Sorry, I'd forgotten that with all the chatter. I found the pdf link you posted for the Peerless BC18's. Do you have a mid in mind; and which 2 inch tweeter were you talking about?
I prefer a full range center as it mates well with my mains. I can hear the tonal change when I have the CC set to 80hz. If your running your mains as small then you may want to consider that for your CC.
Even when set to small (80hz xo) I've found that most small horizontal MTM's don't go low and strong into the 40's to make a good transition with a 80hz xo point from the receiver. Meaning they make a better transition around 120hz than they do 80hz. Measuring with Sound Easy shows an F3 closer to 120 than 80 with the filter engaged.
Regards.
I prefer a full range center as it mates well with my mains. I can hear the tonal change when I have the CC set to 80hz. If your running your mains as small then you may want to consider that for your CC.
Even when set to small (80hz xo) I've found that most small horizontal MTM's don't go low and strong into the 40's to make a good transition with a 80hz xo point from the receiver. Meaning they make a better transition around 120hz than they do 80hz. Measuring with Sound Easy shows an F3 closer to 120 than 80 with the filter engaged.
Regards.
oo i just got the sent the full price list, they also have the H825 and H723.
im quite interested in getting the h723, isnt the h1144 a replacement for it? or.. ?
im quite interested in getting the h723, isnt the h1144 a replacement for it? or.. ?
So is there any opinions over me getting the T17RE over the T18RE ? (Since that's whats available...) I am wanting to get this sorted out today.
sunrice3500,
The T18RE_XFCTV (H1333) is the better coaxial driver if compared with T17REX COAX/F (H723).
H723 should be crossed over at about 3.5 kHz for a smooth FR but the dispersion is not as good as for a separate tweeter because of the wave-guide action of the M-cone.
My opinion is that the coincidence mounting is better if used as an L or R speaker but to narrow for a HT center setup and is not better than small tweeters normally used in cars.
The Seas H1144 Coax Box and Xover pdf show only on axis FR measurement (at 10 degrees) and this cannot assure good of axis response.
I think your listening distance will be important if using coaxial driver if not a larger one is chosen, I agree with LineSourse of the use of a single 12" coaxial driver that can handle a lower crossover frequency for wider than 30 degree dispersion.
b
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The T18RE_XFCTV (H1333) is the better coaxial driver if compared with T17REX COAX/F (H723).
H723 should be crossed over at about 3.5 kHz for a smooth FR but the dispersion is not as good as for a separate tweeter because of the wave-guide action of the M-cone.
My opinion is that the coincidence mounting is better if used as an L or R speaker but to narrow for a HT center setup and is not better than small tweeters normally used in cars.
The Seas H1144 Coax Box and Xover pdf show only on axis FR measurement (at 10 degrees) and this cannot assure good of axis response.
I think your listening distance will be important if using coaxial driver if not a larger one is chosen, I agree with LineSourse of the use of a single 12" coaxial driver that can handle a lower crossover frequency for wider than 30 degree dispersion.
b
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For a centre speaker Altec model 9842 is a good speaker.
Can be either floor or wall mounted.
Here is the web site.Plans are also available.Horn hard to find .MR931-12 XO 1500 HZ.Unless you can find the horn with driver. 7/8 "throat.
I would not try it.
http://www.lansingheritage.org/html/altec/specs/pro-speakers/9842.htm
http://www.lansingheritage.org/images/altec/catalogs/1983-pro-short/page2.jpg
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Can be either floor or wall mounted.
Here is the web site.Plans are also available.Horn hard to find .MR931-12 XO 1500 HZ.Unless you can find the horn with driver. 7/8 "throat.
I would not try it.
http://www.lansingheritage.org/html/altec/specs/pro-speakers/9842.htm
http://www.lansingheritage.org/images/altec/catalogs/1983-pro-short/page2.jpg
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I have good news.
According to a post on the Altec site. The Mr 931-12 is now available @ Great Plains Audio.
This is good news.
According to a post on the Altec site. The Mr 931-12 is now available @ Great Plains Audio.
This is good news.
CONVERGENCE said:
Any idea what the price tag is for the drivers and horn? I only ask for comparison to 18sound and BMS prices.
Thanks
I have not considered any drivers yet for a centre speaker (I will need one). The challenge is not the drivers, but the enclosures and placements.
There are a number of factors to be considered, otherwise even if we have the best speaker in the world it will still sound bad.
One difficulty is that I believe speakers should be placed away from any walls / panels at least 1 metre. If speakers are too close to a boundary, the reflected sound will be mixed with the direct sound. This makes the sound congested, artificially enlarged.
For example, initially I thought I would build the centre speaker placed on the floor just immediately in front of my large rear projection speaker. I actaully designed the enclosure and the XO for it. But then I realised the speakers will only radiate into 1/4 Pi and is too closed to all the walls. It would definitely sound terrible.
