Arke
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Post by Arke on Nov 26, 2022 20:45:15 GMT
I just plunk speakers down where its most convenient and looks best. A bit of tweaking with position and that's it, sorted. But then, after half a century in the hobby it's possibly now fairly intuitive to rapidly hone in on decent positioning in a regular shaped room. I suspect most of us have a surprisingly good room acoustics algorithm in our heads from years of experience. After 50 years it is probably very intuitive. I'm sure your experience is guiding you quite a lot. I reckon around 75% (sounds like yours is in the good 25%) of the systems I hear have reasonably obvious speaker/room issues (usually in the bass) that are often easy to solve. Either the wrong speakers for the room, incorrect setup or poor room treatments. I'm not talking about dedicated/obvious treatments either - just more stealth treatment. It's not that people need to spend lots more, it's often just some straightforward changes/tweaks.
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Post by jandl100 on Nov 26, 2022 20:55:24 GMT
Some speakers have given me trouble.
Audio Physics Virgo 2 had to be very widely spaced. But that was as per the manufacturer's recommendations, even so it took quite a while to get to the sweet spot.
Dali Skyline ribbon hybrids had a 15db bass peak. Impossible to control without some DSP. Nice once sorted, though.
Some Proac Future Point 5 I gave up on. Just couldn't get them right. They were a rather weird hybrid open baffle design. Maybe some proper acoustic science would have helped.
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Arke
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Post by Arke on Nov 26, 2022 21:14:46 GMT
Some speakers have given me trouble. Audio Physics Virgo 2 had to be very widely spaced. But that was as per the manufacturer's recommendations, even so it took quite a while to get to the sweet spot. Dali Skyline ribbon hybrids had a 15db bass peak. Impossible to control without some DSP. Nice once sorted, though. Some Proac Future Point 5 I gave up on. Just couldn't get them right. They were a rather weird hybrid open baffle design. Maybe some proper acoustic science would have helped. In 50 years it's understandable that some speakers just aren't right. It always amazes me how the right speaker/room combo can make even a relatively modest system shine. However, a bad speaker/room combo will hobble even the best systems money can buy.
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Post by bencat on Nov 29, 2022 12:52:45 GMT
Firstly thank you for your very kind and detailed help for many to try and take in without going too far down the math rabbit hole that this sort of measurement and calculation this can become . I have very little technical knowledge about this so simple (well sort of) explanations are very useful .
The only issue I have is that I do not own or use a pair of ported speakers , all those I use are sealed baffle so not to sure of how this would apply . I have a very marked preference for sealed baffle speakers or electrostatics which are in the main dipole with no real enclosure . So what would you suggest for any control of room modes without using and sound absorbing panels which would not be domestically acceptable ?
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Arke
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Post by Arke on Nov 29, 2022 17:42:11 GMT
Firstly thank you for your very kind and detailed help for many to try and take in without going too far down the math rabbit hole that this sort of measurement and calculation this can become . I have very little technical knowledge about this so simple (well sort of) explanations are very useful . The only issue I have is that I do not own or use a pair of ported speakers , all those I use are sealed baffle so not to sure of how this would apply . I have a very marked preference for sealed baffle speakers or electrostatics which are in the main dipole with no real enclosure . So what would you suggest for any control of room modes without using and sound absorbing panels which would not be domestically acceptable ? The worst room/speaker interaction issues I've experienced have always been related to the port. It's certainly not that ported speakers are bad, I just think some matching of the speaker and room can be beneficial. A sealed enclosure is likely to be easier to room match IF it has no other peaks in the bass response. I'm only really aware of two effective ways to counter problem room modes in the low frequencies: Room treatments or Active Bass. My eventual music room (after renovations) will be roughly twice as long as it is wide. This isn't ideal, as the 2nd harmonic length mode will coincide with the fundamental width mode. This will give me a reasonable boost at 50Hz, which isn't ideal. I have decided to use Active bass control on the Vaders (CNO4s) to have some control over this. I will also hide room treatment... There will be a large bank of floor to ceiling shelves behind the speakers with a shelf depth around 45-50cm. Some of the shelving recesses will have significant bass trapping material at the rear (maybe 30-40cm deep) and things (books, ornaments, pictures etc.) will hide the treatment. The positive thing about the new room is the fundamental length mode is 25Hz. This is perfect as it will supplement the low end and mean I don't need as much power (from the plate amp) to produce good SPLs at 25Hz.
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Post by Pigmy Pony on Nov 29, 2022 18:31:01 GMT
I'm thinking that in the case of my system it may be beneficial to try to reduce the base output from my speakers while letting the sub do the heavy lifting.
Reading up on the 'Griewe' system on my Zu Omen Defs, I should be able to reduce bass output by reducing the gap between the speakers' bottoms and the solid oak slabs they sit on. I was going to have a play with this today, with some rubber feet of different thickness under the cabinets, which I recently bought, but I can't for the life of me remember where I put the bloody things! So I've just ordered some more.
One thing does bother me: The lowest crossover point achievable with the sub (REL T9i) is 40hz, which is higher than the lowest reaches of the speakers. So in order to achieve an appreciable output at 30hz and below, will there not possibly be a 'hump' around the 40hz mark, where both the speakers and the sub will be contributing?
