New loudspeakers & room digital correction service

[thumb5]

Hello Thierry, and please let me add my welcome to those already given. I'm very interested in trying your service and will probably be back fairly soon with another bunch of questions (also mostly about the measurement process).

[Dan]

Another question. I use SAM sometings and not others. Should measurements be done with SAM on or off.

[SwissBear]

Another question. I use SAM sometings and not others. Should measurements be done with SAM on or off.

Let me try to answer this one: SAM is altering both the amplitude response (SPL) and the phase. You will therefore theoretically need to have two corrections: one with SAM and one without SAM.

Having said that, the goal of any active correction is to standardize the amplitude response so that you have a correct restitution of the tones.

The best way will probably be to chose one way of operating and stick with it. I personally chose to activate SAM by default. I made my measurements with SAM active. The only variable which I am adjusting is the level of SAM (from 0 to 100). This way, the phase is always correctly managed by the active correction, and the amplitude is adjusted depending on the music I am listening to.

Would this make sense for you ?

[Dan]

You are a few steps above my pay grade on this acoustic stuff....however, of late, I mostly have been listening with SAM on, so it sounds like I should do the measurements with SAM on.

[petrik]

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?

At least a following guide recommends using about 75 dB when taking measurements with REW.
https://www.minidsp.com/applications/aco...p-with-rew

[petrik]

I would also have a question that do cables affect on these measurements? Like if I change for example loudspeaker cables, or the digital link cable between Devialet master & companion, should I then take new measurements?

I suppose I can say that I can hear differences between cables but I'm not sure are the differences visible on these measurements.

[Confused]

Another question. I use SAM sometings and not others. Should measurements be done with SAM on or off.

Let me try to answer this one: SAM is altering both the amplitude response (SPL) and the phase. You will therefore theoretically need to have two corrections: one with SAM and one without SAM.

Having said that, the goal of any active correction is to standardize the amplitude response so that you have a correct restitution of the tones.

The best way will probably be to chose one way of operating and stick with it. I personally chose to activate SAM by default. I made my measurements with SAM active. The only variable which I am adjusting is the level of SAM (from 0 to 100). This way, the phase is always correctly managed by the active correction, and the amplitude is adjusted depending on the music I am listening to.

Would this make sense for you ?

Interesting points regarding SAM.  I would certainly be interested to read Thierry's thoughts regarding SAM.  To me, it does make sense to have SAM enabled to gain the benefits of phase correction.  However, you get the full phase correction even with SAM at 0%, the SAM % is then simply adding gain to provide low bass extension.  One idea I had was to take the measurements at SAM 50%.  That way, when using the correction filters you have the option to leave SAM at 50%, or dial SAM up or down as required to get a small adjustment of the lowest bass.  Seams like a sensible idea to me, but I am not an expert in this subject!

[petrik]

I have been thinking about these digital room and loudspeaker correction things today. If I'm being truly honest to myself, I have always felt that although the DRC (digital room correction) has always fixed most of the bass problems in my listening room, it has usually brought some negative things too. Firstly, although the bass is usually really fast and tight with the DRC filters, I have felt that the bass also looses some impact and power. Secondly, this is much harder to describe, but let's just say that I have felt that the DRC filters usually do some negative things on mids and highs. Results are typically "hifi" but the music isn't anymore as powerful, lively, and exiting if you know what I mean.

Today I did a brief comparison between the HAF filters and listening without these filters. I just wanted to check what negative things do these HAF filters have. And to my surprise again I had difficulties to say anything negative about these filters. To tell the truth, I felt that almost everything was worse when listening without these HAF filters. With these HAF filters in use, the bass is having amazing definition and still it doesn't seem to loose impact & power. And the soundstage, that is clearly more three dimensional when using these filters. Nothing significant negative to say on mids/highs. Perhaps, just perhaps (as I already said before) it might be having a slightly dark sounding target curve for me. Anyway, I'm very much enjoying these.

Well done Thierry!

[homeaudiofidelity]

For some reasons I don't receive anymore alert on thread updates... Let's try to answer with my view:

- sweet spot definition might be confusing : by sweet spot I mean the place where you usually sit for listening. The purpose of DRC is to minimize the negative effects of the room once you have chosen a configuration (or have been forced for different reasons...)

- the level during measurement should not be too high to stay in the linear mode of your audio chain. Said differently you should not have distorsion and this can easily be checked by looking at the impulse response : there should be very little level before the main pulse. While using sweep measurement distorsion will appear as copies of the impulse response but time shifted so visible before the main pulse.

- any version of REW is Ok and it is quite easy for me to check if a measurement is Ok. Following the simple guideline that Petrik copied on this thread should prevent any big mistake

- I am not fully updated regarding SAM but I think it is simply what is usually called a Linkwitz transform (modify a bass reflex alignment with a filter to reduce group delay) : if you are used to have SAM active, then you should make the measurements with it active as well. Otherwise the group delay behaviour will be different and the phase correction will not be appropriate

[homeaudiofidelity]

I missed the cables question : no need to perform measurements when changing cables. Almost all cables have flat frequency response and even if there is a slight deviation it is of much lower order compared to loudspeakers & room