I guess the best place for it is at the top of the TV.
The second issue we need to consider is the polar response and directivity of the speakers.
The conventional MTM placed horizontally is not the best idea because we want wide horizontal dispersion.
The Coaxial driver mentioned above would work well if the driver does not beam to early but if you want to use MT, MTM, TMM, etc, you have to be extremely careful about the radiation pattern. bjorno has posted some pictures.
I have not had the time to revisit my design of the centre speaker but I will one day.
Experts on centre speakers please advise.
There are a number of factors to be considered, otherwise even if we have the best speaker in the world it will still sound bad.
One difficulty is that I believe speakers should be placed away from any walls / panels at least 1 metre. If speakers are too close to a boundary, the reflected sound will be mixed with the direct sound. This makes the sound congested, artificially enlarged.
For example, initially I thought I would build the centre speaker placed on the floor just immediately in front of my large rear projection speaker. I actaully designed the enclosure and the XO for it. But then I realised the speakers will only radiate into 1/4 Pi and is too closed to all the walls. It would definitely sound terrible.
I guess the best place for it is at the top of the TV.
The second issue we need to consider is the polar response and directivity of the speakers.
The conventional MTM placed horizontally is not the best idea because we want wide horizontal dispersion.
The Coaxial driver mentioned above would work well if the driver does not beam to early but if you want to use MT, MTM, TMM, etc, you have to be extremely careful about the radiation pattern. bjorno has posted some pictures.
I have not had the time to revisit my design of the centre speaker but I will one day.
Experts on centre speakers please advise.
well I've purchased the two midrange woofers, gonna pick them up Saturday, gonna do a MTM with it... Also still looking at the coaxials.. Contacted a company in north australia regarding their seas coaxial range, waiting for them to get back to me.
No, It will sound very good if bad speaker placements are avoided in a room suited for a HT.
Not if you use directive speakers or corresponding arrays.
_____________-(25xT)-
Se pic for a (WMMMMMW) center array that has a very low ripple horizontal omni coverage and a vertical 45 degree coverage when placed at floor aiming up (adjustable) or about 90 degrees if mounted high.
__________(25xT)
No, The (WMMMMMW) center array that can be placed high, between or low.
The center has very low horizontal ripple, omni coverage and a vertical 45 degree coverage when placed at floor aiming up (adjustable) or about 90 degrees if mounted high.
This center matches tonally the L and R speakers designed with Scan-Speak drivers (D2905/ 97000, 12M4631G00 and 18W8531G00) and was a requirement when built, confirmed to be true by the HT owner who also claimed the aimed center provides him a seamless focus, flaw free in apparent size when compared to L and R when listening to DVD concerts and seat independent with respect to the whole room width (= 4, 3(m), room Length about 8 m) even if standing up or moving around no ripple or change in the depth perspective could be heard.
So you are falling back to a low performer…. 🙂
b
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bjorno,
Interesting picture.
Are the 25 tiny little black dots on the top tweeters? What are they? How wide is the speaker? Do they need to be tilted up towards the viewer? I guess the directivity is controled by the angled timber? I have no doubt this speaker works, but how many of us can find and build a centre speaker with 25 tweeters?
I can throw in 4 x Peerless HDS 5" and a D2905/9700 tweeter coming from my parts bin for my centre speaker. In that case, how can I control directivity? - wide horizontal dispersion, and at most 45 degree vertical disperson, if the speaker is placed on the floor attached to the front panel of a rear projection TV.
Bill
Interesting picture.
Are the 25 tiny little black dots on the top tweeters? What are they? How wide is the speaker? Do they need to be tilted up towards the viewer? I guess the directivity is controled by the angled timber? I have no doubt this speaker works, but how many of us can find and build a centre speaker with 25 tweeters?
I can throw in 4 x Peerless HDS 5" and a D2905/9700 tweeter coming from my parts bin for my centre speaker. In that case, how can I control directivity? - wide horizontal dispersion, and at most 45 degree vertical disperson, if the speaker is placed on the floor attached to the front panel of a rear projection TV.
Bill
well considering i have 2 midrange woofersbjorno said:
there's not much else I can really do than add a tweeter to it right?
and placed vertically, the dispersion should be acceptable...
so?
sunrise3500 said:
I did this when I was using a tv and it worked dramatically better than horizontal. At least in regard to those who sat ~45 deg off center. You could still add a small mid and eliminate a lot of the combing associated with horizontal mtm's; provided you could find a smallish 2cm tweeter and still get around 2+ octaves from the mid.
Some budget contenders below, not taking into account your location.
Hi Vi dome mid
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Dayton 3/4" tweeter
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the only reason i figured ill just go with a MTM is that the midrange woofers and the tweeter will cover all the frequencies..
