Eq'ed flat response "problem"

[Vaughan Odendaa]

Hi there,

As some of you already know, I've posted quite a few graphs using my new SMS-1. The response is really flat IMO.

It makes sense to think that if one cuts certain frequencies that that would equate to more headroom at higher levels. If I toggle between preset 6 (no eq) there is about a 4-5 dB greater output from 20 hz to 40 hz.

My reasoning is that if I equalize flat that when playing film material at reference level, I'll have more headroom and less output compression. I have an SVS PB10 ISD in a 3000 cubic foot room. The subwoofer is positioned 2.6 meters away from me (I recently moved it).

Playing back any material at reference yields no infrasonic impact whatsoever. I tried the Matrix Revolutions end fight in the street and the slo-motion lightning has no felt impact. Switching to preset 6, there is quite a bit more deep bass.

My problem is that my subwoofer is obviously not capable of pressurizing a 3000 foot cubic space at reference level. What bothers me most is that if I take my EQ'ed result and increase my calibrated sub level from 73-74 dB's to 77-78 dB's that there is considerable more low end that is felt, which means that my subwoofer is then, theoretically, capable of 124-125 dB's at the listening positon.

That's just impossible.

It's not as if it's not to be expected that increasing the sub level will also increase my chances of having more pressurizing bass, but the demands placed on my subwoofer should be far greater and, if anything, I should be experiencing less bass, not more at reference as my subwoofer is notorious from suffering from output compression.

I would have expected reference level bass to be something considerably more powerful than what I am experiencing with a single PB10. I've tried several films. I popped in The Incredibles. I tried Chapter 23. Bass is alright at reference. But there seems to be more "gas" left in the tank so to speak. This is what I don't understand. My sub shouldn't have more headroom at these levels (especially when there is no felt impact at all).

Reference level is supposed to be around 115 dB's and I've set my speakers to small, 80hz crossover so then reference level will equate to 121 dB's. But why is it that my subwoofer can be set to even higher levels and provide more impact especially at reference level (calibrated to 75 dB's for the main's, MV set to 0) ?

Has anyone Eq'ed their frequency response flat from 20 hz to 80 hz, calibrated their subwoofer flat with their main speakers and still experienced bass that they can feel ? Because I'm finding that I can't. It's almost as if I should be experiencing a lot more bass at reference level.

Heck, most people can't even play their subwoofers at reference level for fear of over excursion or thermal compression. In my case, at reference, bass sounds, in a word "blah". Have I done something wrong in my setup ?

I've even considered perhaps purchasing a better subwoofer (an Epik Valor or an additional PB10 ISD) thinking that maybe I don't have enough woof for the room. But then that is thrown out the window when I calibrate at much higher levels and I still experience far higher, pressurizing bass at the listening positoin.

Thoughts and suggestions would be appreciated.

PS Sorry for the long post !

--Regards,

 

[OttoMatic]

So you've EQd flat. A lot of people don't like the sound of "flat" once they get there, especially with movies. It leaves them feeling like they are lacking bass.

Have you tried a "house curve?"

 

[Vaughan Odendaa]

No, I haven't tried a house curve but I am trying to figure out why I'm not experiencing felt impact at reference level. I understand that a lot of people prefer to have a fatter low end as opposed to flat eq'ed, but are my results typical ?

Has anyone calibrated their systems flat (73 dB's as opposed to 75 db for subwoofer) with the mains (75 dB all round) and Eq'ed their response flat to within 2-3 dB's and not experienced any felt impact on any films ?

Perhaps that would be a better question to ask. I mean, I can't seriously imagine that that is all the bass that I am supposed to hear realistically (in an accurate sense). I would imagine that the mixing engineer who crafted the sound track for Master and Commander intended for audiences to be physically moved in Chapter 4.

But then why it is that I get hardly any felt impact on the cannon blasts at reference level ! I can increase my sub level by 3-4 dB's and those cannon hits have more impact and power. Something just seems strange with my system.

