I'm not sure if the answers given directly answer this question...because I have the same one, and I still don't know. I know that John's soffit design that has been posted in this thread numerous times shows hangers.. BUT, what I want to know is what is the point of hangers instead of just filling the cavity with insulation? Seems like an extra complication when enough insulation will absorb anything that the hangers would. Also, what is the point of building a box around the speaker? I remember Barefoot commenting in old threads about soffit mounting that there is no reason to build a box around a speaker, and in fact, a regular stand is fine. As long as the stand and speaker are decoupled from the front wall. Seems like another unnecessary complication. Also, I don't see a point either for separating the sections of the soffit cavity or leaving a gap at the bottom of the soffit wall. I've read this entire thread and many others and don't understand why a speaker on a stand with a wall in front of it with a properly cut hole for the speaker, filled with a bunch of insulation wouldn't be as good as any other soffit design.. at least for a passive speaker that doesn't need to have any kind of air circulation to keep its amps cool. OH, and here is a question. I am putting the mains up above the sight path of the nearfields, and I need to angle my soffit down so that the speakers point at my head of course. I was thinking a cool design would be to just continue the angle of the soffit wall all the way down to the floor. In this design, I end up with less cavity volume on the bottom of course. As opposed to angling the soffits and then straightening it out about half way down. (so that the soffit is at a 90 degree angle to the floor) this way I of course end up with more cavity space on bottom. Anyone have an opinion on if my first idea is an acceptable design and will work as well as the second way?Hey guys, Is it ok to build the entire thing as a superchunk? Just stack the insulation right through top to bottom of the corner. Or should I superchunk the top (above speaker box) and make hangers for the bottom (below speaker), is there a difference?
Soffit mounting?
Originally posted at johnlsayers.com, topic 66.
I'm in the same boat as my friend above with one twist: I'm actually building the speaker cabinets to house my 15" tannoy HPDs. By the time I'm done, my very large cabinets will be almost floor to ceiling. I have the opportunity to do the box within a box design when I build the cabinets, so my plan is to mount them on a cinderblock wall, and make sure the cavity is insulated all around it. Obviously I'll also take great care that the front baffle of my cabinet is not coupled to the front wall.
Has anyone ever tried to soffit mount very large speakers like that? If I don't have room for hangers under the speaker (I probably won't), will that really make a difference? Any advice?
I have a pair of KRK RooKit5 (yes, budget-speakers) What could I expect regarding soffit-mounting them? Oh, and I'm mixing up Suffit with Flush. What's the difference? Edit: Ok, it's the same :)The reason I believe some recording engineers don't like soffit mounting is because it's often done improperly. The most critical aspect of soffit mounting is making sure the monitors are properly designed to work in such an application. Most nearfields and a good deal of midfields are not.
Yep, soffit mount and flush mount is the same thing. "Flush mount" is actually more correct, technically, but "soffit mount" seems to have become the de-facto standard way of talking about it.
Soffits fix the same problems for all speakers: There is a major problem with speakers that are not soffit mounted: the sound wraps around behind them, bounces off the front wall, and interact with itself in various ways. Soffit mounting eliminates all of that: It also improves the bass response, and eliminates the power imbalance inherent to all small speakers. The only issue with the Rokit 5 is that it does not have a bass roll-off control on the rear panel, so you will have to roll that off manually, with an external cross-over or parametric equalizer. If you do that, then your speakers should sound good when sosfit mounted. - Stuart -I have a pair of KRK RooKit5 (yes, budget-speakers) What could I expect regarding soffit-mounting them?
Thanks Stuart! Well, anyway it seems logical for me to design my studio for some new speakers. Buying or making an extra box for just the bass roll-off is probably not gonna be on my priority-list :)Soffits fix the same problems for all speakers: There is a major problem with speakers that are not soffit mounted: the sound wraps around behind them, bounces off the front wall, and interact with itself in various ways. Soffit mounting eliminates all of that: It also improves the bass response, and eliminates the power imbalance inherent to all small speakers. The only issue with the Rokit 5 is that it does not have a bass roll-off control on the rear panel, so you will have to roll that off manually, with an external cross-over or parametric equalizer. If you do that, then your speakers should sound good when sosfit mounted.I have a pair of KRK RooKit5 (yes, budget-speakers) What could I expect regarding soffit-mounting them?
