Exciting times.  I have just ordered some more diffusion panels from Joamonte.  Still arranging / optimising my room.  See update HERE

 

 

Always good news when Joamonte comes to visit!

 

This time he came bearing some more diffusion panels which we parked at various locations on the side wall, took acoustic measurements and listened.

 

The visit once again reconfirmed to me the importance of two things within the context of small listening room acoustical design.

 

First, choosing what you use at the first reflection is a big deal and treatment can be used as an 'imaging vs. spaciousness controller'. Using absorption on the side walls audibly narrows the soundstage and improves imaging.  Leaving the sidewall reflective makes the sound spacious but loses out on pinpoint imaging and detail. Using a diffusor on the side walls is a reasonable compromise between the two approaches.  So what you do with sidewalls really comes down to personal preference.

 

Second, of all the choices one has to make in setting up a good environment in which to listen to music – by far the most important – is selecting the location of your listening chair.  The objective here is to discover where in the room you should sit to take advantage of the least negative room interactions such as obvious peaks and nulls in the bass.  Measurements are the most effective way of achieving this goal and in this visit saw the listening chair location move closer to the rear wall where the best combination of smoothest and deepest bass existed.

 

I will provide further details on recent changes including room measurements HERE.  Still more work to be done on the room but progress is being made

 

 

 

 

 

Photo of room from listening chair

 

Acoustic controls seen in photo

 

GIK Acoustics (USA) Tri-traps in corners

GIK Acoustics (USA) Broadband absorbers at sidewall

Quiet Curtains (USA) Acoustic Curtains

Lim Acoustics (Singapore) 2D Diffusor panels with bass traps beneath at front soundstage and first reflection

Whoa !!!

 

Looks awesome !

 

I like how you hide all the equipments behind the back diffusers !

 

IMO, room treatment is even more crucial than equipment upgrades etc.

 

I still have good memories of Joamonte's last visit  :P

 

 

Got open house or not ? hehe ...

 

 

 

 

Always good news when Joamonte comes to visit!

 

This time he came bearing some more diffusion panels which we parked at various locations on the side wall, took acoustic measurements and listened.

 

The visit once again reconfirmed to me the importance of two things within the context of small listening room acoustical design.

 

First, choosing what you use at the first reflection is a big deal and treatment can be used as an 'imaging vs. spaciousness controller'. Using absorption on the side walls audibly narrows the soundstage and improves imaging.  Leaving the sidewall reflective makes the sound spacious but loses out on pinpoint imaging and detail. Using a diffusor on the side walls is a reasonable compromise between the two approaches.  So what you do with sidewalls really comes down to personal preference.

 

Second, of all the choices one has to make in setting up a good environment in which to listen to music – by far the most important – is selecting the location of your listening chair.  The objective here is to discover where in the room you should sit to take advantage of the least negative room interactions such as obvious peaks and nulls in the bass.  Measurements are the most effective way of achieving this goal and in this visit saw the listening chair location move closer to the rear wall where the best combination of smoothest and deepest bass existed.

 

I will provide further details on recent changes including room measurements HERE.  Still more work to be done on the room but progress is being made

 

 

 

 

 

Photo of room from listening chair

 

Acoustic controls seen in photo

 

GIK Acoustics (USA) Tri-traps in corners

GIK Acoustics (USA) Broadband absorbers at sidewall

Quiet Curtains (USA) Acoustic Curtains

Lim Acoustics (Singapore) 2D Diffusor panels with bass traps beneath at front soundstage and first reflection

@1AngMoh,

 

Results look great. Very neat and tidy.

 

I won't ever let my wife see your system pictures, otherwise she will make me clean up my act for sure.

 

Whoa !!!

 

Looks awesome !

 

I like how you hide all the equipments behind the back diffusers !

 

 

 

Thanks! 

 

I am actually an "old school" audiophile - you know the kind that is a bit dogmatic about not having equipment stacked between the two loudspeakers.  I do understand that sometimes there is not much choice in the issue.

