Danny Richie discusses baffle step loss a lot on the AudioCircle GR Research Forum.
wide baffles and baffle step
Lengthy quotation from Peter Comeau, designer at Wharfedale. Makes a lot of sense to me...
"Th[e] larger ported box, with its subsequent increased baffle size, helps solve a major problem in modern speakers, namely, the baffle step.
I grew up with large speakers with wide baffles, but, as speakers reduced in size over the years I noticed that something was missing from the sound and, when I stuck my head firmly into speaker design, I began to understand the acoustic problems caused by the baffle step.
Put simply, as the baffle size decreases, the point at which the acoustic radiation changes from hemispherical to spherical goes up in frequency. It also becomes sharper and narrower in bandwidth as the sides of the cabinet, and the walls and floor of the room, are further removed from the equation. So, this 6dB step in the power response becomes acoustically more obvious.
I believe that a thin speaker always sounds thinner throughout the midrange when directly compared to a speaker with more generous baffle width. Of course, as designers of modern, slim speakers, we compromise by adjusting for the baffle step in the crossover, but in doing so, we also compromise sensitivity. What starts out as a 90dB at 1W drive-unit often ends up as an 85dB system once we have adjusted for the power loss due to the baffle step."
38 responses Add your response
I’m a big fan of wide baffles. One of the best the Sonus Faber Stradivari, yes to the Snell A series, and of course, Genesis/Infinity line arrays. However!!!! I think the explanation here is BS, as speaker designers are all aware of the baffle step issue and take it into account in the crossover design. What the final speaker does suffer from as a result of baffle step is reduced efficiency. Speaker designers trade off efficiency for bass response. In that respect, yes, a wider baffle will yield a more efficient speaker (assuming equal frequency tuning). The real magic of wide-baffle speakers in my opinion is not in the efficiency but in their ability to convey the recorded room acoustics into the listening space. Paraphrasing Troels Graveson , wide baffle speakers bring the room with them. |
Forgot to point out, that the wider the baffle, the more energy is put into the room before edge diffraction occurs. It is one of several techniques which attempt to deal with this issue. The Snell A series attempted to use a very wide AND curved baffle. Using a chamfer or rounded edge, foam, felt, etc. also work to reducing this effect. But for my money, wide baffles do it best. |
Peter Snell US Patent 3964571 can also be used as a supplement for room boundary design. His use of angles other than 90's will reduce shear wave interference and its recreation into the compressive world. Peter did a speaker demo at a home of mine back in the early 80's. He was a quiet man and a speaker hero. Tom |
wide baffles reflect more midrange back into the room because the larger wavelengths cannot disperse around to the back of the enclosure. this creates an uneven response at midrange frequencies that must be filtered with a BSC circuit in the crossover to yield a neutral frequency response. all things being equal it is better to have a narrower baffle and reduced BSC filterig. |
To solve the baffle step is not necessary to make wide baffle. Actually you have to use 3 way ( not 2 way or single drive , full range) and the choose correct wise cross point , Baffle step issues make suckout 200-500 Hz , you can see plenty in Stereophile measurements and sound coming thinner, adding sub woofer is not helping .Sorry for my English. All my speakers dont have this problem |
the excellent wide baffle designs succeed in spite of the wider baffle not because of it. wider baffles create the need for additional crossover components and complicate the voicing recipe. wider baffles do allow for larger woofers and enclosure volumes which enables excellent low distortion bass. imaging and high frequency dispersion is handicapped as well by wider baffles. they require more care and precision in placement and have a more difficult time disappearing than narrow profile speakers. in other words more expense in design, engineering and user effort are needed for a successful wide baffle system. |
@avanti1960 wrote: " wider baffles create the need for additional crossover components and complicate the voicing recipe. " That has not been my experience. With a sufficiently wide baffle, no dedicated baffle-step compensation circuitry is needed. If some baffle step compensation is still called for, it can be accomplished by choice of low-pass filter component values, with no increase in parts count. To my ears, a baffle-step compensated narrow cabinet does not have the lower-end impact and articulation nor the dynamics of a wide baffle which does not need baffle step compensation. So imo each approach has its place. "imaging and high frequency dispersion is handicapped as well by wider baffles." Yes and no. If edge diffraction is minimized, baffle width isn’t an issue as far as imaging goes. But if there is significant edge diffraction, then yes imaging is better with a narrow baffle. What happens is, the diffraction at the edge of the enclosure sends a false angular cue to the ear, and the farther away the edge is, the longer the time delay and therefore the greater the false angle. This holds true up to the point where the baffle edge is about nine inches away (corresponding to a 19-inch baffle width, assuming a 1" dome tweeter); at that point the time delay is great enough for the "precedence effect" to kick in and at suppress the false localization cues. (This is one of the reason why high-end recording studios often flush-mount their main monitors: Doing so pushes the arrival time for the first reflection past the point of generating significant false localization cues, so that the imaging cues on the recording can dominate.) As for high frequency dispersion, a teeny tiny baffle around the tweeter does result in wider dispersion at the bottom end of the tweeter’s range (think "eyeball" tweeter atop the cabinet). Whether or not this is desirable is debatable from a tonal balance standpoint, but I can see it being desirable from an imaging standpoint. Duke |
