Multiple subs paper and powerpoint for the hard of google
http://www.gedlee.com/Papers/multiple subs.pdf
http://www.gedlee.com/Papers/OptimalBassPlaybackinSmallRooms.pptx
The powerpoint is more interesting as has measurements from which one can draw ones own conclusions.
Sadly no way I can get 3 subs into my hovel.
http://www.gedlee.com/Papers/multiple subs.pdf
http://www.gedlee.com/Papers/OptimalBassPlaybackinSmallRooms.pptx
The powerpoint is more interesting as has measurements from which one can draw ones own conclusions.
Sadly no way I can get 3 subs into my hovel.
just go listen. But mostly do the live- vs -playback test in your room to see just how accurate what you have is. and then what you can do to make it more accurate. No one can get into a LIKE contest.
The figure-of-8 dispersion pattern of panel type speakers have the advantage of limited radiation to the sides... where the walls are. This helps and is in the right direction. Also the box-less speaker has some advantages of non resonance box sound (esp if reflex type).
I would place absoption behind the panels to get a greater direct to reflected signal at the listening position. But, only if you are interested and accurately want to hear the source only without room effects.
THx-RNMarsh
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Uh no it is not. Take a look at the waveform of your AC power line. Typical today is 5% or more distortion. The peaks of the sine wave are lower than they should be. That is from all of the non power factor compensated rectifier into capacitor power supplies loading the distribution system. They only draw current at the peak voltage.
Scott,
If you have trouble understanding one of my posts just ask. Your comments seem to make no sense except perhaps to yourself. It is normal to entertain yourself in private.
Question?
So why isn't anyone here suggesting to build a stage for Sub placement upon?
If you go spend some time at clubs with live music, even small clubs...Stages built upon 2 x 6s with plywood topped seem to work well. If i recall, one built along a back wall about 8foot from corner to back door, and 8 foot from same corner down the adjacent wall. Hypotenuse connecting the two adjacent ends and you have the stage, elevated above the slab, and makes everything coming off the stage sound better, live, visceral etc.
It's just a simple right triangle, isosceles...each leg being the same length.
I bet we could even float the speakers on it or make two smaller stages one for each speaker and a third for the Sub. If done right, my even please the dragon, eh wife?
Worth a try.
Richard, my critic post was not aimed at you. I re-read it and felt it could be taken that I was attacking you persoanlly...I wasn't, just to clarify. It was meant to be read fromthe point of view of how some critics must be thinking... ...instead of doing.
@ anyone, Sub question, if you are making a sub... what is the issue of making it down fired? Facing up, too big with the added cone above it to make it 360 dispersion. So why not down firing...won't that be 360 dispersion also?
Cheers,
So why isn't anyone here suggesting to build a stage for Sub placement upon?
If you go spend some time at clubs with live music, even small clubs...Stages built upon 2 x 6s with plywood topped seem to work well. If i recall, one built along a back wall about 8foot from corner to back door, and 8 foot from same corner down the adjacent wall. Hypotenuse connecting the two adjacent ends and you have the stage, elevated above the slab, and makes everything coming off the stage sound better, live, visceral etc.
It's just a simple right triangle, isosceles...each leg being the same length.
I bet we could even float the speakers on it or make two smaller stages one for each speaker and a third for the Sub. If done right, my even please the dragon, eh wife?
Worth a try.
Richard, my critic post was not aimed at you. I re-read it and felt it could be taken that I was attacking you persoanlly...I wasn't, just to clarify. It was meant to be read fromthe point of view of how some critics must be thinking... ...instead of doing.
@ anyone, Sub question, if you are making a sub... what is the issue of making it down fired? Facing up, too big with the added cone above it to make it 360 dispersion. So why not down firing...won't that be 360 dispersion also?
Cheers,
Actually the PLC stuff does conform closely to the legal requirements. If you look at the spectrum there are notches where ham and other communications services are. That was a battle that the radio guys one. The tech in the PLC stuff is quite sophisticated. However the peak currents into the power line are up to 3A or more.
Cheap switching supplies etc. are the major source of EMI and RFI. They are usually built to just meet the spec. The cost issues for commercial products are brutal and these all just meet the necessary spec. Fine for one but 10 or 20 small USB chargers in your hose could be all it takes to generate a lot of hash.
Sync- its very difficult to make a directional sub. The wavelengths are so long that you really can't direct them in a domestic space. The driver can face in any direction. If it points toward a listener more of the harmonic distortion will be audible so you need better drivers and circuitry. Multiple smaller drivers can work as well or better than single large drivers. When the edge of the cone is 8 inches from the voice coil the cone needs to be really stiff and therefor heavy. 5 8" drivers give many benefits by comparison to one 18" driver for the same cone area.
