EQ Target Response Curves

[esscue]

Hi,

I've been reading through the forums for quite a while now, and googalising a lot on the net over the past few months - and i have a couple of questions that i hope you guys n gals might be able to answer.

what im particularly looking for is the 'target eq response curve for home thearte'.

for example:

Assume that a home thearte has been reliably setup with a reasonably FLAT response, from 20hz - 20khz on all channels

From there... what EQ curves would you apply?
and would you have different ones for DTS vs THX vs Broadcast TV etc... I know already that you would have a different one for music and have that covered.

as further info/explanation- i bring your attention to :HAA Level I Certification Training Course Overview elsewhere on this site (http://www.audioholics.com/techtips/roomacoustics/HAALEVEL1.php), specifically to the following slide: Typical Home Thearte Response (TFR) (http://www.audioholics.com/productreviews/avhardware/images/clip_image008_023.gif)

- this is pretty much exactly what i want... but, cant get enough detail from the small pic. and i thought others in here might know of other audibly nice response curves, and/or, be able to provide more detail info on the slide..

my cinema has 31band + parametrics available on every channel, dedicated outboard poweramps, enough headroom and enough quality to faithfully reproduce 20hz - 20khz. I have considerable experience with and access to an RTA.

please - I do not want this thread to become a " TO EQ/NOT TO EQ" debate.

just trying to find peoples personal (or is there a standard that i've missed??) TARGET reponse curves.

thanks for your time. and i hope you can help me in my quest, as ultimately its a win for all of us.

regards
Wayne

 

[esscue]

perhaps i need to add some further info?

F. Alton Everest in one of his books (the name escapes me of the book right now, but i think it was accoustic techniques for home and studio?..) he details good target curves for the playing back of recorded music. which is roughly applying a 3db/oct slope that runs from +3db (20hz) to -3db (at 20khz), naturally this slope is applied to a flat response of your sound system. ive noticed some other well respected audio sources recommending this kind of response also, Wayne Harris of rockford fosgate for instance (who was the brain behind the symmetry system and all sorts of amazing goodies - for cars.. which is where my true love of trying to get hi fidelity comes from).

knowing that, above, and admitting i also like to put a bit of a small boost on 80hz, this sounds absolutley amazing when listening to cds. however when listening to dvds-movies (havent tried dvd audio) and television, it is obvious that these sources are mastered differently. they sound much better when played back roughly flat. what im hoping to find here, is, that someone says "flats ok..but..try this...its better". i once came across a document that showed mastering techniques applied to television broadcast before it was broadcast (it was similar to the slope i mentioned earlier... i just cant remember!! grrrrr.. which goes some way to explaining why it sounds 'better' (not perfect!) than with the music slope applied).

please anyone? surely someone knows this secret?

if perhaps i've put this in the forum, dear mods, would someone be able to move this to setup->Room Acoustics, System Layout & Setup ? thanks.

for anyones interest, and this is slightly off topic... i use a sine pulse method to tune my gear. over 30 1/3 steps, 3 sine pulses are measured for each step (at different freqs within that 1/3 step) this helps get lower possibly anomalies/errors in the reading (i know... not all eg nulls/modes! but thats what our ears are for right?). this method is way way way more accurate than rta'ing with pink noise as the processor (rta) can compare the exact freq level its outputting to the one the mic is telling it..this is also done at a few different volume steps.. i only say this because i have equipment capable of both methods. the pink noise is great, but the sine method is like chalk and cheese in difference. unbelievably better. normally repeat the whole (7min per channel) process 4-5 times (graphing the differences for visual curve comparison) with different mic positions just to make sure nothing silly is happening in the room.

anyway, that was just a short blurb on better alternatives (in my opinion) to pink noising. and i base that on what my ears have been telling me.

anyhoo, i hope someone has the knowledge on the target curves for dvd/broadcast television and anything else of interest.

thanks for your time. and thumbs up to all the great people who have shared an immense amount of knowledge throughout all the forums.. in the big picture of life - this is how we all win.

wayne.

 

[Buckle-meister]

Assume that a home thearte has been reliably setup with a reasonably FLAT response, from 20hz - 20khz on all channels - From there... what EQ curves would you apply?

Not sure this is the response you want to hear but if the frequency response is as good as flat over the range of frequencies you want - not necessarily 20Hz to 20kHz (refer to link below) - then the simplist way I can think of to add EQ curves in order to shape the sound to how you prefer is simply to use one of the (probably) many sound fields available from your receiver.

just trying to find peoples personal (or is there a standard that i've missed??) TARGET reponse curves.

Again, for me, the sound fields offered by my receiver does exactly as you appear to be asking for. If I don't like 'Sci-fi' but prefer 'Adventure', in essence all I'm doing is switching between preset EQ curves no?

F. Alton Everest...details good target curves for the playing back of recorded music. which is roughly applying a 3db/oct slope that runs from +3db (20hz) to -3db (at 20khz), naturally this slope is applied to a flat response of your sound system.

Take a look (near the bottom) at the plot in this thread kindly provided by WmAx. In it, you can see that a flat response over the full frequency range is not generally desirable.

i also like to put a bit of a small boost on 80hz, this sounds absolutley amazing when listening to cds...

