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Questions about 11-band EQ.


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I wanted to get back into using the analog EQ of my cloth Quatros, and had a few questions.

First off, I want to thank Richard for greatly simplifying the procedure.  The old procedure always confused me (what is 1/3 of 11 trim pots?)

Another thing I've always wondered about is what to do when adjusting one band to the computed target drives a neighboring band down below it's target.  Should one prioritize reducing the peak and not worry about the trough created, prioritize reducing the trough, or try to split the difference some way?

Last question is just general curiosity: what is the Q of the bandpass filters?  Are they are all the same? 

 

 

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Hi Daverz,

It is very important to work from the lowest frequencies first and work your way up as the instructions say.  This is how they are arranged on the disc.  Go through the process twice but adjust to the original target.  Never go from a higher frequency down because this is not how harmonics work!  The "Q" of every band is different and they do not fall on normal fractions of an octave.  This is by design but beyond the scope of this forum and I guarantee it works!

 

RV 

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Thank you, Richard, I think I have it now: 2 passes, always going from lower frequency tones to higher frequencies and bottom pot to top pot, only adjusting the pot corresponding to the current tone without worrying about effect on the previous or next tone. 

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This has been my own bugaboo when setting up the speakers.  I've let it get into my head that it's too difficult to do, but in speaking with Richard about this and when reading this forum, it's helped me realize that this really is fairly easy as long as you have two people.  Great stuff.  

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8 hours ago, ctsooner said:

This has been my own bugaboo when setting up the speakers.  I've let it get into my head that it's too difficult to do, but in speaking with Richard about this and when reading this forum, it's helped me realize that this really is fairly easy as long as you have two people.  Great stuff.  

If you feed the RCA output of the RS meter into a laptop and use something like REW's SPL meter display, you can do it without an assistant to read off the meter.   A long 3.5 mm to RCA cable should work for many laptops, or you can use a USB audio interface if your laptop doesn't have an audio input jack.  

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47 minutes ago, Daverz said:

If you feed the RCA output of the RS meter into a laptop and use something like REW's SPL meter display, you can do it without an assistant to read off the meter.   A long 3.5 mm to RCA cable should work for many laptops, or you can use a USB audio interface if your laptop doesn't have an audio input jack.  

I did a bit of testing with REW.  The procedure I worked out for using it with the Radio Shack meter is

1. Set your input device in REW Preferences.

2. Open the REW SPL Meter display and click "Calibrate".

3. Play the 1000 Hz signal from the Vandersteen CD.

4. Adjust volume until you get a reading of 70 dB on your RS meter.

5. Enter 70 for the REW calibration.

6. Switch the REW SPL Meter to "Z" weighting.

 

The point of all this is to be able to display the SPL level from the RS meter on a laptop that you can read while you are adjusting the bandpass pots.  

Edited by Daverz
Clarification
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7 minutes ago, Richard Vandersteen said:

The 1000Hz tone has nothing to do with the calibration of the system it is only used for high-pass verification.

RV

I only use it to calibrate the levels when using a computer to read the SPL level from the Radio Shack meter's RCA output.  Any tone not effected by the C-weighting should do as well.

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On 5/6/2021 at 9:30 PM, Richard Vandersteen said:

Hi Daverz,

It is very important to work from the lowest frequencies first and work your way up as the instructions say.  This is how they are arranged on the disc.  Go through the process twice but adjust to the original target.  Never go from a higher frequency down because this is not how harmonics work!  The "Q" of every band is different and they do not fall on normal fractions of an octave.  This is by design but beyond the scope of this forum and I guarantee it works!

 

RV 

So…I’m anticipating much scorn from RV, but I’m interested to learn why my approach to low frequency adjustment is not ideal. 
 

When I follow RV’s approach, I seem to be adjusting more pots than necessary. My approach seems to limit the amount of tweaking. 
 

My in-room peak seems to straddle 3 to 4 contiguous pots (most significantly 42 to 60 Hz - this is all I’m seeking to address). I knock the most egregious frequency down about 50% to target, and remeasure. Repeat, and repeat again. I never touch pots 9, 10, or 11 no matter what (too close to the crossover frequency). I never boost any pot. My room comes into balance with about 3 passes and with significant adjustments to only 2 pots (maybe a touch on a 3rd). 
 

Yeah, I’m probably going to be skewered,  it we’re here to learn, right?

