Hilde45, the impulse graph provides a single (multi frequency, I think) short sound (the impulse) and records every reputation of that impulse until it completely decays. You don't need to run the scans again, just select the impulse tab in the row of options above the frequency graph. Set the graph limits at -0.002 on the left and .050 on the right, 0db on the top and -65 dB on the bottom. Each vertical line is a reflection of the initial impulse. You would like to have everything from 3m to 20 m on the X axis at -20 dB. Anything above -20 dB will erode imaging because the brain will merge those early reflections with the 0m impulse signal, thus obscuring the spacial information in the recording. Anything longer than 20m will be perceived as room spaciousness.
Next, set the limits to -.002m on the left and 0.5m on the left. I set the bottom limit to about -85 db. This will show you how long it takes for the impulse to decay to the level of room noise, which is really a picture of how spacious your room will sound. This is a matter of personal taste. Some want as close to an anechoic chamber as they can get. In other words, those folks advocate that everything after the original impulse should be at the level of room noise. Most of us like added spaciousness of the room. My room currently shows a gradual decline to the level of room noise (the more or less flat zero slope area at the right part of the graph) at 0.3m. m is time in milliseconds.
|
@hilde45, I looked at your REW frequency response curves. At a quick glance, they don't look that bad to me. Most rooms that are not custom built for audio that are well treated will still show plus or minus 5 dB below 300 Hz. I usually change the scale so I can get a good feel for the plus minus range. I would suggest you also click on the spectrograph and waterfall tabs and generate the plots. You should be able to see where your long decays are. If you have long decays in higher frequencies, that can make a room sound bright even if your frequency response is pretty flat. Also take a look at the impulse graphs. I like to see the impulse graph achieving room noise level by about 300 ms. You might like a bit more. It looks like your deep nulls are in the statistical zone where moving your mic an inch or two can really change the graph. In other words, don't pay attention to the details above 400 Hz or so. You could look at the psychoacoustic smoothing frequency response and get a feel for what kind of balance you have between low and high frequency.
I don't know what to make of the asymmetry in that sharp null close to 200 Hz. It must be associated with the room asymmetry on the right and left sides. It looks like a pretty deep null, but it is narrow, so it may not give you much trouble. But you might figure out what the exact frequency is and play that tone while you are walking around the room.
|
Hilde45, It sounds like you are making real progress. With respect to spacial issues, your set up has an enormous advantage in that the side walls are completely innocent with respect to early reflections. Side wall first reflections are the most egregious and are also not as easy to treat effectively as most people think. After looking at your impulse graphs and room set up, I suspect your ability to localize is compromised by proximity of your main listening position to the back wall/bookcase. The bookcase is better than a flat wall, but the bookcase is not as easy to improve as a flat wall. This may take a little creativity, but I think you can improve on imaging and localization by doing some things with the bookcase after you lock into the current speaker and MLP as optimal. I'm sure you are getting some reflections off of the ceiling, but the human ear doesn't use sounds from above to for localization nearly as much as those in the horizontal plane, so I wouldn't worry too much about the ceiling unless you've got other issues like flutter echo.
|
As usual, there is a divergence of opinions. I agree with a lot that has already been said, but I'm going to try to tie together the best of it and add one or two other points.
- Pure guess on my part, but of the speakers you listed, I’d lean strongly towards the Fritz. I have experience with Scan Speak soft domes. If they are too bright, look elsewhere for the problem. They are respectable with regard to resolution and imaging, but not necessarily world class. I also encourage you to seriously evaluate the Fritz near field. If the room is part of the problem, and I am almost certain it is, near field listening may be the easiest “quick fix” even if it will only be a partial fix. If I had to move quickly, Id go with the Fritz and start working on the room.
- Your room dimensions are way outside the Bolt area and you also do not have a favorable Bonello modal distribution. Your room IS a problem. I’d avoid full range speakers until you are willing to invest heavily into room treatments.
- 6.5 ft ceilings and 14 ft side walls can be brutal in creating flutter echo. Play some sustained high frequency test tones and if you have flutter echo you will hear it right away provided you hit the right frequencies. This can be ear piercing. My room has 8 ft ceilings and 14 ft side walls and I am still trying to defeat flutter. You are going to have to deal with side wall reflection in a 14 ft wide room to address flutter and get decent imaging. If your floor is not carpeted with a deep pile you are probably going to need to treat the ceiling as well.