 

My equipment rack is on the side wall.

 

 

 

Got open house or not ? hehe ...

 

 

I don't do open homes but 'select individuals' have been through and I would be happy to host you on a forthcoming Saturday afternoon.  :)

 

Thanks! 

 

I am actually an "old school" audiophile - you know the kind that is a bit dogmatic about not having equipment stacked between the two loudspeakers.  I do understand that sometimes there is not much choice in the issue.

 

My equipment rack is on the side wall.

 

 

I don't do open homes but 'select individuals' have been through and I would be happy to host you on a forthcoming Saturday afternoon.  :)

 

Agree that keeping the centre clear is best. You must have had a shock when you came over to mine then :P

 

Think that was the time when the mysterious 96hz boom in my room had appeared suddenly- J and I hadn't realised that the trapdoor on one of the main corner traps had been closed so it wasn't working at all. It really took me far too long to discover that error ::)

Agree that keeping the centre clear is best. You must have had a shock when you came over to mine then :P

 

 

Hi Jimi.  Trust you are well.  No shock really.  I just remember how what a creative and effective (as evidenced by the measurements) solution J arrived at to correct your rooms acoustic challenges.

 

 

I will provide further details on recent changes including room measurements HERE.  Still more work to be done on the room but progress is being made

 

 

Bro,  looking at the RT measurement you done with the XYZ , I think there should have some consistent high frequency noise was exist during measurement , definitely not from the environment because if it is it should be quite audible , I suspect could be the sound card and measurement kits interference...

 

.....have you tried to measure with other computer?

I think positioning still needs to be played with, because for a room with this much treatment the frequency response (within the bass region +- 12 dB) seems to be like it could be improved, not including that small high-Q null which looks like a reflection off some internal furniture.  Perhaps try shifting the speakers + listening postion towards the front wall? (which is the wall behind the speakers).

 

I did notice that you did positioning tests before, but I suspect that was before you had so much bass trapping + j's resonators in. My experience is that once you have so much treatment, and the fact that J's resonators are tunable, the options available to you have increased a lot, and you would be able to get an overall better solution by repositioning again.

 

From a theoretical perspective why this is the case is because all the treatment products absorb different frequencies in differing amounts. Thus, the modal balance of the room when empty, and when fully bass trapped, is very different. Since you have new modal balance in a room with bass traps (due to various modes being unequally damped), you can use positions which were normally worse, but with the "bad" frequencies in the areas where your treatment is strongest at, and using a position which is acoustically more favourable at the frequencies which your treatment is less effective.

 

joamonte:  For the high frequency issues, you notice that past a certain frequency the RT actually starts increasing? I am suspecting that it could be the GIK style method (similar to realtraps) of using membrane absorbers, which usually drops absorption coefficient down to 0.5 or less in the higher frequency range. This would mean that in the horizontal plane there is a lot of high frequency energy being preserved.

 

 

Anyway joamonte what do u think?

I think positioning still needs to be played with, because for a room with this much treatment the frequency response (within the bass region +- 12 dB) seems to be like it could be improved, not including that small high-Q null which looks like a reflection off some internal furniture.  Perhaps try shifting the speakers + listening postion towards the front wall? (which is the wall behind the speakers).

 

I did notice that you did positioning tests before, but I suspect that was before you had so much bass trapping + j's resonators in. My experience is that once you have so much treatment, and the fact that J's resonators are tunable, the options available to you have increased a lot, and you would be able to get an overall better solution by repositioning again.

 

From a theoretical perspective why this is the case is because all the treatment products absorb different frequencies in differing amounts. Thus, the modal balance of the room when empty, and when fully bass trapped, is very different. Since you have new modal balance in a room with bass traps (due to various modes being unequally damped), you can use positions which were normally worse, but with the "bad" frequencies in the areas where your treatment is strongest at, and using a position which is acoustically more favourable at the frequencies which your treatment is less effective.

