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Dialing In Separate Bass Units for Best Response

For speaker systems which have a midrange/tweeter speaker which is separate from a pair of bass towers or panels:

For example:

Infinity IRS
Martin Logan Statements
Martin Logan CLS + Kinergetic woofers
Magneplanar Tympanis
Mini Monitors + pair of subs etc

Could any of you recommend a methodology for "dialing in" the woofers for the best bass response?

Can this be done separately from the mids/tweeters?

Use a Radio Shack spl meter?

Can separate woofer towers or panels be pushed into the corners or closer to the rear wall to "load" the bass response? Or does that create other problems?

Is it more critical to have the mids/tweeters well out into the room for less rear and side wall reflection? While positioning the bass panels only for best bass and without regard for their relationship to the mids and tweeters?

Or does disconnecting the bass and mid/tweeter units in this way somehow decouple them and make the sound less coherent?

My Tympanis sound pretty darn good, but I still somehow think I am missing out on that last bit of bass and coherence.

Picking up heavy spiked speakers and experimenting with 1" movements using Pink Floyd Dark Side of the Moon on repeat seems a little primitive and is making me exhausted.

Thanks for any ideas.
cwlondon
dewald_visser
176 posts
 
Okay - this might be a little scientific but I might just work. Get an oscillator or a CD with frequency sweeps on it. Then try getting an oscilloscope with a very good lab microphone on a stand.

You then need to get the system "IN PHASE" ie. the whole frequency responce from 20 Hz to 40 kHz in exact phase. This will clear up everything. Tru also to get a "phase corrilator scope". See the STAN RICKER MASTERING site for a good explination on that device.

Your ears might be good but to get the best setup I'll suggest that you use some lab-gear.
That is the problem with the ML Statements - the seperate HF/MF & LF units. This is what B&W is going on for the past 30 years - phase coherency! And that is why I am using little wonders like KEF C55s - Its all about the whole frequency-range being in unison.

Good luck with this...

Kind regards,
Dewald Visser
cwlondon OP
1,210 posts
 
Dewald thank you -

You have described with more detail what I was wondering about - what you suggest is "phase coherency"

Now that makes intuitive sense to me and in fact I was wondering about certain speaker designs like the Dahlquist DQ 10 where the tweeters are set BACK from the woofers, supposedly to increase coherence and unity. This was sometimes described as "time aligned" in the marketing literature.

On the other hand, there have been several statement speakers where the woofer towers usually seem to be set back from the mids and tweeters.

The trickiest part about the Magneplanars - and Tympanis in particular - is that their bass can be reallly marvelous when set up perfectly, yet typically a bit thin or once in a while even a bit muddy and boomy if not placed correctly.

In my experience, this "dialed in" position usuallly differs from the best position for the mids and tweeters which would give the best air and soundstaging.

Therefore, I am trying to be less concered with time alignment, and more concerned with great bass, a hallmark of my speakers when correctly installed but I am not sure I have heard it yet.
dewald_visser
176 posts
 
It is difficult then - I don't know your room but like in my room the bass is more pronounced further back in the room that in the 'optimal' listening position. Sometimes the bass waves needs to develop before they have that 'rich' and full sound. Try moving your listening chair! That might be just the cure. Who knows?

I know how difficult planars can be - used to own 4 QUAD ESL 57s.

Regards,
Dewald Visser
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