New loudspeakers & room digital correction service

[SwissBear]

SwissBear

 
Really appreciate you having a look at my measurements, and all the explanations (even if I don't really understand them  ).
 
Firstly, and unfortunately the easiest one to answer is that I won't be able to put any physical Acoustic fixes into the room. Where my hi-fi set-up is in the living room that is open when first entering the house and as such there's Buckley's chance of me being able to change anything without a divorce being on the cards (the Aussies will know what I mean by Buckley's - it's another way of saying 'not a hope in hell').
 
The roof in the room is part recessed, and as such no chance of being able to change this (again will just have to live with it).
 
Also unfortunately I am a complete beginner with this Room Correction stuff, and have never used REW (or any software) before. I really don't have any idea where you got the charts from (look really good, but still trying to get my head round what they mean).
 
I took 8 measurements as Thierry says on his website to do between 5 & 8, and the diagram is pretty random measurements (a bit like what I did, with no real logic behind them except the Left & Right ones always being in the same place). Also when you say about combining all the files into 1, do you mean to zip them, I had a look at REW and can't see how to combine all 16 measurements into 1 file. L1 & R1 are my sweet spot measurements, with 2 to 8 being taken randomly (with one each for Left and Right Speakers each).
 
Another big no no to surely a lot of people is that I normally sit offset from the middle of the speakers and have actually did the measurements with me being in the offset (1/3 to the left side of centre, i.e. 0.5m from the left speaker axis, and 1.8m from the right speaker). Would it be better if I did the measurements sitting exactly in the middle (not where I normally sit unfortunately)
 
Due to not being able to change anything physically in the room, and being a bit of a Luddite with Room Correction software, hence why I was really happy to see the options being given by Thierry. Will forward on your comment about putting in a brick-wall filter to not produce sounds below 20Hz
 
Cheers
John

John,

I have no intention to insist on the acoustic ceiling. Just know that is does not have to be ugly (in my case this is just a stretched ceiling which material is micro-perforated), with an isolation hidden under the stretched ceiling (http://barrisol.com/uk/stretch-ceiling/s...20-acoperf).

When finished, you see a very normal ceiling (the D200 was a replacement for my D900 which was in Paris at that time):
[img][/img]

On the number and location of measurements, I will let Thierry comment directly. My own measurements were made a long time ago, while Thierry was still prototyping his product. His expectations might have changed in between.

One of the great strengths of Thierry's correction is the correction of the reflected field. This allows to have a very good reproduction of the sound where ever you are seated (not necessary in front of the speakers).

[petrik]

SwissBear - Do you know is it better to take all 9 measurements or do 5 measurements be enough? Will more measurements give better results?

Hi Petrik,

The goal of having multiple measurements is to make 'spatial averaging', ie to separate the signal from the noise (see page 16 of this document: https://www.dropbox.com/s/r9ipzfiq46givt...2.pdf?dl=0 ). The more measurements you have, to a certain extend which has been defined as 9 measurements by Dirac as well as by Thierry, the better.

What is important in any case is to have a measurement made in the sweet-spot and to identify it for Thierry.

Thanks. I took only 5 measurements since that was the minimum requirement and Thierry confirmed that those were fine. Also the results are good indeed. I just keep wondering now that could I possibly get even better results if I would do couple more measurements... I'll ask from Thierry what he thinks about it.

[SwissBear]

Thanks. I took only 5 measurements since that was the minimum requirement and Thierry confirmed that those were fine. Also the results are good indeed. I just keep wondering now that could I possibly get even better results if I would do couple more measurements... I'll ask from Thierry what he thinks about it.

Well if Thierry said that 5 was OK, then he had enough information inside your measurements to separate the signal from the noise. Which is fine. And after you had the confirmation that the corrections were good. So what else ?

I understand that you are confirming your positive impressions after the 30 first minutes of listening. Is it correct ?

[petrik]

Thanks. I took only 5 measurements since that was the minimum requirement and Thierry confirmed that those were fine. Also the results are good indeed. I just keep wondering now that could I possibly get even better results if I would do couple more measurements... I'll ask from Thierry what he thinks about it.

Well if Thierry said that 5 was OK, then he had enough information inside your measurements to separate the signal from the noise. Which is fine. And after you had the confirmation that the corrections were good. So what else ?

I understand that you are confirming your positive impressions after the 30 first minutes of listening. Is it correct ?

I think it would be better if there would be some exact number of measurements that is required.

I need to do some more listening but I definitely liked what I heard yesterday. I have created dozens (if not even hundreds) different filters with Acourate since I have had troubles for getting it sound right. For some reason the HAF filters sounded just right immediately.

