Sound traps/acoustic panels to improve the sound


I need advice:

I have open-baffle Concentus Lyra speakers manufactured by Nightingale (Italy). They had marvelous sound, especially with jazz, but when I moved to a new flat, I was aware that they lack HF extension as if covered with a blanket. The amp is Cary SLI-80 (the other amp is the older SLI-50). They are positioned against the short wall opposite the balcony and placed nearly in the middle of the room.
The manufacturer had told me before that these speakers do not require any specific placement or room treatment.
My question is: should I look for any sound traps/acoustic panels or other room tweaks to improve the sound? I have other speakers on loan now (the cheapest Montana DPS speakers) and they sound very balanced, though do not reproduce jazz music as well as the former speakers. With the former speakers, I was surprised to hear the cymbals when I moved close to them (to high frequency drivers), while I don't hear them from my listening spot (which is not the case with Montana - I can hear everything from my listening spot).
I will appreciate all thoughts and recommendations.
transl
Dreadful nulls, Id experiment with placements treatments dimensions and trying to follow that 38 percent rule , or working with it the best possible ways there the real keys to unlocking any system.  
http://realtraps.com/art_room-setup.htm
http://arqen.com/acoustics-101/room-setup-speaker-placement/
Positioning of them...toe in?...i did all the panel my room could support only to toe them in (direct) and find that was what worked for me...
Post removed 
Hi Transl,

Maybe this can help, too:
PZC / Pressure Zone Controller pictures:
http://www.htforum.nl/yabbse/index.php?action=dlattach;topic=47451.0;attach=32146;image
http://www.htforum.nl/yabbse/index.php?action=dlattach;topic=47451.0;attach=32147;image
http://www.htforum.nl/yabbse/index.php?action=dlattach;topic=47451.0;attach=32148;image

Room Tunes:
http://www.htforum.nl/yabbse/index.php?action=dlattach;topic=47451.0;attach=32143;image
http://www.htforum.nl/yabbse/index.php?action=dlattach;topic=47451.0;attach=32144;image
http://www.htforum.nl/yabbse/index.php?action=dlattach;topic=47451.0;attach=32145;image

;-)
I recently received Silverline Sonata-III speakers and the aforementioned unplesant effect disappeared, though I admit that the room may be overabsorbed. Even with Sonatas, the highs are not as prominent as could be expected from these speakers. In any case, they smoked the former speakers hands down.
RPG Skyline really helped my speakers sound more extended in the highs. I swear by them. Absorption can be tricky and have the undisired effect of sucking all of the highs out. Only complaint with Skylines is that too many can make the speaker sound bright.
Thanks to all for great comments!

The room is small, 18 sq.m (6 x 3m), the ceiling is approx. 2.7 m high. The speakers are placed approx. 2.5 meters from the short wall against the draped window. They have a radiating back panel, but the back grille is not removed. You may see their pic at www.nightingale.it. To check the HF driver is a good idea, for which purpose I have to unscrew the driver. Duke's and Herman's recommendations to deal with disperson instead of absoption make me feel that these speakers were better suited for my old apartment (which was brighter and less absorptive than the present one). I will explore this further. Anyway, I am waiting for new speakers to arrive.
If you did want to look into bass absorption, take a look at the StandTraps or SoffittTraps by Real Traps (www.realtraps.com).
According to their tech data, these are traps that actually do absorb low bass notes and leave the mids and highs pretty much alone. They are also reasonably priced.
I tend to agree with the above that's why ASC tube traps are so good. They have a broad band absorption coefficient and you can tune for diffusion or absorption depending on how you position the tube trap in the room. RPG products are good too. Can be expensive but worth the effort.

Good Luck!*>)
For some reason I have a hard time accepting the statement by the manufacturer that the speakers didn't require any specific placement. This is because in my experience the least suitible place to put a speaker is against the back wall. This kind of placement will usually give an enhanced bass response which can make the speaker overbearingly boomy at a volume where you can hear the highs. It will also kill any sense of depth to the stereo image - it will sound flat image wise. It will never sound spacious and airy.

You don't mention how you have positioned your listening position and your speakers. I would suggest that you do some research into proper room/speaker/listening position set up. The difference is huge and will dwarf any change in components, etc.

If you are interested at all in set up give us an outline of your room including dimensions, openings, furnishings, present specific listening position and speaker locations.
I totally agree with Duke about your situation. The last thing you want is more absorption. I disagree with the diffusion, first reflection stuff but that is not the issue you're dealing with here.

I was in Duke's camp until I tried this stuff.

http://www.eighthnerve.com

There is no doubt that adding diffusion and treating reflection points will change the sound. The question is whether doing that or doing it the Eighth Nerve way will result in better sound. From my experience I say the latter.

The cheaper line is good and the second generation is great. Take your time to explore the web site and see if you agree with their methodology.
Increasing the amount of absorptive material in your room is, in my opinion, more likely than not a step in the wrong direction. Nearly all absorptive materials are more effective at short wavelengths (high frequencies) than at long ones, and it sounds to me like the last thing you need is decreased high frequency energy.

Check to make sure the tweeters really are working. It is possible that something got jarred loose in shipment, yet the midrange drivers still put out enough highs so that you can hear the cymbals from up close.

Assuming the tweeters are working fine, unless your room is way overdamped already and your tweeters beam severely and are not aimed at the listening position, I'm stumped.

Back to the issue of room treatment - personally I prefer diffusion to absorption, as diffusion preserves high frequency reverberant energy while avoiding a strong, distinct early reflection (which is detrimental to imaging). Specifically, I use fake ficus trees in the first reflection zones.

Duke