given that the radiation pattern for center channels needs to different from left right or rear channels (or does it?) and that WAF/SAF dictates a short wide box above or below the TV what would be recomended config for the center?
a) MTM
b) W MT W (with MT in vertical array) this usually requires a taller box as the W are usually 6"+
c) MM T MM with outer 2 M's being used for BSC
d) T MMMM T - what would be the XO used here - having 4 Ms prodiuce freq up to 2-3-4k might pose problems related to comb filtering or not?
e) any other ideas such as having 2 center channels one above and one below the TV etc.....
yeah yeah i know this idea has been discussed before but i search did not find it.
a) MTM
b) W MT W (with MT in vertical array) this usually requires a taller box as the W are usually 6"+
c) MM T MM with outer 2 M's being used for BSC
d) T MMMM T - what would be the XO used here - having 4 Ms prodiuce freq up to 2-3-4k might pose problems related to comb filtering or not?
e) any other ideas such as having 2 center channels one above and one below the TV etc.....
yeah yeah i know this idea has been discussed before but i search did not find it.
Theoretically, I'd say the ideal would be a good coaxial driver. I've got a few sets of Radian and JBL coaxials I'm going to experiment with in the future.
Next, I'd say version B is the least likely of your options to compromise horizontal dispersion. If it's practical, I'd suggest crossing the woofers at the baffle step to kill 2 birds with one stone.
Bill
Next, I'd say version B is the least likely of your options to compromise horizontal dispersion. If it's practical, I'd suggest crossing the woofers at the baffle step to kill 2 birds with one stone.
Bill
Yup, I'd agree with Bill, option b is the best bet.
If you need to reduce the box height, you might be able to carefully trim away some of the surround on the tweeter, they are often much bigger than they need to be. 😉
If you need to reduce the box height, you might be able to carefully trim away some of the surround on the tweeter, they are often much bigger than they need to be. 😉
I think it depends where you are placing the center. The ideal place is in the same acoustic space as your L&R. If you can do this, they should be identical or as near as possible.
If you can't position it in the same acoustic space, then I suspect nothing will match without serious experimention.
This was certainly my experience.
Steve
If you can't position it in the same acoustic space, then I suspect nothing will match without serious experimention.
This was certainly my experience.
Steve
thnaks for all the responses.
now to a specifc problem i have - i realise i was not very clear at first.
i have 4 4" mids and 2 19mm hf units. all units are vifa tc series.
so in reality only options a), c), and d) are viable in my case. If I were to use use option b) i would run out of room. the smallest i can make the tweeter is 60mm (after shaving of part of teh plastic flange) and the mids are 110mm so that makes 170mm which is more than the height i have.
i also agree with steve about matching the acoustic space. but WAF dictates the tweeter to be below the TV which means the acoustic space will not be the same given that the center will be about 16.5" from the floor and the L&R mid/Hf unit is about 34" from the floor.
For L&R I have 2 options -
a watt puppy style system using 2 x Focal Neoflex 8N515 woofers in a band pass box (dont laugh this was due to strict volume resrictions) topped by a 2 way using a 6" audax aerogel 170z0 and morel mdt33. the band pass boxes will be fed the sub out from the HT / AV receiver. so difraction compensation is built into the 6" 2way.
a curved cabinet system using a 8" Eminence woofer (again these woofers will be fed the sub signal of teh receiver) near the floor topped by a 2 way using a 6" and 1" vifa TC series drivers and a series XO. (this system is not complete yet). the tweeter is below the woofer in this case. the cabinet of the system has been discussed elsewhere on this forum. some of you have been following that too.
now to a specifc problem i have - i realise i was not very clear at first.
i have 4 4" mids and 2 19mm hf units. all units are vifa tc series.
so in reality only options a), c), and d) are viable in my case. If I were to use use option b) i would run out of room. the smallest i can make the tweeter is 60mm (after shaving of part of teh plastic flange) and the mids are 110mm so that makes 170mm which is more than the height i have.
i also agree with steve about matching the acoustic space. but WAF dictates the tweeter to be below the TV which means the acoustic space will not be the same given that the center will be about 16.5" from the floor and the L&R mid/Hf unit is about 34" from the floor.
