After separating my 2 ch from my HT and moving my 2 ch to several different rooms, I have discovered how vastly different my system sounds in different rooms, and how much effect the room has on SQ.  So now my 2 ch is back in the HT room which has the best SQ out of all the rooms, but can obviously be better.  Before I go down the measurement path, I thought I would start with the obvious, a brick wall, then the 1st deflection point on the side walls, then maybe the ceiling.  One step at a time.  My system sounds pretty good, but I would suggest that I have more of an issue with pitch than bass, so may look at bass next.

My right front speaker is 1.2m from the side wall (glass sliding door).  My speakers are currently 2.4m apart , and the front of my speakers are about 900mm off the back wall.  My listening position is about 3m from the speakers.

Beside the lounge, about 3m in front of the speaker, in the 1.2m gap, is a brick wall on 45 deg. 

what can I put on the wall to assist with SQ.

i am thinking of putting some type of bookshelf or acoustic panel on the right side wall to handle the 1st deflection point

No takers on this.  I am unsure on whether to put some type of wood paneling to try and diffuse the sound, or some type of soft acoustic paneling.

9 hours ago, JkSpinner said:

No takers on this.  I am unsure on whether to put some type of wood paneling to try and diffuse the sound, or some type of soft acoustic paneling.

To be honest without being in the room and "hearing" the problem, it would be hard to offer recommendations on where to go.

Before tackling the room with product, you need to get a sense of what and where the actual problems are.

Measuring will hopefully confirm your concerns about current limitations.

I would suggest watching this video and taking things from there:-

 

 

Hi, what you should do is a bit dependant on the speakers and what their constant directivity is. Beyond that you have the glass sliding door and curtain. If you usually have the curtain drawn than you can look to match the other side and absorb. If you don't then  doing anything at first reflection on one side only may be problematic. It looks like you have an opening to the right which may be at 2nd reflection which again may be problematic due to the non symmetry. It's likely that general absorption around the room will help as the walls are pretty bare and will likely reflect quite a bit but without measurements it's a guessing game , especially if you are not experienced. 

Thanks, I thought the brick wall would be an obvious start, then the open area, then rear walls etc.  I like your idea using an identical curtain on the right side.  I thought I could look at the obvious first before doing any sort of measuring.

1 hour ago, Hydrology said:

To be honest without being in the room and "hearing" the problem, it would be hard to offer recommendations on where to go.

Before tackling the room with product, you need to get a sense of what and where the actual problems are.

Measuring will hopefully confirm your concerns about current limitations.

I would suggest watching this video and taking things from there:-

 

I will take a look at the video, thanks

 

that brick wall will reflect everything back into the room, but it's a small wall - unless you can identify it's causing a specific acoustic issue at the listening position (possible) - ignore it.

 

Mike

 

I will suggest my usual solution for everything..............heavy curtains.

It allows adjustment.

On 13/9/2024 at 4:58 PM, almikel said:

that brick wall will reflect everything back into the room

The wall is on 45deg right next to the lounge, so my concern was that it could potentially reflect straight to the listening position.

i have purchased 6 x Primacoustic panels, + 2 Diffusion panels, so will move them around the room, and measure to see what effect they have on SQ in different position.  For now, there is one on the brick wall

55 minutes ago, JkSpinner said:

The wall is on 45deg right next to the lounge, so my concern was that it could potentially reflect straight to the listening position.

Hi JKS,

 

You need someone to help with this, but you can use a mirror to see where the direct reflections go.

With you sitting in the main listening position, have a friend hold a mirror flat on the brick wall, and when they move the mirror around, see if you can see either of your main speakers in the mirror - that will be a direct reflection for frequencies above the transition zone of the room (let's just say >500 Hz or so).

 

Going a little off topic...

 

Above the transition zone of the room, the sound bounces off boundaries like a billiard ball bouncing off a cushion on a pool table.

 

In the transition zone, modal frequencies dominate - like ripples in a fish tank when you drop a pebble in, and the waves bounce off the boundaries and recombine with constructive and destructive interference, creating peaks and dips in the sound throughout the room.

You get room modes at multiples of (N x wavelenth/2), where N starts at 1, then 2, 3, 4 etc.

At the top end of the transition zone, the room modes (N=1 plus N=2 plus N=3, 4, 5 etc) bunch up close and room modes stop dominating the room behaviour, and we get the pool table reflections.

 

The lowest modal frequency that can propagate in your room is the longest room dimension = wavelength/2, with frequency= 344/wavelength).

 

If your room is 5m long, the lowest room mode that can propagate is:

5m = wavelength/2

wavelength = 10m

frequency = 34Hz - lowest mode that can exist in the room

 

Below the transition zone of your room is the pressure zone.

 

Back on topic...

