Recommended Posts

OK, let us know what Dirac say. I'll be honest it seems pretty clear to me though :).

As it happens my listening position is only about a meter from the middle of the room anyway! (Something like 1.3 m from the back wall in a room around 4.6 m long.)

  • Like 1

Share this post


Link to post
Share on other sites

Also interested in the reply from Dirac as I too thought it could be interpreted two ways. 

Share this post


Link to post
Share on other sites
Super Wammer
15 hours ago, chrisph said:

Also interested in the reply from Dirac as I too thought it could be interpreted two ways. 

Thanks @chrisphI was starting to think I was the only one that thought that could be looked at in a different way . At least when they respond we will know what the designers had in mind for certain which i think at least helps.

Share this post


Link to post
Share on other sites
Moderator
8 minutes ago, bencat said:

Thanks @chrisphI was starting to think I was the only one that thought that could be looked at in a different way . At least when they respond we will know what the designers had in mind for certain which i think at least helps.

Hi Andrew - when it says "1. Place the microphone in the middle of the listening area." I have always interpreted that as meaning the same place that you would put the microphone for your first measurement. Later on, they get into the detail of the listening area and talk about this first position as "the main position", but I think they have just glossed over that early on as it is explained in more detail later. It would have been helpful if they used the same terminology at the start and maybe referred you to the later description to understand what it means. In any event, given that the point of the mic calibration is to adjust the mic for the later measurements, I can see no reason why you would choose a different position (than the first measurement position) to do that calibration - it would make no sense to me.

  • Like 1

Share this post


Link to post
Share on other sites

Just a quick heads up for anyone thinking of giving  room correction a try, I've just had an email from Lee Bevan of Strictly Stereo letting me know that he is about to start stocking the MiniDSP DDRC-22D, previously it seemed they were out of stock just about everywhere.  I have been rather fortunate to find a second hand SHD which I hope will be arriving shortly.

  • Like 3
  • Upvote 1

Share this post


Link to post
Share on other sites
4 hours ago, Tony_J said:

Hi Andrew - when it says "1. Place the microphone in the middle of the listening area." I have always interpreted that as meaning the same place that you would put the microphone for your first measurement. Later on, they get into the detail of the listening area and talk about this first position as "the main position", but I think they have just glossed over that early on as it is explained in more detail later. It would have been helpful if they used the same terminology at the start and maybe referred you to the later description to understand what it means. In any event, given that the point of the mic calibration is to adjust the mic for the later measurements, I can see no reason why you would choose a different position (than the first measurement position) to do that calibration - it would make no sense to me.

And if, when you start doing the Dirac measurements, the volume is set too low or too high, I think it complains anyway.

  • Upvote 1

Share this post


Link to post
Share on other sites
Super Wammer

Okay will add the complete thread from Dirac so you can see all that they said except for thanks and were closing this question .

Flavio Fellah commented:

Hello,

there might be a misunderstanding... the first measurement is the most important one and it has to be taken from the main listening position (i.e. where your head will be)
That first measurement is the one that assigns gains and delays and it will compensate for an asymmetry if the main listening position is not at the center.
These are our guidelines when taking measurements...

The basic principle is that any additional measurement improves the correction. However, depending on the acoustics of your room and equipment the benefit from more measurements may diminish faster. Therefore, note that you do not necessarily need to do all the measurements defined in the arrangement. However, we strongly recommend you to never do less than five measurements.
The measurement points should have a distance of at least 30 cm (12 inches) between each other.
Avoid making measurements in too small a space. Even for the “Tightly focused” listening environment, it is important to spread out the microphone positions in a sphere of at least 1 meter of diameter. Too small a space will result in over-compensation that will sound very dry and dull.
Measure some points outside the listening area, e.g., for a sofa, it is recommended to do a few of the measurements 20-30 cm in any direction outside the couch.
Remember that you are measuring a volume rather than a surface and be certain that you take the measurements in different vertical positions as opposed to in a single horizontal plane.
Point the microphone upwards to the ceiling (90 degrees) when measuring to ensure that additional coloration from the microphone is similar for both the wall reflections and the direct wave from the speaker (the 90° microphones' cal file is needed in this case)
Also, the positions specified in the arrangements act as a guide and you may deviate from them to put or decrease emphasis on particular spaces.

