merlinx76 said:
I just wonder: do you need a shielded center?
If you have lcd/plasma/beamer then you could save yourself a whole lot of trouble by just using a (yes just one!) nice full range like the monacor sph60-x which runs down to 120 Hz in a sealed box (Q=0.7) and is known for its very good voice band reproduction. You will have a very hard time getting the same kind of positioning with a mutichassis system.
Just a thought....
It would have to be shielded unless I can put it a little further from the TV (It's just an ordinary CRT TV). In a multi-way with the spacing on an (of course shielded) tweeter, I might not have to go down by much if any to use an unshielded midwoofer.
I guess I should try for simpler, if possible...a 2-way
Is there a driver that could give me an -3db point near 65-80hz in a sealed box and play very cleanly up to near 3khz without too much beaming? (ie: at least very good at 30deg off axis)
I guess I should try for simpler, if possible...a 2-way
Is there a driver that could give me an -3db point near 65-80hz in a sealed box and play very cleanly up to near 3khz without too much beaming? (ie: at least very good at 30deg off axis)
I had never looked closely at the Extremis before. That FR graph looks pretty damn smooth... Wish they showed off axis. Works out to about a 70 hz -3db point and according to adire can be crossed at 3-4k. plenty of linear xmax, low inductance, shielded. This looks like a near perfect choice for the job.
What do the rest of you guys think about the Extremis?
What do the rest of you guys think about the Extremis?
My experience:
1) a little beaming in the HT center channel is desirable as it locks the voices to the screen
2) coaxial drivers are a good solution for a HT center channel
There are several coaxial drivers that come with a crossover, or you can take a wide bandwidth woofer and create a frame with some steel to coaxially mount a low Fs tweeter like the Seas 27TDFC in front of the woofer phase plug and build your own LR4 or LR6 crossover at 1,200 Hz.
http://www.radianaudio.com/products/coaxial/12_format.php4?viewT=coaxial&viewC=12_format&viewI=
1) a little beaming in the HT center channel is desirable as it locks the voices to the screen
2) coaxial drivers are a good solution for a HT center channel
There are several coaxial drivers that come with a crossover, or you can take a wide bandwidth woofer and create a frame with some steel to coaxially mount a low Fs tweeter like the Seas 27TDFC in front of the woofer phase plug and build your own LR4 or LR6 crossover at 1,200 Hz.
http://www.radianaudio.com/products/coaxial/12_format.php4?viewT=coaxial&viewC=12_format&viewI=
I don't see Coaxial speakers very often. Is it optimal to cross low with that design?
funny you mention the 27TDFC as that's what the tweeters that are in my mains. My main goal was to keep the XO as high as I could though. I was going to consider the shielded 27TDFC/TV so that the highs would blend in with the mains better. The shielded has a higher Fs but I want the XO at 2.5khz+ anyway.
So back to the 2 way TV stand how about an extremis with an Seas 27TDFC/TV??
Matches my mains in the highs and lows well but should behave much differently in the midrange. If I want to best match the bass response of the mains I'll need a Q of almost .7 but this would mean sacrificing quality in the midrange (vs. critcally damped) I take it.
funny you mention the 27TDFC as that's what the tweeters that are in my mains. My main goal was to keep the XO as high as I could though. I was going to consider the shielded 27TDFC/TV so that the highs would blend in with the mains better. The shielded has a higher Fs but I want the XO at 2.5khz+ anyway.
So back to the 2 way TV stand how about an extremis with an Seas 27TDFC/TV??
Matches my mains in the highs and lows well but should behave much differently in the midrange. If I want to best match the bass response of the mains I'll need a Q of almost .7 but this would mean sacrificing quality in the midrange (vs. critcally damped) I take it.
Haven't used it, but it's quite good from a purely technical POV so probably a keeper, and if DW says it's fine to XO at 3kHz, this implies to me that it's within the 30deg window, though I'm sure they will send you a more informative plot if you ask.
