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Digital EQ & XO to correct speakers & rooms (Off Topic)

by Bert @, Thursday, December 20, 2007, 23:13 (3683 days ago)

Okay, lets start fresh giving some personal thoughts about this subject...

Advantages (i.e. what can you do with it):

You name it, alsmost everything is possible. Changing or correcting the frequency response of a speaker itself (phase, amplitude, crossover, etc..)

Disadvantages:

- Extra components in the signal path giving always some sort of distortion and in the worst case molesting the original data simply by changing the bits.

- Any change or correction applied and the signal is not bitperfect anymore (assuming the Digital EQ is fed by a bitperfect signal).

Why using it?

Okay, your speakers are not perfect (or good enough) for which I can understand that this might be an easy tool to correct their behaviour if nothing else is possible or when you want to take the "easy" way to do things.

With such a device it doesn't matter how the speakers are build or aligned, the machine will solve all your problems... :lol:

This is okay with me and I can see the advantages doing this but what I can not accept is that people are using the same device at the same time to correct their room response....this is simply wrong and will never lead to the most optimal performance of your system!

Why not using it?

A microphone will never be able to see what your ears are able to detect. Let alone a "stupid" device (compared to your brain!) with the limited knowledge that people learned the thing to do...

One example is that your ears are able to detect the differences between direct sound and reflected sound, your microphone can't, just as simple as that. A microphone only detects a mixture of direct and reflected sound.

The communication between the ears and the brain gives you the illusion of true space and depth (as present on the recording), correcting the speaker and the room at the same time using a microphone to correct this will only result in a more artifical, more flat and more technical sound, what has that to do with music?

The only result is that your brain is then working very hard to cope with all the unnatural information it receives trying to change it all into the "desired" illusion while listening at the one spot in the room....

Bert

--
BD-Design - Only the Best!

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by PeterSt. ⌂ @, Netherlands, Thursday, December 20, 2007, 23:51 (3683 days ago) @ Bert

(reference : http://forum.bd-design.nl/index.php?id=14901 )

but what I can not accept is that people are using the same device at the same time to correct their room response....this is simply wrong and will never lead to the most optimal performance of your system!

I'm not sure why this is impossible (IOW I think it just is), but another thing is that it is not needed, should not be, is wrong for treatment.

This needs another few pages to explain, but

a. This is what GC gets the headache from (hi mr. Lyngdorf)
b. For me (and others) it is sufficiently proven that it is not needed indeed.

May it be amps, speakers or playback device (random order), when all are sufficiently right, you would not want any room correction.
Room correction is needed when what comes from the speakers (incurred by the whole chain) is so much wrong that only room correction can make you think it's allright again. Ehh, on that one calibrated spot only.

You don't believe that ? come over and have a listen.

Bert, I was addressing people in general. Not you.

Peter

PS: Now start thinking about what you would prefer :
1. An exact copy of the hall etc. where the recording took place (fake in 90 % of cases anyway)
2. Let your room act as the room where the recording took place.

Hint : When you don't choose 2, you get a headache. :secret:

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by Bert @, Friday, December 21, 2007, 00:00 (3683 days ago) @ PeterSt.

Peter,

You don't believe that ? come over and have a listen.

Bert, I was addressing people in general. Not you.

Thanks for not inviting then...:cry::

PS: Now start thinking about what you would prefer :
1. An exact copy of the hall etc. where the recording took place (fake in
90 % of cases anyway)
2. Let your room act as the room where the recording took place.

I'll go for option 1 and the 10% remaining... :grin:

Bert

--
BD-Design - Only the Best!

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by PeterSt. ⌂ @, Netherlands, Friday, December 21, 2007, 00:08 (3683 days ago) @ Bert

You don't believe that ? come over and have a listen.

Bert, I was addressing people in general. Not you.


Thanks for not inviting then...:cry::

Hahaha, it's so difficult to write properly.
:biglol:

PS: Now start thinking about what you would prefer :
1. An exact copy of the hall etc. where the recording took place (fake

in

90 % of cases anyway)
2. Let your room act as the room where the recording took place.


I'll go for option 1 and the 10% remaining... :grin:

So that's a nice discussion (of which we both know we don't have the exact answer).
But if I perceive a churche of 100 meters long in my room of 10, my brain gets damaged. Maybe I should close my eyes and open my mouth ... :read:

But okay, sorry I put the question. It's a discussion by itself (but an interesting one).

