whitesox Posted January 16, 2017 Posted January 16, 2017 What is REW real time measurement ? Hmmm... Initially I thought it is too complicated to learn for my old brain that was why I ignored it but bcoz I was poisoned heavily after visited bro Roni... Heard rumbling effects of his Rythmik+KK subwoofers therefore I decided to give a try and begin my journey with. I am so lucky that bro Roni helped me to tune my 3 subwoofers. We have a good discussion ! (He told me that bro Jag is his si-fu and helped him too. He learned a lot from bro Jag) Used REW to locate my best locations, manipulate room gain and how to integrate between subwoofers and Centre Speakers. Surprised me that my good location end up become my worse location to place one subwoofer there. One subwoofer needs to turn 180 deg for phase... OMG I never expect that before :o Tweak here and there for phase, distance and Xover I used Fantastic-4 (2015 movie) to test. So now, I have new experience to enjoy my movie (don't know how many layers of bass..haahaa but surely my sofa vibrate longer than usual without bass shakers). Because of this experience that's why I would like to encourage HT lover to learn this powerful tool. ;D Watching movie without good bass (rumble experience) something like eat good food but without salt ... After Audy calibration was being carried out, I still don't understand why I must set same reading (-8) in the AVR for sub-1 and sub-2 despite location of sub-1 is closer than sub-2 towards MLP? I thought nearest sub will get trim/cut more as what Audy gave. (note: all knobs at sub are pointed to the same level 78db) ???
ronildoq Posted January 16, 2017 Posted January 16, 2017 Hi Bro, Had a great sweaty time calibrating the system, but was well worth it. We have successfully gain matched all 3 subs, so now all 3 subs are working equally hard. You dont have to worry about any of the subs running out of steam, all will run out of steam at the same time. But you have tons of headroom. So that is fine. All you need to do is adj the AVR trim equally for subs 1 and 2 for syokness SPL level.
ronildoq Posted January 16, 2017 Posted January 16, 2017 Visited bro whitesox yesterday and helped our fellow member with his set up. He had 3 similar svs SB12 subs but wasnt happy with the bass. Thank god we have REW to thank for that. We ran through some measurement and sweeps and this is his original A+B+C subs response. His MLP was at 2/3 back wall, but I was shocked, as all 3 subs were measuring as follows. We used REW's RTA feature to find the best location for the subs and then Phase aligned all 3 subs, so here is the response after our exercise. So much better! turns out the subs were not phased aligned and was co located at the worst place. Ideally if you have 3 subs, try to spread them out, that is the best! Its very difficult to find subs best location without REW, crawling helps but REW is powerful,accurate and free. We all love our FREE stuff!! Listening to phase align subs is for pros, after tweaking repeatedly over time, you will be able to phase align the subs without REW. But before that, your ears need to be trained by measuring and seeing the response. Once you have that experience, it becomes easier. You could see why bro whitesox was not enjoying his bass despite having 3 subs. Hopefully he is now able to enjoy his system ;)
ronildoq Posted January 16, 2017 Posted January 16, 2017 Bro has a very nice B&W centre speaker, very powerful centre. Nice. But after audyssey, you can see the response of the C+Subs crossed at 60,70,80 Since we know the subs are flat up to 100hz, and there is dip in the crossover region after measuring C+subs, a way to solve this is to use the AVR's sub distance to tweak by bringing up the dip in applying equal distance increments to both subs. or reduce in equaly amounts for both subs. we went with steps of 30cm. It was already late and we went with the following distance between sub 1 & 2 That brought up the dip a little, but it was not the best. I wish i had more time to fine tune to perfection. See the response above of the C+Subs after distance tweak. Hopefully you are now able to do your own measurement and compare the results. There are a lot of other features on REW, these are just the basic stuff and you can always use this when you upgrade your subs to a more powerful sub! You will definitely enjoy since your room is very good and you have no room modes. Very lucky !