 

joamonte:  For the high frequency issues, you notice that past a certain frequency the RT actually starts increasing? I am suspecting that it could be the GIK style method (similar to realtraps) of using membrane absorbers, which usually drops absorption coefficient down to 0.5 or less in the higher frequency range. This would mean that in the horizontal plane there is a lot of high frequency energy being preserved.

 

 

Anyway joamonte what do u think?

 

grarrgrarr ,the frequency response graph you see from his post at the link is the old measurement , below is the latest graph of before and after the last 2 sets of diffuser come in  and seating position re-positioning.

 

 

the speaker basically start to roll off at 90 hz but the port behind is tune at 65 hz , we can see that 65Hz peak in the last year Nov older measurement too, that was before the last 2 set of diffuser came in .. so the deep dip below 65Hz I think is unavoidable, however , "thanks" to the lowest room mode at 35Hz , the speaker seem sound able to go "deeper" in the bass on some music...... do note the older measurement is smoothed with 1/6 oct while the 2 new measurement above is save with 1/12 Oct smoothing.

 

 

 

 

As for the RT , 2khz RT above do increase after 1angmo shift the side wall 1st reflection point from absorption to diffuser....but I look at it in this way, 1Angmo room whole ceiling is using hanging ceiling board (look like echophon) and so mid/high adsorbing is very strong;  thus unlike most common bedroom, after add in the GIK bass trap and Diffuser in this room, the mid frequency between 300Hz to 2Khz seem a little to "dry" as compare to this high and low, I have suggest 1angmo to reduce the adsorption surface of ceiling to increase the mid Reverberation so as to get a more linear RT performance....IMHO increase the RT between 200Hz to 2Khz up to around 0.2sec will sound more forgiving on bad recording.

 

 

BTW . 1angmo basstrap wasn't tunable type, I fixed the center frequency at around 120Hz due to the small box size ...... IMHO his room bass consider quite tight ,as we can see from the waterfall.

 

 

I did notice the increase of RT in frequency lower than the effective range of Real trap or GIK type of bass trap...for example if a fiber glass panel bass trap with reflective paper in front work until 70Hz , strangely RT below 70Hz will increase ; but for high frequency , I did not notice too much different in RT , maybe because the surface of this panel is to little compare to the total wall surface of a room....in fact, those panel seem able to adsorb some high too , I often see that from the RT measurement.

 

I think positioning still needs to be played with, because for a room with this much treatment the frequency response (within the bass region +- 12 dB) seems to be like it could be improved, not including that small high-Q null which looks like a reflection off some internal furniture.  Perhaps try shifting the speakers + listening postion towards the front wall? (which is the wall behind the speakers).

 

I did notice that you did positioning tests before, but I suspect that was before you had so much bass trapping + j's resonators in. My experience is that once you have so much treatment, and the fact that J's resonators are tunable, the options available to you have increased a lot, and you would be able to get an overall better solution by repositioning again.

 

 

Hello Grarrgrarr,

 

Thanks for your comments.

 

Joamonte has responded above to your question on bass FR which has shown clear improvement with the additional treatments and revised seat positioning.

 

More generically (i.e. not my room specifically), I’d be interested in your response to the following questions.

 

1. What is the ideal FR in the bass region from a theoretical viewpoint?

2. Would that ideal FR in your opinion produce the best listening environment?  Does a flat response in the bass sound good?

 

 

I raise these questions because after the latest round of changes the bass FR is uniform within +/- 7.5dB further narrowing to a total 8dB range after the Schroeder or transition zone.  Fletcher-Munson and subsequent ISO 226:2003 Equal-loudness contour studies / findings point out that our hearing is not linear across all frequencies and indeed in the bass arena our hearing is poor, being significantly reduced in sensitivity.  Indeed other auditory studies have shown that Ref to 1KHz at 90dB SPL amplitude – our hearing has rolled off by 20dB at 40Hz and 30dB at 20Hz with even greater attenuation recorded for lower amplitudes.  Falling out of that observation is a school of thought that we should actually desire some upward tilt in FR in the bass to compensate for our reduced auditory sensitivity and thereby gain a ‘fuller’ sound.    Comments?

