Mpr_65 Posted February 12, 2021 Author Share Posted February 12, 2021 7 minutes ago, davewantsmoore said: Like all acoustic cancellation issues.... You have the following choices. Move the speakers Move the listener Add more sound sources (eg. a subwoofer) Thanks https://www.stereo.net.au/forums/profile/108814-davewantsmoore/some pretty succinct and valuable advice there. Appreciate the feedback from yourself and https://www.stereo.net.au/forums/profile/107174-satanica/, https://www.stereo.net.au/forums/profile/105652-steffen/ https://www.stereo.net.au/forums/profile/109073-sakabatou/. Much appreciated. 1 Link to comment Share on other sites More sharing options...
davewantsmoore Posted February 12, 2021 Share Posted February 12, 2021 For now, just correct it with Dirac... and be happy. The only thing which will solve it, really.... is, as mentioned... move it low enough (it almost is, but not quite) and add a subwoofer. The reason "not quite" is that if you added a subwoofer that you were going to play up to well over 120Hz .... then you would need to position it close to your main speakers..... and you are right back at your original problem. 1 Link to comment Share on other sites More sharing options...
Mpr_65 Posted February 12, 2021 Author Share Posted February 12, 2021 Thanks Dave. Bit of a learning curve but I’ve got it now (I think) Good news is Mrs gets a new rug and I get a new house! One day. Cheers. 1 Link to comment Share on other sites More sharing options...
Guest DrSK Posted February 12, 2021 Share Posted February 12, 2021 (edited) Others are already on it, SBIR. As soon as you said 120Hz I calculated 70cm and saw your speaker distance to the wall. Take 343/120 gives wavelength. SBIR is a quarter wave issue, so divide wavelength by 4. Others have given suggestions. Another thing to remember is that base is relatively omni directional. The effect can be largely tuned out if space permits by adjusting speaker placement to control side wall reflection. The side wall reflection will again have a timing delay relative to the direct speaker signal and can either make the dip worse or resolve it somewhat depending on how you space things. Many technical combing effects are actually resolved by good side wall reflections, especially within our auditory system. For example the spacing between my speakers is purely about controlling timing delays of my side wall reflections relative to the direct signal at the listening position. With the aim to optimising and controlling base response and imaging. After speaker width I made small adjustments to seating position to tune effects of a room mode. Then speaker toe to compensate for width of speakers as was a bit out of the equilateral triangle rule of thumb. Edited February 12, 2021 by DrSK Link to comment Share on other sites More sharing options...
Mpr_65 Posted February 12, 2021 Author Share Posted February 12, 2021 1 hour ago, DrSK said: The effect can be largely tuned out if space permits by adjusting speaker placement to control side wall reflection. Sadly space is the issue here. I don’t really have much room to move. Initially I thought some absorption/reflective panels might help placed behind the speakers. However this does not appear to be a solution. I actually quite like the sound with Dirac running however chasing rainbows seems to be the audiophiles lot. Link to comment Share on other sites More sharing options...
Guest DrSK Posted February 12, 2021 Share Posted February 12, 2021 (edited) 15 minutes ago, Mpr_65 said: Sadly space is the issue here. I don’t really have much room to move. Initially I thought some absorption/reflective panels might help placed behind the speakers. However this does not appear to be a solution. I actually quite like the sound with Dirac running however chasing rainbows seems to be the audiophiles lot. Yep, chasing rainbows! I'm an audiophile and acoustic engineer. Sometimes I have to invite mates over just to enjoy and stop analysing. At 120Hz your only hope potentially without use of a sub to fill may be a helmholtz resonator panel behind it. Note box behind panel needs to be sealed. The theory works well for design. Use a model for panels with multiple holes. Could home build and cover in speaker cloth to hide the drilled hole spacing imperfections. Covering will slightly broaden the tuning. If worried about tuning error, could screw together multiple thinner layers before hitting with holesaw and remove a layer to increase resonant frequency. I haven't built one for 16 years. Edited February 12, 2021 by DrSK Link to comment Share on other sites More sharing options...
Decky Posted February 12, 2021 Share Posted February 12, 2021 Manage those corners somehow. Link to comment Share on other sites More sharing options...
davewantsmoore Posted February 13, 2021 Share Posted February 13, 2021 (edited) 5 hours ago, DrSK said: helmholtz resonator panel behind it IME they need to be waaaay too big to be effective... 6 hours ago, Mpr_65 said: seems to be the audiophiles lot. I think the best advice short of adding another source, is to say that it's not as bad as the "giant chasm" in your response might make you think. Most system measurements look a lot worse. Let dirac do it's thing and sleep easy. Edited February 13, 2021 by davewantsmoore 2 Link to comment Share on other sites More sharing options...
btiltman Posted February 13, 2021 Share Posted February 13, 2021 'What does it sound like? If you don't hear anything obviously wrong don't worry about it. ie If you didnt look at the graph would you have felt there was an issue? Link to comment Share on other sites More sharing options...
davewantsmoore Posted February 13, 2021 Share Posted February 13, 2021 11 minutes ago, btiltman said: 'What does it sound like? If you don't hear anything obviously wrong don't worry about it. ie If you didnt look at the graph would you have felt there was an issue? In most ways I think this is terrible advice. Most things I fix in audio systems, I wouldn't be able to "pick out" with my ears.... but one the thing is fixed, and you (if you have the opportunity) switch back and forth, the difference is well audible. But... the opposite (agonise over every wiggle in the response), can be problematic too. The perhaps obvious thing is that the solution is knowing what in a chart is problematic, and whether it can be solved (with practical / available options). In this case (like many/most) the chart makes it look worse than it is.... and it isn't easily fixable. In short it's why a decent sized room, and multiple subwoofers (or at least one) are a good solution...... but that's impractical for lots of people as you can't (always) just go get a new house and / or a new wife, because of your audio setup. 1 Link to comment Share on other sites More sharing options...
Mpr_65 Posted February 14, 2021 Author Share Posted February 14, 2021 20 hours ago, davewantsmoore said: The perhaps obvious thing is that the solution is knowing what in a chart is problematic, and whether it can be solved (with practical / available options). In this case (like many/most) the chart makes it look worse than it is.... and it isn't easily fixable. I think you’re spot on, hence the reason I started this thread. Thanks to all that have contributed. The advice/feedback I’ve received has saved me $100’s possibly $1000’s in products which would have had a negligible impact correcting this issue. Additionally I’ve learnt a few things along the way. As for the sound? The Revels Sound great! Easily the best speakers I’ve owned. Could they sound better in a different room without the need for Dirac? .....probably/maybe. Either way its not an option for now. Thanks again. Link to comment Share on other sites More sharing options...
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