whitesox Posted January 17, 2017 Author Posted January 17, 2017 Hi Bro, Had a great sweaty time calibrating the system, but was well worth it. We have successfully gain matched all 3 subs, so now all 3 subs are working equally hard. You dont have to worry about any of the subs running out of steam, all will run out of steam at the same time. But you have tons of headroom. So that is fine. All you need to do is adj the AVR trim equally for subs 1 and 2 for syokness SPL level. haaahaa... yeah it was so hot... sweat, sticky and smelly... ;D Really sorry, I have no choice must turned OFF AC otherwise cold air blowing to your mic umik-1 and affecting all measurements. We should 'bottom up' to celebrate this with beer after successfully improve my 3 subwoofers. Thank you so much beyond words ! Let's arrange for a good time ;D
whitesox Posted January 17, 2017 Author Posted January 17, 2017 Since we know the subs are flat up to 100hz, and there is dip in the crossover region after measuring C+subs, a way to solve this is to use the AVR's sub distance to tweak by bringing up the dip in applying equal distance increments to both subs. or reduce in equaly amounts for both subs. we went with steps of 30cm. It was already late and we went with the following distance between sub 1 & 2 That brought up the dip a little, but it was not the best. I wish i had more time to fine tune to perfection. See the response above of the C+Subs after distance tweak. .... Current crossover applied at 80hz for centre speaker so since there is dip at (70-90)hz so do you think it will get better response if I can change (down it) to 70hz ? Audy gave 40hz value for my centre. My centre spk has rear port, 7cm placed away from wall.. do I need to move forward in order to get more space to 'breath' then will get room gain? will it help? Hear your opinion (Jag, Sevenz need your help by giving opinion also pls) :)
ronildoq Posted January 17, 2017 Posted January 17, 2017 bro, you can try 70 or 60hz also, then tweak the distance. But you will need a Umik 1 measurement mic to do it. A lot of times, we just follow the audy recommended crossover of 80hz. Audy doesnt set the crossover, the crossover is set by the AVR. And in this case, your centre can go up to 40hz flat, no downward slope. Hence you can play around with 60,70,80 hz. All will work. The dip you are seeing is after integrating C+subs, it is common to see a dip in the crossover region. As far as your LFE channel goes, you have no dips till 100hz. So audy got the distance set correctly for both your subs. I believe no one can answer your question, it is only through measurement you will know this. I tried 60 & 90hz, i went with 60hz in the end. 60hz was very pleasant especially when it came to music (i watch a lot of animation). So the midbass is not over bloated. When you cross at 90hz, you will be sending <90hz information from the centre chanel to the subs. That wasn't as nice for me. So its down to preference Get a UMIK -1 mic, its not expensive. then you can slowly take your time measure and tweak to nirvana. It will also help u when you upgrade your AVR or subs etc. Because you have all the power to measure and implement whats best for your set up with a simple mic.
deadrick Posted January 18, 2017 Posted January 18, 2017 hi roni and whitesox, like to understand why changing the sub distance will affect the dips? is it a tweak for multi sub or can tweak for single sub too?
ronildoq Posted January 18, 2017 Posted January 18, 2017 hi roni and whitesox, like to understand why changing the sub distance will affect the dips? is it a tweak for multi sub or can tweak for single sub too? Hi Deadrick, Changing the subs distance = changing the delay. here is a simple explanation by Rythmik. Quote: How to adjust phase with a home theatre receiver The simple method is to compensate by changing the speaker distance setting on your receiver. Bass management in HT receivers has a speaker distance adjustment which process the signal on digital domain. If one puts distance of the sub x feet further away than its physical distance relative to other speakers, the HT receiver will put out the signal to the sub x/1000 sec before it puts out signals to other channels. That essentially puts a negative delay on the sub which can be used to reduces the "phase lag" on the sub and therefore reduces the phase difference between the sub and the front speakers. This trick enables us to use the speaker distance as a tool for phase adjustment between subwoofer and front speakers. Since it is a constant delay adjustment, the phase adjustment is not fixed for all frequencies, instead it is proportional to frequency. That does not affect its effectiveness as our objective is to get correct phase alignment at the crossover frequency. Unquote The reason you are seeing the dip after measuring the Centre Channel with subs is because when you set the Mains Crossover at 80hz after audy, the mains will cut off at 80hz and start sending all information below that to the sub. Because of this, a lot of times there is cancellation at the crossover region. and the way to solve this is to use the distance to tweak for integration of mains and subs. That is also another reason why i dont like to High Pass one sub and Low pass the other, it will always somehow screw up the response because we are not taking advantage of the power of dual subs to even out the response. Also I prefer not to set it beyond 90hz as the subs will start to localise, which is not pleasant. Most just set it at 80hz and assume thats it. It is very important to make sure the mains integrate well with the subs, that makes or break a system as a whole. The only way you can check if this is done correctly is by using a Mic to measure. There is no way you can tell at which crossover there is a dip at which freq if you do not have the measurement tool. You would just have to stick to 80hz and hope for the best. Mic is not exp, USD75, great tool! Learning REW is a little bit of a challenge, lotsa reading to do. But its never too late to start, highly encouraged
kopidilo Posted January 19, 2017 Posted January 19, 2017 do you think it will get better response if I can change (down it) to 70hz ? My centre spk has rear port, 7cm placed away from wall.. do I need to move forward in order to get more space to 'breath' then will get room gain? will it help? Hear your opinion (Jag, Sevenz need your help by giving opinion also pls) :) 7cm from wall for rear ported speaker IMO is too near and likely affect the Sq. Suggest at least 1-2 feet if u can. The xover, u need to measure the FR and do trial and error by changing freq and dist Bro. No bao chiak straight forward solution. Agreed w what ronil suggested, invest in a mic and learn rew.
