Post by ajski2fly on Sept 29, 2022 15:01:03 GMT
I thought some of you may find this interesting and possibly helpful. I am not a sound engineer or an REW expert but have some understanding of how to use it to effect.
Many years ago I worked for the Wolfson Unit Sound and Vibration laboratory at Southampton University, I would set up experiments, take measurements and make changes to determine improvement to various pieces of equipment, generally in lowering sound levels, but also measuring a few loudspeakers. This gave me a basic understanding of how to interpret sound measurements.
Some years ago I tried using REW to assess speaker and listening positions in our previous house, with some success, but limited it to speaker position and listening. We moved into our new house 18 months ago and I now have time to do similar, the lounge is a rather an awkward room, with two large windows along one wall and pocket sliding glass doors on the opposite wall and a glass door in the corner accesing a hallway, so lots of room for reflections.
I am using REW on my MacBook pro (9 years old) and a simple Panasonic TV USB Microphone, the microphone has 2 pairs of mics on each channel and is quite good but nothing special. Before some of your hold your hands up in horror, I do appreciate using a USB mic such as the miniDSP UMIK-1 would give more accurate results as it has a very flat frequency response, however at present I am more interested in comparative measurements so the simple USB mic will suffice for now until I can afford £130 for the miniDSP.
the first thing do in REW was to use Room Simulator, you enter room W*L*H and then you can define where your speakers are in the room, and your sitting position, you also can define the absorption of each wall, floor and ceiling (higher the value the less reflective it is, so carpet is a high value). The software then gives you the anticipated frequency response and modal distribution in a graph, as shown below. What you then do is to adjust the speaker positions, being as practical or not as you wish, and the seating position, you can then compare up to five plans. By taking your time with this you are able to find the best speaker position and listening spot. The aim is to get as smooth response as possible avoiding large peaks and troughs.
Below you can see the room set up I ended up with and the comparison between what I started with and now have. In pic below, top is plan view and below it is elavation. Note my speakers are toed in towards my head which helps minimise reflections from side walls, our room is quite narrow, 10' 6", so awkward, but at least no square.
Frequency and Modal 20-300hz
After the above I took two measurements with REW with the Mic where my head would be and ran a Frequency sweep through my system from REW and recorded the result. The first was the original position and the second with the position from the Room Sim as above. As you can see there is less drop out between 50-80hz and 80-200hz is smoother, and generally at the new position it is smother at the higher frequency as well.
So what does this mean? Well basically it means that there should be less interference to the produced sound at the new listening position. So the proof of the pudding is listening, using some good known tracks at the old set up and then the same at the new. I did this with around 10 tracks and the result was very clear, I had gained an improved and more focused soundstage, more depth and width, the clarity and definition of the mix opened up further and on some tracks I heard aspects of detail more clearly.
Believe me this is not hocus pocus, I trust my ears and I know when it sounds better, give it a go if you can you may be surprised with the results.
We have parque floor and I measure with no rug and with a rug as below, as is easily seen there is less re-enforcement across the mid to upper frequency ranges just my putting a 2m by 2.8m thick pile rug down. So obviously the rug stays. Simpy put the result is more clarity in the sound and less mid range emphasis, so more natural. We used to have the rug down anyway but recently redid the floor and was interested in the difference it caused.
Onto the next stage which is on going. Our lounge, as I have said, has rather a lot of reflective glass, not much I can do about that, but it also has hard reflective walls, behind speakers, rear of sitting position and either side of the sitting position. Based on my limited understanding and experience of how sound behaves in rooms, I want to see what improvements can be gained by placing sound deadening materials at these points, and then decide if some carefully chosen GIK panels would be worthwhile.
The first thing I did was to place a Peruvian decorative rug/wall hanging, that we have had for years, across the rear wall behind the speakers. It is not large only 1.6m by 0.6m and is 400mm down from the ceiling. I followed this by placing an old valet curtain on a clothes horse in front of the wall at mid point, rising to 2m and about 600mm wide. The results you can see below in the before and after frequency sweeps.