...if you can see either of your main speakers using the mirror approach - given the angle of the brick wall, and speaker position, toe in etc, the sound hitting the wall could be close to the "on-axis" sound of the speaker.

 

If you subscribe to the Toole/Olive approach (where 1st lateral reflections should maintain the same frequency content as the direct sound), it may be beneficial not to apply absorption, as absorption will alter the frequency content of the reflection (absorb more top end than bottom end).

 

I would first try the mirror technique to place diffusion on the brick wall rather than absorption.

 

Were the Primacoustic absorption traps you purchased their Broadband Absorbers or their Control Columns?

 

The Primacoustic Broadband Absorbers are big enough to benefit from straddling a corner (any corner), not mounted flat on a wall - the airgap behind improves their lower frequency absorption (significantly).

 

IME the Primacoustic Control Panels are only useful for absorbing top end - every restaurant you've been in with too many hard surfaces, and you can't have a conversation at your table without shouting, needs lots of these!

 

Our listening rooms are different - you have carpet and a big absorbing couch - both absorbing lots of treble.

 

Before applying further absorption focused only on the top end (ie thin and/or flush on the wall), measure your room's reverb times and look at your waterfall charts (frequency response over time). 

 

You want reverb times relatively constant across the frequency band (20Hz-20kHz), accepting that reverb times will increase at lower frequencies below 300Hz or so - because we listen in rooms with reflections, not tents.

 

IME every room benefits from broadband absorption targeting the lower frequencies (ie placed avoiding direct reflections, and straddling corners to increase low frequency absorption).

 

Absorption gets too big and too large to be effective <150 Hz or so - but it works incredibly well 150Hz-500Hz to clean up the upper bass/lower mids, and placed well, avoids absorbing too much treble.

 

Below 150Hz, in my leaky room which lets all low bass out, EQ is sufficient to have my room's bass relatively under control.

 

IMVHO, once you have your room's bass under control, you're 80% done on acoustic treatment - and I'm happy to stop at 80% solutions.

 

Post your REW waterfall chart with the mike at the listening 20Hz-20kHz with 300ms limit on time.

Post your reverb times (REW has multiple different versions, T60, T30, Topt etc - put them all on 1 graph).

 

The reason why REW has so many different measurements for reverb is that the concept of reverberation measurements assumes a very large room with a diffuse sound field (Wallace Sabine invented the T60 measurement by measuring auditoriums)...but our listening rooms are not big enough to generate a diffuse sound field, so REW includes a bunch of calculations to attempt to make sense of reverb times in our small rooms.

 

cheers,

 

Mike

Thanks Mike, I used the mirror trick to find my 1st and 2nd reflection point, but did not think of it for the brick wall.  I have also placed my speakers on timber so I can slide them around to find the best position, so it is all work on progress.  I took some initial measurements and posted in another thread, I have also taken some measurements with four panels on the rear wall.  I have 6 panels all up + 2 Hybrid panels I can also use for absorption, so I need to find some time to move them around a bit, and re measure.  As you probably know, it is very time consuming.

On 17/09/2024 at 5:35 PM, JkSpinner said:

I used the mirror trick to find my 1st and 2nd reflection point, but did not think of it for the brick wall.

If there are no direct reflections ignore the fact the wall is brick, and focus on overall room absorption from a waterfall and reverb perspective...

 

On 17/09/2024 at 5:35 PM, JkSpinner said:

so I need to find some time to move them around a bit, and re measure.  As you probably know, it is very time consuming.

oh yeah - with lots of woop woops to annoy the family 😞

 

Mike

On 15/9/2024 at 4:00 PM, almikel said:

Were the Primacoustic absorption traps you purchased their Broadband Absorbers or their Control Columns?

Broadband 1200 x 600 x 50

 

On 15/9/2024 at 4:00 PM, almikel said:

I would first try the mirror technique to place diffusion on the brick wall rather than absorption.

Mirror used and it’s a reflection point, I have absorption there now, but will be moving panels around in the following weeks

 

On 15/9/2024 at 4:00 PM, almikel said:

improves their lower frequency absorption (significantly)

I am lacking in bass, so I am avoiding and bass absorption.  I have large openings and glass doors.

 

i will post some REW charts up, probably in one of my other more relevant threads.  I broke my questions into individual threads, kinda saves going off topic.

 

for this thread, I thought the wall would offer reflection, and the mirror shows that, I already had a panel up there

 

installing 4 broadband panels on the rear wall, brought the frequency response curve down to an acceptable level, but it stayed flat, they also Brought the RT Decay times down.  Now I need to move panels around to see where I get the best results, a bit of work in that me thinks

19 minutes ago, JkSpinner said:

I am lacking in bass, so I am avoiding and bass absorption.  