WRT co-axes, I'm a big fan of them, especially for HT apps, though I have doubts about using one for just the CC and cone/dome in the mains since the tonal balance will be way different.
I'm coming in late, but frankly, I would just do a tightly focussed horizontal MTM with the same drivers/XO/cab Vb as your mains, adjusting the BSC as required to account for the TV's impact on it. Also, rather than add a woofer, add a CC LFE sub.
GM
WRT co-axes, I'm a big fan of them, especially for HT apps, though I have doubts about using one for just the CC and cone/dome in the mains since the tonal balance will be way different.
I'm coming in late, but frankly, I would just do a tightly focussed horizontal MTM with the same drivers/XO/cab Vb as your mains, adjusting the BSC as required to account for the TV's impact on it. Also, rather than add a woofer, add a CC LFE sub.
GM
Merlin,
After looking at the Adaire woofer and the seas tweeter this looks like a very promising set of drivers for a two way system.
They shoud work well together and the Adaire has a very smooth high end frequency response for a driver of it's size. You may be able to push this speaker up to a 3000 hz crossover point. With a 12 bd or 18 db crossover.
IF you have a friend with experience designing crossovers see if they can help you. If not I would contact Madisound and have them LEAP design a crossover for you. They will have design data for the Seas tweeter but you might have to supply them with the specs for the Adaire.
If you want your life to be even simpler you can spring for a good quality 5-6 inch fullrange and have no crossover to design. And have only one speaker. Most full ranges are designed to go up to 5000 - 10,000 Hz.
I like the two way combination. I can supply you with the box volumes for either a vented or sealed box. As I can run a quick simulation for you.
Hezz
After looking at the Adaire woofer and the seas tweeter this looks like a very promising set of drivers for a two way system.
They shoud work well together and the Adaire has a very smooth high end frequency response for a driver of it's size. You may be able to push this speaker up to a 3000 hz crossover point. With a 12 bd or 18 db crossover.
IF you have a friend with experience designing crossovers see if they can help you. If not I would contact Madisound and have them LEAP design a crossover for you. They will have design data for the Seas tweeter but you might have to supply them with the specs for the Adaire.
If you want your life to be even simpler you can spring for a good quality 5-6 inch fullrange and have no crossover to design. And have only one speaker. Most full ranges are designed to go up to 5000 - 10,000 Hz.
I like the two way combination. I can supply you with the box volumes for either a vented or sealed box. As I can run a quick simulation for you.
Hezz
GM said:
Playing with the BSC in this XO would be kinda hard since the design uses a minimalistic crossover (schematic)
also the drivers aren't shielded so they'd have to be alittle further from the TV.
I would also like to get my feet wet and design an XO myself. I already have almost everything I need to build a jig...I just have to put it together. I have already built one design created by someone else and since this will only be a 2-way it seems like a good place to start designing for myself.
Merlin,
I say go for it. I think it would be better to design a high quality center channel on it's own merits than try to make it fit the topology of your front mains. A center channel is a good place to start your own speaker building. Then once you have a really good center channel that you like and you know how to get a good sound that you like then you can carry the design ideas over into building a really nice set of mains if you like.
Try to download one of the freeware or shareware crossover design software packages to help you if you like. These can give you a place to start.
One more thing. If you decide to build the TV/stand center channel it needs to be built to high standards to keep speaker vibrations low and out of your TV set. I used double 3/4 MDF for the side walls and have two internal shelf type braces.
Hezz
I say go for it. I think it would be better to design a high quality center channel on it's own merits than try to make it fit the topology of your front mains. A center channel is a good place to start your own speaker building. Then once you have a really good center channel that you like and you know how to get a good sound that you like then you can carry the design ideas over into building a really nice set of mains if you like.
Try to download one of the freeware or shareware crossover design software packages to help you if you like. These can give you a place to start.
