Soundstage improves with Volume?

[agrobler]

Hi

I am curious with regards the soundstage in my setup. It seems with low volume listening the sound "sits" around the speakers, but as soon as you get up to normally loud (80 dB with Nokia5100 dBmeter 2m away) volume the soundstage spreads nicely, when listening gets a bit louder (90+ dB) the soundstage seems wider than the speakers... The speakers are set-up to try and smooth below 120 Hz in almost square room. Taking into account room modes, Allison effect and heaps of listening (ceiling 3m high - concrete - i live in a flat...). The speakers cross about 300mm infront of my nose, moving forward or backwards doesn't help... so toe-in seems to be OK... Soundstage depth is possibly not what it can be imagined to be, gathering from some people's description.
I have no acoustic damping on first reflections or anywhere else anymore - repainted the room and foam blocks on wall did not complement ...

Setup is large stand mounted speakers - MTM but actually -from top to bottom: Woofer(<300Hz) - Tweeter(>2.2kHz) - Midwoofer (<2.2kHz) X-O linear phase active(3way), amp six channel LM3886. CD - souped up Rotel RCD855...

The area I live in is at times fairly noisy... might be that... or I'm getting spoilt and above-mentioned phenomenon is normal , anally retentive, or spoilling for some type of upgrade

Thanks a bunch!

[richie00boy]

Most likely due to psychoacoustic effects. Starting from a low level, as volume increases we get more sensitive to bass. This will have an impact on the perceived sound. Check out Fletcher-Munson curves for more info.

[RJ]

It could be the near field/far field effect.
For a better description read Jim Griffin's White Paper;
http://www.audiodiycentral.com/awpapers.shtml

I have a line array and do not have this problem. Even at 80 db....
I also use the line array for very loud, very clear listening levels also.

[agrobler]

Mmm... the line array seems cool - nice readable article, The array seem a little complex, but well suited for active, but I think my room is perhaps a tad small. The backwall probably gives a nearfield farfield change-over distance .5m - 1m from the speakers... I must say the added efficiency of the system probably has a lot to do with the sounstage... ito direct versus reflected sound

The FM curve thing makes sense, because at low-ish levels bass is up at 50, 100, 200 Hz, down between 40, 60, 80, 120, 160 Hz... Nice little multiples I notice for the first time now... need to sort it out.

I think a lot of it has to do with the direct versus reflected sound volume - the better this is the better focus... But I think efficiency and quality amplification at low volumes will probably help out here...

BTW my local hi-fi designer / handholder (over the PHONE) during construction process, came by last night... Besides that the dB meter is worthless He cranked up the system quite more than I thought capable... and voila - you have depth... Two o'clock on Volume control is just made for good dynamic recordings.... Orchestra's and some good Jazz...

Thanks for the pointers... will see If I can find a tweeter that fits, and can go down to 1000 Hz (have 24dB/octave slopes so we can try!) to build a "mini" line array (mid-woofer centres are 265mm apart) Will also see to some aesthetical first reflection dampers.... to knock down the worst part of the reflected sound...

Thanks a bunch

[agrobler]

BTW

After taking all the lounge suite cushions and stacking them at the floor, rear wall and sidewall first reflections points... (they are on average 250mm thick by 500mm wide, by 600mm high, should be effective down to 750 - 800 Hz... The following improvements were noticed by my Girlfriend.... just to prove that the audio junkie isn't alone in his beliefs/thoughts/observations... And her hearing is still better than mine...

Test done with Rossini overture domingo & Battle live in Tokyo DG...

Difficult to put finger on it, but better. Sounds like the notes have depth... (after further coaxing it seems that this means that the instruments stand out in 3-D better... not a flat picure any more)
More richness to the instruments... (this was then found to be better balance in room FR and being able to hear the harmonics of the instruments better... low-level detail not being obscured... I think)
Sound is now roomfilling when she walks around... doesn't sound terrible at any other place... just not as good as listening position.

All this seems to point to the nearfield/farfield aspect... because we don't hear the reflections anymore...

So now we are off to get some foam whilst having a place to sit...


P.S. When you hear the reflections of line-array... does it act like line or point-source ? I ask because if the line-source loses only 3dB per meter and the pointsource 6dB/m... the reflection has to act as pointsource in order to become relatively lower in dB than speaker...

[agrobler]

Have Polyester insulation stuff.

Supposedly 100mm thick will attenutate down to 300Hz... 10kg/m3 - Sound Absorbtion coeff. = 0.85 Noise reduction coeff. = 0.75... Dunno about 300Hz with only 100mm thick... Have made 600mm tall x400mm wide x300mm deep panels (larger than speaker baffles)

Have sinusitus, so will report back after recovery, so far soundstage is better HF just attenuated too much???

