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Another sub position question

Orbison

Well-Known Member
In general, would the best sub location in a room be the same no matter what brand/model sub is used?

The reason I ask is that I want to do the test where the sub is put in the normal seating position and the mic is moved around the room. However, my SVS pb12-NSD is too big/bulky for me to lift by myself into my listening position safely. I have an old DefTech ProSub 200TL which is smaller & lighter with a 12" woofer. If I use the DefTech for the test, would the resulting best location indicated be valid for the SVS? Granted, the frequency response is not going to be the same, and the SVS certainly goes lower than the DEF Tech, but I'm concerned more about the response flatness in the 40- 70 Hz response range.

:text-feedback:
 

Rope

Well-Known Member
Famous
Orbison said:
In general, would the best sub location in a room be the same no matter what brand/model sub is used?

The reason I ask is that I want to do the test where the sub is put in the normal seating position and the mic is moved around the room. However, my SVS pb12-NSD is too big/bulky for me to lift by myself into my listening position safely. I have an old DefTech ProSub 200TL which is smaller & lighter with a 12" woofer. If I use the DefTech for the test, would the resulting best location indicated be valid for the SVS? Granted, the frequency response is not going to be the same, and the SVS certainly goes lower than the DEF Tech, but I'm concerned more about the response flatness in the 40- 70 Hz response range.
:text-feedback:

The only reservation I have is with the lower frequencies, although if that's not a concern, I don't know any reason why the Def Tech wouldn't work perfectly in that capacity.

Rope
 

Alien

Active Member
Yeah I would think that in that short of a frequency range you could transpose whatever you measure to the other sub, it seems the best you could do with the situation. The only other factor I could think of is the phase response...
 

Orbison

Well-Known Member
Thanks Rope. Considering the lack of responses, I guess it was A: a really dumb question, or B: something nobody had ever tried.

So yesterday I tried it - put the Def Tech sub in my listening position at ear level and ran tests in various locations including the spot where my SVS sub is positioned. Due to the room layout the 10 test locations were each about a foot apart in a line across the front of the room (none closer than 3' to side walls or corners) where the TV and L/C/R speakers and sub are. I used a pink noise track on a CD and my frequency spectrum analyzer. The Def Tech sub low-pass filter was set to the maximum of 150 Hz and has a 250 watt amp vs the 325 watt SVS. Both have 12" woofers. Test levels were run at about 70 dB. No room acoustic treatments, carpet on floor, leather furniture, ceiling slopes up from 8' on left to about 12' on the right when facing the front where the L/C/R's are located. Room size 15' wide across the front by 20' deep with openings to dining room, hallway and stairs behind the listening position. No EQ applied to sub. Weighting set to C-slow.

All of the Def Tech results were very flat and very similar along a 10 foot line, the best being +/- 3 dB between 40 Hz and 100 Hz. The sub didn't have the significant response dip in the 40 Hz to 50Hz range that the SVS has. (the SVS test result was with the mic in the listening position)

My conclusion based upon my limited understanding of this stuff: the extended low end of the SVS (down to 20 Hz vs 30 Hz of the Def Tech) is exciting room modes causing bigger dips in the response curve.

Perhaps one of our members can confirm my conclusion or explain where I'm going wrong.

p.s. I would have liked to run a series of TrueRTA quick sweep tests, but that program with my M-Audio Mobile Pre had previously shown to be wildly inconsistent in it's results.
 

Orbison

Well-Known Member
Alien said:
Yeah I would think that in that short of a frequency range you could transpose whatever you measure to the other sub, it seems the best you could do with the situation. The only other factor I could think of is the phase response...

Thanks Alien. The SVS phase was previously tested and set to the optimum. The Def Tech has no phase adjustment.
 

Flint

Dog Faced Pony Soldier
Superstar
While not absolulte ideal, it is fine to use a smaller sub in place of a larger one for this method. The frequency ranges where placement are most critical tend to be above 30Hz anyway, so just about any moderate quality sub could work in most cases.
 
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