IMVHO this is a bad idea.

In this thread or another thread myself and others recommended adding a sub to your system to improve your system's low bass.

Adding EQ to push your existing speakers lower within their excursion limits (and your amps' clip limit) would also be an option, but not as good as adding a sub, which could be best placed in the room for smooth bass at the listening position.

 

Avoiding placing treatment targeted at bass frequencies allows bass frequencies to bounce around creating "boomy" bass, taking ages to decay...

...this is not good bass...

...you want tight/dry bass without ringing/overhang.

 

The sort of bass that inclines you to turn the bass up rather than turn the stereo down 🙂

I love having EQ/Tone controls on my remote!

 

Mike

8 hours ago, almikel said:

IMVHO this is a bad idea

Hi Mike, Subwoofers are on the maybe futures list, as you know this is a journey.  I will be spending time moving my panels around the room and measuring to see what difference the different locations make.  With four panels across the rear wall, the corners were covered.

one front corner is a glass door, so also have some room issues.

i will also try placing the broadband panels at first reflection point, which on one side is in front of the window, and in an opening on the other, creating some symmetry, and measuring.  I also have a large sheet of play to place in the corner in front of the glass effectively creating a corner and creating symmetry with the other side just to see what difference it makes.

its a journey.

in the mean time, most people tell me my systems sound great, it’s the best system they have ever heard, and they do not know why I am making these changes, so I can be assured my systems already sounds OK.

 

On 20/09/2024 at 6:25 AM, JkSpinner said:

Subwoofers are on the maybe futures list, as you know this is a journey.

 

I'm going through this myself, as advised by a pro audio engineer, setting up the speakers to image at their best, seems to sacrifice some bass.

That's why he recommended setting up the speakers at the best image position, then use two subs to dial the lows say around below 40Hz, subject to speakers & room, the integration of the subs to the system must be setup correctly to achieve a seamless result, which seems many people have trouble getting it right.

 

I'm pretty much sick of the journey now, I just want to get to my destination...🎼🍷

 

On 20/09/2024 at 6:25 AM, JkSpinner said:

its a journey.

agreed!

 

On 20/09/2024 at 6:25 AM, JkSpinner said:

in the mean time, most people tell me my systems sound great, it’s the best system they have ever heard, and they do not know why I am making these changes, so I can be assured my systems already sounds OK.

Knowing when to sit back and just listen to great music is something some audiophiles can struggle with 🙂

I'm not saying this is you 🙂 🙂 

I thought the bass from my stereo TD18's was OK, but I built my sub after friends told me I was missing something in the bottom octave (yikes)...I'd been confusing great mid bass with truly low bass.

 

 

You say your system lacks bass - what do your friends say about the bass?

Looking at your measurements in your other thread

I'm thinking you don't need bass extension, but a well integrated sub (or subs) will fill in the dips.

 

cheers,

Mike

 

 

 

 

 

 

 

 

 

 

 

 

 

17 hours ago, Bass13 said:

I'm pretty much sick of the journey now, I just want to get to my destination

That’s my problem.  I do enjoy it.  I put many hours on my equipment.  And it’s the reason I have not finished this whole acoustic treatment as yet.

16 hours ago, almikel said:

You say your system lacks bass - what do your friends say about the bass?

Looking at your measurements in your other thread

I think my systems sound great, I know there is some improvement, and I have improved it a noticeable amount over the last three months, but realistically, it sounds pretty good.   I don’t necessarily think my systems lacks bass, but it was pointed out to me by several members on here when I posted my first charts, lacking bass between 50 - 150 Hz. My family and friends think it sounds fine, no one has ever picked up on the lack of bass, and most have disagreed with me when I point it out.

to test my bass response with an audience, I usually play Dire Straits Ride across the River or Money for nothing, as I believe those two song are a good example of bass definition, and drum separation.  To me and music I listen to, bass is about drums, not duf duf.  But as you mentioned, my definition of bass may be mid bass and not low bass.  Feel free to recommend music for me to test this.

I also have tone controls on my amp, but I do not use the tone controls when I am measuring.  I might and see what happens.  Hopefully might be able to do some measuring today.  I think that the tone controls do improve the bass, but it can also get a bit muddy.

i am still playing around with speaker placement.

but really, bass response it not really a concern right now.  I will focus on freq response and RT’s, absorption panel placement, then Diffusion.

i am playing around with placing panels in front of windows and in open walls creating some symmetry, and I still think that me adjoined entrance and hall wall cause some issue, so a bit of playing around to be done as yet.

but for now, and in relation the the topic in this thread, the brick wall is a first reflection point, the left side of the wall to be precise, but the panel looks better in the centre of the wall = WAF.  I might change the 1200 x 600 for three 1200 x 300.