Finally, let me add that I'd avoid having an object interposed between the speaker and the mic nor a surface too close to the microphone... in that case I'd modify the mic positioning instead.

I hope this helps, best regards


Me to them

Hi Flavio

 
Thank you for your response but I may have not made myself clear . I do understand the importance and placement for the first measurement and this is very clear.
 
What I am asking is for the initial Volume Calibration of the Mic to ensure that the level is in the green zone ie not too quiet and not too loud . Now for the Mic placement for just this calibration should this be the same as the first measurement in the ideal listening position. Or should it be in free space in middle of the room between the two speakers at about your sitting head height . Then after setting the volume calibration move the Mic to the correct listening position for the first real session measurement.
 

Flavio Fellah commented:

Hi Andrew,

I now understand your point... the volume calibration should match the measurement phase so I'd use the same position.
Reaching the green isn't always essential, Dirac Live is finicky so if the measurement is accepted it will be OK.

Best regards


dirac admin changed the status to Waiting for customer.

So all those that told me it was obvious and there was no confusion were right and as usual I was trying to read too much in to things. In my defence I had up now used the first measuring position to calibrate I just did not want to have got it wrong and then skew the sessions I had completed . Ah well at least we all know now . I am making no comment on the last bit .
  • Like 1
  • Upvote 3

Share this post


Link to post
Share on other sites
Moderator
13 minutes ago, bencat said:

Okay will add the complete thread from Dirac so you can see all that they said except for thanks and were closing this question .

Flavio Fellah commented:

Hello,

there might be a misunderstanding... the first measurement is the most important one and it has to be taken from the main listening position (i.e. where your head will be)
That first measurement is the one that assigns gains and delays and it will compensate for an asymmetry if the main listening position is not at the center.
These are our guidelines when taking measurements...

The basic principle is that any additional measurement improves the correction. However, depending on the acoustics of your room and equipment the benefit from more measurements may diminish faster. Therefore, note that you do not necessarily need to do all the measurements defined in the arrangement. However, we strongly recommend you to never do less than five measurements.
The measurement points should have a distance of at least 30 cm (12 inches) between each other.
Avoid making measurements in too small a space. Even for the “Tightly focused” listening environment, it is important to spread out the microphone positions in a sphere of at least 1 meter of diameter. Too small a space will result in over-compensation that will sound very dry and dull.
Measure some points outside the listening area, e.g., for a sofa, it is recommended to do a few of the measurements 20-30 cm in any direction outside the couch.
Remember that you are measuring a volume rather than a surface and be certain that you take the measurements in different vertical positions as opposed to in a single horizontal plane.
Point the microphone upwards to the ceiling (90 degrees) when measuring to ensure that additional coloration from the microphone is similar for both the wall reflections and the direct wave from the speaker (the 90° microphones' cal file is needed in this case)
Also, the positions specified in the arrangements act as a guide and you may deviate from them to put or decrease emphasis on particular spaces.

Finally, let me add that I'd avoid having an object interposed between the speaker and the mic nor a surface too close to the microphone... in that case I'd modify the mic positioning instead.

I hope this helps, best regards


Me to them

Hi Flavio

 
Thank you for your response but I may have not made myself clear . I do understand the importance and placement for the first measurement and this is very clear.
 
What I am asking is for the initial Volume Calibration of the Mic to ensure that the level is in the green zone ie not too quiet and not too loud . Now for the Mic placement for just this calibration should this be the same as the first measurement in the ideal listening position. Or should it be in free space in middle of the room between the two speakers at about your sitting head height . Then after setting the volume calibration move the Mic to the correct listening position for the first real session measurement.
 

Flavio Fellah commented:

Hi Andrew,

I now understand your point... the volume calibration should match the measurement phase so I'd use the same position.
Reaching the green isn't always essential, Dirac Live is finicky so if the measurement is accepted it will be OK.

Best regards


dirac admin changed the status to Waiting for customer.