--Regards,

 

[AcuDefTechGuy]

So when they make the original movie soundtracks or music CDs, did they intend to make the sound with a totally FLAT frequency? Are the sounds that we hear in live concerts or recordings flat in frequency response?
I guess I have always assumed that a flat frequency is perfect, but is it real life? When birds sing, is it a flat frequency to our ears? Does the sound of a gun shot sound flat to our ears? When people talk, are their vocal frequencies flat to our ears?

 

[Vaughan Odendaa]

That's a very good question and I would be willing to find out. I have made the assumption that films recorded in recording studio's are mixed flat. And so the assumption being that the filmmaker wants you to experience what he heard when he made the film.

I see so many articles encouraging people to get a flat response, or as flat as possible. Why would I need more than two subwoofers if my single PB10 can somehow cope right down to reference level ?

A single 10" driver can't produce 121 dB's. That reference figure is set assuming one calibrates their subwoofer to 73 dB's flat with the mains. Radioshack SPL meter reads a bit low so 73 dB's should equal 75 dB's. So the real question then becomes, is there something wrong with my system ?

--Regards,

 

[AcuDefTechGuy]

That's a very good question and I would be willing to find out. I have made the assumption that films recorded in recording studio's are mixed flat. And so the assumption being that the filmmaker wants you to experience what he heard when he made the film.

I see so many articles encouraging people to get a flat response, or as flat as possible. Why would I need more than two subwoofers if my single PB10 can somehow cope right down to reference level ?

A single 10" driver can't produce 121 dB's. That reference figure is set assuming one calibrates their subwoofer to 73 dB's flat with the mains. Radioshack SPL meter reads a bit low so 73 dB's should equal 75 dB's. So the real question then becomes, is there something wrong with my system ?

--Regards,

I know this doesn't help at all, but personally, I set my subwoofer level (when using the 5.1 speaker calibration disc) about 20 dBA below the rest of the speakers. The reason is because when I set the LFE level the same as the mains (60 dBA), it produced WAY, WAY, WAY too much BASS for movies and music. Even at 20 dBA below the mains, it is already causing my walls to rattle when watching the Matrix Revolutions HD DVD. I use the Galaxy Audio SPL digital meter because I hate my Radio Shack analog SPL meter.

So are we suppose to set the LFE Subwoofer channel to match the rest of the channels? If that is true, I don't like it one bit.

 

[OttoMatic]

So when they make the original movie soundtracks or music CDs, did they intend to make the sound with a totally FLAT frequency? Are the sounds that we hear in live concerts or recordings flat in frequency response?
I guess I have always assumed that a flat frequency is perfect, but is it real life? When birds sing, is it a flat frequency to our ears? Does the sound of a gun shot sound flat to our ears? When people talk, are their vocal frequencies flat to our ears?

Well, that's quite a bit different -- real life as opposed to the reproduction of sound in our homes.

Although birds and gunshots take up a certain part of the frequency spectrum, they cannot over accentuate it artificially. What I mean is, they sound how they sound. Now if you record that on devices that have a flat frequency response, and play them back on speakers that have a flat frequency response, in an ideal world, they would sound as they were in nature.

When a speaker or device has a non-flat frequency response is where the problem occurs. If a speaker is very rolled-off in the highs such that the bird singing sounds very muffled, then there's a problem. And that's to do with the poor frequency response, not the "noise" (the bird) that was originally recorded.

I'm sure that recording engineers have all different types of setups, and most of them are likely very nice. I don't know how they mix things, but I do believe that each one does it a little different.

