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Powered Sub Woofer Calibration


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I guess this question would be best answered by Richard but feel free to chime in if you have a better understanding of the subject than me.

I am awaiting delivery of my Quatro Wood CT's and decided to watch RV's video of the sub woofer room calibration process. As I recall, RV states that it is not necessary or even desirable to achieve a flat low end response via the 11 pots. To do so would result in a "flat" sound. I believe he suggested one shoot for approximately a 1/3 correction of any rise in response at a particular equalization point. That got me thinking...

When evaluating a phono cartridge, preamp, amp or other piece of electronics the goal is to try and achieve as flat a response curve as possible from 20 to 20K Hz. Why then would that not be the case when equalizing the sub woofer on a Quatro? Why would a flat response below 100 Hz be undesirable when it comes to a loudspeaker?

Thanks in advance for your reply.

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Our ear/brain needs to be in a defined space to be comfortable.  This space is what causes standing waves and nulls because of its unique dimensions, listening position and construction.  We correct to 33%, as an example a 9 dB peak would be 3 dB in the target column on the work sheet.  The reason we don't want to correct to 0 dB is because our ear/brain would say, wait a minute we did not fix the room this is BS!  We have discovered we can minimize the amplitude 66% and keep our ear/brain happy with a dramatic improvement in sound.  This phenomenon is why our analog Room EQ works better than digital correction, unfortunately our system is not automated.  Takes a little time but works great.  You could do it both ways and listen for yourself if you don't believe me.  RV

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1 hour ago, Richard Vandersteen said:

Our ear/brain needs to be in a defined space to be comfortable.  This space is what causes standing waves and nulls because of its unique dimensions, listening position and construction.  We correct to 33%, as an example a 9 dB peak would be 3 dB in the target column on the work sheet.  The reason we don't want to correct to 0 dB is because our ear/brain would say, wait a minute we did not fix the room this is BS!  We have discovered we can minimize the amplitude 66% and keep our ear/brain happy with a dramatic improvement in sound.  This phenomenon is why our analog Room EQ works better than digital correction, unfortunately our system is not automated.  Takes a little time but works great.  You could do it both ways and listen for yourself if you don't believe me.  RV

Thank you Richard for your prompt reply. With all due respect I am still not fully grasping the concept.  When you say the ear/brain would react  with something like "Wait a minute we did not fix the room this is BS" I don't understand why. Believe me I do not doubt for a minute the veracity of your findings but my curious mind just wants to better understand the phenomenon. Perhaps it is related to the fact that if one were to listen to a speaker in an anechoic chamber it would sound horrible (or so I'm told)? As you say, "Our ear/brain needs to be in a defined space to be comfortable". Without taking up too much of your valuable time, any further clarification would be appreciated.

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7 hours ago, Gsal said:

I guess this question would be best answered by Richard but feel free to chime in if you have a better understanding of the subject than me.

I am awaiting delivery of my Quatro Wood CT's and decided to watch RV's video of the sub woofer room calibration process. As I recall, RV states that it is not necessary or even desirable to achieve a flat low end response via the 11 pots. To do so would result in a "flat" sound. I believe he suggested one shoot for approximately a 1/3 correction of any rise in response at a particular equalization point. That got me thinking...

When evaluating a phono cartridge, preamp, amp or other piece of electronics the goal is to try and achieve as flat a response curve as possible from 20 to 20K Hz. Why then would that not be the case when equalizing the sub woofer on a Quatro? Why would a flat response below 100 Hz be undesirable when it comes to a loudspeaker?

Thanks in advance for your reply.

 

We hear the direct sound for imaging, and the reflections give timber and space.
Ideally the reflections all decay at a short and consistent time interval.
In reality the room modes have strong peaks in the <100,200,400 Hz

IMO (but not IME), it would be better to first treat the low frequency decay rate with absorbers.
Then whether the low frequencies are worked with DSP,  or in the 11 pot case with ASP (Analogue Signal Processing) then one gets the timber to be more right.

But some may prefer the flatness to be tapered up a bit from 100Hz towards 20Hz, at least when in the room. But anechoically they may be flat… just not when in the room.