So all those that told me it was obvious and there was no confusion were right and as usual I was trying to read too much in to things. In my defence I had up now used the first measuring position to calibrate I just did not want to have got it wrong and then skew the sessions I had completed . Ah well at least we all know now . I am making no comment on the last bit .

One interesting thing that these responses brings out is that we should be pointing the mic at the ceiling when doing the Dirac measurements, which I have not done in the past - I must give that a try.

  • Like 1

Share this post


Link to post
Share on other sites
Super Wammer
5 minutes ago, Tony_J said:

One interesting thing that these responses brings out is that we should be pointing the mic at the ceiling when doing the Dirac measurements, which I have not done in the past - I must give that a try.

When measuring for room correction in REW I always do that, using the 90 degree file. I only measure in a 3 feet circle around my listening position though, I may try a larger area.

  • Upvote 1

Share this post


Link to post
Share on other sites
2 hours ago, Tony_J said:

One interesting thing that these responses brings out is that we should be pointing the mic at the ceiling when doing the Dirac measurements, which I have not done in the past - I must give that a try.

I haven't either. Previously I've only seen this recommended for AV systems, where it obviously makes sense give you have sound arriving from all directions. I'm intrigued by the reason given though. In my own room the strongest early reflection by some margin is actually from the ceiling rather than the side walls.

Unless someone has a sofa/chair with a very low back I'd have thought a vertical microphone would be problematic for most? It would be for me, with even a horizontal microphone means the lower rear positions aren't really as low as they should be. I suppose the microphone could be pointing vertically down though.

One other point I'll add is that while the e-mail stresses that the first measurement sets the main gain and delay adjustments I believe it is actually the central measurement location that does this, which the last time I tested doesn't need to be measured first. When I last had a quick play with multiple measurement positions I deliberately measured the central position last so that I could then measure what Dirac was doing at the exact same spot. 

Share this post


Link to post
Share on other sites
13 minutes ago, MartinC said:

I suppose the microphone could be pointing vertically down though.

On reflection (!) this would probably be a dumb idea :doh:. In that this would compromise measurements from above which I'd have thought are generally more important than those from below, since there's more likely to be more absorption or objects in the way for the latter.

The straight ahead and vertical calibration factors for my UMIK-1 only differ above about 700 Hz actually, so all of this probably only matters above around this point. 

  • Upvote 1

Share this post


Link to post
Share on other sites

Bencat, many thanks for getting confirmation on the measurement approach and supporting info.

Good to get confirmation I have taken the first measurement in the right position and with microphone at 90deg.  

I have been measuring for a tightly focused environment and based on the comments re a sphere of 1m I will revisit my measurement positions.

  • Like 2

Share this post


Link to post
Share on other sites
Super Wammer

Before anyone goes off and does lots of new measurements please see the below which is from the MiniDSP UMIK-1 page . While the Dirac advice seems to say that 90 Deg is the way to go MiniDSP as Martin has said advise this position for AV multi speaker systems only . As on the DDRC 24 has four slots I think just to see what the results are I will do a session with the Mic at 90 Deg for the stereo set up if nothing else it will be a little different .

Which calibration file should I use and where to point the UMIK-1?

We provide two calibration files to be used depending on your application.

- For stereo system (e.g. 2ch dirac live, single speaker measurement), use the 0deg file and point the UMIK-1 at the speakers
- For multichannel system (E.g. 5.1/7.1) or a surround application where multiple speakers are spreadout around the room, use the 90deg file and point the UMIK-1 at the ceiling.

Recommended by our Friends

The miniDSP team built long term relationships with the following leading software applications and is proud to showcase them as our recommeded software solutions:

REW: miniDSP worked along with John Mulcahy to develop even greater compatibility for the UMIK-1 inside REW! With the latest beta release of REW (v5.01 and up), the UMIK-1 is automatically recognized by the software and prompted for use when REW is started with the microphone plugged in.

Prompt_REWPrompt2_REW

Please follow our application note for more information.

Dirac Live: As a well known reference in the world of room correction with countless high end audio/automotive, we're honored to have Dirac as part of our partners. The UMIK-1 is the recommended microphone by Dirac Research.

  diraclive2.