Has anyone calibrated their systems flat (73 dB's as opposed to 75 db for subwoofer) with the mains (75 dB all round)

Well, having a 2 dB difference between sub and mains isn't necessarily in and of itself flat. If anything, I'd say that your sub is low. If I understand what you are saying, I'd start by changing the level of the sub to match that of the mains (and all other speakers) at 75 dB. Why would you run your sub 2 dB lower than the mains. OK, I see that you are trying to accommodate the SPL meter at low frequencies by adding 2 dB. That may be part of your problem -- perhaps your meter is worse than you think. I thought that the RS SPL meter actually falls off quite a bit more than that. IIRC, you've posted before about REW. I think that's really the tool you're in need of at this point. It'll show you how your sub and mains are working together. The RS SPL meter isn't the greatest for this level of accuracy.

As you probably know, the house curve isn't about simply boosting the overall level of the sub. It's about gradually increasing the sub's frequency response as frequency decreases. I think I'm about 6 dB hotter at 20 Hz than I am at 60 Hz. I get plenty of impact at the low end. I use a much flatter frequency response for music. This division -- one setting for music, one for movies -- works out pretty well for me.

I know this doesn't help at all, but personally, I set my subwoofer level (when using the 5.1 speaker calibration disc) about 20 dBA below the rest of the speakers. The reason is because when I set the LFE level the same as the mains (60 dBA), it produced WAY, WAY, WAY too much BASS for movies and music. Even at 20 dBA below the mains, it is already causing my walls to rattle when watching the Matrix Revolutions HD DVD. I use the Galaxy Audio SPL digital meter because I hate my Radio Shack analog SPL meter.

So are we suppose to set the LFE Subwoofer channel to match the rest of the channels? If that is true, I don't like it one bit.

Yes, you should probably use the LFE channel of the test disc to set the levels. You should also be using "C" weighting on the SPL meter. That should give you a better result. Does your receiver or pre/pro offer test tones to help set levels? How do those results compare with those of the test disc?

 

[Vaughan Odendaa]

Ottomatic, how does your Galaxy SPL meter compare to the Radioshack in terms of level ? If you set your Radio shack to read 72 to 73 dB's on the scale, what would the Galaxy read ? Please, if you haven't already tried it, do the test and let me know. I would be interested to know.

As you probably already know, I've posted before in several threads regarding REW. I even posted at the Home Theater Shack but it seems that REW is just too time consuming for me. This is one of the reasons why I bought the SMS-1. It tells you where the subwoofer levels are in relation to the speaker levels.

Looking at my graph now, I see that my subwoofer portion in terms of level according to the SMS-1 is proportionate with the speaker level portion. So I *should* be flat. If I calibrate my subwoofer to read 75 dB's with my Radioshack meter, then if I go back to the SMS-1 graph, it shows the subwoofer portion to be completely out of balance to the speaker section.

You know, I just don't know. Surely people with JL Fathom and SVS PB13 subwoofers calibrated the way I've done and Eq'ed the way I've eq'ed should be feeling bass at reference level ? Surely ? Or is it simply one of the byproducts of equalizing ones system flat ?

I knew that eq'ing my system would result in less bass. It seems that for music I actually have a lot more bass than before. It also seems, for some strange reason, to decay at a slower rate than before ie - bass seems to linger on even more than pre-equalization.

Although I must say that if it weren't for the SMS-1, I wouldn't have known that my system response had major, major dips at and around 50-80 hz. Is it possible that my SMS-1 is adding ringing to the frequencies I've boosted to flatten my FR ?

--Regards,

 

[OttoMatic]

Ottomatic, how does your Galaxy SPL meter compare to the Radioshack in terms of level ? If you set your Radio shack to read 72 to 73 dB's on the scale, what would the Galaxy read ? Please, if you haven't already tried it, do the test and let me know. I would be interested to know

Hi,

I wish I could help you there, but I don't have an RS meter anymore. However, I think you could figure this out by comparing the RS meter's cal file to the Galaxy meter's cal file. They are both available at the Shack. The Galaxy meters have been very consistent between devices.

