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

@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

Hey eric 
. Aren't  reflection points playing a big role there also . When i used treatment on the points . The ole mirror reflection spot gik talks about it helped immensely. Op cant run treatment though 

@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

@leotis 
Your 8/13 2:27AM post seems very helpful.  THANK YOU.

I'm planning to try it integrating SVS SB1000s with Silverline Prelude Pluses that claim a lower end of mid 30s Hz.  

For anyone interested, an on-line tone generator is available at the link below.

http://www.szynalski.com/tone-generator/