I am about to make some sattelites using a pair of Tang Band 871's in each speaker, and I though about crossing over one of them so it only covers the lower frequencies, but I can't help but think about the center channel I made using 2 other TB drivers (the neodymium 3" ones) and how excellent it sounded having the drivers only running in series with no crossover. I mean, are the effect really obvious enough to warrant using a crossover at all? Because I sure havn't heard them.
Plus all the speakers, including the center channel, will have the drivers arranged vertically, so horizontal dispersion will not be a problem either. Is it really worth the trouble? Or is it another "I think I might hear a slight difference" thing?
Plus all the speakers, including the center channel, will have the drivers arranged vertically, so horizontal dispersion will not be a problem either. Is it really worth the trouble? Or is it another "I think I might hear a slight difference" thing?
But how audible are the effects? Or is it one of those things that you can only hear with an RTA? Isn't that the only difference, a slight change in frequency response?
baffle step shows up quite clearly on an rta, but you will hear it as well, it tends to make the midrange sound "thin".
This is one of the reasons that dipole speakers sound so good, the large baffle lowers the baffle step to a point that the room boost (depending on speaker position) starts to compensate for the loss in output below the baffle step frequency.
This is one of the reasons that dipole speakers sound so good, the large baffle lowers the baffle step to a point that the room boost (depending on speaker position) starts to compensate for the loss in output below the baffle step frequency.
It depends on the baffle size. The larger the baffle the audible the effect is. In my opinion wo compensation the speaker starts to shout. In theory it causes a 3-6dB/octav rise in the repsonse, but the compensation room and position dependent.
Some software like Loudspeaker Lab can calculate the necessary coil and resistor from the woofer and box properties. Try and see ...I mean hear !🙂
Zozo
Some software like Loudspeaker Lab can calculate the necessary coil and resistor from the woofer and box properties. Try and see ...I mean hear !🙂
Zozo
Very audible!
Even the most hard-core so-called objectivists will tell you that swings of 3-6 dB in midrange frequency response are clearly audible. These absolutely swamp any of the more subtle (or sometimes nonexistent) effects that audiophiles agonze over.
The simple 6dB response step nearly never occurs- it's generally more complex than that, and a function of baffle geometry and driver position, as well as size. But once you measure (or do a good model) to see what the baffle effect is for your particular geometry, it's pretty easy to compensate for.
Even the most hard-core so-called objectivists will tell you that swings of 3-6 dB in midrange frequency response are clearly audible. These absolutely swamp any of the more subtle (or sometimes nonexistent) effects that audiophiles agonze over.
The simple 6dB response step nearly never occurs- it's generally more complex than that, and a function of baffle geometry and driver position, as well as size. But once you measure (or do a good model) to see what the baffle effect is for your particular geometry, it's pretty easy to compensate for.
I used BDSC networks in my Tangband speakers and it does make a huge difference. I also noticed a difference wiring the resistor and inductor parallel rather than series. When it came to the surrounds however, I decided to skip it. I think with the configuration of drivers, the type of drivers and the bottom firing port I managed to minimize the effect.
The center driver is a W3-879 which doesn't have the top end the two W3-871s do.
The center driver is a W3-879 which doesn't have the top end the two W3-871s do.
Attachments
Re: Very audible!
It is also a function of driver placement with respect to room boundaries, i.e., the "Allison effect", and/or relative postion to other drivers operating in the same range. As the baffle step is simply a change in radiation impedance due to the loss of the baffle boundary (with corresponding loss of speaker power output), which is wavelength dependent, other room boundaries next to the speaker may come in to play at appropriate wavelengths to cancel out the baffle loss. Similarly, two woofers, for example, can reinforce one another to increase power output more than the two standing alone. Again, this is wavelength dependent, and dependent upon distance between the drivers. If all of these effects are taken into account, they can be played off with one another for smooth power output into the room. Roy Allison's patent is good reading on this situation.
SY said:
It is also a function of driver placement with respect to room boundaries, i.e., the "Allison effect", and/or relative postion to other drivers operating in the same range. As the baffle step is simply a change in radiation impedance due to the loss of the baffle boundary (with corresponding loss of speaker power output), which is wavelength dependent, other room boundaries next to the speaker may come in to play at appropriate wavelengths to cancel out the baffle loss. Similarly, two woofers, for example, can reinforce one another to increase power output more than the two standing alone. Again, this is wavelength dependent, and dependent upon distance between the drivers. If all of these effects are taken into account, they can be played off with one another for smooth power output into the room. Roy Allison's patent is good reading on this situation.
pooge, that's exactly right. And that's exactly why so many smart designers put the woofer near the floor- the superb NHT 3.3, for example. Allison has written quite a few clear and pertinent papers on the subject.
Allison and floor boundary
Allison wanted to avoid the response through caused by first cancellation due to path length from a high positioned woofer (normally on a stand mount cabinet) and floor. There is destructive interference between axis propagation and reflected off the floor midbass wavelengths. With common setups is occurs between 150-200 Hz. You get the thin midbass associated with good floorstanding speakers.
The baffle step is broader, roughly from 200Hz to 1kHz.
Allison wanted to avoid the response through caused by first cancellation due to path length from a high positioned woofer (normally on a stand mount cabinet) and floor. There is destructive interference between axis propagation and reflected off the floor midbass wavelengths. With common setups is occurs between 150-200 Hz. You get the thin midbass associated with good floorstanding speakers.
The baffle step is broader, roughly from 200Hz to 1kHz.