As can be seen from the above whilst all the frequency sweeps look similar there are variations but the most noticeable thing is using makeshift sound absorption at each end of the room the general sound re-enforcement across the frequency range is lowered, my investigations will continue with side walls as well. Lowering frequency re-enforcement is something that we should all aim to achieve, especially at the lower frequencies, but do not miss-understand me on this, if you go out and buy a myriad of sound deadening foam and bass traps and stick it all over the room you will start to approach a room that sounds like an anechoic chamber and your music will sound completely dead and lack lustre. The key is to smooth things out and to try lessen re-enforcement at frequencies that are being enhanced.
You may be wondering how my system sounds compared to when I started on this three days ago, using my ears and listening at each stage I could detect decernable improvements in soundstage, clarity and perceived detail. I would not be wrong in saying that as a whole the sound is now more enjoyable overall, and the exercise has been definitely worthwhile as far as I am concerned.
In answer to the title of this thread I would say that REW is a very worthwhile tool to use to help you adjust your listening room to get the most from your system. What's best of all it is free, runs on a Windows or Mac machine, and with just a simple USB Mic it can be used to reasonable effect for comparative measurements, or for a £120 USB Mic get very accurate results.
From what I have read and listened to, one of the most overlooked aspects of an audio system is setting it up and the room. There is no point spending large amounts on HiFi and just placing it in a room where it looks best cosmetically for what ever reason, it will more than likely sound poor and be a real disappointment, also if the room has few furnishings or has lots of reflective surfaces this will also have a bad impact on the sound. This does not just apply to more expensive equipment, any carefully set up system in a well adjusted room can give very good results, at least the best that can be got from it. IMO making the most of your system and spending time setting it up and tweaking the room to get this best from it is very important, it may even stop you changing speakers or amplifiers unnecessarily if you realise the full potential of your system and the room it is in.
PS If you do change speakers or amplifier because you want to, I would strongly advise using REW and taking measurements again to get the best Speaker/Listening position, this is because all speakers have different frequency characteristics and have a different synergy with amps they are used with. So changing either is likely to result in a different listening experience from subtle to large. Obvious really but I thought I would mention it.
Many years ago I worked for the Wolfson Unit Sound and Vibration laboratory at Southampton University, I would set up experiments, take measurements and make changes to determine improvement to various pieces of equipment, generally in lowering sound levels, but also measuring a few loudspeakers. This gave me a basic understanding of how to interpret sound measurements.
Some years ago I tried using REW to assess speaker and listening positions in our previous house, with some success, but limited it to speaker position and listening. We moved into our new house 18 months ago and I now have time to do similar, the lounge is a rather an awkward room, with two large windows along one wall and pocket sliding glass doors on the opposite wall and a glass door in the corner accesing a hallway, so lots of room for reflections.
I am using REW on my MacBook pro (9 years old) and a simple Panasonic TV USB Microphone, the microphone has 2 pairs of mics on each channel and is quite good but nothing special. Before some of your hold your hands up in horror, I do appreciate using a USB mic such as the miniDSP UMIK-1 would give more accurate results as it has a very flat frequency response, however at present I am more interested in comparative measurements so the simple USB mic will suffice for now until I can afford £130 for the miniDSP.
the first thing do in REW was to use Room Simulator, you enter room W*L*H and then you can define where your speakers are in the room, and your sitting position, you also can define the absorption of each wall, floor and ceiling (higher the value the less reflective it is, so carpet is a high value). The software then gives you the anticipated frequency response and modal distribution in a graph, as shown below. What you then do is to adjust the speaker positions, being as practical or not as you wish, and the seating position, you can then compare up to five plans. By taking your time with this you are able to find the best speaker position and listening spot. The aim is to get as smooth response as possible avoiding large peaks and troughs.
Below you can see the room set up I ended up with and the comparison between what I started with and now have. In pic below, top is plan view and below it is elavation. Note my speakers are toed in towards my head which helps minimise reflections from side walls, our room is quite narrow, 10' 6", so awkward, but at least no square.