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Why would I skewer anyone as I am here to help get optimal results knowing how the system was designed!  You own the speakers and I don't care how you adjust YOUR speakers.  The system is very simple and works very well and I stand behind it.  Again its is your choice but it sounds like you are trying to argue what would adjust the system best.  For what purpose?  Are you trying  to change the way Vandersteen owners set up their speakers?  Do you believe you have discovered a better way?  Again I have this forum so Vandersteen owners can share experiences and I participate to help owners get what I know the product is able to deliver in your home.  Hopefully this minimizes confusion and advances everyone's musical enjoyment.

RV    

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LOL. I figured I’d (rightfully) be skewered because you’ve clearly outlined the recommended approach (per the guy who designed the speakers) and then me, some knucklehead, proposes something different. 
 

I’m not audacious enough to suggest a different method…but maybe I am.
 

In my room, my resonance peak looks like a slightly asymmetric bell curve that spans 3 to 4 pots (which, for reference, the peak is a good 10+ dB above the 70 dB baseline). If I start adjusting from the left side of the bell curve (the lowest frequency pot with the resonance peak) the Q of the first pot I adjust impacts the frequencies lower than those I’m trying to tame (which WERE ideal, but now much lower in output, taking them out of my target range). This is due to how much I have to cut that frequency to hit the target.

 

If I start with the pot that is closest to the peak of my resonance bell curve, and use my approach, I can tame that entire range by cutting only 2 pots. I use the Q of those 2 adjacent pots to my benefit. 

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For the other owners of Vandersteen Quatro, Five, Kento and Seven's speaker systems how many pots need to be adjusted has no effect on the end result quality if the process is followed with the correct amount of correction.  If it takes 8 out of the eleven pots, so  be it.  It is not sonically superior to use two or three when more are needed as long as dips remain were there were  dips and 30% peaks remain where there were peaks.  Flat response is not the goal because it sounds equalized only minimizing the bumps caused by standing waves.  Once you have tried the system as designed please use the pots however you like as you are the only arbiter.

RV 

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The next step is what I call the "Soular Energy" step.  As described in the manual: "Select a clean jazz recording with a stand-up bass scaling up and down. Adjust the Low-Frequency Level controls on the speakers until the transition from the subwoofer to the upper part of the speaker is seamless and linear"

I never know what to listen for in this step.  Yes, I know "seamless and linear", it would seem to be obvious, yet I'm completely clueless here what to listen for here.  Maybe I should crank up the pots so the sound is obviously wrong and back down from there.

For the contour step, since I'm in a second floor condo in a wood-frame constructed building, I've always left this at #1.  

 

 

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I have a couple of tracks I use for this step, namely the opening track “Windfall” off Son Volt’s first release Trace. In my mind, I’m listening for “balance”. I know that track well enough that if the bass-line is nicely balanced in proportion with the other elements, my low frequency level is “correct” (according to my tastes).  If any note of the bass-line overloads the room, I know didn’t accurately address the room issues, and I have to remeasure and run the the 11 bands again. I’ll then confirm the overall low frequency level with something a bit heavier and much louder (like Rage Against the Machine’s “Bombtrack” or “Know Your Enemy”) to see of the bass overloads the room. For my final test and setting, I’ll increase the low frequency level just until I “hear” the subs, and then pull it back the tiniest bit. For reference, this all happens between +0.25 and +1.00 on the low frequency level. 

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Daverz, listen for the notes as Ray Brown scales up and down and adjust the Sub-woofer Level control up or down until the notes are equal loudness through the crossover region.  Track 13 and 14 on the test disc were recorded by Joe Harley for this purpose.  I like track 14 best for this.  Once the loudness sounds correct adjust the "Contour" up for more warmth or fulness or down for a dryer leaner sound to taste.  This will tend to be 1-5 for tympanic (wood) floors and 5-10 for concrete floors.  As you will read in many show reports I tend to go to the  fuller side as I like bass and many recordings are too dry for me anyway.

RV 

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This has been a great thread for me.  I’ve always leaned towards Richard when listening to music. Johnny Rutan and I hear a bit differently. That’s always the case.  I too enjoy a bit fuller bass and when EQ’d properly, it’s engaging and takes nothing away from the rest of the spectrum. I’ve just never heard you say that about your preferences. Once i get my speakers set up where I want them and where the cables and cords allow me to set them up, I’ll just get the disk and meter and a helping hand to set them up. It takes a bit of time, but will be fun to do I think. 

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