 

But it all goes down the S-Bend, in Sean Olive’s “Circle of Confusion” if the mixes are down with monitors that are bright or dull, as then the recording itself is only flat on the speakers that the mastering person used… and they master by ear…

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7 hours ago, Gsal said:

Thank you Richard for your prompt reply. With all due respect I am still not fully grasping the concept.  When you say the ear/brain would react  with something like "Wait a minute we did not fix the room this is BS" I don't understand why. Believe me I do not doubt for a minute the veracity of your findings but my curious mind just wants to better understand the phenomenon. Perhaps it is related to the fact that if one were to listen to a speaker in an anechoic chamber it would sound horrible (or so I'm told)? As you say, "Our ear/brain needs to be in a defined space to be comfortable". Without taking up too much of your valuable time, any further clarification would be appreciated.

If one tries to correct to "0" it removes some very important clues about the space that our ear/brain needs because it knows the room is not without issues causing discomfort.  Like I said try it both ways.  RV

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8 hours ago, Richard Vandersteen said:

If one tries to correct to "0" it removes some very important clues about the space that our ear/brain needs because it knows the room is not without issues causing discomfort.  Like I said try it both ways.  RV

I appreciate your additional comment. I will trust in my dealer to set up my Quatro's correctly according to your dictates. Like I said I was just intellectually curious. Thanks again.

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11 hours ago, Richard Vandersteen said:

If one tries to correct to "0" it removes some very important clues about the space that our ear/brain needs because it knows the room is not without issues causing discomfort.  Like I said try it both ways.  RV

Ah… 💡
Does this mean that in an REW sense that the delay=0 would be loser to flat, even if the resonances persist for a longer time?
So that the direct sound is not attenuated too much?

Or is it more of, “listen to what sounds good, but be cautious about twisting the pots too much as nirvana is not there”?

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8 hours ago, Holmz said:

Ah… 💡
Does this mean that in an REW sense that the delay=0 would be loser to flat, even if the resonances persist for a longer time?
So that the direct sound is not attenuated too much?

Or is it more of, “listen to what sounds good, but be cautious about twisting the pots too much as nirvana is not there”?

Mr. V. probably has the best idea of what works and why, but I think that adjusting everything to a flat response would make it sound rather lifeless. 

Bob

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@ctsooner, when we auditioned the William Tell's and the grounding unit. I later emailed Johnny that the Sub 3 seemed a bit 'aggressive.'

His response was that most people enjoyed a more robust sound (vs properly calibrated). So, if the OP wants to goose his system for bass, it certainly can be done

 

To be honest, I find myself attracted to just a bit more bass punch vs. proper calibration.😊

Bob

 

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2 hours ago, GdnrBob said:

@ctsooner, when we auditioned the William Tell's and the grounding unit. I later emailed Johnny that the Sub 3 seemed a bit 'aggressive.'

His response was that most people enjoyed a more robust sound (vs properly calibrated). So, if the OP wants to goose his system for bass, it certainly can be done

 

To be honest, I find myself attracted to just a bit more bass punch vs. proper calibration.😊

Bob

 

Me too but…

Many people doing the mixing have small rooms with room modes that make what they hear different to what we hear in our rooms.
So it could be somewhat common to find a bimodal distribution of LPs with too little bass and ones with OK bass.
Hence a knob somewhere could be handy.

Or we found that our room have room modes and the mix didn/t and the bass is too much.
Hence a knob somewhere could be handy.

 

But the good recordings, and better rooms, would probably be “Goldilocks”… and many of the recordings are very good.
So it is different scenario than with my non adjustable Vandy sub.

Edited by Holmz
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2 hours ago, GdnrBob said:

@ctsooner, when we auditioned the William Tell's and the grounding unit. I later emailed Johnny that the Sub 3 seemed a bit 'aggressive.'

His response was that most people enjoyed a more robust sound (vs properly calibrated). So, if the OP wants to goose his system for bass, it certainly can be done

 

To be honest, I find myself attracted to just a bit more bass punch vs. proper calibration.😊

Bob

 

I have been criticized at shows and in the press for liking bass, I do!  We need to be careful because being a "music lover and one who enjoys the equipment", it would be a shame to tarnish those precious recordings that are recorded SOTA.  We desperately need a knob or two, so we don't need to recalibrate our system for all the different recordings.  RV

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6 hours ago, GdnrBob said:

@Richard Vandersteen

Do you envision making a tone control for your preamp, or an add on? Something along the lines like the Schiit Loki?

 

Bob

It will have a "Smoke and Mirrors" section on the remote fully defeated by hitting the largest button on the remote labeled "Direct" this section is used by injecting a signal across an existing component in the circuit using relays.  No extra switches, relays or components in the "Direct" signal path!  RV

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