pjpoes said:
There was some discussion somewhere on LF damping in rooms and how to do it. Don't remember where though.
TRADERXFAN said:
Not steam. After stretching the fabric, and it doesn't have to be that tight, I just mist it down with a plant mister. It dries tight as a drum - no wrinkles.
Are you referring to the stuffed partition discussion?
That was discussed in the waveguide thread, as an indirect result of my errant post, I believe.
That was discussed in the waveguide thread, as an indirect result of my errant post, I believe.
"Having gone the high gain route, I fully agree. I don't fully understand the infatuation with it. If that's what people want, they should be buying higher powered projectors, not HT projectors for light controlled rooms. Gain increases everything, including blacks, which I don't think is a good thing. The only advantage I hear is the rejection of stray light, but it comes at the expense of black levels and viewing angle."
A bright projector with high contrast ratio (i.e., one intended for HT) costs $K more than a high gain screen.
If you want a big screen w/adequate brightness a high gain screen is the most practical way.
A bright projector with high contrast ratio (i.e., one intended for HT) costs $K more than a high gain screen.
If you want a big screen w/adequate brightness a high gain screen is the most practical way.
noah katz said:
This seems reversed to me. The projectors have gotten cheap and brightness is far more than necessary (I turn mine down), so screen gain seems unnecessary.
I guess it's a matter of taste.
I have a 133" Hipower and a JVC RS1, which is brighter than most, and it was only bright enough for the first couple of hundred hours.
I should note that I can't place the projector optimally; I think I'm getting about 1.8 gain.
I have a 133" Hipower and a JVC RS1, which is brighter than most, and it was only bright enough for the first couple of hundred hours.
I should note that I can't place the projector optimally; I think I'm getting about 1.8 gain.
My new projector just arrived yesterday, a Sony VPL-VW40. The contrast ratio is much higher than what I had, mixed with it's brighter image, I still find now that a low gain screen will be better.
I might be nut's (it's been said before), but I find with my screen that very bright parts seem to have an almost metallic shimmer to them on my screen. I went and got my samples of higher powered screen materials, including High power, and I noticed it with them too. Then I grabbed my sample of the Stewart Greyhawk material, I didn't see the shimmer. I need a full screen to really know what I'm seeing, but I think the retroreflective material and the metallic's used to enhance reflectivity of these screen's causes the shimmer.
133" screen is a lot bigger than what I currently have, so maybe I would feel the same way. I also watch movies most seriously mostly at night, so maybe it's a light in the room issue? Might even just be a difference in taste, but I do find that the image, even turned down a lot, can be almost too bright with such a high gain screen. With my screen and this new projector in normal mode (not even dynamic mode) and low lamp mode, I'm getting peak whites at over 30 foot lamberts. I can watch pretty clearly now with lights on in the room at that level, and the sony is no torch. In cinema mode with the iris on auto I can't get it down to thx recommended levels of 12-16 foot lamberts.
Going with an ultra bright home theater projector does mean that you probably have to spend more money. However, there are projectors designed around other markets which can give the brighter image, even at that resolution, but with lower contrast ratios and often in something like 15:9 or even 4:3 formats. I'm thinking of models like the LCOS from Canon or some of the pro models from the likes of Panasonic, Optoma, and Infocus.
I might be nut's (it's been said before), but I find with my screen that very bright parts seem to have an almost metallic shimmer to them on my screen. I went and got my samples of higher powered screen materials, including High power, and I noticed it with them too. Then I grabbed my sample of the Stewart Greyhawk material, I didn't see the shimmer. I need a full screen to really know what I'm seeing, but I think the retroreflective material and the metallic's used to enhance reflectivity of these screen's causes the shimmer.
133" screen is a lot bigger than what I currently have, so maybe I would feel the same way. I also watch movies most seriously mostly at night, so maybe it's a light in the room issue? Might even just be a difference in taste, but I do find that the image, even turned down a lot, can be almost too bright with such a high gain screen. With my screen and this new projector in normal mode (not even dynamic mode) and low lamp mode, I'm getting peak whites at over 30 foot lamberts. I can watch pretty clearly now with lights on in the room at that level, and the sony is no torch. In cinema mode with the iris on auto I can't get it down to thx recommended levels of 12-16 foot lamberts.
Going with an ultra bright home theater projector does mean that you probably have to spend more money. However, there are projectors designed around other markets which can give the brighter image, even at that resolution, but with lower contrast ratios and often in something like 15:9 or even 4:3 formats. I'm thinking of models like the LCOS from Canon or some of the pro models from the likes of Panasonic, Optoma, and Infocus.
Then you are in a big group, because I ( and others I know & work with ) noticed that "metallic shimmer" when video material we were developing and presenting ( ie we had seen this material literally hundreds of times ) in different venues/projectors/screens.
meaning I'm not that nuts? So what did your group attribute it too? For a while I thought it was mosquito noise, but I'm not so sure anymore, since it seems like lower gain screen's seem to reduce the effect some.
I could not say for sure:
In my case we edited an approx 50 min avi (90G), To present it gets trans-coded to fit on a DVD. So we dealt with a lot of compromise decisions in the downgrade and the fact that video was edited for TV concerns.
Because of the circumstances: Arrive and do a presentation; Usually there is no time to investigate.
I have particularly noticed in 2 tone ( B/W ) images that the image had a silvery ting like the sheen on an old fashion print plate.
I have not been able to compare to see if it varies w different source material, different screens, different projectors or combinations of the above.
Interlacing is a problem but I don't know it's role in it.
http://neuron2.net/LVG/interlacing.html
In my case we edited an approx 50 min avi (90G), To present it gets trans-coded to fit on a DVD. So we dealt with a lot of compromise decisions in the downgrade and the fact that video was edited for TV concerns.
Because of the circumstances: Arrive and do a presentation; Usually there is no time to investigate.
I have particularly noticed in 2 tone ( B/W ) images that the image had a silvery ting like the sheen on an old fashion print plate.
I have not been able to compare to see if it varies w different source material, different screens, different projectors or combinations of the above.
Interlacing is a problem but I don't know it's role in it.
http://neuron2.net/LVG/interlacing.html
pjpoes said:
Matt - I'm with you. I have the exact same experience. To me it's the people who want glaring brightness that are nuts. I find this fatiguing on the eyes after a hour or so.
Are there any studies to what "brings on" eye fatigue?
The popular editing techniques used today:
Jump editing and "blow to white" ( vs fade to black or cross-fade ) for me are very tiring.
The popular editing techniques used today:
Jump editing and "blow to white" ( vs fade to black or cross-fade ) for me are very tiring.
If you need to clean a bed sheet screen you could probably reclaim the original finish by ironing it using spray on sizing. (In the supermarket next to the spray on starch). They probably used the same or similar stuff when they finished the fabric.
If it gets on the floor, it's very slippery.
If it gets on the floor, it's very slippery.
Well this has hit a tangent.
Ok back to the speakers. I continue to be amazed with the performance of these speakers. I think at this point the next thing I need to do is devote some time to setup. I won't spend any time working on that until I get the equipment and sub moved away from the front of the room. I made up some 12 foot cables so that I can keep the amps up front near the speakers, and move the rest of the equipment to the side wall.
After that I think it's time to further work on the bass. I need more bass sources. I did finish a bandpass sub using some small Mpyre 7" woofers I had, but they aren't right for what I want to do. I'm thinking I really need an efficient broad band bandpass sub. Something using a 12" or 15" pro driver. If it can be designed to fit into a corner that might be nice. The other option could be a tall but narrow enclosure, but with a driver that big, certain minimum size limitations will exist.
I will keep working on a bed sheet screen and report my results when that's finished. Given that it's not audio, I will keep video comments and pics to a minimum, but I would like to confirm that the sheet has minimal effect on audio while offering an acceptable picture. I also have a sample of the solar shade screen material coming, and plan on testing that as well as I can.
Ok back to the speakers. I continue to be amazed with the performance of these speakers. I think at this point the next thing I need to do is devote some time to setup. I won't spend any time working on that until I get the equipment and sub moved away from the front of the room. I made up some 12 foot cables so that I can keep the amps up front near the speakers, and move the rest of the equipment to the side wall.