However there are a few tricks that make a big difference.
First do not sum bass. All that does is cancel out any bass content that was recorded in stereo. Both mikes will have phase difference from a source and cancellation is inevitable. If you only have one sub, connect it to one channel.
Second map the room resonances. Most rooms have several strong resonances between 50 and 150 Hz. They are related to the dimensions of your room. You can use a parametric eq to notch those out. If the parametric is reasonably high q you will not be able to hear the notches but an octave or 2 of bass will come from nowhere that was masked by the hangover from the resonances.
Three, move the woofer closer to you. The low pass filter adds a delay to the woofer. To get things coherent you would need to move the woofer forward of the midrange. A 100 Hz 3 pole low pass filter may be around 3 mS or 3 feet of delay for example.
Four, setting woofer balance by ear can easily backfire since you have little to go on and your hearing is far from flat. I used to get complains about too much midrange and then determined that the bass was as much as 20 dB too high. Most people have little or no experiece of low bass. That 80Hz midbass thump is what they think low bass is. real low bass is sensed more than heard.
However there are a few tricks that make a big difference.
First do not sum bass. All that does is cancel out any bass content that was recorded in stereo. Both mikes will have phase difference from a source and cancellation is inevitable. If you only have one sub, connect it to one channel.
Second map the room resonances. Most rooms have several strong resonances between 50 and 150 Hz. They are related to the dimensions of your room. You can use a parametric eq to notch those out. If the parametric is reasonably high q you will not be able to hear the notches but an octave or 2 of bass will come from nowhere that was masked by the hangover from the resonances.
Three, move the woofer closer to you. The low pass filter adds a delay to the woofer. To get things coherent you would need to move the woofer forward of the midrange. A 100 Hz 3 pole low pass filter may be around 3 mS or 3 feet of delay for example.
Four, setting woofer balance by ear can easily backfire since you have little to go on and your hearing is far from flat. I used to get complains about too much midrange and then determined that the bass was as much as 20 dB too high. Most people have little or no experiece of low bass. That 80Hz midbass thump is what they think low bass is. real low bass is sensed more than heard.
I found this preconception to be erroneous. Omni speakers integrate into most rooms better than highly directive speakers, as counter-intuitive as that may be.
If you 'like' maximum room influence... maximum reflections off everything --- I don't think so. Another "Like". Tell it to all the Mastering and recording studios with LEDE, near-field monitors etal who want accuracy in thier monitoring/playback system as a basic fundamental requirement. Same needed for accurate playback listening.
THx-RNMarsh
THx-RNMarsh
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Tests showed that many devices on the market did not have the required notching (even though the chipsets supported it, it was turned off). Many that do, still fail the requirements of EMC legislation in the EU. Ofcom, the regulator here, when it was taken to task that the system provided by a major Telco did not meet EMC requirements said "we don't get many complaints"...
You are right about cheap switchers - many consumer devices on the market fail the requirements - USB chargers, PC and laptop PSUs, LED bulbs.....
It's just getting worse...
Almost all the good new pro subs are directional. Most use two drivers and DSP. The one standout is from Fulcrum which uses a tuned bass port. Woofer on the front face, port out the back. Proper tuning gives significantly improved directivity!
If it weren't patented I suspect the technique would get quickly adopted by some consumer lines.
Mains filter simulation results
The first C is 10uF, each following C is halved
All inductors are 1mH
The green line is no filter, each following line adds one network (right[smallest C] to left[largest C])
The 10uF C (or even the 5uF C) are still a bit large to my taste.
Attached is also the simulation source, have fun
The first C is 10uF, each following C is halved
All inductors are 1mH
The green line is no filter, each following line adds one network (right[smallest C] to left[largest C])
The 10uF C (or even the 5uF C) are still a bit large to my taste.
Attached is also the simulation source, have fun
Attachments
I suspect that US hams have similar troubles to us, except that perhaps housing densities may be smaller over there so the interference is thinned out a little.RNMarsh said:
Not in Europe. There is a general legal requirement not to cause harmful interference, and adherence to standards is a way of showing that you have taken this seriously but it does not guarantee that you cause no interference. An installation made from standards-compliant equipment can still violate the general requirement but unfortunately this is not enforced because governments have taken the view that encouraging internet communications is more important than avoiding RF pollution.1audio said:
The band notches are not always implemented, especially in grey imports.
In many cases it is worse than that. They are designed to just meet the spec (and the spec itself is quite weak). Then they are built with EMC suppression components omitted to save a few pennies. You can open many PSUs and find wire links where the inductors should be and fresh air where the capacitors should be. And don't get me started on filterless Class D, and spread spectrum RFI . . .
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