I generally use the meter to get a ballpark balance of levels. Once I'm close, I'll tweak the level per the program material. As I'm sure you've noticed, some things are very bass-heavy and some are very bass-light. That's your mixing engineer inserting himself into your living room again! Those are the times where you have to go and increase or decrease sub volume to get it right. I've never, ever been able to simply cal my sub levels and then leave them. I just can't. Sometimes I need more and sometimes I need less. Perhaps you are running into some of that. I use a little remote control preamp after my sub's EQ stage to increase and decrease the volume for the sub. Works great.

I know how you feel, though -- you want to get it just right and can't understand why there is so much variation. I also have trouble letting that go, but I have to try! It'll never be perfect.

As you probably already know, I've posted before in several threads regarding REW. I even posted at the Home Theater Shack but it seems that REW is just too time consuming for me. This is one of the reasons why I bought the SMS-1. It tells you where the subwoofer levels are in relation to the speaker levels.

Yeah, I understand. REW has a bit of a learning curve, but it's a great tool if you get it up and running. Don't get me wrong, as I understand it, the SMS-1 is a great tool. But if you have the time and interest, REW does fill another gap.

 

[AcuDefTechGuy]

...Why would you run your sub 2 dB lower than the mains...The RS SPL meter isn't the greatest for this level of accuracy...Yes, you should probably use the LFE channel of the test disc to set the levels. You should also be using "C" weighting on the SPL meter. That should give you a better result. Does your receiver or pre/pro offer test tones to help set levels? How do those results compare with those of the test disc?

No, I don't use a receiver or a pre-pro. I use 4 stereo preamplifiers (Acurus RL-11) + 4 external amps (Acurus 200X3). So I use a DTS-CD 5.1 speaker setup disc and the Video Essentials 5.1 setup disc. I have the pink noise test tones for each channel @ 60 dBA, slow response. But when I set my LFE channel to 60 dBA, it is too loud and rattles the walls. So I set it to 40 dBA.

I recall when I still had the NHT SW2P powered subwoofer. When I set the SPL level to match the other channels, it was to loud also, but it was not as drastic as my current setup (subwoofers are powered subs in the BP7000SCs Towers, which have their own LFE RCA Coaxial inputs).

 

[ParadigmDawg]

I often think that we as audioholics get too caught up in the numbers and graphs of this hobby. For the first time, I am very happy with the look and sound of my system and dont care where the dips and peaks are. Use your ears every once in a while and set your system to what sounds good to you.

 

[jonnythan]

A speaker should have equal response to any input frequency within our hearing.

The recorded material should not have equal levels of all frequencies, of course. The recorded material should reflect the actual sound recorded and the speaker should reproduce it without favoring any of the frequncies in the original recording.

Personally I don't care whether my system has a totally neutral response or not. I just want it to sound good to me, so I listen to music and movies I'm familiar with and tweak it until I like it best. Am I getting closer to neutral response as I tweak it? Probably quite the opposite. Do I care? No.

 

[AcuDefTechGuy]

I often think that we as audioholics get too caught up in the numbers and graphs of this hobby. For the first time, I am very happy with the look and sound of my system and dont care where the dips and peaks are. Use your ears every once in a while and set your system to what sounds good to you.

That's what I'm thinking too!

Two examples:

1) Some movies have dialogues that are not so easy to hear. So in this case, I just crank up the center channel level, which are then no longer matched with the other channels.

2) If matching the LFE channel level with the other channels causes my bass to be higher than my PERSONAL perference, I just turn it down to a comfortable level.

So numbers are "more like guidelines really", as they say in Pirates of the Caribbean

I guess this is how we audition speakers. Just because a Klipsch has a better frequency response number doesn't necessarily mean it will sound better than a Paradigm to your ears/perferences, right?

 

[avaserfi]

I often think that we as audioholics get too caught up in the numbers and graphs of this hobby. For the first time, I am very happy with the look and sound of my system and dont care where the dips and peaks are. Use your ears every once in a while and set your system to what sounds good to you.