This is partly the problem with your question as clearly you describe a personal preferance above which may or may not also be shared by others.

...what im hoping to find here, is, that someone says "flats ok..but..try this...its better"...

Personal preferance again I'm afraid.

 

[Sleestack]

I have one of the few pre/pros that visually lets you see your room's measured response and allow you to literally draw target response curves. Although the TACt TCS MKII (and RCS 2.2.XP) also makes other corrections (time, level, etc.) it also provides a great software interface for designing and testing frequency response curves.

The shape of your curves will depend on a number of factors, including your speakers, the room and your personal listening preferences. In addition, depending on the listening volume, the same curve may or may not sound right. The TACT 2.2. channel RCS 2.2XP addresses fletcher-munson v0lume dependent issues by layering additional curves for different volume levels on top of your target curve.

In my 2.2 channel setup, I prefer a curve with a 2 - 3 dB bump in bass starting at around 140Hz. On the lower end, I roll off the curve at 25Hz. On the upper end, I generally start rolling off the treble at around 10kHz, with about 2 dB of attenuation by 20kHz.

In my 5.1 setup, my target curves have more dramatic bumps in bass and the curve is flat down to 20hz. the LFE channel has an additionl 2dB bump. The high end looks similar to my 2 channel. I use 5 floorstanders, so the target curves for each of my speakers is identical and drawn flat down to almost 20hz. If I used monitors, I would limit the target curves on the low end more severely.

 

[esscue]

Thanks for the reply sleestack, im familiar with the fletcher-munson effect and applying overlaying curves to compensate for them. i was hoping not to get too much into that in this discussion, but thanks you were thinking along my lines

thanks buckle-meister was a good read, and a great start to research. you were correct - a flat response is not generally desirable, previously i mentioned that i liked the sound of it flat (for movies), though, a bit more investigation into my receiver found that it was applying a "re-eq curve compensation" which rolls off the top end, it is a similar curve to the one you linked to. so when i eq'd it flat (post receiver) it was actually outputting a curve similar to what you were talking about.. (high end rolled off..) i just didnt know the receiver was doing it..

anyway expanding on this "re-eq" stuff,
(i would love to be corrected with constructive criticism):

further research has turned up the "x-curve" (and some variations for smaller rooms including home theartre - re-eq is supposedly a small room version of this x-curve.

anyway for those who are interested, here's what i've found:
****
The "X" curve is also known as the "wide-range curve," and is codified in ISO Bulletin 2969.
Specifications call for pink noise, at listening position in a re-recording situation or two-thirds of the way back in a theater, to be flat to 2 kHz, rolling off 3 dB per octave after that. This curve is found in all motion picture theaters and re-recording stages worldwide.
(source: National Film and Sound Archive Australia - http://www.nfsa.afc.gov.au/glossary.nsf/Pages/x+curve?OpenDocument)
****


so the x-curve is how a full sized movie theatre is set up. it turns out there are some modifications to that curve which makes it more applicable/useful for smaller rooms: neee Re-EQ for home thearte.

quote: From THX CC4 Manual (document sourced from thx website)

Re-EQ: Switches in a Re-Equalization high frequency correction filter in the 5
main channels. This filter provides for correct spectral balance monitoring of
film soundtracks mixed for a large auditorium with ISO X-Curve EQ, and
played back in a small room with flat frequency response speakers.

Re-EQ: Use for the monitoring of ISO2969 X-curve film mixes in small rooms.
Re–EQ re-establishes the correct High Frequency balance.

*elsewhere on the net i found some reference to only applying x-curve/re-eq to the front main channels and not to the surround, will have to dig around and see where i put that info.. because it contradicts the above thx application to the 5 main channels. hmm

here is another document which covers the history of the x-curve and why it's used. it also stretches into re-eq (but can't remember if it calls it that outright).. this is probably the most useful:
http://www.hometheaterhifi.com/volume_9_2/feature-article-curves-6-2002.html


i hope that helps someone else out as much as it has me. i've searched high and low for knowledge of how to configure home theartre responses, but people who know were generally less willing to share the info as its the meat of their income. anyway that concludes a few months of my research.

as most people would say its better to fix a rooms accoustic naturally, and thats fair enough - if practical... but in anycase the responses i've tried to find within this document are the target responses that one would try to achieve..(regardless of the method of getting there).

enjoy.
think i've written too much in this post,
wayne.

 

[jefffrizzle2001]

test 1 2 3

test 1 2 3

 

[jcrobso]

fletcher-munson effect

They were engineers at Western Electric that plotted the response of the human ear at different SPL.
At a 1db SPL the difference in sound pressure at 20hz vs 4khz is around 40~50 db. At 90db SPL the difference between sound pressure at 20hz and 4hz is about 10db. Yes we do hear better at loud sound levels! The down side listing to loud sounds for long periods of time will destroy you hearing.
Don't use EAR BUDS!!!!! John

 

[Sleestack]

I can design pretty much any set of curves I want, so I'm defniitely going to try some of those curves out. It's nice having the tools to see exactly what you are doing: