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Parametric Quandary

D700

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Spent the weekend playing around with Housecurve, Wiim PEQ 4 Band and learned a ton. What an interesting science.

Questions:
  • Why do I have a valley @250hz that no amount of EQ solves?
  • Why do I prefer the sound "without EQ"?

I've listened to a lot of familiar and not so familiar tracks A/B comparison with EQ on/off...I seem to prefer without, even though my corrected curve looks pretty good. With EQ I do hear different detail in some passages...but it seems...smeared somehow. I don't have the language for it. Is this something to do with how EQ is applied? I read something about FIR filters which Wiim doesn't support yet.

Or have I just gotten used to my speakers and that's become my baseline over the years?

With EQ:
With EQ.jpeg



Without EQ:
Without EQ.jpeg
 

OldHvyMec

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Crossover point of poorly designed passive crossover. The mids wired out of phase. A funky reading and false assumption?

That is pretty high actually. Do a test tone on your phone 250 hz is pretty high. 300 hz is actually used in meditation to gain focus.

That's also a VERY steep drop from the bass driver. How do male voices sound, if they aren't there or difficult to understand that
would be the reason. If you hear them with no issues, calibrate and retest. It starts at 200 and notches to 300+ hz.

Regards.
 

fpitas

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Why do I have a valley @250hz that no amount of EQ solves?
Because waves intersect and cancel there. If you boost the power, the waves get stronger, but still cancel.
 

DVDdoug

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Standing wave cancellation (nodes) in the bass range can be impossible to correct with EQ. :( A +6db boost is 4 times the power and +12dB is 16 times the power so you can end-up driving your amplifier or speakers into distortion.

Moving the speakers (or subwoofer) can sometimes help (but it often moves the dips & peaks in position and in frequency). If you want to "get serious" and do acoustic treatment, bass traps can kill the reflected bass which smooths both the dips and bumps.

Why do I prefer the sound "without EQ"?
That's hard to say, but don't lose-sight of the fact that music is for your enjoyment! If something measures better but sounds worse to you, don't do it! ;)
 

TheBatsEar

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  • Why do I have a valley @250hz that no amount of EQ solves?
Other said it perfectly.
  • Why do I prefer the sound "without EQ"?
Maybe because you try to fill a null and that drives up distortion?
I for one just cut the tips off from the bass modes and call it a day.
 

RayDunzl

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Play stereo music and observe the 250Hz dip using the RTA window in REW.

It will probably largely disappear, as the phase of the waves around the 250Hz dip will differ.

I have a black hole at 48Hz with test tones (and another at 220hz) that often is gone with music where the low bass is not monofied..

Music:

1702322334026.png


Test Sweep:

Left, right, and both speakers (unsmoothed to reveal all cancellations, and there are plenty)

1702322428141.png


My room is a rectangle with the left rear corner behind the listening position wide open to the kitchen, etc.

Standing waves of left and right go 180 degrees out of phase around 48Hz and cancel at the listening post.

1702325305787.png
 
Last edited:
OP
D700

D700

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What wonderful responses, thank you. Yeah, I read something about an "anti-node" in the HouseCurve stuff. I'm raw to this topic but it's fascinating. I looked at REW, that might be more learning/setup than I want to take on right now but I've bookmarked it.

So I'll just ignore correction in that valley

Male voices sound great actually, Lyle Lovett, Van Morrison, Mark Knopfler...that's actually what sounds better with EQ off, as well as the "thwap" of snare and kick drums are just a little more crisp without EQ...but I hear other instruments/sounds better with EQ on, so not sure to believe my ears.

I was giving this system a go with the Wiim 4 band to see if it was satisfying. Am contemplating a KH120ii with MA-1 eq system..but I'm at 9-10 feet away from the speakers.

I'm going to fiddle with speaker positioning, currently they are pointing exact diagnal from front corner (bookshelf) to opposite corner in a 11.5' x 16' cabinet paneled office. The opposite end is 80% bay window with S-Curve vertical vinyl blinds. Echo isn't too bad, I think all the little angles due to the cabinet panels must help.

Thanks again!
 

OldHvyMec

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Male voices sound great actually, Lyle Lovett, Van Morrison, Mark Knopfler...that's actually what sounds better with EQ off, as well as the "thwap" of snare and kick drums are just a little more crisp without EQ...but I hear other instruments/sounds better with EQ on, so not sure to believe my ears.
Alway trust your ears and then confirm. BUT I'm a retired master mechanic. If I suspected an issue like an OX actually blocking the frequencies at the wrong place
I'd run sweeps to confirm it or not. Not hearing issues with voices is certainly an indication that the dip is a result of cancelation and not present in the whole room.
Personally I could give a hoot as long as the sweet spot is actually SWEET and bigger that a .177 BB.