Umik-1 on Ipad: Our technical team has been testing the UMIK-1 along with few ipad apps. A plug&play setup for a full featured measurement + SPL meter running from the Ipad. Check out our application section for more info. 

umik-1-signalscope

Please follow our application note for more information.

Fuzz Measure Pro v4: Fuzz measure is no stranger to acoustic measurements. This very powerful Mac only software is now fully integrating import of UMIK-1 calibration file and automatic SPL calibration. Make sure to check it out!

FuzzMeasure Pro UMIK-1 calibration 2

Amarra Symphony: Amarra Symphony with IRC is an advanced music file player for the Apple Mac platform. It includes a feature called "Impulse Response Correction" (IRC), that corrects for acoustical errors at the listening position caused by early reflections from the speaker and listening room. It also provides the ability to tailor the response at the listening position using target curves.

amarra-symphony-irc-button.png

Please follow our application note for more information.

 

Related Products
 
  • Like 1

Share this post


Link to post
Share on other sites

I haven’t found too much practical difference between using the mic vertical and straight ahead. IIRC it is supposed to be omnidirectional although I can’t see how it can be absolutely. FWIW I tend to point the mic up about 30 degrees from the horizontal and pointing to a point midway between the speakers in the horizontal plane.

I do think it is essential to have the first measurement taken at the listening position because the software needs to know which measurement is taken at that position, and given that it is not essential to do all the listed measurement positions, the first is the only one it can identify as being in the listening position. Interesting to note the comment about assigning gains and delays from this first and known measurement, I assume it also slopes other measurements to the first measurement. To ensure that I can return to the listening position measurement I put masking tape on the floor below the centre of the mic stand. I have been known to forget to return the mic to this position before taking follow up measurements in REW! Usually realise when I look at the plots. I also move my listening chair back, partly to give room for the mic stand and also to avoid close reflection from the chair back which don’t seem to matter in practice but might affect the measurements.

For my solo listening position I normally make the measurements quite closely spaced, but I have found the more tightly spaced the measurements the more necessary it is to adapt the target curve to generally follow the measured curve to avoid that dull and lifeless sound. A straight (ish) descending frequency response might seem like a good idea but I have come to the conclusion that it is not a good idea to negate the sound of the room as a whole so much as curtail excessive peaks in the bass area. I run dirac full range, which gives best results for me.

  • Like 1

Share this post


Link to post
Share on other sites
9 hours ago, Camverton said:

I haven’t found too much practical difference between using the mic vertical and straight ahead. IIRC it is supposed to be omnidirectional although I can’t see how it can be absolutely.

The lower the frequency, the closer it will be to omnidirectional. Below is what the two calibration curves look like for my microphone to give some idea. (Edit: I think the vertical scale here is dB but I'm not certain. I've just plotted what is in the calibration files.)

466568528_UMIK1response.thumb.JPG.284446f938a5dca4c2c7f84add248b3d.JPG

Quote

I do think it is essential to have the first measurement taken at the listening position because the software needs to know which measurement is taken at that position, 

Sorry, I should have said, you can click away from the central location to measure an alternative first, then back onto the central location at the end to measure this one. Each measurement should absolutely be measured where it is indicated on the picture. Note that you also have the option to go back and remeasure any individual point if you want to, by clicking on it first.

I'm not really encouraging anyone to do anything other than measure the central location first but just mentioned the option for anyone like me who really wants to try to see what Dirac is doing.

Quote

Interesting to note the comment about assigning gains and delays from this first and known measurement, I assume it also slopes other measurements to the first measurement.

I'm not sure what you mean by this? Based on the e-mail I think the gain and delay applied will be only based on the central position, which makes sense.

Quote

Usually realise when I look at the plots. I also move my listening chair back, partly to give room for the mic stand and also to avoid close reflection from the chair back which don’t seem to matter in practice but might affect the measurements.

That's interesting, and not something I'd really thought of since there is no practical way I could move my sofa significantly out of the way for measurements. Reflection and absorption effects of your chair will be present when you listen though, so it's not obvious to me whether moving it would be a good idea or not?

Edited by MartinC

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Recently Browsing   0 members

    No registered users viewing this page.