- Download Room Equalization Wizard and learn how to use it and interpret the results. It takes time, but it will save you a lot of wasted time, effort, money, and frustration in the end. The individual who said “the room is the speaker” was correct. In most rooms, at least 80% of what you are going to get out of a system is based on optimal selection of speaker and main listening positions.
|
Yes, the diagram helps. I don't know how much flexibility you have with rearranging the room, but if you can move stuff around, I would rotate the bed 90 degrees and move it to the other end where the gear currently resides. Put the sofa next to the bed, and locate the gear along the short wall firing towards the bed. This more conventional short wall arrangement should give you a much smoother frequency response, especially the low frequencies. My room is 21 x 14 x 8, and with a long wall arrangement like you have I had a 30 dB null at 70 Hz. I know your most urgent issue is the high end, but it's easy to tame a room that is too hot. But even if you accomplish that you won't get good sound unless you get the low frequencies, especially below 300 Hz, straightened out. If you start using REW, you will see what I am talking about right away.
|
@b_limo and @hilde45, You will get a null at any frequency resulting from a distance that corresponds to one quarter wavelength from any room boundary. A sound wave reflecting off of a surface will be exactly out of phase with its primary wave at 1/2 wavelength creating a substantial cancellation of that wave. The formula is 281.5/ ft.to back wall = frequency of null. So if your ear is at let's say, 2 ft from the back wall surface, there will be a substantial null at 281.5/2 = 140.75 Hz. With a 6.5 ft ceiling and normal seating height, one would expect a null at 87 Hz and its multiples. With a 14 ft room depth, there will likely be reinforcement of at 40, 80, and 160 Hz, so one might in fact get some significant low frequency reinforcement from the back wall, consistent with b_limo's comment above and your subjective impression of bass frequencies. In your case there could be some fortuitous cancellation of the 87 Hz null by the 80 Hz back wall reinforcement leading to unexpectedly flat low frequency response. This could be one of those rare cases where long wall orientation is better than a short wall orientation.
With respect to imaging, if your ear falls at 2 ft or less from the back wall, that would give you a delay of 4 milliseconds or less, which might be early enough to not be heard by the ear as a separate signal.
All of this gets an order of magnitude easier with REW measurement. Before I started using REW, I had an acute awareness of things not being quite right, but I wasn't able to put my finger on exactly what was causing the problems and figuring out what to do about it. When you are able to get REW up and running, it will be interesting to see how the room actually measures. I expect you will be able to correlate what you hear with what you measure, and it should enable getting whatever speaker you are working with to perform well in your setting.
|
@decooney, I just bought the MiniDSP mic sold by Dayton and run that into my iMac. Nothing else. All, I use test tone generators as well as REW. Tone generators are great for finding room resonances, and when I have a deep null, I like to play the center frequency and walk around the room to find the low and high pressure areas. Tone generators are great, but REW gives you so much more useful information! Waterfall plots and impulse graphs are usually more useful than just frequency response curves. I'm also starting to use the REW spectrograph. This is a test tone generator I like to use. You can select frequency or a musical note (assuming 440 Hz tuning). http://https//www.szynalski.com/tone-generator/ This is an SBIR calculator that is very useful in my opinion. http://tripp.com.au/sbir.htmThe Amroc calculator has already been mentioned. Here is the link\ https://amcoustics.com/tools/amroc?l=20&w=13.9&h=8.1&ft=true&re=EBU%20listening%20ro... |
@hilde45, it is good to see that you found a speaker that meets your needs so well. You have pursued this project thoughtfully and have put in a lot of hard work. In my opinion, you have assembled some really nice pieces that will serve you very well for a long time. As time permits, a bit of work on your room will pay additional dividends. Nicely done!
|
@hilde 45 and @decooney, tube rolling in the Orchid was a brilliant (if obvious) lever to use. I’m just glad someone finally looked at the problem holistically instead of focusing on a single variable. A while back, there was an extensive thread on tube rolling in the Orchid. You probably saw it, but just in case, https://forum.audiogon.com/discussions/mhdt-orchid-tube-rolling?highlight=orchid. Folks were using adapters to utilize 6SN7, the 6922 family, and some other stuff as I recall. That gives you an almost infinite number of great choices that can certainly emphasize or deemphasize any number of sonic attributes. My one and only experience with Be tweets was in a Ref 3A speaker. It was a lovely tweeter. Very resolving but never bright. Unfortunately, it was much faster and much more articulate than the mid woofer, so it did not make a happy match. You could identify the tweet and midrange immediately as two separate drivers. My guess is that the Fritz and Salk both exhibit excellent coherence. The monitors I use in my secondary system have Scan Speak Revelator soft domes, which are great tweeters, but I think one of the better Be tweets might be a better match in my living room. If you guys do a swap, please let me know what you think. One of those monitors might be in my future. |