 

 

Fletcher-Munson and subsequent ISO 226:2003 Equal-loudness contour studies / findings point out that our hearing is not linear across all frequencies and indeed in the bass arena our hearing is poor, being significantly reduced in sensitivity.  Indeed other auditory studies have shown that Ref to 1KHz at 90dB SPL amplitude – our hearing has rolled off by 20dB at 40Hz and 30dB at 20Hz with even greater attenuation recorded for lower amplitudes.  Falling out of that observation is a school of thought that we should actually desire some upward tilt in FR in the bass to compensate for our reduced auditory sensitivity and thereby gain a ‘fuller’ sound.    Comments?

This is interesting, thanks for sharing. I personally have a frequency chart of my own ears (done at Raffles Hospital) and it does show a lower sensitivity for lower bass frequencies. I recall being quite surprised by the results given the db drop (maybe similar to the ranges you state above or marginally better), and thought it was a unique issue with my ears. I was into HT back then, and preferred a slight upward 'house curve' in the bass region as compensation.

 

Anyway, I don't have my chart on hand, but the frequency drop-off point may not be that high to affect mid-range fullness for me..

Hi guys,

 

Everything seems to be in order now, I was not aware that I was looking at the wrong graphs.

 

Answering your questions:

 

1.  From a theoretical viewpoint the best FR is +- 0.0 dB throughout the entire frequency spectrum, throughout the entire listening area. After all, the aim of a loudspeaker is to reproduce the sound waves from an electrical signal without any distortion. This of course is impossible, and current technology is not even remotely close to being able to achieve this. Among all sections of the audio chain, loudspeakers and room acoustics are the areas in which our current level of quality approaches very far from the theoretical ideal.  This is unlike areas such as electronics and amplification where generally most products available, if measured, show only very small deviations from perfection.

 

2.  This is highly dependent on the specific case. Personally, I like electronic music and generally also listen to more popular music. Even in modern non-electronic genres, the use of electronic instruments are becoming commonplace. Such music often includes strong evenly-loud bass notes in the 40Hz to 120Hz region, and is often sustained and played in a certain pattern. For music such as this having a poor FR response is going to be a disaster for the listening experience.

 

However, for music made with acoustic instruments, usually there is not much strong bass content except for percussion. This means that having an uneven bass FR is not going to affect the enjoyment of the music as much because there are no closely-pitched bass notes played sequentially in these genres. In some cases, a boomy bass might even give the perception of better sound, because as a side effect it increases the dynamic range of the reproduced sound. For instance, one of the notes played on the acoustic bass might lie in a room mode, and another might lie in a modal null. Although not in the original recording, when listening through a system with uneven bass FR, one might perceive that the music is more dynamic and engaging.

 

This of course might be hit and miss depending on the key the song is in, because if the boom note is at an inappropriate frequency for the key of the song, then the effect is opposite, and any dynamic emphasis from the room modes will sound misplaced.

 

 

Coming from a sound engineering background, I prefer listening systems to be as close to reference as possible. It is a matter of protocol, in which any decision made regarding the sound should be made by the creative talent during the music production phase, and faithfully reproduced at the listener system.  If more bass was suitable for that particular piece of music, then more bass should have been added before the song was released. This gives more insight for the point about Fletcher-Munson curves.

 

You must realize that in the studio the engineer's ears are also affected by Fletcher-Munson curves, and if a particular level of loudness is required for bass frequencies, the engineer would have boosted the bass during mixing to make it sound good. Generally, one has to have faith that the engineer's listening system is of reference quality to make this judgement. However, now that piracy has caused the collapse of the music industry, more and more music is made in smaller project studios with dubious system design (equipment + acoustics) and the quality of engineering in general has been going downhill since the invention of MP3.