Edited September 21, 20241 yr by JkSpinner

5 hours ago, JkSpinner said:

But as you mentioned, my definition of bass may be mid bass and not low bass.  Feel free to recommend music for me to test this.

LoL - most of the tracks I like are mostly mid bass also 🙂

 

Dire Straits - Telegraph Road 

Fleetwood Mac - Sarah, Tusk, The Chain, Monday Morning...

...Monday Morning is one of my favourite tracks for "bass slam" - and the bass always gets turned up on the remote...

...but "bass slam"/"hit you in the chest" bass is not low bass, but 40 - 120Hz

 

The track we were playing on my system when my friends noted I was missing the bottom octave was the Boston Philharmonic Orchestra's version of "Fanfare for the Common Man" - hilariously I previously thought Emmerson Lake and Palmer had written this 🙂

The kettle drums at the crescendo go quite low.

 

Crossing to movies - maybe heresy to play movies on your 2ch setup? - but useful for testing bass extension:

• Lightning strike scene close to the start in the Tom Cruise version of War of the Worlds
• Depth charge scene close to the start of U571

cheers,

Mike

6 hours ago, JkSpinner said:

I also have tone controls on my amp, but I do not use the tone controls when I am measuring.  I might and see what happens.

Try dialing the treble down in increments and measure - making notes on your REW measurements of the treble knob position, and see if you can create something like the room curve @Keith_W showed in your other thread. 

(edit - added here for clarity)

The red line is the proposed "room curve" (end edit)

 

You can do the same with turning the bass up on the tone control - measure and note on your REW measurements.

Tone controls are a bit of a blunt instrument but see how you like it.

 

Something to note on "old school" tone controls is that the "Q"/steepness of the filter will increase as the tone dial moves further - you generally want to apply EQ broadly with low Q - so don't crank either (other than just to see the effect).

Tone controls are a simple shelf filter at a set frequency, with the Q changing as the tone dial moves.

Modern DSP EQ provides parametric EQ - more flexible than tone controls.

With parametric EQ you can adjust the frequency, Q (width/steepness) and gain (cut or boost), and with multiple EQ points create shelf filters or any shape of EQ.

 

I use the tone controls on my remote all the time! treble too hot, dial it down, great bass line, dial the bass up.

But for my room curve I use global EQ, the same for applying EQ cut on bass peaks not sufficiently ameliorated by absorption and my leaky room.

 

Mike

Edited September 22, 20241 yr by almikel
clarity

Turns out I had four reflection points on the left side due to the brick wall at 45 deg right beside the lounge.  An extra absorption panels takes care of the those additional reflection points.  Did it have any effect on SQ, who knows, overall, with other panels, new cables, Isoacoustic GAIA feet, my systems sound very nice now

Edited November 17, 20241 yr by JkSpinner

Out of interest, weighted limp membrane bass trapping can be "hand made" to treat brick walls or, a brick/cement room. Experimenting with loaded air chambered single and double membrane weighted membrane trapping ATM at 190mm thick around 4m2 area. One particular area, of 2 thirds concrete room, 1 third timber and double plastered wall, perforated CSR plaster ceiling, with rear brick wall entirely cladded with a chambered 400mm deep, limp membrane wall, measured the best I've seen in a cement area. Fixed bass reverb and the pumping phenonium, with 4 x 18" sealed Malstrom X subs operating in the zone.  

Another area, of entirely double solid plaster was treated with 3 large 4m2 190mm deep sealed single and double limp membrane traps also performs well to tame 2 pairs of 21's operating as sub/low range bass to great effect.

Out of interest,,,,it's a lot of work/time and takes a special type of tenacity to complete/test and cosmetically integrate, hand made bass treatments.

Well done for having a good hard crack at this area of the discipline.

Watching on 🙂 

Matt

 

 

 

On 18/11/2024 at 10:47 AM, playdough said:

limp membrane bass trapping can be "hand made" to treat brick walls or, a brick/cement room

I love the concept of limp mass bass traps using mass loaded vinyl (MLV)!

 

On 18/11/2024 at 10:47 AM, playdough said:

Experimenting with loaded air chambered single and double membrane weighted membrane trapping

Double membrane! - love your work!

 

My lightly constructed room leaks the low bass out - but if I needed "proper" bass traps, I would build limp mass traps.

 

Mike

On 17/11/2024 at 1:25 PM, JkSpinner said:

Turns out I had four reflection points on the left side due to the brick wall at 45 deg right beside the lounge.  An extra absorption panels takes care of the those additional reflection points.  Did it have any effect on SQ, who knows, overall, with other panels, new cables, Isoacoustic GAIA feet, my systems sound very nice now

IMO that wall should have QRD diffusers NOT absorption panels.