[agrobler]

For interest sake the damping panels have been a success.
The soundstage is cohesive over the whole listening volume range... The soundstage is also better than ever before. This is not my opinion only. The sound improved much like with the cushions mentioned before, but the hf is not so badly damped... sinusitis was the culprit, hf is better than with the cushions.

I don't know how high the harmonics of the double-bass goes, but only the lower ones, like those from 50 and maybe 40 Hz fundamentals are still a bit "unfocused" the rest is now well damped / "focused" and you can distinguish much better than before the individual notes and placement of the instrument.

Onto orchestral music - much better orchestra and individual instruments... violins are still screaming a little, still have a 2kHz clap response - flutter or boiiiing or what ever it should be called...

I have 4 absorbers (2 behind the speakers, two next to the speakers, So far so good, but we will go for the concrete ceiling and maybe the floor too, maybe also the 300mm deep ones, may only 200mm, don't know. maybe just 100mm on large part of ceiling to kill flutter echo?

They look awful... well not quite, the girlfriend said less awful than expected... but how else do you describe large semi-circular white polyfill stuck against the wall? We need something to cover them... on some web-site a long time ago I read that some material called "burlap" is better at not reflecting hf than speaker grill cloth... Problem is none of the stores here seem to know what it may be... anybody have a clue?

[BobEllis]

burlap is a coarse cloth made of a natural fiber. Often seen wrapping the roots of plants for sale or as a bag for coffee beans. You might find it at a garden shop. Your girlfriend will probably like speaker grill cloth better.

this room treatment stuff is interesting, isn't it? I was amazed at the detail improvement when I placed a 54" square piece of 2" acoustic foam on the sides of my room to do some measurements on a speaker I was building. I guess early reflections were masking the low level stuff. I've got to make some nice looking mount for them now. Even without SAF to deal with I cannot stand to look at raw foam duct taped to the wall.

[johninCR]

It's probably just that your amp doesn't sound its best until it's putting out some juice. It's the only thing changing with volume.

[agrobler]

Hi BobEllis

Cool - I'm not crazy, nor is the GF and various others.. Did it measure differently? I am trying to get the designer dude to bring some proper measuring equipment out and do some with and without tests... but it might take promises of lots of wine

I was thinking about foam, but high density foam in 600x400x 400mm pieces work out to about 35 US$ a piece... Polyester insulation worked out to 35US$ for 1,2m x 6m x 100mm... enough for 8 damping panels - but you definitely need a frame to mount it in...

Thanks for description, we call burlap "hessian" the girlfriend suggested this.... and there are various grades of it from the rough and ready to the more densely woven nicer looking stuff - will have to see how dense it goes before we run into reflection problems... BTW lifting the damping material like 2 inches of the wall improves the absorbtive qualities of the foam... something to do with the changes in acoustic impedance.... if it goes from free air to foam to free air to wall to free air to foam... it aborbs better than free air to foam to wall to foam to free air

Also try doubling up the thickness - 100mm of the polyester only took down the higher frequencies - the foam's probably better than polyfill... but still would theoretically only attenuate down to 1720Hz...
the Polyester I used is about 10kg/m3... squashed to about 2/3 of the volume it started to reflect hf - not sure how high... so for higher ( I think it was mentioned 5kHz) Frequencies you need a rough surface, or less dense material... which I got by fluffing out the front layer of the polyester.

BTW the esoteric all natural girl friend prefers the hessian - at least it hides the unnatural polyester.... and she can hear a difference if I remove one of the damping panels from a first reflection point...

Hi johninCR

Agreed it's LM3886 chip-amps and they are probably better with at least a few watts cranking out... And they still do sound better and more detailed when being cranked a bit... no disagreement.

The soundstage and other details are however, now improved at very low volumes - to such an extent that I can easily listen at 70 dB peaks (mids run at 88dB 1W/1m and tweet at 90dB1W/1mall each driven by dedicated LM3886) - when surroundings are quiet - without missing that much detail - this is something that I couldn't do before. The sound was, as described centred around the speaker - i.e. no soudstage except maybe for strong vocals, and then the vocals was dead centre and the rest around the speaker... and very muddled. Now soundstage is just slightly smaller at low volumes...

So it's a case of better sound at same low volume... and at higher volumes...

I must state that I do have a small "lively" room, this effect might be considerably less in more damped rooms. But it's cheap enough to try it for yourself... I liked the results...