One more thing. If you decide to build the TV/stand center channel it needs to be built to high standards to keep speaker vibrations low and out of your TV set. I used double 3/4 MDF for the side walls and have two internal shelf type braces.
Hezz
Since I may be building another center channel TV stand I have included a couple of design mockup models here.
I need to lower my TV about 4 inches to make more room on the wall for the front projector so I am thinking about building a new design based on a two way as the MTM design cannot be made any lower.
Hezz
I need to lower my TV about 4 inches to make more room on the wall for the front projector so I am thinking about building a new design based on a two way as the MTM design cannot be made any lower.
Hezz
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Guys,
thought you just might want to see a picture of the Madisound MTM rebuilt that I did for my center channel. I don't have a table saw so the joints are not perfect. Also I was really cold when building this outside in December so needless to say the cabinet tilts a small amount due to some cutting clamping error.
Hess
thought you just might want to see a picture of the Madisound MTM rebuilt that I did for my center channel. I don't have a table saw so the joints are not perfect. Also I was really cold when building this outside in December so needless to say the cabinet tilts a small amount due to some cutting clamping error.
Hess
Attachments
That kinda looks better than I expected. You went the easy way...no pyramid shape!... I was thinking of all those angles and all the mistakes I'll likely make when I buid it. Maybe I should make it rectangular too and keep it simpler.
I'm debating whether to build a center or a sub first. I'm leaning towards the sub because I really need it but the center would be more fun to build.
I'm debating whether to build a center or a sub first. I'm leaning towards the sub because I really need it but the center would be more fun to build.
Hi Merlin,
that picture is of my first design. The pyramidal shaped one I havn't tried to build yet but is a future project.
I know what you mean about trying to figure out where to start. If you are playing a lot of games a sub might be more fun first but it will also cost more to build.
Also don't worry too much about small mistakes. Most of them can be covered by rounding corners and with bondo before painting. As long as the joints are strong and secure good results will be achieved. The sound waves do not care if the box is not perfectly square.
Here is the conceptual design for my first TV stand center channel speaker. The one you see in the picture.
Hezz
that picture is of my first design. The pyramidal shaped one I havn't tried to build yet but is a future project.
I know what you mean about trying to figure out where to start. If you are playing a lot of games a sub might be more fun first but it will also cost more to build.
Also don't worry too much about small mistakes. Most of them can be covered by rounding corners and with bondo before painting. As long as the joints are strong and secure good results will be achieved. The sound waves do not care if the box is not perfectly square.
Here is the conceptual design for my first TV stand center channel speaker. The one you see in the picture.
Hezz
Attachments
I didn't realize the unusual scale Adire uses for the Extremis. That and the smoothing really makes it look better than it is. I read about a few people's plans for them and it seems they want to XO quite low around 1700hz or thereabouts. Seems like that's what most people prefer with a 6.5"-7" 2-way. Maybe I should forget crossing so high.
If I do go lower I don't know if I should use the Seas 27TDFC/TV because the Fs of this shileded version is fairly high at 950hz. And because the extremis is expensive, inneficient, and the FR isn't as good as I first thought, I am rethinking that as well...
I am almost back where I started.
With regards to the tweeter: What difference should I expect between the sheilded and non shielded Seas tweeters? What happens as you get too close to Fs with your crossover? How close is can you get with a say 2nd or 4th order XO for example. Since the tweets are both the same otherwise would the higher Fs one still be able to handle as much power before distortion at the lower freqs? I ask this because the tweets are what limit how loud I can go before it starts to sound bad in my mains.(which isn't all that loud either)
If I do go lower I don't know if I should use the Seas 27TDFC/TV because the Fs of this shileded version is fairly high at 950hz. And because the extremis is expensive, inneficient, and the FR isn't as good as I first thought, I am rethinking that as well...
I am almost back where I started.