Peter

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by Bert @, Friday, December 21, 2007, 00:14 (3683 days ago) @ PeterSt.

Peter,

But okay, sorry I put the question. It's a discussion by itself (but an interesting one).

You can always start a new topic and ask again... :wink:

Bert

--
BD-Design - Only the Best!

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by GC, Friday, December 21, 2007, 01:09 (3683 days ago) @ Bert
edited by GC, Friday, December 21, 2007, 07:36

Opaaaa:grin:

And this walse is too interesting to comment at this time of the day :sleepy:

Hear U

GC

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by Gasper, Friday, December 21, 2007, 11:17 (3682 days ago) @ Bert

One little comment:

On the latest Show in Ljubljana were presented OB loudspeakers (from USA) which are using digitEQ with mic. The sound ... was dead:shame:

Ciao,
Gasper.

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by Bert @, Friday, December 21, 2007, 12:00 (3682 days ago) @ Gasper

Hello Gasper,

On the latest Show in Ljubljana were presented OB loudspeakers (from USA)
which are using digitEQ with mic. The sound ... was dead

That is probably becasue you were not listening on the "hot" spot or those people do not listen themselves and fully trust on what the machine is telling them... :fool:

Bert

--
BD-Design - Only the Best!

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by Gasper, Friday, December 21, 2007, 14:09 (3682 days ago) @ Bert

Dear Bert,

You are right... the right spot was in the next room where was playing horns...:wink:

I have learn to trust just one microphone...my ears :grin:

Be cool :cool:

Ciao,

Gasper.

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by GC, Friday, December 21, 2007, 16:40 (3682 days ago) @ Gasper

Dear Bert,

You are right... the right spot was in the next room where was playing
horns...:wink:

I have learn to trust just one microphone...my ears :grin:

Be cool :cool:

Ciao,

Gasper.


:teasing: :naughty:

:lol::lol::lol::lol::lol::lol::lol:

:wave:

:cool: :cool: :cool:

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by GC, Friday, December 21, 2007, 12:03 (3682 days ago) @ Gasper

One little comment:

On the latest Show in Ljubljana were presented OB loudspeakers (from USA)
which are using digitEQ with mic. The sound ... was dead:shame:

Ciao,
Gasper.

Hi Gasper

I did unfortunately/fortunately (hehe) not hear too many solutions to digitized room tweaking or even room disappearance (what a word...the room is still there? or?) as it's many years since I stopped visiting Hi-Fi shows where all new solutions can be found and many manufactores demostrates all this.

I lean a little bit to Berts stance from what I know and heard and trust. Peter might be able to handle everything from one common platform, which I also trust is a quite heavy task do deal with, should the bits in there remain perfect and no harrasment with jitter faults etc occur. Whatever Peter has in mind, I don't think that will come so cheap either.

Then again discussing the braindamages such devices could cause, I'm a bit in lack off vocabulary as I'm not a digi nerd.

Frankly, I would even not have owened a DAC if it wasn't for the industry that forced me to.
Now of course I got used to the thought and use of them, the befits and conveniency. But still if there were a solution out there that made me have an option then it would be my system where no DAC exist.

GC :grin:

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by GC, Friday, December 21, 2007, 13:55 (3682 days ago) @ GC

As this is off topic I might be allowed to add a very simple comment on rooms.
It's completely out of any digital EQ domain.

Well we all have rooms except for the few who lives in a climate that allowes outdoor listening. :grin:

Let's take my room. I have no problem with it.
When my wife speaks to me, and it still happens :shame: , when I try to sing in it, drumming with my hands on my knees or table pots and pans whatever, when I fumble in the kitchen and drop glasses, plates and what else I do to avoid doing the dishes after dinner, I can't find one thing that sounds wrong.

In that very same room are other sources of sounds: My Speakers. Neither they sounds wrong. Why? Because they act like natural sounds as a causeffect of their perfectionism in the phase domain. What is there to be corrected then?

I don't need any form of digtal EQ!