For L&R I have 2 options -
a watt puppy style system using 2 x Focal Neoflex 8N515 woofers in a band pass box (dont laugh this was due to strict volume resrictions) topped by a 2 way using a 6" audax aerogel 170z0 and morel mdt33. the band pass boxes will be fed the sub out from the HT / AV receiver. so difraction compensation is built into the 6" 2way.
a curved cabinet system using a 8" Eminence woofer (again these woofers will be fed the sub signal of teh receiver) near the floor topped by a 2 way using a 6" and 1" vifa TC series drivers and a series XO. (this system is not complete yet). the tweeter is below the woofer in this case. the cabinet of the system has been discussed elsewhere on this forum. some of you have been following that too.
If you're limited to those dimensions and drivers, I'd suggest something like this. Roll one of the midwoofs off with a coil for BSC and minimize their c-c separation. This should keep horizontal dispersion wide. It also moves the tweet up and closer to the vertical axis of the other wideband mid, within your overall height limitation.
Attachments
thanks Bill, I will check dimensions and get back to this forum. links the driver are:
http://www.d-s-t.com/vifa/data/tc20sd05-06a.htm
and
http://www.d-s-t.com/vifa/data/tc11sg49-08a.htm
actually what i have is a TC11SG69-08 which is simlar to the 49 but for the fact that the 69's flanges are flat on 2 sides and not fully circular like the 49.
maybe this can help
http://www.d-s-t.com/vifa/data/tc20sd05-06a.htm
and
http://www.d-s-t.com/vifa/data/tc11sg49-08a.htm
actually what i have is a TC11SG69-08 which is simlar to the 49 but for the fact that the 69's flanges are flat on 2 sides and not fully circular like the 49.
maybe this can help
sorry Bill could not get the tweeter to fit between the mids. so i am stuck with MM T/T MM where T/T is 2 tweeters odified so that their centers are 2.5" apart.
considering that this is center channel 2.5" c-c would push the comb effects to the upper hf where there wont be much significant info. also consider that this speaker will ONLY be used in HT mode where things are a little less critical than pure stereo.
now i debating between a 2.5 way parallel XO or a 2.5 way series XO. Series XO Guru Andy Graddon is already helping me on this. Wonder what I'd do without him!
Once this is done expect pics of finished work sometime late next week. if i dont (i get carried away with other posts) etc... wake me.
considering that this is center channel 2.5" c-c would push the comb effects to the upper hf where there wont be much significant info. also consider that this speaker will ONLY be used in HT mode where things are a little less critical than pure stereo.
now i debating between a 2.5 way parallel XO or a 2.5 way series XO. Series XO Guru Andy Graddon is already helping me on this. Wonder what I'd do without him!
Once this is done expect pics of finished work sometime late next week. if i dont (i get carried away with other posts) etc... wake me.
I guess I didn't realize you were contemplating using 2 tweeters... Doing that will significantly narrow dispersion along the axis of alignment, so I hope you'll be arraying them vertically. You might also experiment with a protruding block of acoustic foam between them like M&K uses on their tweeter arrays to fix some of the worst of the lobing.
For the midwoofers, I'd still experiment with rolling off either the outer drivers or one side pair. I'd guess the first would give you symmetric lobes and a narrower pattern while the second would give you asymmetric lobes and a wider pattern.
yes vertical and i am modifying the flanges so that the centers are about 70mm apart. that is as close as i can get teh domes. this should push comb effects to the upper hf (10k+). for a center this might suffice.
the outer pairs are going to be rolled off. i am now working on 2 XOs.
1. parallel XO 2nd order.
2. series XO (still wondering if I shoudl use 1st order zeta of about 1 or second order).
the outer pairs are going to be rolled off. i am now working on 2 XOs.
1. parallel XO 2nd order.
2. series XO (still wondering if I shoudl use 1st order zeta of about 1 or second order).
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