I am currently using a pair of rear ported BR cabinets with Fostex F200A drivers and Hi-Vi RT2-Pro ribbon tweeters for either stereo or home theater use. These speakers are 13" wide, 17" deep and 40" tall. I either use a 300B amp for stereo, or an Onkyo receiver for HT, by swapping speaker cables. I am hoping to do a center channel with the same driver and tweeter. The space below the big screen TV is 22" wide, 22" deep and 16" tall. I only need the center channel to go to 60 - 70 Hz.
I have seen a Fostex recommended BR for the F200A that is 45 l., 11.8" wide, 11" deep, and 21.6" tall, ID. There is no info on low frequency limits. As the design would need to be fudged to fit the space, any suggestions on alternate designs? I would need something like 16" of height to just fit in the drivers. The back of the space is open, so a rear port could be used.
Also, does anyone out there have experience using either of these drivers as a center channel? I did a search, and could find no specific info on this combo. Any suggestions or ideas would be appreciated.
I have seen a Fostex recommended BR for the F200A that is 45 l., 11.8" wide, 11" deep, and 21.6" tall, ID. There is no info on low frequency limits. As the design would need to be fudged to fit the space, any suggestions on alternate designs? I would need something like 16" of height to just fit in the drivers. The back of the space is open, so a rear port could be used.
Also, does anyone out there have experience using either of these drivers as a center channel? I did a search, and could find no specific info on this combo. Any suggestions or ideas would be appreciated.
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Rick - the F200A is not a budget driver, nor a tiny one, and there are likely few folks with the wherewithal to play with them for this type of application.
That said, as the center channel is both the most important of the 5 or 7 mains in a surround system (responsible for up to 60% of the total soundtrack), and its bandwidth can easily be restricted through surround processor's bass management into the low 100-150HZ range, there's likely no reason that a small(ish) sealed enclosure couldn't be devised as Norman suggests.
However, while sharing the same tonality of the L&R mains, that approach might not maintain the same dynamic signature. How wide is the TV? - Would the existing enclosures laid on its side fit under? Or you could reduce cabinet dimensions and retune venting for higher cut-off - just don't ask me how
That said, as the center channel is both the most important of the 5 or 7 mains in a surround system (responsible for up to 60% of the total soundtrack), and its bandwidth can easily be restricted through surround processor's bass management into the low 100-150HZ range, there's likely no reason that a small(ish) sealed enclosure couldn't be devised as Norman suggests.
However, while sharing the same tonality of the L&R mains, that approach might not maintain the same dynamic signature. How wide is the TV? - Would the existing enclosures laid on its side fit under? Or you could reduce cabinet dimensions and retune venting for higher cut-off - just don't ask me how
I already have the drivers and ribbon tweeters, I got a great deal on them used. The L&R speakers are big, with a volume of about 140 l. The TV is a 70" Sony, rear projection and sits on a custom made stand that includes spaces for various electronics. The space in the center is 22" deep, 22" wide and 16" tall. In theory you could put a 120 l. cabinet if you filled the space. If I built a cabinet the same width and depth as the L&R's, and the full 16" available in that space, I could get about 65 l. of volume. Because the drivers would be taking up most of the front, it would have to be rear ported. Of course, the AV receiver can cut the signal off from 60 Hz or higher, to match the cabinet frequency.
That assumes the ribbon tweeter is set above (or below) the F200A. If I were to but them side by side, I could have them higher up from the floor. I have tried using two way monitor speakers horizontally as center channels and it worked fine. I also tried a pair of monitors head to head horizontally, and that was even better. However, in this case, I don't have the horizontal room to do so.
Since I have a pair of drivers and tweeters, I suppose the best would be a single ribbon in the center and one F200A on either side. Since these are 8 ohm drivers, the receiver should be able to run them both. Wow, now this is really getting crazy.
That assumes the ribbon tweeter is set above (or below) the F200A. If I were to but them side by side, I could have them higher up from the floor. I have tried using two way monitor speakers horizontally as center channels and it worked fine. I also tried a pair of monitors head to head horizontally, and that was even better. However, in this case, I don't have the horizontal room to do so.
Since I have a pair of drivers and tweeters, I suppose the best would be a single ribbon in the center and one F200A on either side. Since these are 8 ohm drivers, the receiver should be able to run them both. Wow, now this is really getting crazy.
I'd just do a sealed box, given placement there should be some room gain to get response below a 60-100 Hz cutoff. I also did a 50 litre reflex sim, tune 35-39 Hz. The vent would likely needto be a slot wraped around the box. You do not want to use 2 F200A in the centre, that will just ruin things.
dave
dave
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More isn't always better? I guess that's why they are called single driver speakers. A closed box it is.
Given a set volume for a closed box, are the ratios of the dimensions flexible? Would making it wider and less deep change the sound quality, for example. I was thinking of perhaps 12 x 20 x 18, which would be around 65 l.
Given a set volume for a closed box, are the ratios of the dimensions flexible? Would making it wider and less deep change the sound quality, for example. I was thinking of perhaps 12 x 20 x 18, which would be around 65 l.
well, for our own reasons we try to keep aspect of 3 dimensions at GR (Golden Ratio - .618 / 1 / 1.618 ) but at the very least try to avoid cubes except for "subs"
what are the dimensions of the ribbon?
Ignoring potential doubling up of standing waves (2 dimension the same) and keeping in mind that the front has to be large enuff to accomodate the driver, you are free to change the aspect ratio.
Given the placement i would recommend trying to push the baffle to close to filling the cavity it will be in, with enuffspare to get it up on something that will isolate it from the cabinet (ie a chunk of foam or isolation feet)
dave
Why a 65L box?
The reason 2 drivers is bad, is because (unless you low pass one of them) they will interact with each other in a very bad way at higher frequencies. Google comb filtering to get an idea, or just take our word for it. For the same reason I'd suggest orientating the ribbon vertically with your F200A if possible. Otherwise you may be better of not using it at all. I can't say for sure as there are not enough details.
The reason 2 drivers is bad, is because (unless you low pass one of them) they will interact with each other in a very bad way at higher frequencies. Google comb filtering to get an idea, or just take our word for it. For the same reason I'd suggest orientating the ribbon vertically with your F200A if possible. Otherwise you may be better of not using it at all. I can't say for sure as there are not enough details.
Ya, I don't see the issue either. But wouldn't a smaller box give better power handling and match to his cross over point better? I dunno though. What's the target cross over? I suppose the lower q would offer more cross over flexibility. Especially if his room does have some peakiness in the 100 to 200hz range.
The ribbon is 6" high and 8." wide. I could not use the golden ratio because the max of 22 would not give the smallest side room for the drivers. The closest I could come is something like 11 x 15 x 22. That would give me room for foam isolation and be about 60 l. volume. Thanks for all the input and suggestions.
warning, heresy alert:
the ribbon's mounting is not all that much smaller than the F200 itself, and while vertical MTM with these drivers could be stupidly good (but certainly not "frugal" ), as Ryan suggested, just for kicks you might try a single F200 on small OB in the center position to see if you desperately miss the top end
here's the heresy: if you do find the top needs some work, how about mounting the ribbon beside the F200? it might just work
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