GC:cool:

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by PeterSt. ⌂ @, Netherlands, Friday, December 21, 2007, 14:07 (3682 days ago) @ GC

GC,

(I'm not sure anymore where to post this, but let's try ... :grin: )

Yes. This is the very best example of how things can only be mangled with for the worse. Or better to the subject : if something *has* to be mangled with, better take the cause away.

And GC, allow me ...

... and your room is far from one of the best ...

:swoon:

... which actually doesn't matter. Handclaps echo to a certain extend, and with the proper playback chain audio playback does not suffer from it.


Right. Now everyone can start shooting. :dance:

Peter

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by GC, Friday, December 21, 2007, 14:12 (3682 days ago) @ PeterSt.

My shot is Peter, that you're right in each and everything you say :good:

That's my room. Perfect for any sound that may occur there.


GC

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by Sjef @, Saturday, December 22, 2007, 02:14 (3682 days ago) @ GC

I think I have said this a couple of times before but read my lips, you guys are all going to use some form of digital xo/eq somewhere in the next few years once you will discover the disadvantages of analog filtering. All the complains here sound to me like history repeating. Digital xo/eg is just a complete new way of looking at things and needs a complete new learning curve to get the best out of it, many commercial solutions are doing it only halfway at the moment but things will change for sure.

before judging on anything that messes around with bits just start to realize what the oh so many disadvantages of linkwitz/bessel/butterworth etc filtering are compared to phase linear (when executed the right way) then you will find out that there simply doesn't excist a way of excecuting a analog filter the right way. And before judging any form of eq just realize that a crossover like the one used in the oris system IS a equalizer and also realize that a perfect listening room DOES NOT excist, eq can help here and that is in fact also what yoy guys are doing with crossover tweaking as well. In my room the implementation of a digital xo/eq has made some improvements wich I simply couldn't achieve with better speakers/amps/playbacksystem/acoustics treatments, specially the low end has improved tremendously and with the low/end the whole presentation of the music has also improved a lot. Digital xo/eq is not a cure for all and it has disadvantages as well I know (those thamn opamps again, the first thing you will have to get rid off) I also know that it will take you about forever to get it right, just trying it on a afternoon says nothing, it will take you months, yes much more time than with analog filtering.

And what the use of bit perfect when the rest of the system is not "analog perfect" anyway, messing with bits can make the system more "analog perfect"

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by GC, Saturday, December 22, 2007, 08:39 (3681 days ago) @ Sjef
edited by GC, Saturday, December 22, 2007, 10:41

Hi sjef

I think I have said this a couple of times before but read my lips, you
guys are all going to use some form of digital xo/eq somewhere in the next
few years once you will discover the disadvantages of analog filtering.

Would you name a few of these disadvantages that you discovered?

> All the complains here sound to me like history repeating. Digital xo/eg is

just a complete new way of looking at things and needs a complete new
learning curve to get the best out of it, many commercial solutions are
doing it only halfway at the moment but things will change for sure.

No doubt this approach is under development.

before judging on anything that messes around with bits just start to
realize what the oh so many disadvantages of linkwitz/bessel/butterworth
etc filtering are compared to phase linear (when executed the right way)
then you will find out that there simply doesn't excist a way of
excecuting a analog filter the right way.

Oh sjef I really have to disagree here. There are no any other disadvantages than those apllied to the use of components itself.
You mention a few transfiguration equations. Have you ever heard a filter that apllies 1 in 1 out acoustically? I mean this is analogue perfect.
For the digital controlled loudspeaker you can achieve the same. So where I differ from your stances here is that digital filtering 1=1 just has so many anomalities that it IMO can't compete with the correct analogue approach. Not that I heard of at least.

If you have not heard an *analogue perfect* loudspeaker, ehh what to say then? Then you just missed it. And this is very likely to be the case as you can hear that only a few places in the world.

Looking into the Digi-eq/DSP world I see a few more components messing with sound.

Would you also be kind to tell me how you are able to hear differences between a phase turn of say 360 degrees within a frequency bandwith, your choise, compared to a 0 degree phase liniar bandwith? How do you percieve this?

I ask because I caNot and there are eveidence enough to find on the net that proves the oposite of what you claim here. Such as blind-tests. Most test persons reacts to that like we reacts to placebo effect.