Frequency and Modal 20-300hz
After the above I took two measurements with REW with the Mic where my head would be and ran a Frequency sweep through my system from REW and recorded the result. The first was the original position and the second with the position from the Room Sim as above. As you can see there is less drop out between 50-80hz and 80-200hz is smoother, and generally at the new position it is smother at the higher frequency as well.
So what does this mean? Well basically it means that there should be less interference to the produced sound at the new listening position. So the proof of the pudding is listening, using some good known tracks at the old set up and then the same at the new. I did this with around 10 tracks and the result was very clear, I had gained an improved and more focused soundstage, more depth and width, the clarity and definition of the mix opened up further and on some tracks I heard aspects of detail more clearly.
Believe me this is not hocus pocus, I trust my ears and I know when it sounds better, give it a go if you can you may be surprised with the results.
We have parque floor and I measure with no rug and with a rug as below, as is easily seen there is less re-enforcement across the mid to upper frequency ranges just my putting a 2m by 2.8m thick pile rug down. So obviously the rug stays. Simpy put the result is more clarity in the sound and less mid range emphasis, so more natural. We used to have the rug down anyway but recently redid the floor and was interested in the difference it caused.
Onto the next stage which is on going. Our lounge, as I have said, has rather a lot of reflective glass, not much I can do about that, but it also has hard reflective walls, behind speakers, rear of sitting position and either side of the sitting position. Based on my limited understanding and experience of how sound behaves in rooms, I want to see what improvements can be gained by placing sound deadening materials at these points, and then decide if some carefully chosen GIK panels would be worthwhile.
The first thing I did was to place a Peruvian decorative rug/wall hanging, that we have had for years, across the rear wall behind the speakers. It is not large only 1.6m by 0.6m and is 400mm down from the ceiling. I followed this by placing an old valet curtain on a clothes horse in front of the wall at mid point, rising to 2m and about 600mm wide. The results you can see below in the before and after frequency sweeps.
As can be seen from the above whilst all the frequency sweeps look similar there are variations but the most noticeable thing is using makeshift sound absorption at each end of the room the general sound re-enforcement across the frequency range is lowered, my investigations will continue with side walls as well. Lowering frequency re-enforcement is something that we should all aim to achieve, especially at the lower frequencies, but do not miss-understand me on this, if you go out and buy a myriad of sound deadening foam and bass traps and stick it all over the room you will start to approach a room that sounds like an anechoic chamber and your music will sound completely dead and lack lustre. The key is to smooth things out and to try lessen re-enforcement at frequencies that are being enhanced.
You may be wondering how my system sounds compared to when I started on this three days ago, using my ears and listening at each stage I could detect decernable improvements in soundstage, clarity and perceived detail. I would not be wrong in saying that as a whole the sound is now more enjoyable overall, and the exercise has been definitely worthwhile as far as I am concerned.
In answer to the title of this thread I would say that REW is a very worthwhile tool to use to help you adjust your listening room to get the most from your system. What's best of all it is free, runs on a Windows or Mac machine, and with just a simple USB Mic it can be used to reasonable effect for comparative measurements, or for a £120 USB Mic get very accurate results.
From what I have read and listened to, one of the most overlooked aspects of an audio system is setting it up and the room. There is no point spending large amounts on HiFi and just placing it in a room where it looks best cosmetically for what ever reason, it will more than likely sound poor and be a real disappointment, also if the room has few furnishings or has lots of reflective surfaces this will also have a bad impact on the sound. This does not just apply to more expensive equipment, any carefully set up system in a well adjusted room can give very good results, at least the best that can be got from it. IMO making the most of your system and spending time setting it up and tweaking the room to get this best from it is very important, it may even stop you changing speakers or amplifiers unnecessarily if you realise the full potential of your system and the room it is in.
PS If you do change speakers or amplifier because you want to, I would strongly advise using REW and taking measurements again to get the best Speaker/Listening position, this is because all speakers have different frequency characteristics and have a different synergy with amps they are used with. So changing either is likely to result in a different listening experience from subtle to large. Obvious really but I thought I would mention it.