Yup deffo worth the effort. Its a strange thing is BS and is very room dependant including where you sit. If you sit near a back wall then BSC may sound as it isnt neccessary as you get bass lift near the walls. However as ppl have stated BS occurs high up too at like 1k, which your walls dont boost. Anyway to cut a long story short, adding it fills out the sound, making it sound more relaxed and natural rather then "shouting" as ppl have stated bfore. Adding it also adds detail to the sound, as vital information is present from say 150-500hz this being all rolled off masks detail, or so ive found.
It also opens up the soundstage, well in my case it did, which I stumbled upon by accident. I was playing a pair of speakers, crap box no top or bottom, with drivers I had bought from ebay thru a digi xover to see how they sounded. They had a very nice wide expansive free flowing soundstage that was wonderful. I had no bass but what the hell I had brill SS that you just drink in as fast as the speakers can pour it. Anyway, these speakers had large front baffle and 8" drivers. Now my W15's in a narrow box didnt (just 5mills wider then the driver) have this wide expansive SS. So as I was doing these digital too (kxdrivers) I added a BSC sort of thingy, and bang wide expansive SS.
Bassically as BS is a function of the baffle dimesions, the wider the baffle the later on the effect occurs (ie lower) so with the crap box with nice SS it was occuring lower or lower enough not to screw up the SS, but high enough to mess it up in the W15's. Experimentation is the key, but thats hard unless you have a variable active xover, or a digital equivalent.
It also opens up the soundstage, well in my case it did, which I stumbled upon by accident. I was playing a pair of speakers, crap box no top or bottom, with drivers I had bought from ebay thru a digi xover to see how they sounded. They had a very nice wide expansive free flowing soundstage that was wonderful. I had no bass but what the hell I had brill SS that you just drink in as fast as the speakers can pour it. Anyway, these speakers had large front baffle and 8" drivers. Now my W15's in a narrow box didnt (just 5mills wider then the driver) have this wide expansive SS. So as I was doing these digital too (kxdrivers) I added a BSC sort of thingy, and bang wide expansive SS.
Bassically as BS is a function of the baffle dimesions, the wider the baffle the later on the effect occurs (ie lower) so with the crap box with nice SS it was occuring lower or lower enough not to screw up the SS, but high enough to mess it up in the W15's. Experimentation is the key, but thats hard unless you have a variable active xover, or a digital equivalent.
Would it make sense to place satelites in pyramid shaped enclosures positioned in the ceiling corners of the room?
Yes, exactly what I was thinking. I've got lots of these I've been playing with, and I'm still looking for more ideas for enclosures.
Seems like a neat rear satelite, in the right room.
I'm not inspired to build the "Needles" yet. Any new ideas for me?
Seems like a neat rear satelite, in the right room.
I'm not inspired to build the "Needles" yet. Any new ideas for me?
Yup cheers for that Dave I've always wanted one of those ^.^
I wondered if there was a formula to calculate F3 and there it is
>.<
Matt
I wondered if there was a formula to calculate F3 and there it is
>.<
Matt
The baffle loss is not merely an on-axis frequency response dip. It is a 3 db POWER loss that results in a 6db frequency response dip on axis. Thus, electrically equalizing the on-axis frequency response will not give the same POWER output as mounting the speaker in an infinite-baffle or 2pi acoustic load. Me thinks that adjusting acoustic load impedance to maintain a smooth power output, as well as a smooth frequency reponse, is a better approach. This can be approached by designing a baffle of appropriate width, appropriate positioning of a driver on a baffle (e.g., near the floor, etc.), use of plural drivers in band, positioning of the loudspeaker with respect to room boundaries, or more likely a combination of these approaches. (The technique of loudspeaker positioning in a room is more a "power output" tuning issue than the oft-cited wall-reflection issue.) If you electrically equalize the on-axis frequency response, the power response will rise ABOVE flat. This is the likely reason why many subjectively recommend equalizing back only 3 db on-axis rather than the full 6db. The full 6db sounds too heavy. Also, electrical equalization is difficult, because at lower frequencies, "room gain" comes into play, which itself may raise the frequency and power responses well above flat, even disregarding baffle loss. This is because, at low frequencies, the room boundaries ultimately more than offset the loudspeaker's acoustic load impedance in the opposite direction than baffle loss does. Thus, "equalization" must be limited to a band, and/or change through different bands.
On another note, Allison did not regard "floor bounce" as a mere cancellation effect. He regarded it as an acoustic load issue, with a resulting actual change of loudspeaker power output. His "effect" extended beyond mere "floor bounce" issues. I did extensive studying on this issue years ago for an article, but I dropped the project when I found out how little a certain DIY magazine offered to publish it. It wasn't worth the time involved in writing it.
On another note, Allison did not regard "floor bounce" as a mere cancellation effect. He regarded it as an acoustic load issue, with a resulting actual change of loudspeaker power output. His "effect" extended beyond mere "floor bounce" issues. I did extensive studying on this issue years ago for an article, but I dropped the project when I found out how little a certain DIY magazine offered to publish it. It wasn't worth the time involved in writing it.
Ok, so as we speak I am building wall-mountable enclosures for my front three (including center channel ,I know it's not recommended, but let's just say my wife recommends it ) , so which of all the above mentiones ideas and techniques should I focus on? Should I use the Loudspeaker Lab program to figure a passive correction, or are there other things I can do with the exterior design that might help enough to make that unnecessary?
The Paulinator said:
http://www.diyaudio.com/wiki/index.php?page=Baffle-step+Physics
Given that they are wall-mounted you have already taken care of the baffle-step. See 1 above.
dave
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