I have heard speakers showing both 0 phase linear perfomance achieved analogue and digital. Neither of the approches showed even one advantage to me comparing to an analogue perfect speaker showing a phase turn as long as everything in there has the same phase turn

And before judging any form of
eq just realize that a crossover like the one used in the oris system IS a
equalizer and also realize that a perfect listening room DOES NOT excist,
eq can help here and that is in fact also what yoy guys are doing with
crossover tweaking as well. In my room the implementation of a digital
xo/eq has made some improvements wich I simply couldn't achieve with
better speakers/amps/playbacksystem/acoustics treatments, specially the
low end has improved tremendously and with the low/end the whole
presentation of the music has also improved a lot. Digital xo/eq is not a
cure for all and it has disadvantages as well I know (those thamn opamps
again, the first thing you will have to get rid off) I also know that it
will take you about forever to get it right, just trying it on a afternoon
says nothing, it will take you months, yes much more time than with analog
filtering.

And what the use of bit perfect when the rest of the system is not "analog
perfect" anyway, messing with bits can make the system more "analog
perfect"

Sjef somehow I think I know what you point at. I'm not attacking your approach and your vote for Digi EQ etc. This is your opinion.

But I certainly do not agree with you about your analogue oppinions...far from.
I can of course not know what unluck you had with your approaches to "analogue perfect" that lead you to have such a stance as you point out here?
Maybe you did not have the right approach to dial this in? Anyhow I have still to hear the digital perfect dialed in system, as the few I heard, no matter how much *they* were dialed in made me run away.

GC

But this of course just about different oppinons :grin: as no one of us actually prove anything here. Do we? :wink:

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by PeterSt. ⌂ @, Netherlands, Saturday, December 22, 2007, 10:16 (3681 days ago) @ Sjef

And before judging any form of
eq just realize that a crossover like the one used in the oris system IS a
equalizer and also realize that a perfect listening room DOES NOT excist,
eq can help here and that is in fact also what yoy guys are doing with
crossover tweaking as well.

Hi Sjef,

All together things are so complicated that it has become sheer impossible to know evrything - or think of everything at the same time.
The quote above does not take into account that room correction is not needed.

(Btw Bert, it doesn't help much that all threads are torn apart.)

If we assume that we all hear as well (why not), then apparently it is your idea Sjef, that room correction is needed, while at the same time it is my (and a few others') idea that room correction is not needed at all.
Please note the reference to GC's room (but my own would be an example just the same) of a room being far from optimal for listening conditions, while the "corrections" needed just were applied by ... good playback means.

Again, we hear as well, and you apparently did not have the experience yet.
Of course it is too hard to believe it is so, but why not trust me as a person hearing as well as you yourself.

By now there is sufficient proof that a room with a bad response, derived from playback (and not from measuring !) shows this bad response because of poor playback means. The most important (as by my experience) is impedance problems, or IOW that shows best how reverberations, sibilance, standing waves - emerge in a room without the room being guilty. Oh yes, you can start decorating the room all over to get rid of the anomalies, but the point is ... it's the wrong treatment. It's the wrong treatment as long as playback means can solve it just the same.

It is hard to explain ... Besides impedance problems, a wrongly tuned xover can cause the anomalies, a not so good amp can, and a not the best player can. In fact it is the latter which does the most to it all, or better : I can guarantee that when you have room problems and your equipment is right (impedance matches) it's the player doing it to you (with a small chance it's the speakers).

I do not say that each room will behave the same, but I do say that a room should not be decorated to solve "room problems".
What this comes down to, is that no room-correction is needed at the equipment side. Might it be digital or analogue, it is not needed.
The very last thing that would be happening, is that "we" would tweak rooms by means of xover settings. Oh, you saw me say similarly above, but different : the xover must be just GOOD. Good = good from theories, and not good for a room or something like that.


The best of it all (the theory that a room doesn't harm) is that it can be used as a means to check the playback chain. When the room responds wrongly, go and search for problems in the playback chain. I GUARANTEE that a problem can be found. Since I apply this theory, it always worked ... (and not only by myself, but also with GC as THE example with his large undecorated wooden floor room).

Peter

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by GC, Saturday, December 22, 2007, 10:37 (3681 days ago) @ PeterSt.

Hi Peter

I am not sure that a room correction made by tweaking it with furnitures, bookshelves, pillows and carpets caNot make it up for room anomalities. I think such things can help.

