Subwoofers and Crossovers.

@avanti1960 , my main aim in high passing the Spendors is to eliminate intermodulation(amp) and doppler distortion(speakers). I will also be setting one of the presets to disable the subs and run Spendors full range.  I will post my experience in this thread. 

Also, I have been reading such good things about bi-amping and adding subs with high passing the mains is another form of bi-amping.

PS. In this journey, I read your subwoofer threads in the other forum.

Yes, thank you.  I have learned a lot in my journey!   

Some speakers work well with the right subs, some do not, and ultimately if you value speed, dynamics and lightening burst timing no subs are best.  

Not everyone values that however.  

Good luck! 

I had Rythmik FM8s and miniDSP SHD delivered by Saturday and have been fiddling with REW and miniDSP software until now. The subs are flanking the Spendors on the inside.

Myt steps in setting them up.

1. Level matching the subs to the mains. Initially I put them one notch above zero, but dialed them back to zero.

2. Measured subs and the mains one channel at at time at different crossovers ranging from 80 to 150. Left channel was fine all across, but the right channel was not performing well between 100 and 120. So I had to choose either 90 or 140/150 and I decided to cross them over at 150 with 24db/octave.

3. Time delaying the mains was the most time consuming step, as I had to learn the process. After several measurements and methods, the results I had was 7.5ms for the left and 7ms for right channel.  I decided to set both of them to 7.5ms

4. Finally ran Dirac Live to flatten the response curve with a little boost in the bass area.

I am going to leave it with these settings for some time.

I am noticing two immediate benefits:1. There is more bass with more texture and the drum beats have a sharper starts/stops. 2. Vocals are clearer without being effected by base notes.

I am grateful  to the forum members for all the help and guidance.

@dimbhaka thanks for reporting back with your results!  This is a very interesting solution and I hope you'll report back again in a few months after these changes settle in. I look forward to your update and I'm pretty sure I'm not alone.

When I measured the time difference previously, I had 7.5ms for the left and 7ms for the right main/sub matching. It is probably related a little asymmetry in my room.   So I was looking for another way to calculate the time delays for the mains and I came across an article by Merlijn van Veen.

I set the main and sub with baffles in the same plane and setup my microphone directly pointed directly at them from around 5ft. I took three measurements each for the sub and the main.

First I used another method I read elsewhere to calculate the time difference using the step graph in overlays window. I calculated the average of all the nine combinations and arrived at a time delay of 6.06ms for the main.

Then I followed Merlijn's method:

1. The phase lines of the subs and mains were clustered together respectively. So that gave me confidence in my measurements.

2. The phase offset was 305 degrees at the crossover frequency of 150Hz; so they are off by 0.85 cycle.

3. Full cycle time is 6.67ms and 85% of it is 5.67ms.  This is the delay if the baffles are coplanar.

4. I positioned the speakers where I had them since before the subs came in and placed the subs 6 inches behind them. As the mains are ahead, I had to add the time for 6 inches which came out to be 0.44ms.

5. Time delay set in the miniDSP SHD is 6.11ms(5.67+0.44).

So far  the improvement is good with a cleaner mid-bass.