Very good point, but sometimes without those numbers you don't always know what you are missing. Before I started equalizing my sub and working with its placement I never realized how much bass I was missing. My system sounded good to me, but I didn't realize how much better it could sound! For me at least ideal sound comes from using my ear, but being guided by hard numbers as sometimes we don't realize what we are missing until we hear it.

Vaughan I strongly recommend you trying out a house curve at least for movies. It will likely help with your room pressurization issues and fill in the low frequencies you are looking for. As we delve into the lower octaves higher SPLs are needed for humans to perceive equal responses thus people use house curves. With your given room size and subwoofer you should be careful not to bottom out the woofer. Perhaps adding another and then using a house curve would be ideal as it will give you more output, pressurization and allow for an even flatter frequency response.

As Greg said just because your line is perfectly flat doesn't mean it is "perfect" experiment until you find something you like don't seek perfection just to have it in spite of what you like. You are shorting your self by doing this.

 

[ParadigmDawg]

This coming from a guy who is always throwing out specs no matter how inappropriate they are????....

I have never had to adjust my center before; it is so clear and crisp but I do increase the 60hz region on my sub by 5 db for movies

That's what I'm thinking too!

Two examples:

1) Some movies have dialogues that are not so easy to hear. So in this case, I just crank up the center channel level, which are then no longer matched with the other channels.

2) If matching the LFE channel level with the other channels causes my bass to be higher than my PERSONAL perference, I just turn it down to a comfortable level.

So numbers are "more like guidelines really", as they say in Pirates of the Caribbean

I guess this is how we audition speakers. Just because a Klipsch has a better frequency response number doesn't necessarily mean it will sound better than a Paradigm to your ears/perferences, right?

 

[AcuDefTechGuy]

This coming from a guy who is always throwing out specs no matter how inappropriate they are????....

I have never had to adjust my center before; it is so clear and crisp but I do increase the 60hz region on my sub by 5 db for movies

Number are fun, though. How could be have a debate without numbers?
Why, the whole universe is based on calculus.

When I watched Constantine on HD DVD, I thought, "What is wrong with my system?" I had to crank the center channel level way up. Later I read on Audio Video Revolutions that Warner Bros. had screwed up and decreased the center channel level by 10 dBA!

 

[jonnythan]

Why, the whole universe is based on calculus.

The universe is only based on calculus to people who don't know tensor fields

 

[Vaughan Odendaa]

avaserfi, what subwoofer do you have ? Would you be able to (or anyone) to verify that my results are normal ?

I know that it's a bit of an undertaking (actually one heck of an undertaking) but if you could eq your system flat and then calibrate flat with the mains, could you tell me whether you get felt impact on your favourite movies ?

I just can't believe that a single PB10 can get the most from these films at reference when I can't feel a thing from them. Tried The Incredibles, tried Master and Commander, tried Matrix Reloaded (and Revolutions).

100 odd db's down low should give me considerable felt action.

--Regards,

 

[Vaughan Odendaa]

And another thing. If, according to my SMS-1 graph, my levels on the right are equal to the levels on the left, does that mean that if I used my SPL meter that it should be equal for the mains and the sub ? Because I am finding that it's pretty darn close.

Would buying this Galaxy SPL meter perhaps be beneficial ? Because I absolutely hate the inaccuracy of the Radio shack meter. The needle shifts from 73 and holds for four seconds and then shifts to 75 and then to 72, and then to 75. So I assume that I'm leveling at around 73 dB's which is equal to the mains.

--Regards,

 

[Vaughan Odendaa]

Perhaps someone can answer this question. Is there a reason why once my response has been equalized, the bass while sounding much fuller also sounds more boomy ?

If I pick preset 6, there is less bass but it seems to be "quicker" sounding. Is it possible that once the levels have been increased to create a flatter in room response, the modal resonances in my room are causing them to decay at even slower rates than before ?

Here are two updated graphs. I think I've come a long way with my SMS-1 after having it for just 2 weeks.

Unequalized :

Equalized :

--Regards,