My point is as long the playback chain is delivering *perfect* sound in harmony with the human brain, then that sound does not scare you out of any room damped or not. You simply co-exist without trouble.
If the playback system does not tell what will be expected from the brain to happen, the adrenalin will force us out of there.
Anything unexpected will always cause a shock to us.

And when I talk about the chain in this context it caNot be either the one or the other member of the chain that can take the honor for delivering the perfect non disturbing sound. Each member counts even.

GC

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by PeterSt. ⌂ @, Netherlands, Saturday, December 22, 2007, 10:56 (3681 days ago) @ GC

Hey GC,

I am not sure that a room correction made by tweaking it with furnitures,
bookshelves, pillows and carpets caNot make it up for room anomalities. I
think such things can help.

Oh yes, they will. But how to judge whether they were the thing to apply. I mean, how to judge whether / when the playback chain is optimal (and ehh, what was optimal 3 months ago is obsolete today, right ?)

So you could grab your blanket over the lamp picture (it must be here somewhere) as the example. Did it help ? yes. But when did it help ? when things were still wrong / not optimal. Was it needed when things were optimal (at that time) ? NO !
We even OPENED curtains ...

But of course you are right, but to my theories this will be so when other things are still wrong.

We could also turn things the other way :
Bert's room is rather optimized. The sound coming from it certainly is different. At aspects we could say it is better. At other aspects maybe just not. Then, you could say this is personal or subjective. On the other hand you could say that a room is ALLOWED to create the sound. This is IMO similar to your expression that clapping your hands etc. will never disturb to the matter of unnatural sounding hand clapping. That an echo is there in your room, and no echo is there in another's (like Bert's) is another matter.
What it is about, is that the echo belongs to the room you listen in, and that to my findings (over and over again) such an echo (most probably not in the recording obviously) caNot harm. BUT : it is the most obvious - and known to the world, that those same echo's "will" create room anomalies like standing waves (not only with bass but also in the highs). The "will" is between quotes, because exactly that is not true. Not anymore.
But indeed, detariorate one part of the chain, and they are back ...

Peter :cool:

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by GC, Saturday, December 22, 2007, 11:11 (3681 days ago) @ PeterSt.

So you could grab your blanket over the lamp picture (it must be here
somewhere) as the example. Did it help ? yes. But when did it help ? when
things were still wrong / not optimal. Was it needed when things were
optimal (at that time) ? NO !
We even OPENED curtains ...

But of course you are right, but to my theories this will be so when other
things are still wrong.

Yes Peter I remember the lamp trick and things were not *chain perfect* at that moment.

As they are now, I can repeat the lamp trick. I does the same to the room as before. But now it's indifferent to my brain wether it's there or not.

I think we say more or less the same thing here... :yes:

GC

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by Bert @, Saturday, December 22, 2007, 11:35 (3681 days ago) @ Sjef

I think I have said this a couple of times before but read my lips, you
guys are all going to use some form of digital xo/eq somewhere in the next
few years once you will discover the disadvantages of analog filtering. All
the complains here sound to me like history repeating. Digital xo/eg is
just a complete new way of looking at things and needs a complete new
learning curve to get the best out of it, many commercial solutions are
doing it only halfway at the moment but things will change for sure.

Everything is a compromise, nothing is perfect and that is what this is all about. As long as the compromise is in favour to use passive filters (not easy but very possible) then this is still the way to go. If you can't make your system work with passive filters and the best compromise is using digital means then use that, I do not care...but don't try to tell that what you can't achieve passively isn't possible for others.

...excecuting a analog filter the right way. And before judging any form of
eq just realize that a crossover like the one used in the oris system IS a
equalizer and also realize that a perfect listening room DOES NOT excist,
eq can help here and that is in fact also what yoy guys are doing with
crossover tweaking as well.

You are wrong here, yes some limited passive EQ is implemented for tuning in the bass towards the Oris horns used in a specific room but it does not correct room anomalities. A smaller room just gives more bass compared to a large room and that is all. But this does not affect the Oris horns themselves which will happen when you connect your digital EQ in their path...

For bass tuning only I do see some advantages which has less negative impact on the whole system making things more easy to dial in but still, even used there, it destroys nice things...

Bert

--
BD-Design - Only the Best!