 

This and the loudness wars means that until the industry makes a breakthrough in the quality of music, the situation for audiophiles in the area of modern popular music remains grim (in terms of absolute sound quality). This does not mean that we cannot enjoy the music, but I'm sure you all have experienced the world of difference in terms of emotional engagement when playing a dynamically compressed track right next to a full dynamic range one.

 

http://turnmeup.org/

For your curiosity, this is one of the movements trying to influence the music industry to produce better quality audio.

Thanks for the well-considered reply Garrgarr – particularly refreshing when so many conversations in the forum are reduced to prepositional and allegoric phrases related to the food court.

 

What you have diligently laid out describes for me the fundamental difference between a studio and a listening room.  From your reply I gather that you are more comfortable with the former than the later.

 

Studios are designed to give back to the recording engineer an uncoloured – and thus unflattering – presentation of what is/was being recorded and mixed.  Studios are often heavily damped and in general operate with a quantitatively superior frequency response and typically lower RT-60.  Studios sound "sterile" for the most part and are not engaging or involving. Studios increasingly tend to be small environments with monitors designed for near-field listening.  As a sound engineer I could almost guarantee (without having ever met you) that you listen to music via small monitor speakers in a near-field configuration and thus a smooth frequency response ought to be a given.  That said, please keep in mind these comments are generalized; there are absolutely studios that exist that would not fit into this category.

 

Listening rooms should be designed to some degree to add to the musical experience.  I have listened to "dead" rooms that cost upwards of $150k to build. I personally thought they sounded dreadful as a listening room, but might make a good recording studio. The biggest difference is the reverberation times. They should be longer and create a spaciousness that envelopes the listener and recreates a soundstage and the experience of "being there".  It is my opinion that the listening room is part of the equipment so to speak.  It can have as much to do or more than any individual component and unlike most components; it can be tuned like an instrument. You wouldn't play a musical instrument way out of tune, but so many listening rooms are deliberately played that way.

 

While I fully realise that a studio engineer's ears are also affected by Fletcher-Munson curves and that an engineer may have boosted the bass during mixing process to improve the sound – it is indeed an article of faith that the engineer's listening system (including the room) is of reference quality to make a sound judgement in this respect.  Some engineers for example mix with less than full range monitor speakers and obviously they can’t compensate for that which they don’t hear.  Further, I quite agree with you that piracy, small project studios and the advent of MP3 have not been helpful in bringing us closer to the absolute sound.

 

In sum I might say that while the acoustic principles of a studio and a listening room are the same, the goals are very different.

 

Just to share....one of the most hardcore acoustic treated room in HK I visited not long ago...

 

 

 

The room is Designed by Mr Tom Hidley , a legend in room acoustic design , some call him "father of modern studio design" ....

 

Inside the fabric covered side wall and ceiling are 2 feet of hanging sound trap and the listening back wall are 4 feet of heavy hanging sound trap treatment , the monitor is KINOSHITA RM 8 driven by FM acoustic power amp, the sound is totally out of this world , so clean , so neutral and so detail.... the room total disappear until the very bottom end of bass , amazing!

 

 

The Rey Audio TAD monitor in the room is also design by another legend Mr KINOSHITA , original Designer of TAD driver....

 

http://www.reyaudio.com/history-e.html

 

....30 Hz , 130 dB at 30 meters at outdoor !!  WOW!!!

 

 

Someone mention the Naim are the best Rock speaker in the world in the Harberth Tread....he should listen to this system.. ;D

You are there vs. They are here

 

Additional work on acoustics in my listening room has led to expanded thinking on this topic.

 

I am looking for a “you are there” experience when music is reproduced. I like the prospect of being transported to another space – even if such an objective seems hopelessly implausible given the physical confines of a small room.

 

Revisions to acoustic control configurations have taken me a step closer to the objective.

 

What about for budget seekers for their room treatment!