Non cost solutions are easy enough. Placement!

One way that will always tell the story is setting up kitty corner. I found that if I'm in a weird room or any room for that matter, treatment falls to placement
of speakers and for some reason (If I pick a good full range) NO SUB is required for good sound. Treatment was pure Helmholtz for ceiling heights with
NO TRAPS of any kind. One; they are ugly as hell and second for them to work they really have to be BIG, UGLY and DEEP!
I use rugs for vibration control and curtains to tame a highly reflective but CLEAR reproduction. 250 hz < adjustable Tube Resonators, they are NOT traps.
They cancel, not trap and you can increase or decrease the taper by adding to the number and size if you're that picky.

Don't let what you feel through your feet and bottom throw your timing off either. The main reason to DECOUPLE the subs/bass first.
Air bellows work very well to run test to HEAR the effects of decoupling vs not. You just turn the valve and the sub is coupled back to the floor.
Three pumps the subs are off the floor. You don't even have to move. Use a foot pump.

Your ears are good? I keep a baseline on my hearing and have my whole life. Mine was DOT required for 30 of my 49 years as a mechanic.
Ear plugs and muffs work to preserve your ears, BIG TIME. I never leave home without hearing protection and a dust mask in pocket.

Fruit for thought.

Time to feed the chickens.

Regards
 
OP
D700

D700

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Time to feed the chickens.

Regards
Thanks you for ideas, I will look into those. It's an empty room except for a standup desk and office chair, I'm building in layers, audio first. I know once I get rugs down, furniture and things hanging on the wall, it will change again. I downloaded and played a 20 to 20 sweep. I'm getting physical resonances in the room at various frequencies, going to start there making sure things are isolated. Seems like my bookcases amplify the bass a lot, I'm going to put more books down low with the sub.

I can't hear anything above 10K since I was 27 and got stuck under a commercial fire alarm going off for 20 minutes...so I'm not bothering with those frequencies....and we don't own dogs.

My bass response is spot on with specs for my equipment, so leaving that alone. I'm just adjusting powered sub volume to blend with crossover set to 50
 

Mr. Widget

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Questions:
  • Why do I have a valley @250hz that no amount of EQ solves?
Because waves intersect and cancel there. If you boost the power, the waves get stronger, but still cancel.
Probably... it could also be an error in measurement cause by floor mic placement and floor bounce.

Questions:
  • Why do I prefer the sound "without EQ"?
That's hard to say, but don't lose-sight of the fact that music is for your enjoyment! If something measures better but sounds worse to you, don't do it! ;)
Agreed. My first experience with DSP was using a DEQX preamp/crossover in the early 2000s. I flattened the hell out of that curve and crushed the life out of the sound!

Since then I have learned to use DSP in moderation... funny how moderation seems to be the best policy in so many things. As others have said, it is rarely good to try to fill in a hole, though a mild wide Q filter may be OK, but focus on the peaks that need to be pulled down. That said even these are best treated with moderation and experimentation.

At the end of the day, the system is there for your enjoyment. If you like it better, then it is better.
 
OP
D700

D700

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Probably... it could also be an error in measurement cause by floor mic placement and floor bounce.



Agreed. My first experience with DSP was using a DEQX preamp/crossover in the early 2000s. I flattened the hell out of that curve and crushed the life out of the sound!

Since then I have learned to use DSP in moderation... funny how moderation seems to be the best policy in so many things. As others have said, it is rarely good to try to fill in a hole, though a mild wide Q filter may be OK, but focus on the peaks that need to be pulled down. That said even these are best treated with moderation and experimentation.

At the end of the day, the system is there for your enjoyment. If you like it better, then it is better.
thanks, this kind of advice helps. Ive split the difference on the 2 lower frequency filters and got some bass and drum kick back…when I couldnt make out the bouncing bass line in a few Steely Dan songs I knew the EQ had gone too far. I do Wonder if the advanced EQ of the Neumann or others would sharpen the sound even more
 
OP
D700

D700

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welp...had a great time researching this problem and glad to report, after a couple dozen hours of reading, researching, podcast listening, I finally fixed it in less than 5 minutes and zero investment. Check this out:

IMG_2952.PNG
 
OP
D700

D700

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For anyone passing by looking for solutions to unfillable frequency dips in the 100-400hz range that no amount of PEQ or room correction seems to solve, let me introduce "Speaker Boundary Interference" or SBIR. Found a good podcast here talking about EXACTLY my problem:

Here was my quick solution to remove the "Cancellation Dip" and get the above fixed response measurement:


IMG_2953.jpeg
 

Rednaxela

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Cool trick. Glad it worked for you. Might try it myself too. Thank you for sharing.
 

Ron Texas

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Try moving the speakers closer or further from the front wall.
 
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