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by PeterSt. ⌂ @, Netherlands, Saturday, December 22, 2007, 12:38 (3681 days ago) @ Bert

A smaller room just gives more bass compared to a
large room

Hi Bert,

I don't want to interfere with your statements, but did you not intend to say this the other way around ?

:rolleyes: Peter

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by robmatthew @, Saturday, December 22, 2007, 15:59 (3681 days ago) @ Bert

Everyone who comes to my house seems to think the room is very good. I also have always felt that the room was good and the sound excellent as well.

After I incorporated the DEQX I never even tried the room correction aspect of the DEQX until last year, when , just for fun, I measured the room found that it was pretty good but there where soom relatively small hills and valleys in the response spectrum of a few dB here and there but no serious notches.

I corrected those areas, which is very easy to do with the DEQX connected to the computer, and was simply amazed at the very significant change that occurred. Until then I never believed that room correction could ever help if you start with a good room whose sound you know very well.

My pont is that unless one has a very good calibrated microphone and a unit like the DEQX which is powerful enough to do the job, you really do not know if the sound could be better even if it is already wonderful to your ears.

I never would have believed it if I had not done it myself. I think it is worth a try because one might really be missing something otherwise.

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by Bert @, Sunday, December 23, 2007, 00:03 (3681 days ago) @ robmatthew

Hi Bob,

I never would have believed it if I had not done it myself. I think it is
worth a try because one might really be missing something otherwise.

I am sure that there are things which can be improved by using a digital EQ/XO like the DEQX but it is so easy to accept for most people that this is the best solution without telling the whole story. I can see the advantages having a bi-amped system and let the filtering, time-alignment and even, to some point, correcting the behaviour of drive units done by a digital EQ.

What a DEQX never ever is able to do is to take away the signature of a driver, removing resonances of a driver or loudspeaker system, make it more dynamic, reduce dynamical compression or even give it more resolution than it is capable to give on its own. Before starting to use such a device would be best after everything else is as good as it can be...

Using a DEQX with a lousy system to optimise will never grow to be the best sounding system, a good tuned and fully analogue filtered system will wipe the floor with it!

The only thing the DEQX does is flattening the frequency response by optimising phase behaviour and related time-alignment the best it can. This is a very good thing though, relative easy and useable if you are capable to achieve that and know about the behaviour of loudspeakers in general to do this optimally...

The disadvantages taken it could be the best compromise while optimising a system further though and I will probably give it a try some day to see what it brings to my system.

Bert

--
BD-Design - Only the Best!

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by Sjef @, Sunday, December 23, 2007, 03:12 (3681 days ago) @ robmatthew
edited by unknown, Sunday, December 23, 2007, 03:16

I corrected those areas, which is very easy to do with the DEQX connected
to the computer, and was simply amazed at the very significant change that
occurred. Until then I never believed that room correction could ever help
if you start with a good room whose sound you know very well.

My pont is that unless one has a very good calibrated microphone and a
unit like the DEQX which is powerful enough to do the job, you really do
not know if the sound could be better even if it is already wonderful to
your ears.


That's excactly my point, thanks for putting it into words.

I have a DEQX as well and it is possible to build a very good system around it as long as you have studied it's behaviour well enough, otherwise chances are that the system will only be worse, the DEQX is not quite as easy as it might look.

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Digital EQ & XO to correct speakers & rooms

by Rooze ⌂ @, Wisc USA, Sunday, January 13, 2008, 01:04 (3660 days ago) @ Bert

Very interesting comments in this thread on room correction and digital EQ.

I started the earlier thread (now closed) before the Holiday about using digital XO's with an Oris system, and it yielded many interesting comments, some of which I tried to implement with varying degrees of success.

I took some very useful information from the other posts, now I'd just like to give some feedback on my trials and tribulations with room correction and setting crossover points.

I realize people have very different approaches to achieving system bliss, and that this post won't be of interest to most people, but hopefully someone might glean some information and something worthwhile.

So, I'm using dual stacked Oris 150 with Fostex 208 Sigs and bass cabinets with 16" fostex drivers. Horns driven by Cary 2A3 mono's, with Sophia Electric 300b tubes, Audio Aero Capitole MKII CD player, and a Aesthetix Calypso preamp, just replaced with the focus of this post, a Lyngdorf TDAi 2200 - digital integrated amplifier with room correction.

