The HiFi Myth and Professional System Design

ryart

Thanks for sharing the graph and getting this thread back on track. My first question is, why does the corrected response have such a dip at about 110hz? Is the graph decided by the equipment or has there been any extra adjustment to suit your personal preference?

My other question is much more difficult to answer or put into words and is, in what way do you think the presentation of music has improved? Is it easier to follow different musical instruments for example?

BlueWizard

No, you never said you were an expert but you are claiming some expertise and that is what I am trying to get you to tap into.

You never said you were trying to get 'flat response', but that is generally the objective of speaker and amp design, and also, generally, the objective of tuning a given room.

Now, truly flat response is rarely to never achieved.

Next my examples of how easily room equalization and acoustics can be thrown off, was not to imply that is was worthless. Only that perfection itself is a pointless and unachievable goal. If I tune my room both acoustically and electronically flat, which implies that I have also dealt with reflections, standing waves, and dispersion, then even if I invite some friends over and destroy the theoretical perfection, it is still going to sound sweet.

One doesn't have to achieve perfection in any aspect of the system or equipment, one only needs to have dealt realistically with the common problems that plague us all, and in that case, the music and the room will sound better and work together.

Doing something is always better than doing nothing, but there is a point of Diminishing Returns. As you get closer and closer to perfection, each incremental improvement costs substantially more. So, at some point, rather than perfection as the goal, a far more realistic goal is 'good enough'.

I don't think anyone is disputing your basic premise, but one that premise is established, the next question is 'Now What?'. Where do I go from here? What do I need to know to make informed decisions on the matter? Etc...

Steve/bluewizard

craigd

There is a null at 90Hz and what looks like two discrete peaks that have superposed at 110Hz and 130Hz. In targetting the 110Hz peak I would imagine the unit has also also decreased lowered the level too far. I have actually contacted the vendor to see if there is a way to get better results in this frequency range and am awaiting a response.

The response is calculated by the unit with no customisation on my part. There are predefined voicings which can be used as a kind of global EQ e.g. adding traditional shelf filters to increase/decrease bass and/or treble. The come with various self explanatory names liek 'Treble', 'Warm', 'Bright', 'Bass', etc.

Low bass is tighter and punchierMid bass is thinner but is no longer masked by so much excessive low bassStereo image is improved and instruments are easier to placeClarity and detail is improved

ryart

Many thanks for the reply, fascinating stuff.

I would say your list corresponds pretty well with my experience of the Meridian system, although that only makes adjustments up to 200hz, and it does not attempt to level out troughs, only peaks. I think they feel that to be able to smooth out a trough would need too much extra amplification or require lowering the whole range in order to bring back the troughs. Always a compromise I suppose.

In my room taking out the peaks in the bass does allow me to follow the lower pitched instruments in an orchestra much better. Meridian equipment is, of course, pretty expensive but I do think its use makes the most of the rest of the equipment in a way that I have never been able to achieve with speaker placement and furnishings. Within the context of a fairly high end system it is cost effective and the returns are significant enough not to be diminishing.

Rob Sinden

One of the reasons for the lack of in depth information about room correction in my initial threads is that I now realise that it's such a horribly complex science.
About 2 weeks ago I was looking at a thread about room acoustics and it quickly became very, very technical as two people who looked as if they had degrees in audio from Salford exchanged their thoughts. The things they were talking about were above me.
My interest in room correction is increasing the understanding of what it tries to do, pointing out some of the basic differences between systems and to get people comparing different systems. I dont think there is much interest or discussion of this on the Forums under the section aimed at music listeners perhaps becuase only Lyngdorf makes a product that is aimed at this market and very few dealers stock these products - possible because they are not interested in acoustics.
There are over 40 audio engineers at Lyngdorf and I have spoke with many of them, however I find much of what they have to say about audio completely inaccessable. Audyssey aren't much better, but at least they provide a before and after graph showing, typically showing a nice smooth graph after their correction has been applied. Showing this before and after graph and listening to the results is easy to grasp and is a point that I think that everyone interested in audio should consider trying to understand because it doesnt take much understanding and at the end of the day it comes down to what it sounds like anyhow.
While many people will have had good experiences with Audyssey products built in to AV amps they are unlikely to have heard this correction system at it's best because of the set up equipment that it was used with. Obviously the quality of the mic is very important in creating a map of the rooms acoustics and the mic included with AV amps with Audyssey products is pretty mediocre. The professional set up kit that can be used with many Audyssey enabled receivers uses a high quality, factory calibrated mic and pre amp and more sophisticated software to run the programme so the results are much more impressive. Next month Audyssey will be launching their own Bass Eq device that will require this same set up kit which I think will make it the best bass tweak available. Phil Hintons review of the Sound Equaliser on the AV Forums will tell you more and I'm sure he'll be reviewing the new device when it becomes available and the importance of the set up kit will come out then.
What I now relaise is that the before and after results that Audyssey produce only tell part of the story. You need 1000's of filters in you are to accurately address correcting 20,000 frequencies. The resolution of the graph that was required to accurately portray this would not look like a nice smooth line - but to show the "high res" graph to the casual reader would probably proove be confusing.
Now I realise that any single point reading in a room is virtually meaningless - because if you move 6" it may look completely different. This is why Lyngdorf never claim to be able to produce a nice smooth graph of the in room response at the listening position.
The problem is that to get the best response at one place in the room, the acoustics of the whole room must be considered. To put it another way you cannot correct a three dimensional problem with a one dimensional reading.
Finally Lyngdorf are not looking at frequency response alone, the power response and several other factors are just as important to rectifying "real sound" but these elements are much more difficult to convey.
If you want to know more about this there is more info on their site.
Personally I think it much more interesting to more people to talk about the principals of room correction than for a few experts to be discussing stuff that the rest of us wont understand.

phil t

A graph showing the reference tone please?

Mark.Yudkin

Your graphs would be more useful if you listed the complete kit involved in its production, as well as giving us a basic idea of the room's layout and furnishings. As it is, I don't like any of the graphs, but have no idea why the response is as it is.

Rob Sinden

It's a National Holiday in Denmark today so I can't get this information yet. I don't believe it's one tone but a series of them but this is something that I'd need to ask the factory.
Would it be more appropriate to move this to another area of the Forum as I can see this turning very technical, very quickly?

Rob Sinden

I wonder how many people would have been interested if the first thing I’d put on the thread had made reference to the type of test tones used and the issues of timing, power and frequency response measured in a 3 dimensional space?

CJROSS

Craig I think you have to step back from the whole room correction issue here, which many of us know is a legitimate way to get a system working optimally in your room if you have problems, as is tuning a system via ears and positioning.

Many of us on the thread (long term contributors to this forum) have a serious concern that a dealer/installer can create a inflammatory thread under the auspices of assured advertising about how people should go about getting a great end product from their kit, we have already seen as the thread develops, suggestion and innuendo of how bad other dealers are (some legit but should not be aired IMHO), my way is best etc, all packaged up to push wares being sold by said advertiser. It is also very worrying to see customers (potential too) backing up and defending the advertiser to the extent we see, when in all honesty they are hardly ever on this forum. Let’s face it guys this thread is not about room correction to me, it is about a practice of putting the boot into other dealers, suggesting to users that the way they have assembled systems is wrong and should be done in a way that financially suits the advertiser making the inflammatory posts.

Now if this is an acceptable way for the forums to head, then I for one see it turning into a dealers/advertising forum. Room correction today, Shatki stones tomorrow.