After that I think it's time to further work on the bass. I need more bass sources. I did finish a bandpass sub using some small Mpyre 7" woofers I had, but they aren't right for what I want to do. I'm thinking I really need an efficient broad band bandpass sub. Something using a 12" or 15" pro driver. If it can be designed to fit into a corner that might be nice. The other option could be a tall but narrow enclosure, but with a driver that big, certain minimum size limitations will exist.
I will keep working on a bed sheet screen and report my results when that's finished. Given that it's not audio, I will keep video comments and pics to a minimum, but I would like to confirm that the sheet has minimal effect on audio while offering an acceptable picture. I also have a sample of the solar shade screen material coming, and plan on testing that as well as I can.
"Something using a 12" or 15" pro driver...the other option could be a tall but narrow enclosure, but with a driver that big, certain minimum size limitations will exist."
I forget if it was here or at AVSForum, but I think there may have been a thread about a DIY version of Tom Danley's tapped horn sub, which might fit the above description.
I forget if it was here or at AVSForum, but I think there may have been a thread about a DIY version of Tom Danley's tapped horn sub, which might fit the above description.
I'll probably end up going with one of Dr. Geddes Bandpass designs. My hope is that he can make form factor flexible for me.
Woofer Gasket
Matt,
Based on this picture it looks like you did not transfer the woofer gasket to to back - or did you use something else?
Matt,
Based on this picture it looks like you did not transfer the woofer gasket to to back - or did you use something else?
The kits have a woofer gasket molded into the enclosure. You don;t need to move the gasket and can't even if you wanted to because it holds down the cone.
Hey Dr. Geddes, I think I recall you mentioning something about the Klippel method being a bit better than most for measuring a speakers limits, no? I only recently realized (i've used it plenty before, just didn't realize what it was) that my measurement suite has the Klippel method built in for measuring a speakers maximum clean output. It's the same method that Klippel talks about in his papers, one is the Rub and Buzz paper and the other is the large signal perameters paper (as I understand it, the software is German and not well translated). The software uses a "quality Index" as the output, instead of a percentage. I'm wondering if you are familiar enough with Klippel's work to explain a little how his metric compares with yours (if they are even at all related), and what it tells you about a speakers "large signal" performance. Also, is the Q index something unique to Kirchner's implementation, or is it consistent with Klippel's method, what doe the Q numbers represent? Would you consider it an "acceptable" way to look at a speakers large signal performance?
I have measured a series of drivers, dome tweeters, midbass, woofers, even whole systems, but don't fully understand how to read the results. The actual graphs seem straight forward, like any typical distortion graph, showing each order below the fundamental. However the Q I don't understand, I guess it's just a single publishable metric to represent a speakers large signal performance?
Could this type of measurement be used for something other than the drivers. For instance, to look at the performance of low frequencies in a room at "large signal" levels. It appears, from reading Kirchner's papers, that if you progressively raise the output, you will hit a point where the Q-index falls, indicating the limit of the system. I'm wondering, since you can chance the frequency of the paired tones used, if it could also be used to maximize setup of the speakers in the LF department.
I have measured a series of drivers, dome tweeters, midbass, woofers, even whole systems, but don't fully understand how to read the results. The actual graphs seem straight forward, like any typical distortion graph, showing each order below the fundamental. However the Q I don't understand, I guess it's just a single publishable metric to represent a speakers large signal performance?
Could this type of measurement be used for something other than the drivers. For instance, to look at the performance of low frequencies in a room at "large signal" levels. It appears, from reading Kirchner's papers, that if you progressively raise the output, you will hit a point where the Q-index falls, indicating the limit of the system. I'm wondering, since you can chance the frequency of the paired tones used, if it could also be used to maximize setup of the speakers in the LF department.
Matt
Honestly, I haven't kept up with any of that work. So I'm not really in any position to comment on any of its validity. Maybe you could describe the basics.
Honestly, I haven't kept up with any of that work. So I'm not really in any position to comment on any of its validity. Maybe you could describe the basics.