joagib Posted January 19, 2017 Posted January 19, 2017 7cm from wall for rear ported speaker IMO is too near and likely affect the Sq. The xover, u need to measure the FR and do trial and error by changing freq and dist Bro. No bao chiak straight forward solution. Agreed w what ronil suggested, invest in a mic and learn rew. Wah..bro! You very Pro leh...Hopefully you can help me out for my next setup..
kopidilo Posted January 19, 2017 Posted January 19, 2017 Hopefully you can help me out for my next setup..
ronildoq Posted January 20, 2017 Posted January 20, 2017 7cm from wall for rear ported speaker IMO is too near and likely affect the Sq. The xover, u need to measure the FR and do trial and error by changing freq and dist Bro. No bao chiak straight forward solution. Agreed w what ronil suggested, invest in a mic and learn rew. Bro, u wouldn't want any "boundary gain" for your Centres, what u want is clarity. Bass is handled by subs, If ur back wall is reflective, u want your Centres away from the wall for better clarity, 7cm is too near to wall as Sevenz mentioned. Same for your mains. Having said that, move your Centres 3 cm forward will still not solve the dip in the crossover region, neither will placing treatment at the wall. U can experiment with phase tweaking the mid wall subs, we have seen that 2 subs are good enough to smoothen the response, the 3rd sub didn't contribute much. U can try using the dial on that sub to tweak for integration. this will be very time consuming as chances r u will have a dip in another range. I've experimented and the best way I feel is using the avrs distance tweak. In your case, go with equal increments to max, then slowly come down. Again, an experienced person can tell u yes it doesn't sound right and u can use ears to tweak but it is very time consuming and has its limitation. Very hard to fix the problems and get it right without any measurement tools.
deadrick Posted January 20, 2017 Posted January 20, 2017 How abt experiementing w speaker port foam for speaker placement close to the wall? I find it helpful for my 2.0 set up. Reduced the boomy effect quite alot.
whitesox Posted January 20, 2017 Author Posted January 20, 2017 Bro, u wouldn't want any "boundary gain" for your Centres, what u want is clarity. Bass is handled by subs, If ur back wall is reflective, u want your Centres away from the wall for better clarity, 7cm is too near to wall as Sevenz mentioned. Same for your mains. Having said that, move your Centres 3 cm forward will still not solve the dip in the crossover region, neither will placing treatment at the wall. U can experiment with phase tweaking the mid wall subs, we have seen that 2 subs are good enough to smoothen the response, the 3rd sub didn't contribute much. U can try using the dial on that sub to tweak for integration. this will be very time consuming as chances r u will have a dip in another range. I've experimented and the best way I feel is using the avrs distance tweak. In your case, go with equal increments to max, then slowly come down. Again, an experienced person can tell u yes it doesn't sound right and u can use ears to tweak but it is very time consuming and has its limitation. Very hard to fix the problems and get it right without any measurement tools. When I look at Sevenz's measurements, I noticed higher Xover will get less dip when his C spk interacting with 2 subs. He ran 3 xover frequencies. - RED - when i crossed at 80Hz, there seems to be nulls/ cancellation/ modes between 50-80Hz. See the huge dip between the freq? - YELLOW - crossed at 90Hz, the null seems to be better. But still no good. - BLACK - crossed at 100Hz, the null seems to be minimized. http://www.xtremeplace.com/yabbse/index.php?topic=231629.45 but if I adjust it to 90-100hz then will I still get dip at 80hz for 74db although 50-70hz is good? He has steeper slope down at 50-70hz thats why he tried to use Xover 80hz get <74db, Xover 100hz to get max reading 76db @70hz.... :o I am so confusing??? Anyway, I do appreciate for your value-able advise. I will take note on that ! Let me get Umik-1 microphone... BTW, how did you get yours? I hope other brother are also keen to buy so we can combine for cheaper shipment cost :)
ronildoq Posted January 20, 2017 Posted January 20, 2017 In order to find the best cross over, u need to look at the centre channel and the roll of point, then u also need to look at the measurement of combined 3 subs roll off point, You must put the two graph together and see. My advice is don't go above 100hz, especially when u r running 11 channels, don't forget each individual channel is sending bass info to the subs. It will start to localise and get bloated, especially the midbass. I believe your Centres r using at least 61/2" woofer , so u can comfortably cross over at 60hz. Go with distance tweak, u won't go wrong. Let me upload the graph then will be easier to see
ahduck Posted January 20, 2017 Posted January 20, 2017 Hi Bro Ron, Is it possible to invite me if you happen to drop by anyone of follow members place to assist in measurements or setting up multi subs. I'd like to learn a thing or two on REW s/w and umik. Sent from my Game Boy Advance 32gb 4GLTE/WiFi using Tapatalk
kopidilo Posted January 20, 2017 Posted January 20, 2017 How abt experiementing w speaker port foam for speaker placement close to the wall? I find it helpful for my 2.0 set up. Reduced the boomy effect quite alot. Also will work I guess.... i would only put speaker foam if i have no other choice..... u would lose quite a bit of the mid bass and might face more challenge when integrate/ cross with subs. Esp when u have no sub, u tend to lose a lot on the low and mid bass and overall sound might not sound so 'full' (not sure what is the best word to describe it... ha....)