You can get a basic crossover for under a hundred dollars new, and probably much cheaper than that on e-bay. It would one option, but if you plan on upgrading your speakers soon, then you could live without it initially, and probably just compensate in your DAW. You mentioned building one: that's an option too, if you are electronically minded. Barefoot once published a circuit here on the forum for a simple one. Not sure if it is still around... - Stuart -Buying or making an extra box for just the bass roll-off is probably not gonna be on my priority-list
Yes, I saw Barfoots circuit here somewhere. I'm into DIY on everything :) but it often takes time and money. Must be handy with some sort of eq-control for the monitors. Crossover? Isn't it suppose to be a low-shelf or something? (Don't worry, I'll find the info there :) )You can get a basic crossover for under a hundred dollars new, and probably much cheaper than that on e-bay. It would one option, but if you plan on upgrading your speakers soon, then you could live without it initially, and probably just compensate in your DAW. You mentioned building one: that's an option too, if you are electronically minded. Barefoot once published a circuit here on the forum for a simple one. Not sure if it is still around...Buying or making an extra box for just the bass roll-off is probably not gonna be on my priority-list
Exactly. And that is what crossover's do. Theoretically it should be shelving, but in practice for small speakers you can just implement it as a high pass (low cut) with 6db/octave roll off, since the speaker response itself rolls off anyway, just a bit lower down. If you use the output for the mid-range speaker, set the high end to flat response and shelving or high pass on the low end, to correct the power imbalance caused by the soffit. Or rather, to "un-correct" the speaker's own built-in power balance correction, since it is no longer needed with the soffit. The only reason the speaker has that power balance correction circuit (also known as baffle step compensation) is because the speaker cabinet does not have a large enough front surface. Since you are fixing that with the soffit, you no longer need the baffle stop compensation that the manufacturer built in. So that's what you do with the crossover: the manufacturer increased the bass response by 6 dB below the baffle step, and now you need to undo that by decreasing it again by 6 dB. The concept is simple. Any good crossover will allow you to adjust the frequency and slope to get a close match in reversing the baffle step compensation. - Stuart -Crossover? Isn't it suppose to be a low-shelf or something?
Thanks!Exactly. And that is what crossover's do. Theoretically it should be shelving, but in practice for small speakers you can just implement it as a high pass (low cut) with 6db/octave roll off, since the speaker response itself rolls off anyway, just a bit lower down. If you use the output for the mid-range speaker, set the high end to flat response and shelving or high pass on the low end, to correct the power imbalance caused by the soffit. Or rather, to "un-correct" the speaker's own built-in power balance correction, since it is no longer needed with the soffit. The only reason the speaker has that power balance correction circuit (also known as baffle step compensation) is because the speaker cabinet does not have a large enough front surface. Since you are fixing that with the soffit, you no longer need the baffle stop compensation that the manufacturer built in. So that's what you do with the crossover: the manufacturer increased the bass response by 6 dB below the baffle step, and now you need to undo that by decreasing it again by 6 dB. The concept is simple. Any good crossover will allow you to adjust the frequency and slope to get a close match in reversing the baffle step compensation. - Stuart -Crossover? Isn't it suppose to be a low-shelf or something?
Is it right that a reason why active monitors have been so popular the last 10-20years, is the possibility to tune the bass right for free-standing placement?
And if I go soffit-mounting with passive speakers, the bass-fix is not so needed in the first place?
Not really, no. Active monitors are popular (I think) because they are "all in one". You don't need a separate amplifier, equalizer, crossover, delay, etc. Everything has been designed together to work as an integrated unit. You just plug it in and it plays, unlike a passive speaker where you need to add other things, cable them together, then calibrate and tweak to get the same result. IMHO.
And ALL speakers suffer from power imbalance, or "baffle step response", regardless of whether they are passive or active, or any other factor. This is related to the size of the cabinet and the frequency response of the speaker, nothing else. It is caused by the fact that wavelengths that are smaller than the dimensions of the cabinet tend to be projected forwards, into half space, while wavelengths that are larger than the dimensions of the cabinet tend to wrap around behind it, radiating into full space. The area around the transition frequency, where waves are roughly the same size as the dimensions of the speaker cabinet, is where the "baffle step" occurs on all speakers, active or passive. So high frequencies (shorter waves) are radiated into half space, and therefore are twice as loud as the lower frequencies (longer waves) that are radiated into full space. There is a difference of 6 dB between the two (twice the intensity = 6 dB).
The advantage of active speakers here is that the manufacturer can also build in controls that allow you to correct for this problem, if your speaker is located near a wall, or in a soffit. That is harder to do in a passive design. You can still compensate, of course, but you usually need an external crossover to do it.
- Stuart -
Thanks a lot!