Thank you, Duke, @audiokinesis , for bringing your specialized and hands-on knowledge to this issue. What you refer to lower-end impact and articulation is something that I remember as experiencing first-hand when I auditioned the Spendor Classic 100 directly against the Spendor D7. From the 100 there seemed to be just more music coming at me, something that at the time I thought of as "wave launch". |
Thank you very much, arion and twoleftears. Imo "wave launch" is a good description of what a wide baffle does well. I don't know whether it is technically precise or not, but the image it conjures up in my mind is of a sound wave getting a better "push" off of a wide cabinet than off a narrow one. A horn can be thought of as a special case of a wide baffle, with the baffle wrapped forward to get a still more efficient "wave launch" within its angle. Or on the other hand a flat baffle can be thought of as a 180-degree horn, effective down to the frequency where the "horn" is too short relative to the wavelengths... and that's where the "baffle step" kicks in. Duke |
Duke - I disagree, unless you meant to say out of phase wave launch bounce... the big baffle has two “ advantages” the power response and the averaging engine that constructive and destructive interference off a large baffle creates. In a time and phase correct design, both of those are of course not positives. Snell of course had more complex shapes but in the end it’s a two dimensional horn.... |
Tomic601, my understanding is that sound waves are longitudinal pressure
fluctuations, not transverse waves (even though we tend to draw them that way), and therefore there is no phase change when they reflect or diffract. There is of course a time-delay built into the path length to the reflecting or diffracting discontinuity, and that time delay works against preservation of time and phase coherence. Imo the solution is to minimize edge diffraction effects either by having minimal baffle dimensions or large-radius roundovers or sufficient directivity to avoid significant cabinet edge interaction in the first place. Since I like the other benefits which come with having a wide baffle, I try to figure out ways to minimize the downsides. But it's a juggling of tradeoffs, and arguments can be made for either side. Duke |
This is what I think is sad. https://www.bluebirdmusic.com/edit/files/images/gallery/spendor_str_nov_18.jpg |
@audiokinesis With respect to baffle step compensation, unless the baffle is wide enough to impinge on the limits of room space and physical practicality there will be an audible 3db loss of all frequencies below the baffle step frequency. For example the baffle would need to be 33.76 in. wide for a frequency of 400 hz. With that width, frequencies below 400 hz will drop off by 3db relative to frequencies above 400 hz. Lower baffle step frequencies will require a wider baffle (increasingly less practical), the baffle can decrease in width for higher baffle step frequencies (increasingly practical). Example, 9 in. width for a 1500 hz. baffle step frequency, easily managed physically and electronically). With the loss in output of all frequencies below the baffle step frequency, some form of compensation will be required. A BSC circuit is a popular and effective method for doing so. |
@avanti1960 wrote: "With respect to baffle step compensation, unless the baffle is wide enough to impinge on the limits of room space and physical practicality there will be a 3db loss of all frequencies below the baffle step frequency. For example the baffle would need to be 33.76 in. wide for a frequency of 400 hz. With that width, frequencies below 400 hz will drop off by 3db relative to frequencies above 400 hz... "With the loss in output of all frequencies below the baffle step frequency, some form of compensation will be required. A BSC circuit is a popular and effective method for doing so." The baffle step happens gradually, so in practice we really don’t need 33.76" width in order to be good down to 400 Hz. AND that baffle-stepping side-spilling wrap-around energy isn’t "lost" - it just becomes off-axis energy. It arrives after some time delay and some attenuation due to path length and some absorption at the surfaces it reflects off of. In the meantime, the woofer’s radiation pattern is also trending towards omnidirectional at longer wavelengths. So as we go down in frequency, we are getting proportionally more reflected energy from two phenomena: Baffle-stepping and pattern-widening. Thus obviously as we go down in frequency, the room acoustic situation plays a progressively greater role in what we hear, especially with narrow speakers. In situations where the direct sound dominates, I can definitely see an argument for baffle step compensation. As the relative contribution of the reverberant energy at the listening position increases, imo baffle step compensation becomes less necessary and/or less desirable. I can easily see baffle step compensation being the right choice for a 9" wide speaker which is not designed to go up against the wall. I also think it’s a tradeoff, degrading the spectral balance of the reverberant sound for the sake of the first-arrival sound. And using a wide baffle is also a tradeoff. It’s a matter of picking one’s poison... or perhaps more precisely, picking the poison which is most palatable (and most practical) to the most potential buyers. And I’ll readily admit that’s NOT a 33.76" wide baffle! Duke |
Hello Everyone.I would like to humbly ask: What if I build a wide baffle and use thick absorbing material around mid and high frequency drivers to avoid diffraction or too much attention or that "speakers do not disappear as with narrow baffles" factor? Wouldn't that help get to a middle ground and both have and eat some of the cake? |