Dynaudio (Evoke) + ExpertPro 220

[David A]

@Confused ,

Thanks for pointing out that you can play test signals from Roon and measure the results in REW. I found your comments on the results of your experiments quite interesting, especially in relation to SAM. Would it be possible for you at some stage to post some of your results with SAM, especially some frequency response plots made with SAM at different settings, including one plot with SAM actually turned off and another with SAM on at 0%. That would definitely be off topic for this thread and would definitely deserve a head of it's own but that kind of information would be extremely useful for me and I suspect for many others here as well.

[Delija]

These are the measurements of my ex Dynaudio Contour 60s, full range, without subwoofers - with SAM 50% and without SAM. FR with SAM 0% is exactly the same as without SAM - what cannot be seen on FR (and what can be easily seen when subwoofers are being integrated) is phase shift which SAM introduces in both cases - 0% and 50%. It would be interesting to see phase and impulse measurements with REW.

[Axel]

I have actually used REW, used with both frequency sweeps and pink noise played via Roon.  In REW you can generate a sweep file and save this as a WAV file to play in Roon.  The file uses a timing reference tone as a trigger to commence the measurement in REW.

Arguably better than the above, you can use the RTA measuring system which requires pink noise, which similar to the above can be generated in REW as a WAV file.  I only recently realised this method even existed after  @Soniclife posted about the "moving mic" method in another thread.  See link below.  (Thanks for this one Soniclife, a great tip, and it shows the power of this forum, we can all learn from each other for the greater good)

https://devialetchat.com/Thread-Sweet-Ro...1#pid96941

https://www.youtube.com/watch?v=6Riuwqzj...e=emb_logo

I have not enough time to fully explore what can be done with the above, but I have got to the early stages of experimenting.  Last weekend I was able to play pink noise in Roon, and play with the settings in the Roon PEQ and see the influence on the REW RTA in room response curve in real time.  I tried a similar thing with SAM, I could adjust the SAM% on the remote, and actually see the low end of the frequency curve rising and falling.  This alone was educational, as I could see that the main influence of SAM was operating at a frequency below my largest room node peak, so SAM was actually leveling off the very lowest bass versus the adjacent peak, rather than directly adding to it.  Fascinating stuff.  I will be honest here, it did need quite a bit of time experimenting with the various REW RTA settings before I could get this to work satisfactorily, and I am still learning.  That said, this does look like a very powerful tool, you can adjust SAM, adjust the Roon PEQ, anything you want, and see the results in REW RTA in "real time".

As an aside, playing with the above does serve to highlight the room issues, and also highlight how tricky they are to resolve.  Hence in my case leading to the conclusion that I really should focus on getting better room treatment in place before worrying about room correction too much.

EDIT:  How off topic is all this!  One day I will post about this in the Sweet Room thread, if I ever find the time to get everything fully worked out.

I’ve had a umik-1 for about 18 months and used it in conjunction with REW just to get the feel of things I.e. playing test tones through my system and finding my way round REW, although I never got round to doing anything with my measurements.  I find the posts in this thread very interesting. They have whetted my appetite and I think this subject definitely needs its own thread. @Confused , could you oblige, please?

[David A]

These are the measurements of my ex Dynaudio Contour 60s, full range, without subwoofers - with SAM 50% and without SAM. FR with SAM 0% is exactly the same as without SAM - what cannot be seen on FR (and what can be easily seen when subwoofers are being integrated) is phase shift which SAM introduces in both cases - 0% and 50%. It would be interesting to see phase and impulse measurements with REW.

It's interesting that the results with SAM off and SAM at 0% are identical apart from the phase correction. Floyd Toole states in his book "Sound Reproduction - Loudspeakers and Rooms" that phase correction in the bass can result in up to half an octave of bass extension and I was interested in seeing whether there was any extension at a setting of 0%.

[Delija]

I would expect that impulse response is affected, but XTZ Room Analyzer doesn't have that analysis. I haven't seen any significant differences in waterfall diagrams.

I didn't spend too much time on analysis since I use subwoofers and now my new speakers don't have SAM profile.

[jvoki]

what makes SAM in my room
sw REW, mic in listening position. 
SAM 0 and SAM OFF are absolutly diferent.
next pictures are spectral analysis like top 3D view hill map sound energy in time

[David A]

@jvoki , @Delija ,

Thanks for those posts and measurements, much appreciated, but I find myself left with a problem. I got the sort of information I was looking for but I didn't get the answers I was looking for, instead I was left with more questions.

OK, we're looking at data from 2 different rooms with 2 different pairs of speakers. That means I really can't compare one set of measurements with the other but one set shows a significant difference with SAM off vs on at 0% and the other includes a report that there is no difference between SAM off and SAM at 0%. I think we can reasonably expect that if there is a difference, it should show in both cases and if there isn't a difference, that should show in both cases. Something is going on.