$10 per sq meter (excluding installation cost), of course.... :)

What about for budget seekers for their room treatment!

$10 per sq meter (excluding installation cost), of course.... :)

 

what is this for?

To be installed on the wall.  Rock wool behind these acoustic panels.... :)

Reminds me of Swiss wood...

What about for budget seekers for their room treatment!

$10 per sq meter (excluding installation cost), of course.... :)

 

There are lot of different perforated board in market, especially China mainland furniture manufacturer like to make this type of "acoustic panel" because of their mass production capability....but I not too sure they understand the physic theory behind it or just anyhow copy or "re-inventing" ....

 

http://www.alibaba.com/showroom/perforated-acoustic-panel-board.html

 

But I would suggest user to have some basic acoustic knowledge before using this type of product......the percentage , the diameter of the holes, the total surface of the board, the depth behind the board etc etc all affected the effective absorption frequencies and coefficient of the performance ; For normal conference room or office, you will not do wrong with it because human voice frequency range is relatively narrow and SPL is relatively soft  ;  but for music room , be caution, it is not wise to use the same specification of this panel all over the room because you might end out adsorb too much on certain frequency especially if the Q factor of the absorbing frequency is high ; use panel with different % of opening, with different depth , at correct ratio of total cover surface area of the room is a better way,  because that will broaden the absorption frequencies..

 

.....and also not to forget there are other frequencies that this board didn't treated , you will still need some bass trap , high frequency absorber etc to get a more balance absorbing through out the lower room mode to 20000Hz music frequency range. 

 

 

For those who are interested to know more of this perforated board , here is a online calculator...

 

http://www.mh-audio.nl/ACalculators.asp#showcalc

 

chick at the "Helmholtz Panel Resonator" , see how the opening, depth, % affected the absorbing frequency and bandwidth ....

 

 

 

..... "Acoustic Panel" is just a common name like " car" , " food" , "drinks" etc , under this common name there are lot of different type of panel for different function and purpose..... to understand how different type of "acoustic panel" affected different room acoustic response, is a very deep and wide knowledge ocean need to be study and understand , even after all this years of reading and experimenting , I still feel like I am a primary school children in front of lot of real acoustic experts...

 

:)

This is a very good PDF for those who are ready interest to understand more about the Audio,

 

http://www.freewebs.com/studio139/PDFs/SAE_Recording_Guide.pdf

 

Some pages like from Page 13 onward , 95 onward, 108 onwards, 154 onwards, 175 onwards... etc ... mention about simple acoustic (Room and speaker) that I think many audiophile should know.....the information is basic "primary"  school knowledge in room acoustic but I sure quite lots of audiophile will find it useful...

 

Enjoy !

 

 

 

The Audiophile graciously invited me to The Listening Room this week for "just one album." To his credit, the session truly did involve just one album, and a good one at that. Sure, all of his albums are good, but some are definitely more gooder than others.

 

Midway through the album, he hit the pause button and abruptly asked me what the song meant. Meant? The song? You mean the song that the girl was singing just now?

 

I had no idea there was going to be a pop quiz or I would have brought my etch-a-sketch to take some notes. Had he asked me how many sound panels were in the room I would have been golden because I had just counted them from left to right and then from right to left to validate there were 16. This counting exercise led me to wonder if The Audiophile had achieved his goal of "getting the room out of the way of the music."

 

I tried to pay close attention to the next song in case he solicited my lyrical expertise again, but it was difficult to focus on the music because the sound panels had arrogantly challenged me to admire their equidistant placement and not-so-subtle domination of the room. So although I don't know the message being conveyed by the female vocalist of the evening, I do have a pretty good sense as to whether the room has gotten out of the way of the music.

 

And that, my friends, is audio winning.

So  , who is the writer and what does this story tell us? Room acoustic is not important??

She cannot concentrate on the music as she felt uncomfortable with so many panels around her..

Means environment still has relevance, even though the end result of having good sound is important.