Subwoofers.... one 10" or two 8"?

In theory, if  you have the time and space to find the optimum location for the subs, 2 assymetrically placed subs will usually yield a smoother combined response.

Having said this, a 10" sub is a lot better than an 8". The surface area a 10" driver can move is close to that of 2 x 8" woofers, so distortion, low frequency and dynamic range all get much better with those 2 extra inches.

Looking at the review though, I would think an EQ is a better solution than a sub for you.  Or an EQ and a subwoofer. I'm actually really surprised to see measurements that show such a difference between the treble and bass (10 dB!) That's kind of huge. Adding more bottom end weight may be the worst possible thing.  The only way to tell is to measure in room though.

Best,


Erik

A phone with a calibrated mic does much better than the SPL meters of yore for consumers.

The Dayton Audio imm-6 ($24) with something like the Android Audio Tools is really very very good.

Doesn't come up to the level of Room EQ Wizard or OmniMic, but for basic calibration it's hard to beat.

Best,

Erik

The latest Music in the Round from Stereophile features the use of two JL subs, and charts showing how they fill in.

Still, it's not unreasonable to get one very good sub, see if you need two. :)

I most certainly am more than happy with 1 Hsu 15" sub. My listening space does not lend itself well to characterization and I have bass traps where they need to go. YMMV.

Best,


Erik

@oleschool

Um, not sure the context, but true subwoofers have no real reflection points, the waves are so big that a reflection point would be around 10’ wide. At the mid to high frequencies where the wavelength is near or smaller than the driver dimension, sound travels like rays, so reflection points in a room matter a lot and are easy to treat with conventional panels and diffusers.

On top of that, most panels are completely ineffective below 300-400 Hz. Instead we rely on bass traps placed in corners where the maximum pressure points occur. Even a lot of "bass traps" don’t go much lower than 120 Hz, and below that is where the big issues occur. In this area, the GIK Soffit traps are unbeatable for effectiveness and cost. 

Best,


Erik

Um, yeah if that’s all you are trying to do. However you are not guaranteed accurate amplitude or phase matching above and below that point.

I’ll give you that it’s quick and good enough for many, but it's hardly comprehensive.


Erik

@leotis

That's a huge amount of "group delay." I think you are confusing that sub's are often located several feet behind the mains.

As for aligning by ear, great googly moogly no! :) It's far easier, faster and more accurate to fully align with a tool like OmniMic or AudioTools or Room EQ Wizard than by ear! :)

Assuming the room modes are dealt with, the second stage in integrating a sub are to integrate it with the main speaker. This runs into the same issues a speaker designer would have in blending one driver with the next. Meaning, crossover slopes and phase alignment to provide a seamless transition from the subwoofer to the main's output. You should not be able to tell by looking at the frequency response where the sub ends and mains start, it should appear like 1 single speaker.

Best,


Erik

@larstusor

It means a lot of things, but in general it means making sure that each driver you are listening to blends seamlessly with others despite being located at different distances from the listener.  It matters in multi-way speakers as well as in integrating a subwoofer with a main speaker. This really is "phase alignment" but in use it's often called "time aligned." 

In flat baffle designs, each driver has a different acoustic distance from the listener. Phase alignment means you've taken that and the phase of the crossovers into account so that the frequency response has no dips/valleys where they meet.  Here is an example from a speaker I designed, the LM-1.  Look at the second and last chart for more information. 

At it's most stringent, time alignment may mean having a perfect impulse or step response.  Van DerSteen is famous for this type of design.  Look at the step response in Stereophile's review of the Seven and compare it to the LM-1.  Thiel is also a manufacturer that specialized in time-alignment.

Best,


Erik