I have to say that, based on the comment from Floyd Toole which I mentioned, and what I hear when I compare SAM off and SAM on at 0% in my system, I expected to see a difference which leaves me with 3 possibilities I can think of to explain the different results:

1- the speakers because they are going to have different frequency and phase responses in the low bass;

2- the difference in software and mics used is a factor;

3- XTZ Room Analyzer and REW are doing something different in their measurement process.

There is also another possibility which is that neither set of measurements relates to the most indicative parameter and that parameter is probably phase response.

My interest here is that I'd really like to get some kind of useful sense of what the difference between SAM off and SAM on at 0% is because I do hear a difference, and also some understanding of what the % setting adjusts—does it affect the range over which phase correction occurs, does it introduce some level of bass boost over a freqiemcy range with a change in either or both depending on the level of the setting, or is it a combination of bot of those things or even possibly something else. Devialet are fairly uninformative on what actually is going on, as usual.

It would be interesting to see this discussion taken further but I think if that's going to happen we should really move it to another thread because it is off topic for this thread but I think it may be simpler just to leave things where they stand at present. I have a suspicion that it would be a lot easier to get measurements which give us a better idea of what is going on if Devialet were more informative about what actually is going on so that we knew the appropriate measurements to make but then, if Devialet were more informative, there wouldn't be a need for this sort of discussion.

Once again, thanks for your measurements and information which has been really interesting, even if I am left with a few more questions than I started with.

And apologies to @zoran_pavlovic for raising an issue which has taken his thread so far off topic.

[Jean-Marie]

@jvoki , @Delija ,

Thanks for those posts and measurements, much appreciated, but I find myself left with a problem. I got the sort of information I was looking for but I didn't get the answers I was looking for, instead I was left with more questions.

OK, we're looking at data from 2 different rooms with 2 different pairs of speakers. That means I really can't compare one set of measurements with the other but one set shows  a significant difference with SAM off vs on at 0% and the other includes a report that there is no difference between SAM off and SAM at 0%. I think we can reasonably expect that if there is a difference, it should show in both cases and if there isn't a difference, that should show in both cases. Something is going on.

I have to say that, based on the comment from Floyd Toole which I mentioned, and what I hear when I compare SAM off and SAM on at 0% in my system, I expected to see a difference which leaves me with 3 possibilities I can think of to explain the different results:

1- the speakers because they are going to have different frequency and phase responses in the low bass;

2- the difference in software and mics used is a factor;

3- XTZ Room Analyzer and REW are doing something different in their measurement process.

There is also another possibility which is that neither set of measurements relates to the most indicative parameter and that parameter is probably phase response.

My interest here is that I'd really like to get some kind of useful sense of what the difference between SAM off and SAM on at 0% is because I do hear a difference, and also some understanding of what the % setting adjusts—does it affect the range over which phase correction occurs, does it introduce some level of bass boost over a freqiemcy range with a change in either or both depending on the level of the setting, or is it a combination of bot of those things or even possibly something else. Devialet are fairly uninformative on what actually is going on, as usual.

It would be interesting to see this discussion taken further but I think if that's going to happen we should really move it to another thread because it is off topic for this thread but I think it may be simpler just to leave things where they stand at present. I have a suspicion that it would be a lot easier to get measurements which give us a better idea of what is going on if Devialet were more informative about what actually is going on so that we knew the appropriate measurements to make but then, if Devialet were more informative, there wouldn't be a need for this sort of discussion.

Once again, thanks for your measurements and information which has been really interesting, even if I am left with a few more questions than I started with.

And apologies to @zoran_pavlovic for raising an issue which has taken his thread so far off topic.

I would definitely expect the difference between SAM off and SAM at 0% to be very speaker specific.
As a thought experiment let's assume the following:

1. Floyd Toole's statement that phase correction in the bass can result in up to half an octave of bass extension
   
2. a pair of Speakers A where the geometry and the filter performs phase correction
   
3. a pair of speakers B where phase has not been considered as a pertinent dimension. 
   

It seems quite logical to me that there would be no difference between SAM off and SAM at 0% for speakers A (because SAM would not add any additional phase correction while speakers B would exhibit the expected difference.

My two cents,

Jean-Marie
 

[David A]

@Jean-Marie ,

You said "2. a pair of Speakers A where the geometry and the filter performs phase correction". Point of clarification, what "filter" are you referring to? If that filter is SAM then surely we should expect a difference between SAM off and SAM on but set to 0% for that speaker.

[thumb5]

Possibly @Jean-Marie is referring the cross-over?