Yes, They are PartsExpress Dayton ND20TB-4 but there are not available anymore and replaced with newer types:
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=275-035
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=275-025
The first tweeter is identical in size and probably better than the Dayton ND20TB-4.
The center is 1.05 m or 41.34” wide, 0,35 m deep (13.78”) and the height is 0.3 m or 11.8”.
No, The center is supposed to be placed upright at floor level or higher up, even close upside down to the ceiling.
The nominal directivity is about 45 degrees at the floor or ceiling levels and max about 90 degrees or limited by the driver dispersion when placed higher up.
In additional the aiming and directivity is further controlled with a built-in rotating and tilting feature for the T array, pivot points are attached to the ends of the array, this gives at maximum + - 10 degrees.
At last also by electrical reversing the filter, where + – 15 degrees can be added by shifting the T array polarity (the crossover).
The tweeters are only at $4.10 EA (4 +).
For this case my rec. to you is to add a fifth HDS 5” or another 4” driver for the middle M driver in a WW-MT-W-W layout where the T is mounted above slightly recessed below the rim of the M driver for minimum speaker height.
This configuration assures a horizontal dispersion as good as the vertical aligned T/M drivers.
The T/M drivers can easily be tilted electrically if needed by choosing an odd order filter up or down.
See picture 1(1) where the photo is a center WW-MT-WW (or easily switched to a Bessel type if preferred) I made 3 years ago to a friend whose work is to record music in churches and at concerts using the B-format for 5.1 productions.
sunrise3500;
You’re right; it’s better than a horizontal MTM anyway.
b
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well now that I've got the midrange woofers, I wanted to just do some quick testing, and I've hooked them up to a tweeter/crossover i've got in an old bookshelf, and wired up the 2 woofers in series. the effective resistance of the whole system is ~12ohm according to my multimeter.
the specs on my amp are 6-16ohms, so obviously that's fine, but was just wondering, all my other speakers are 8ohm, is there any con at running at 8ohm, obviously, takes more power to get more volume, but besides that. was also wondering am i better off running in parallel than throwing in a resistor or something (to bring it up from ~3ohms), or is it fine as is, which is what my current thoughts are. (I'm just thinking ahead to when I do this properly, rather than the current quick testing...)
the specs on my amp are 6-16ohms, so obviously that's fine, but was just wondering, all my other speakers are 8ohm, is there any con at running at 8ohm, obviously, takes more power to get more volume, but besides that. was also wondering am i better off running in parallel than throwing in a resistor or something (to bring it up from ~3ohms), or is it fine as is, which is what my current thoughts are. (I'm just thinking ahead to when I do this properly, rather than the current quick testing...)
I would opt for parallel. Given a shared cavity for the two drivers you net around a 6dB increase when wired this way. If you have some specs or better yet some Clio files I'd be happy to run some enclosure models for you. Oh, and no - there's no problem running a 12ohm speaker for your amp, nor is it usually a problem running a 4ohm speaker in 8ohm amp mode, provided the electrical phase response is reasonably benign.
here's a laugh for ya's
put the woofers in a cardboard box, they're in series.. and parralel with a midrange from my current center(so that got my resistance down to ~8ohms now), and tweeter from the center too .... amd using the crossover from an old bookshelf
purely for the sake of trying it out and seeing what a result. (and a bit of a laugh too)
the crossover obviously isnt designed for the woofers or this arrangement, and the box dimensions werent made to suit, it's all abit random
but hell it sounds alright! .. it did sound like *** when i used the tweeter out of the bookshelf, then i ripped out tweeter from old center, and it's way+ better.
in terms of sound to my old center, upper frequencies sound exactly the same, much more depth in the lower-mid frequencies, but i think the old center was a bit more crisp/clear, although this is in a freaking cardboard box, and nothing - dimensions,xover have been done properly.. so... yes... roflmao
put the woofers in a cardboard box, they're in series.. and parralel with a midrange from my current center(so that got my resistance down to ~8ohms now), and tweeter from the center too .... amd using the crossover from an old bookshelf
purely for the sake of trying it out and seeing what a result. (and a bit of a laugh too)
the crossover obviously isnt designed for the woofers or this arrangement, and the box dimensions werent made to suit, it's all abit random
but hell it sounds alright! .. it did sound like *** when i used the tweeter out of the bookshelf, then i ripped out tweeter from old center, and it's way+ better.
in terms of sound to my old center, upper frequencies sound exactly the same, much more depth in the lower-mid frequencies, but i think the old center was a bit more crisp/clear, although this is in a freaking cardboard box, and nothing - dimensions,xover have been done properly.. so... yes... roflmao
An externally hosted image should be here but it was not working when we last tested it.
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