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bass boom

S-Man said:
I must be imagining the large differences in response below 250Hz shown in the room sim in REW, when moving the speakers a couple of inches back/fowards ;)

Maybe the REW people have cheated physic?
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I have measured with REW to an moved the speakers in 10cm steps, no BIG difference at the lowest room node, maybe above 150Hz, but that's it.
 
Chris81 said:
I have measured with REW to an moved the speakers in 10cm steps, no BIG difference at the lowest room node, maybe above 150Hz, but that's it.
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Darren has provided the answer in the preceding post.

The way the fundamental and the harmonics of a bass instrument combine is critical to get subjectivity clean and even bass.
 
darrenyeats said:
True if you consider a single low frequency in isolation. But the overall bass balance /can/ change a lot as you get two inches nearer to a wall - I'd say two inches when near the wall isn't the same as two inches far out - due to SBIR impacting all the frequencies across the bass (not necessarily a lot, or even in a predictable way, if you were to consider just a single low frequency, but subjectively and overall yes IME).
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These are measurements of one of my speakers, rear face at 55cm (red) and 22.5cm (blue) distance from wall (listener to from wall distance was some 30cm different as well).
Peak and dip frequencies don't seem to change much, only relative amplitude.

IcFQr8K.png
 
tuga said:
These are measurments of one of my speakers, rear face at 55cm (red) and 22.5cm (blue) distance from wall.
Peak and dip frequencies don't seem to change much, only relative amplitude.

IcFQr8K.png
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I'm guessing your ceiling is around 10 to 11 feet high and the ~53Hz peak is your axial height mode?
 
ToTo Man said:
Nothing stops bass modes, the best you can hope to achieve is to ameliorate them to the point that you can live with them. I've managed to control my bass modes down to frequencies of 50Hz to a satisfactory level with room treatment alone. My 40Hz axial length bass mode is still problematic and I'm told would require treating the entire front and rear wall with 40cm deep absorption. I'm not in a position to do this, but if I was then I would, because at the moment I am confined to sitting in the middle 20% of my room. If I move forward or backward any more than this, the 40Hz boom becomes intrusive and gives me a headache. Not a problem most of the time because I have the sweet spot all to myself but when I (occasionally!) have guests I need to sit 3 feet behind the sweet spot and it isn't a pleasant experience! I could, of course, EQ the 40Hz mode to make it more tolerable in the 'back row' but that would be at the expense of my guests sat in the 'front row'!
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Sounds exhausting.
 
whsturm said:
I've also found that speaker cables can affect the balance of bass in the overall sound mix with some over emphasising bass. Whilst a change of speaker cable won't affect the room resonance nodes it may reduce the amount of resonance created in the first place such that most music becomes much more listenable. Tuning your system through appropriate cables use is a topic of its own but if you have a friend who can lend you a different make of speaker cables it might be worth a try to explore the affect in your system...and it's 'free'.
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lol
 
tuga said:
I wish...
Room dimensions are 6.45L x 3.75W x 2.30H, so 7.55ft :p
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Ah, so the 53Hz peak is the 2nd harmonic of your 26.5Hz axial length mode? According to standing wave theory, that mode should reduce in amplitude, not increase, as you pull your speakers further away from the wall, and reach its null point (minimum amplitude) at 1/4 the length of the room (i.e. 1.7m from the wall). However, your measurement shows it increasing, albeit marginally.

I'm confused by your 42Hz peak as none of your room dimensions correspond to a 42Hz mode. Is that the port tuning frequency of your loudspeakers? Your axial width mode is 46Hz but if you sit dead on centred between the side walls this should cancel itself out.
 
Or , if you can, integrate a Wiim Pro or Pro Plus into your system and use the onboard PEQ ( with the help of the £10 House Curve app if necessary) to EQ your system by ear or by graph or both.
 
Decent isolation will help too. The Townsend speaker supports have already been mentioned, but don’t dismiss system support too. It has been my experience that a proportion of ‘boom’ in systems can be attributed to some degree of feedback mechanism, and if you can reduce that feedback then a significant amount of the disruptive nature of any bass boom can be eliminated. A bit like howl-round in upper frequencies, I suspect the low frequency energy can find its way back into the system (esp but not exclusively with vinyl systems - it happens with CD too) and create time delayed acoustic feedback that plays merry hell with system timing. Managing that issue first has, in some instances, made any remaining room-related boom a second order problem, and much easier to ignore as it’s a sonic rather than a musical effect.
 
ToTo Man said:
Ah, so the 53Hz peak is the 2nd harmonic of your 26.5Hz axial length mode? According to standing wave theory, that mode should reduce in amplitude, not increase, as you pull your speakers further away from the wall, and reach its null point (minimum amplitude) at 1/4 the length of the room (i.e. 1.7m from the wall). However, your measurement shows it increasing, albeit marginally.

I'm confused by your 42Hz peak as none of your room dimensions correspond to a 42Hz mode. Is that the port tuning frequency of your loudspeakers? Your axial width mode is 46Hz but if you sit dead on centred between the side walls this should cancel itself out.
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I think that the ports are tuned to ~37Hz. I wonder if the large glazing area on one of the long walls affects the modes…
I can’t pull the speakers into the room much so I’ve chosen to push them back and EQ the peaks instead.
 
A few people mentioned ports (and bunging them) ... my speakers have a rear port. Not sure whether that gives any indication as to how they would perform close/near/away in relation to walls. I notice the HiFi choice review says "No port blocking arrangements are available here, so the A6 should be kept well clear of walls".

tXem3x9.jpg
 
Neil P said:
A few people mentioned ports (and bunging them)
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Please don't do it. The speaker, crossover and driver are designed to work together, bunging a bass reflex port is IMO nothing I would ever recommend, I have tried it in the past many times and it made things even worse. It didn't solve the problems but brought other problems (unwanted dips in the frequency response.
 
Some frequency response modulation from room modes is inevitable. As the frequency drops the standing waves become more difficult to treat and wall diffusers, damping panels and ‘bass traps’ become less effective (or entirely ineffective). The only way to deal with the 50Hz ‘room boom’ typical of U.K. homes is a dose of DSP.
 
YNWOAN said:
Some frequency response modulation from room modes is inevitable. As the frequency drops the standing waves become more difficult to treat and wall diffusers, damping panels and ‘bass traps’ become less effective (or entirely ineffective). The only way to deal with the 50Hz ‘room boom’ typical of U.K. homes is a dose of DSP.
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Helmoltz resonators (2x fridge-freezer size) and membrane traps at the room boundary here made a SMALL difference at 35Hz centre frequency. So I wouldn't go quite as far as saying /impossible/ at 50Hz but yeah very difficult. You can forget foam at such frequencies though!

The biggest levers for improving bass are listener and speaker placements - traps help in finding a slightly better compromise with these (rather than solving the problem, for sure).
 
Chris81 said:
Or a speaker with a falling bass curve bass response
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IMHO, yes. At audio shows with the same types of room for the different demo systems I have occasionally observed which 'speakers boom (to my ears) and which do not.

My experience may not really be extensive enough to generalize but from some research I think 'speakers that have a reputation for lean but extended bass work well in real untreated rooms. They seem to work with the usual levels of bass room gain to give you the bass at levels that sound about right (for my taste anyway) but without the boom.
 
Agreed re: roll off needs some matching of speaker and room / situation but it can work well when matched IMO. Anechoic flat to DC is for outside e.g. concerts in fields (or at altitude actually!)
 
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