kopidilo Posted January 20, 2017 Posted January 20, 2017 When I look at Sevenz's measurements, I noticed higher Xover will get less dip when his C spk interacting with 2 subs. Yo bro, u cant assume and apply like that. =) EVERY room is DIFFERENT. The FR that i posted is how it behaves in MY ROOM. Maybe yours, u use higher freq, it will dip more or react differently. Hope u get what I mean.... :)
whitesox Posted January 20, 2017 Author Posted January 20, 2017 Yo bro, u cant assume and apply like that. =) EVERY room is DIFFERENT. The FR that i posted is how it behaves in MY ROOM. Maybe yours, u use higher freq, it will dip more or react differently. Hope u get what I mean.... :) Hahaa... you might be right bro... different room will have different curve... but higher Xover will get flatter response right...? correct or not? BTW, did you do measurement when your C spk and 2 subs interacting (sounding) together after Audy calibrated them? (I am not referring to your combine graphs but something like my graphs) :)
kopidilo Posted January 20, 2017 Posted January 20, 2017 Hahaa... you might be right bro... different room will have different curve... but higher Xover will get flatter response right...? correct or not? BTW, did you do measurement when your C spk and 2 subs interacting (sounding) together after Audy calibrated them? (I am not referring to your combine graphs but something like my graphs) :) U buy umik mic already then I tell u... ;D ;D muahahaha
Jag Posted January 20, 2017 Posted January 20, 2017 Current crossover applied at 80hz for centre speaker so since there is dip at (70-90)hz so do you think it will get better response if I can change (down it) to 70hz ? Audy gave 40hz value for my centre. My centre spk has rear port, 7cm placed away from wall.. do I need to move forward in order to get more space to 'breath' then will get room gain? will it help? Hear your opinion (Jag, Sevenz need your help by giving opinion also pls) :) My name popped up in this interesting thread. Sorry I didn't reply earlier with me occupied with a very busy day job. Here are my thoughts about Whitesox's measurements: 1) A measurement of just the center channel alone would be very helpful in determining the correct cross-over point and phase alignment of center and subs. 2) Right now, its most LIKELY the center is cancelling the sub at 65Hz. Measurement from (1) would confirm this. 3) When doing measurements, measure each speaker and each subwoofer independently. This is so as to identify the FR of each transducer first in its individual form. 4) REW could really pick apart all the problems. For sure, your before curves were so bad that just one 1 subwoofer could do far better than 2 subs. 5) I have been adovating the science of HT, rather than the "poetry of words" that overflowed from the audiophile world. Measure, measure , measure. Your example is a classic text book example of maximizing multiple subs. 6) Get a Umik-1 mic and SPL meter from CSL. I'm willing to chip in with shipping costs since I would like to get a SPL meter to replace mine. 7) Don't assume that another friend's same exact model and speaker can go down to 60hz, that means yours also can. At LFE frequencies, the room can change the bass more than you think Can someone send me whitesox's MDAT file so that I can help to analyze? The 80hz dip is considered a wide band dip and its not good. But its a better FR than original. The data tells me that the Center and LFE channels are not properly time aligned. If they were properly aligned, you would have peaks at the cross-over freq where they constructively combine.
whyeme Posted January 20, 2017 Posted January 20, 2017 I am also ready to make the commitment to try learning REW myself. Too bad there is no sticky thread here in XP to ease less technically/mathematically inclined guys like myself into it :-[ Nevertheless, I would like to join in any mass order purchase for the Cross Spectrum Labs Umik-1 mic and SPL meter to lessen our overall shipping costs. http://www.cross-spectrum.com/index.html Also thinking of getting this budget tripod for the umik and spl meter https://www.aliexpress.com/item/Top-Sell-Portable-Professional-Aluminum-Telescopic-Camera-Tripod-Stand-Holder-For-Smart-Phone-For-iPhone-For/32622915038.html?spm=2114.13010208.99999999.264.trIYNd Okie now to search for some basic guides to REW...
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