But when soffit-mounting, isn't the point that sound below the baffle-step is directed into half space?
Or does this just happen to some degree, so let's say I'd only need a 3db boost below the baffle step?
Great info for me, as I'll need a plan for speaker/amp-type, set-up and placement :)
Exactly! And since you have now corrected the 6 dB power imbalance with the soffit, you no longer need the electronic correction. The manufacturer had to design that inside the speaker for people who don't soffit mount, and therefore do have their speakers radiating into full space.But when soffit-mounting, isn't the point that sound below the baffle-step is directed into half space?
You might need less, depending on how the rest of the room loads the speaker. There are also more complex things going on, such as impedance mismatch between the speaker cones and the room volume, that could affect the response. But you will very likely need more than 3 dB. Soffits also correct other issues: they eliminate SBIR completely, for example, and also totally prevent first reflections off the front wall, edge diffraction, comb filtering, phasing, and a few other unpleasant things. - Stuart -Or does this just happen to some degree, so let's say I'd only need a 3db boost below the baffle step?
Thanks!
It seems like the bottom-line for me is aiming for some active speakers with bass-shelf, like the Adam A7.
Would be easier than eq, amp, speakers and advanced analysis.
Ahh, yes!!!! No question about that. I'm 100% with you on that. Of course, I'm probably just a bit biased, since I own a pair of A7's... :) - Stuart -like the Adam A7.
Hehe :)Ahh, yes!!!! No question about that. I'm 100% with you on that. Of course, I'm probably just a bit biased, since I own a pair of A7's... :)like the Adam A7.
Adams A7 soffit mounted.
http://www.johnlsayers.com/Studio/Pages/Somewhere.htm
Thanks! Very interesting to see. Adams S25A it says..Adams A7 soffit mounted. http://www.johnlsayers.com/Studio/Pages/Somewhere.htm
Very similar design to the A7, A7X, A8X, etc. All from the same family, with similar characteristics. John's point was how you mount them so that the front panel of the speaker is flush with the soffit face. - Stuart -Adams S25A it says..
The thing that bugs me most with flush mounting is that on one hand such importance is placed on a hard, flush, uninterrupted baffle.. but then others recommend use of 3-6" of absorption which makes the front baffle neither flush nor hard.
Then there's the support of the monitors. The kind of framing I see so often implemented really contradicts the typical emphasis on heavy dense stands that are fully decoupled from the room. 5/8" plywood and soft framing lumber?
Lastly, it seems there should be a significant difference depending on whether you mount them in boxes with only a few mm of space rather than a space big enough for adjustable shelves etc.
I'm trying to process it all but it seems there are some contradictions with the matter?
Not contradictions, really. More of "ignorance", I'd say. Taking your points in reverse order:It seems there are some contradictions at work here?
Right! The entire point of soffit mounting is to convert the small front baffle of the actual original speaker cabinet into a very large front baffle, with a lot of area around it. In fact, technically the term is "infinite baffle", since the optimum design would make the baffle infinitely large with respect to the sound waves that it must deal with. In practice, that isn't possible of course, but the idea is still to make it as large as possible, exactly as you say. I've never seen a soffit with "adjustable shelves", although there are designs that allow you to replace the speaker with another model of a different size. However, when properly implemented, those designs still do have a large amount of area around the speaker on all sides. Without that large area, there is no point to soffit mounting. There are other important points that should be taken into account, such as making sure that the speaker is offset from the center of the baffle, to prevent symmetrical artifacts forming around it and creating intense patterns of comb filtering. So there's a trade-off here between the need to have as much area as possible around the speaker, and also to not have the speaker in the center. A good rule of thumb is to have it offset to about 2/5 of the width and around 1/4 of the height of the baffle. But just like the infamous "38% rule", those are not absolute perfect positions, written in stone: just good starting points.it seems there should be a significant difference depending on whether you mount them in boxes with only a few mm of space rather than a space big enough for adjustable shelves etc.