With regards to the tweeter: What difference should I expect between the sheilded and non shielded Seas tweeters? What happens as you get too close to Fs with your crossover? How close is can you get with a say 2nd or 4th order XO for example. Since the tweets are both the same otherwise would the higher Fs one still be able to handle as much power before distortion at the lower freqs? I ask this because the tweets are what limit how loud I can go before it starts to sound bad in my mains.(which isn't all that loud either)
Merlin,
Somehow I feared that the Adaire speaker was rather expensive and if you decide to go with another speaker that is no problem. As far as the tweeter goes you need to have the crossover point at a minimum of one octave higher than the Fz so for a tweeter with a 900 Hz Fz you would want a minimum of a 1800 Hz crossover point with a 12 db or higher crossover. For a 6 db crossover you want the tweeter Fz to be at least two octaves below the crosover point. The Seas tweeter is very good but you can go with a Vifa which are as good and often a little less money.
You will definately need a shielded tweeter and mid-bass. The magnets of unshielded speakers will make large distortions in the TV out to about 18 - 24 inches away. People who are using unshielded speakers close to the TV with no problems are using speakers with small low power magnets which are typical of low bugdet mass market speakers. The the good quality tweeters with large magnets will have a really bad effect on the TV so you must go with a shielded tweeter. The unshielded tweeters are comparable in thier Fz ratings to shielded ones.
I would recommend an Audax aerogel polycast frame mid bass. They are very good sounding for the money. Quite adequate for a center channel and in fact are of significantly higher quality than the speakers in mass market consumer speakers.
You can get a 6.5 inch shielded version from parts express for 32 dollars USD and order it online if you wish. Or you can opt for the die cast magnisium frame model for 77 USD.
I am considering mounting the mid bass speaker in my new two way design center channel on the top of the tweeter to get the midrange and midbass up higher from the floor. This method will decrease the tweeters ceiling reflections and increase the midrange ceiling reflections which may not be desireable for mains but I think it will work well with the center channel because of it's norrowing focus on voice frequencies.
Also, there is no reason why you need to build the pyramidal shaped design. It offers a little better performance but with proper speaker stuffing the more rectangular approach will work very well and is easier to built.
Here is a model of the new design:
Hezz
Somehow I feared that the Adaire speaker was rather expensive and if you decide to go with another speaker that is no problem. As far as the tweeter goes you need to have the crossover point at a minimum of one octave higher than the Fz so for a tweeter with a 900 Hz Fz you would want a minimum of a 1800 Hz crossover point with a 12 db or higher crossover. For a 6 db crossover you want the tweeter Fz to be at least two octaves below the crosover point. The Seas tweeter is very good but you can go with a Vifa which are as good and often a little less money.
You will definately need a shielded tweeter and mid-bass. The magnets of unshielded speakers will make large distortions in the TV out to about 18 - 24 inches away. People who are using unshielded speakers close to the TV with no problems are using speakers with small low power magnets which are typical of low bugdet mass market speakers. The the good quality tweeters with large magnets will have a really bad effect on the TV so you must go with a shielded tweeter. The unshielded tweeters are comparable in thier Fz ratings to shielded ones.
I would recommend an Audax aerogel polycast frame mid bass. They are very good sounding for the money. Quite adequate for a center channel and in fact are of significantly higher quality than the speakers in mass market consumer speakers.
You can get a 6.5 inch shielded version from parts express for 32 dollars USD and order it online if you wish. Or you can opt for the die cast magnisium frame model for 77 USD.
I am considering mounting the mid bass speaker in my new two way design center channel on the top of the tweeter to get the midrange and midbass up higher from the floor. This method will decrease the tweeters ceiling reflections and increase the midrange ceiling reflections which may not be desireable for mains but I think it will work well with the center channel because of it's norrowing focus on voice frequencies.
Also, there is no reason why you need to build the pyramidal shaped design. It offers a little better performance but with proper speaker stuffing the more rectangular approach will work very well and is easier to built.
Here is a model of the new design:
Hezz
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