REW, is it worth using to assess your system/set up?

[sailor]

Hi Adrian, good see you having lots of fun there. You are quite correct that without treatment a huge amount of quality reproduction is lost. A mediocre system in a correctly set up room will provide more enjoyment than throwing mega-bucks at expensive components while eschewing the room acoustics.

Basically there are the 3 axes to take care of: front to back, side to side and top to bottom. It is desirable to absorb some of the energy and this absorption should be broad-band and needs to be done for each axis. The rug on the floor helps with top to bottom axis but being a narrow-band absorber it would be great if you could fabricate a frame that houses some rockwool and suspend it from the ceiling. The biggest room problem is the modal region, which are low frequencies that combine in and out of phase creating peaks and nulls or partial nulls. A full null is like a black hole where the sound cancels. If one thinks about this it is apparent then that a particular narrow range of frequencies are missing, gone and never to be heard. Unless something is done you will never hear parts of the music, parts that make up the foundation.

So it's time for bass traps but unfortunately the link you posted to some Amazon foam will not do anything for bass frequencies. They are just 8" (200mm) across and will disappoint. My traps are the recommended size and measure 900mm across and using Omnimic they do as intended, smooth out the lows and paradoxically although some bass is absorbed more and better bass is heard along with an improved mid and high range.

You mention overdoing the treatment resulting in a dead/dull room which is entirely possible, however you have the means to avoid this. Not sure if you are aware of this: there is a target to strive for which is dependent on the volume of your room, tables can be found online for the decay time which in your case might be somewhere around 300ms. With a plot of the decay presented by a waterfall or cumulative spectral decay on REW the decaytime can be examined and will indicate the problem areas. What is being attempted is to see how long it takes for the sound to decay by 60dB, known as T60 across the full spectrum. If you keep your treatment within the target area you have arrived and will experience sound that is full, informative and .. well just bloody marvelous. 2 or 3 subs will complete the sound and they need not be huge. In a small space 8" or even 6.5" subs will surprise you. Do not envisage thunderous bass but think of them as tuning devices and REW will help you position them.

By the way your images did not appear at first but I see them now. With the curtain you have there it is possible to improve on that, rendering them more broad-band in absorption (good) I recommend looking for 2 or better 3-rail curtain track. The quality thick fabric is hung on the outer rail and then any cheap fluffy fabric hung on the next 2 rails. By necessity these rails are spaced apart providing a wider more broad-band absorption. Also the 3 curtains can be tweaked whilst watching REW. Might like all 3 closed for movies but draw aside the window curtain for music. This 3 curtain trick is the least intrusive treatment and surprisingly effective.

[AJSki2fly]

A brief follow up, this morning I tried something else out which was to put all our venetian blinds down in the lounge with each one at a different angle so still letting light in. Both windows have 3 panes of glass with a blind attached to each. I took REW measurements and the results are good in fact slightly better that with just a curtain draped in front of the 1st and 2nd reflection points of the main window.

I can only think that what is happening is the blinds slats are causing sound to be reflected at differing angles away from my listening position and also impeding the sound that hits the glass and then reflects back to the blind slats. So if you have large windows in you listening room then trying venetian blinds of vertical ones may be a simple solution to help and be wife friendly.

[Qwin]

Jeeees, that's a lot of messing around with your room.
it does nothing for the appearance.

Just sit and enjoy the music.

[AJSki2fly]

Hi Charles

Thanks for the advise. I have looked at curtains similar to what you mention, also I am considering GIK bass traps, at the moment experimenting is interesting, but at some point I am likely to take the plunge but will need to persuade SWMBO.

[Pepperamip]

Would there be any benefit to treating the walls directly behind the speaker or does so little sound travel in that direction that it doesn't really matter?

I'm close to buying some rockwool rwa45 to put behind my speakers and against each side of the TV unit that the speakers sit adjacent to but unsure if there's any benefit to be had by doing it. Also my right side speakers is In a corner albeit with some breathing space but I'm sure I'm getting an unwanted bass boost from that side.

Sent from my M2103K19G using Tapatalk

[Macca]

A brief follow up, this morning I tried something else out which was to put all our venetian blinds down in the lounge with each one at a different angle so still letting light in. Both windows have 3 panes of glass with a blind attached to each. I took REW measurements and the results are good in fact slightly better that with just a curtain draped in front of the 1st and 2nd reflection points of the main window.

I can only think that what is happening is the blinds slats are causing sound to be reflected at differing angles away from my listening position and also impeding the sound that hits the glass and then reflects back to the blind slats. So if you have large windows in you listening room then trying venetian blinds of vertical ones may be a simple solution to help and be wife friendly.

Blinds act as diffusers rather than absorbers so you're scattering the high frequencies instead of attenuating them.

This can give better subjective results than absorption in some situations. I did point this out on another thread but was told I was wrong and then directed to some infomercials on Youtube.

[Pigmy Pony]

Would there be any benefit to treating the walls directly behind the speaker or does so little sound travel in that direction that it doesn't really matter?