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Arke
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Post by Arke on Nov 29, 2022 18:58:45 GMT
I'm thinking that in the case of my system it may be beneficial to try to reduce the base output from my speakers while letting the sub do the heavy lifting. Reading up on the 'Griewe' system on my Zu Omen Defs, I should be able to reduce bass output by reducing the gap between the speakers' bottoms and the solid oak slabs they sit on. I was going to have a play with this today, with some rubber feet of different thickness under the cabinets, which I recently bought, but I can't for the life of me remember where I put the bloody things! So I've just ordered some more. One thing does bother me: The lowest crossover point achievable with the sub (REL T9i) is 40hz, which is higher than the lowest reaches of the speakers. So in order to achieve an appreciable output at 30hz and below, will there not possibly be a 'hump' around the 40hz mark, where both the speakers and the sub will be contributing? I can't comment on your exact speakers, so am not sure what effect reducing the gap will have exactly. Like you say, give it a try and see. The ideal would be to measure - but most people don't have a calibrated mic. I used to have REL t7is and the lowest crossover was 30Hz, I believe the t9i is the same. I used to cross the t7is into the Ektas at 30Hz. My room has a lift at 32-33Hz, so that filled in between the sub and where the Ektas roll off (mid 30s).
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Post by Pigmy Pony on Nov 29, 2022 23:18:44 GMT
You're right Jason, I checked, and my sub is also specifying a 30hz roll off. But what I can't get my head around is that when I increase sub's volume, the increased bass output seems to be well above that. Probably 40 or 50hz I'd guess. I can only think the roll off is not very steep.
I'll just leave it as is until my rubber feet arrive, then have a tinker with it.
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optical
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Post by optical on Nov 30, 2022 7:45:16 GMT
@pigmy Pony (not sure why I can't successfully 'tag' people anymore??)
Sub's do usually have similar roll-off curves to make them predictable (in a vague assessment of about 3-4 sub brands I have owned). Jason will be able to tell you better than I, but if you set the roll off at around 30Hz say, the curve will continue to affect frequencies well up to 40 and probably well into the 50's, quite audibly. So it all depends on the natural room response and 'hump' that is present in your listening environment combined with the roll off of your speakers when combined with your room.
This is where (as Jason suggested) room measurements come in very handy. As this is not viable for many it is always best to experiment until you settle on a balanced sound, then apply tweaks (small increments/decrements) of volume and roll off frequency as well as playing with (if you have it) phase. Good subs have fully adjustable phase (0-180') as a simple 'invert' switch (0 or 180') is a bit rudimentary for balanced integration.
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Post by bencat on Nov 30, 2022 8:02:45 GMT
Right this is for those much more able to read the figures and understand or translate them in to something meaningful . This is were those individuals and I part company as I can generate the numbers as per this or an REW sweep with a UMIK 1 calibrated mic but then the results just mean nothing at all to me . amcoustics.com/tools/amroc?l=393&w=339&h=285&r60=0.6The above is the generated results after feeding in my room measurements in CM 393 L x 339 W x 285 H . If I am reading it right then I have one room mode at 43.6Hz then one at 50.6 Hz then one at 60.3Hz . Is this good or bad ? What could I do about it ? Speakers in this case are QUAD ESL 57 so dipole and effectively no real cabinet just a frame plus rear padding . Also does the huge number of room modes at the high end of 59 look right is this sort of normal ?
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Arke
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Post by Arke on Nov 30, 2022 8:36:30 GMT
Right this is for those much more able to read the figures and understand or translate them in to something meaningful . This is were those individuals and I part company as I can generate the numbers as per this or an REW sweep with a UMIK 1 calibrated mic but then the results just mean nothing at all to me . amcoustics.com/tools/amroc?l=393&w=339&h=285&r60=0.6The above is the generated results after feeding in my room measurements in CM 393 L x 339 W x 285 H . If I am reading it right then I have one room mode at 43.6Hz then one at 50.6 Hz then one at 60.3Hz . Is this good or bad ? What could I do about it ? Speakers in this case are QUAD ESL 57 so dipole and effectively no real cabinet just a frame plus rear padding . Also does the huge number of room modes at the high end of 59 look right is this sort of normal ? It's not really a matter of good or bad. It's essentially just physics! We all have room modes, some can be worse than others as it depends on your your room shape and speaker response in the LF too. Your fundamental Axial modes (length, width, height) do not coincide which is good. Solving room modes is not usually trivial and acousticians can charge £1000s to properly investigate the issue and suggest remedies. It is a very complex relationship between the room, the speaker, speaker positioning, listener position etc. My OP was mainly to highlight that I have always experienced issues with Port tunings (generally over 40Hz) coinciding with room modes. It is hard to properly alleviate a certain room's issues without actually being there and taking detailed measurements. If you have active DSP, then that is probably the best bet for you. It's normal to have loads of room modes in the 100-300Hz its just all the harmonics and tangential and oblique modes. These modes are not usually as dominant at the modes under 100Hz.
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Arke
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Post by Arke on Nov 30, 2022 18:27:16 GMT
You're right Jason, I checked, and my sub is also specifying a 30hz roll off. But what I can't get my head around is that when I increase sub's volume, the increased bass output seems to be well above that. Probably 40 or 50hz I'd guess. I can only think the roll off is not very steep. I'll just leave it as is until my rubber feet arrive, then have a tinker with it. Ah the joy of sub integration! It isn't easy as it's a balance of different variables. I believe most REL subs have a 24db/octave roll off, so a crossover at 30Hz will still have some output at 40Hz. It's hard to say exactly without measuring it's response. If you then increase the sub woofer gain there could often be excessive output in the 40-50Hz region (even when crossed at 30Hz) as your speakers are adding to this as well. Most rooms have a fundamental mode in the 40Hz region, so that will add to the output there too. Your port is 42Hz I believe too. Some room measurements would be useful to help guide you. I used to crossover my REL at 30Hz and then increase the gain until it sounded slightly too much and back off a click or two. I use tracks with double bass and bass guitar notes playing in the 40-50Hz region. If these sound bloated or too full I back the gain off slightly.
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