Collecting data from around the web and from the designer of my speaker system, I was under the impression that optimum XO point for this system was around 150hz. This is how I've run the system for quite a while, using an integrated subwoofer amp and crossover from Gallo Acoustics - but I was never completely satisfied with results(poor bass quality and integration).
Though I've read various accounts of why a XO setting in the region 150hz should be optimal, I haven't fully understood the explanations so I've remained open-minded as to the best setting of the XO point, and decided to just trust my ears.

So the story starts around the holiday when I loaned a new piece of equipment (loaned to me by a local dealer in Port Washington WI) - the Lyngdorf TDAi 2200 - an impressive box with a very high quality digital amp, digital crossover and "room perfect", which is Lyngdorf's term for their room correction package. The unit is fully digital, so you can connect a transport and a pair of speakers and that's all you need, or you can control a more complex satellite speaker system using its various crossover functions, which is how I use it. In my configuration I use the internal digital amp to drive the bass modules, then use the line outs into my Cary 2A3 SET's. This is quite incredible, since I have the best of all worlds with SET amps driving my horns, a digital amp on the bass, and the whole system controlled by the room correction module.

My mission was to first set the best bass response I could, using the digital XO and also the delay function, which allows position of the bass modules against room boundaries.

Using a test CD and SPL meter, I measured output which was only 2db down at 90hz, without the bass towers active. I have the graphs, but this is really an overview so I won't get into too much detail.

Moving down in 5hz increments from 150hz, I now have the XO set in the Lyngdorf at 90hz on a eighth Linkwitz Riley. This has given me the best integrated bass that I've had from this system. I still plan to take the XO point even lower in small, measured increments. Note - Each time I adjust the XO point I first measure the output using test-tones and the SPL meter and record it, then attempt to confirm the measurements with extensive listening. That way I know I'm not painting myself into any corners. Of course, with the Lyngdorf I can manually set the gain of the horns, differently from the bass modules. So I can balance the bass of the system manually before introducing the room correction DSP. Getting the system to sound at its best without DSP, yielded the best results once DSP is activated.

So with the system manually balanced, the next step is to go through the room measurement procedure, which involves placing the supplied mic at the listening seat and measuring a series of test tones, then moving the mic randomly into other areas of the room, until the Lyngdorf has a good picture of your room acoustic, expressed back to the user as a percentage of knowledge gained.

The whole process of room measurements takes 20 minutes, at which point you can sit down and hit "play".

Room correction via the Lyngdorf is simply a revelation. The soundstage takes on a 3 dimensional shape that I've never been close to with a conventional system and many, many room treatment experiments. Layering, depth, width, space between instruments/performers, tonal balance, everything is so much more realistic.

So I'm close to reaching the goals that I set for my system a few years ago.
The tasks I have left are to complete the bass integration and arrive finally at the best XO settings, then the replace the Fostex T90 supertweeter with something that gives me more HF information and seamless integration (ideas welcomed).

So I understand people's skepticism about DSP, EQ and room correction, but if you can do it all without changing the tonality of your system and without essentially changing the character of your system, then it has to be a good thing?

Sorry for my lengthy ramble. :grin:

Rooze

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Digital EQ & XO to correct speakers & rooms

by GC, Monday, January 14, 2008, 10:53 (3658 days ago) @ Rooze

Very interesting Rooze...

I have neither been sleeping since this thread started.

I have no doubt that finding the right slopes bewteen the engaged speakers should be done with great care. No doubt about that in any case..digi or analogue.

Where I was more curious were how DSP'ing possibly could compete with bit-perfect. So of course I started to inevestigate a bit on the matter and found a couple of guys who really have spend life time with all this.

However they did not exactly use Lyngdorf but a SW program called http://www.acourate.com/ and they told me that if you don't go *over-dosing* with the room correction you can achieve quite good results.
They also told me that it takes a very long time to reach the goal this way and the road is full of pritholes.

So what I decided was that this should be due to finding out myself and not let theories dump any solution.

So left with my safe knowledge that a bit-perfect signal should not be moslested with, I will in the future stick my nose into DSP'ing to see if the headache I get from it is comming from the wrong way of using it.

That might take a very long time to come through- :eek:

GC

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