Welllll.... yes and no... Sort of! :) Heavy dense stands are meant for speakers that are NOT soffit mounted, but are free-standing in the room. The same concept applies to soffit mounting, but there's a difference: With a stand, the only support the speaker has is from below. With a soffit, it is supported from all sides: top, bottom, left, right and also from behind. So it is already being held in place far more rigidly, since it has framing on all sides. Also, there are two different basic approaches for designing soffits. The first is to hold the speaker and baffle in place so rigidly that the cannot move at all. This is what John normally does with his designs. The soffit is a very massive, very rigid, very solid frame where the speaker cabinet itself is held tightly by a box that it just fits in to, and the entire structure is attached very firmly to the floor, with no decoupling. This works due to the sheer mass and high rigidity of the soffit. The other concept is to decouple the speaker from the framing, with suitably dimensioned (and carefully calculated!) rubber strips around it, so that it can vibrate freely without transmitting that to the structure. In this design, there is a small gap between the speaker and the infinite baffle, so that the speaker can move freely without touching the baffle. There is even one design (by Barefoot) where the baffle and the speaker are on two separate, independent frames that don't touch. Both designs work when done properly, but it is important to not confuse the two.Then there's the support of the monitors. The kind of framing I see so often implemented really contradicts the typical emphasis on heavy dense stands that are fully decoupled from the room.
Yup! That's a problem, for sure. I'm not sure where it comes from, but there seems to be some place that is recommending exactly that, which makes no sense at all. If your speaker is surrounded by soft absorption, then you DO NOT have a soffit mount! There might be reasons why some people would want to do that, but it is NOT soffit mounting, and will NOT produce the same benefits as a true soffit mount. The entire purpose of soffit-mounting is to remove the speaker from the room. Any time that a speaker is close to walls, ceiling or floor, then that creates artifacts where the sound waves "bouce" off the walls and return to interact with the direct sound. This creates things like SBIR cancellations, comb-filtering, early reflection issues, phasing, and a bunch of other undesirable problems. Soffit mounting eliminates all of those, since the speaker is no longer in the room, technically. The correct name for soffit mounting is "flush mounting", since the front of the speaker is flush with the wall, thus removing the speaker from the room. But if the speaker is NOT flush with the wall, then it is NOT a soffit mount, and those artifacts will still be there. The speaker itself must be surrounded by a hard, flat, rigid, massive surface: that is the most basic definition of what soffit mounting is. The only "exception" to that is what John often does: A few inches below the speaker he has a box on the front of the soffit with insulation in it, that absorbs the strong reflections from the front of the desk and the console. That is important in rooms that have large consoles or desks with large vertical surfaces facing the speakers: those surfaces are a big problem, since they reflect a lot of loud sound directly back to the lower part of the soffit, where it bounces back once again into the room (causing artifacts), and can even create standing waves at some frequencies. So if you have a large console or a desk with speakers, then it's a very good idea to do that. It does not affect the "infinite baffle" principle much, since there is still a hard, solid, rigid surface just behind that absorption, which is only a couple of inches behind the rest of the baffle, and is far enough from the speaker as to not affect things too drastically. This is a bit of a trade off, but those early, very strong reflections are far more important than the slight effect of not having the baffle perfectly flat. So yeah, it can be confusing when you see these things, and you are right that some of them are just plain illogical and silly, but some of them do have a purpose as well. Probably the best thing you can do is to post the design you are thinking of for your soffits, so that we can take a look at it and suggest ways to improve it, if necessary. - Stuart -The thing that bugs me most with flush mounting is that on one hand such importance is placed on a hard, flush, uninterrupted baffle.. but then others recommend use of 3-6" of absorption which makes the front baffle neither flush nor hard.
Excerpt from Genelec's site: "The following should be considered when flush-mounting any monitor: •For the benefits listed above the wall construction should be solid and consisting of heavy mass material. However this can lead to reverberation time problems at low frequencies •If the wall is totally solid and reflective then some lower midrange boost may occur, so make the wall slightly absorptive around the 200 to 500 Hz region - use 10 to 20 cm thick rock wool or foam plastic glued onto the front wall surface •The flush mounting details around the enclosure should be as smooth as possible; otherwise the cabinet edge diffraction benefits will be wasted."Yup! That's a problem, for sure. I'm not sure where it comes from, but there seems to be some place that is recommending exactly that, which makes no sense at all.The thing that bugs me most with flush mounting is that on one hand such importance is placed on a hard, flush, uninterrupted baffle.. but then others recommend use of 3-6" of absorption which makes the front baffle neither flush nor hard.
I keep thinking about this, but is there really any point in attempting to enclose the rear panel of the mounting box if you're already making it a few inches longer for cabling plus cutting big ventilation ports in it? I'm having a hard time seeing how this would serve a purpose and am tempted to just leave mine open. I already have a tight fit around the sides and top.
For acoustics and cooling: No, no reason at all. But for structural integrity there's a good reason: that's the only piece that keeps the box square. That might or might not be an issue, depending on the overall design. - Stuart -is there really any point in attempting to enclose the rear panel of the mounting box
How can I sofit mount if I cant have the box all the way to the floor as described from John Sayers?