[SwissBear]

I need to do some more listening but I definitely liked what I heard yesterday. I have created dozens (if not even hundreds) different filters with Acourate since I have had troubles for getting it sound right. For some reason the HAF filters sounded just right immediately.

I am on the same page as you are. When I started listening to the last version of Thierry's correction, I immediately decided to stay with them whatever the efforts I had achieved with all other correction systems. The magic of his unique technology I guess

[Confused]

Traditional room correction tends to reduce bass peaks (easy to do), but does little to 'fill' bass nulls (difficult to do) caused by room reflections.

Is this this equally true of these HAF filters?

[SwissBear]

Traditional room correction tends to reduce bass peaks (easy to do), but does little to 'fill' bass nulls (difficult to do) caused by room reflections.

Is this this equally true of these HAF filters?

It's not different, for a 'mechanical' reason which is that you cannot fill a bottomless hole.
In more technical terms, you can only bring appropriate correction to the upside to a system when it behaves as a minimal phase system. Which means when you look at the Group Delay (GD in REW) and this Excess Group Delay is not very different from 0.

To illustrate, on my main system, which amplitude (SPL) is here:
[img][/img]

you cannot fill the gaps bellow 80Hz because of this:
[img][/img]

The technical explanation is on page 54 of this manual: http://www.roomeqwizard.com/REWhelp.pdf

The only way you can act is to position the speakers and the listening position in order to solve this problem.
Please note that REW has a function (RTA) which allows to listen to a pink noise and look at the screen while changing the positions of the speakers and the microphone for this purpose.

[homeaudiofidelity]

Hi all,

Following SwissBear suggestion I am now registered on this forum and will be happy to exchange with you. I am very glad to see the overall interest and as well some first positive feedback.
Where to start ? SwissBear has given most of the background and it is true that I have developed specific algorithms as I was not satisfied by the "state of the art" for a specific case.
As the last questions are related to the number of measurements I confirm that the number itself is not so critical as long as the usual listening area is covered. For a small listening area sweet spot + 5 others will be fine, for a larger one more measurements will be required. There is as well no need to have precise symmetrical positioning.
Don't hesitate if you have further questions !

Cheers,
Thierry

[SwissBear]

Following SwissBear suggestion I am now registered on this forum and will be happy to exchange with you. I am very glad to see the overall interest and as well some first positive feedback.

Hi Thierry,

Glad to see you here: you will be able to answer questions in a more precise manner than I could.
Welcome to the forum.

[Confused]

Thierry, I think it is excellent that you have chosen to join the forum.  Welcome!  Plus, I think you joining the forum does indicate that you have confidence in your product, I see participation like this as a very positive sign.

I do have some questions.  Firstly, your website details taking measurements, one at the 'sweet spot', others around the 'sweet spot'.  OK, this makes sense, but I would like to clarify exactly how the sweet spot should be defined.  For example, I can sit exactly equidistant between the speakers, in the classic triangle formation.  So this is my 'sweet spot'.  However, if I walk forwards and backwards in my room, I can hear that the bass increases and decreases, almost as a wave, depending on where I am.  This is entirely normal, and I think I understand the basic reasons behind this phenomenon.  They key point I want to clarify is that my preferred 'sweet spot' does correspond to the point where the bass reinforcement or bass level is subjectively more or less at the maximum.  So in other words, I like to listen where there is more bass not less.  This is my choice, but I do know of another person who more or less does the opposite and has set up his room so he sits where the bass reinforcement or level is more or less at it's lowest.  This is personal preference, but if we both used your service I would be providing measurement where the bass peaks, and the other guy where it drops.  My question is, does this matter?  If it does matter, where should we measure, at max bass, min bass or somewhere in between?

My second question relates to the volume level at which to makes the measurements.  Personally, I do not have a preferred volume level to listen at, sometimes it is loud, sometimes very loud(!), sometimes moderate, sometimes quiet, it depends on many things.  Plus, if I use REW to take measurements, there is a volume range through which I can get error free readings.  So when taking measurements should you aim for high volume, low volume, bang in the middle of the range REW can cope with, nearest to your most common preferred listening level, or again, does it not matter?

My third question is that although I can use REW to take measurements and look at the nice 'All SPL' graphs and similar, I have no idea if I am doing this correctly for the purpose of your measurements.  So as not to waste lots of time, is it a case of someone like myself taking a measurement, sending one though to yourself, you check and confirm it is OK (or otherwise), I can then take the time to do the multiple left / right measurements knowing I am getting things right and not wasting my precious time and indeed yours.  

As a final question, is there a preferred version of REW to use, or just a case of 'use the latest'.

Quite a lot there I know!  But I do like to understand things and get things right.  Plus for me, no rush for a response, it will be a few weeks before I have enough time to quietly take the measurements!