Thanks for all the suggestions everyone. I will try the owens corning stuff to see if that may work. The room is large and some treatment may be in order. I have also played with one sub at a time in all the areas that are easily able to house a sub. Between all of the spots i found, if i have 4 subs in those places it may fill in the voids. I also played with the mic in several areas like was suggested and it seems that the seats are in the exact spot that sucks in that area unless i move the subs around. Then that gap fills but a different one shows up. so maybe having 4 subs going it may even the response....................i hope. The biggest reason i really started messing with it is the bass in some of the music i listen to seemed to be weak. Movies seemed to be pretty strong though. I think this may be the reason.
 

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