I'm close to buying some rockwool rwa45 to put behind my speakers and against each side of the TV unit that the speakers sit adjacent to but unsure if there's any benefit to be had by doing it. Also my right side speakers is In a corner albeit with some breathing space but I'm sure I'm getting an unwanted bass boost from that side.

Sent from my M2103K19G using Tapatalk

Boundary reinforcement of bass frequencies will occur at all walls to some degree as bass is pretty much omnidirectional. And I imagine corners will be even more problematic. So I would think trying your rockwool thing might be helpful, certainly worth trying.

[AJSki2fly]

Would there be any benefit to treating the walls directly behind the speaker or does so little sound travel in that direction that it doesn't really matter?

I'm close to buying some rockwool rwa45 to put behind my speakers and against each side of the TV unit that the speakers sit adjacent to but unsure if there's any benefit to be had by doing it. Also my right side speakers is In a corner albeit with some breathing space but I'm sure I'm getting an unwanted bass boost from that side.

Sent from my M2103K19G using Tapatalk

As Steve(pigmy-pony) says bass re-enforcment is omni-present, but how much will depend on room characteristic and where speakers are sited, close to walls and in the corner will make it worse. I would have a look at the GIK web site they give good advise about room treatment, my understanding is the generally you want to address the 1st and 2nd reflection point each side of the listening position, as said earlier can be found by using a mirror along each wall. At these points you want to use some sort of damping/dispersion to minimise reflection of sound to the listening position, effectively a delayed echo causing a smearing of the sound.

The wall behind the sitting position is usually to worst for bass re-enforcement but its impact depends on where how far you are siting from it and where in the room, remember different frequencies have different wave lengths, so depending on the room my understanding different frequencies will get re-enforced more than others. Final to wall behind the speakers can/will re-enforce bass and higher frequencies so treatment there is wise.

It is also a good move to not put sound treatment panels symmetrical in the room end to end, so offset the panels, that way they will be more effective.

[AJSki2fly]

Jeeees, that's a lot of messing around with your room.
it does nothing for the appearance.

Just sit and enjoy the music.

I agree, but the effort will be worth it, once I have established the best way to treat the room to get the best sound from it then I will invest in some sound treatment panels. GIK look good and give free advice, my room as you can see is very tricky due to the glass and limited system and listening position, so trying stuff out first is wise IMO.

Actually it may look messy but as I say just the simple temporary changes make quite a big improvement to definition, detail and listening enjoyment.

Hopefully the once finished it will look better.

[AJSki2fly]

Continuing on my Room Treatment investigations this morning as at the weekend I was allowed to purchase a pair of cheap wall canvas paintings/hangings from TK-Max, these replace the rug hung up there before, there was a method to my madness as I thought SWMBO(Sue) would be keen to loose it. The pictures are simple 30mm deep frames with wrapped canvas, I have been told these type of hangings can help.

I went back to basics, first measuring with the Venetian Blinds down and the newly installed pictures, I already established this produced an improvement through general mid-high dispersion, by shielding the windows glass.

Then I added the side curtains, Right first and measured and then added the left and measured. Next I then erected a simple rear bass trap/dissipator(behind listening position) - a thick fleece blanket over some clothes horses and measured again. Things now were improving and so I put the thin rug over the glass door and measured again.

What I noted as I took the REW measurements, as advised by Sailor(Charles), was that the CT60 decay figures were gradually improving and I was approaching the 300ms decay times across the Frequency sweep, I think my understanding of this is correct. Finally I covered the 55" TV with another fleece blanket and took my final REW measurement with the temporary room treatments.

As can be seen in the RT60 graph the decay times in Yellow, the last measurement, nearly all is below 300ms, below 80hz and 168-352hz are just above 300ms but not by much. Considering this has been achieved with somewhat basic stuff it is a good starting point, I am rather surprised to have got it that low.

I think I have persuaded Sue to allow me to purchase some proper treatment panels from GIK Acoustics for the wall behind me and I will get some simple panels that can be free standing to the left and right, instead of the curtains, these can be moved out when I am not doing serious listening. I think to shield the door behind me whilst listening I will use the Inca rug hung vertically from hinged pole that can be swung into place when required. I may put 3-4 300mm round panels on the left side wall, and above the turntable, but these can be added later. I am quite happy to just cover up the TV when needed.

Summing Up:-

I sat down and had a good listen to my usual test listening tracks and I would say that I am now hearing the system as good as I have ever heard it in this room. Detail and clarity is much improved, the lower end frequencies are under much greater control, tighter and better defined, hi-hats and cymbals for example sound crisper and cleaner, vocals are more focused and more nuances can be heard, it is very evident that separation and detail of the music as a whole sounds better(clarity). So I am absolutely convinced that room treatment is the way forward.

I am no acoustic engineer or expert in sound analysis but have found that by using REW it has helped me and enabled me to compare measurements as I have experimented, and I can see and hear changes and improvements. I hope some of you have found this this interesting and possibly helpful. I would recommend that if you want to get the best from your system, whatever it may be, you look into room treatment, it can be very surprising and satisfying.