midrange for center channel?

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I want to build a 5 channel speaker system this fall and have ironed out some of the details. I will be using the Stryke audio SA071 7"woofers in MTM for the mains, and TM for the surrounds. The tweeter will be the audax TM025F1 1" textile dome tweeter.

My question is on the center channel. I know it is important to integrate the center with the mains, but it is also not good to have a horizontal MTM for the center. I do however want to have this alignment, so I am leaning toward using a midrange below the tweeter and crossing over the woofers relatively low. Will this make the center not mesh well with the mains? If you guys recommend using the midrange, what driver would you suggest? I was hoping for a 3" or 4" unit that would probably be crossed over at 6kHz on the high end. I would also like to keep the price under $40.

Also, any suggestions for low end cossover freq. for the midrange?

Thanks,
Austin
 
additional info

I forgot to mention that the mains and surrounds will most likely be vented, but the center will be sealed. I really do want to pay close attention to the center channel, as I am a movie fiend. My current center channel is just too muffled and I often have trouble understanding quiet speech in movies.

Another idea I had was to modify one of the SA071's into a passive radiator, so I only have one woofer driving and the other setting the tuning freq. I really have no experience doing that, but if it would produce the best results, I may consider it.

If anyone has built the adire 281's and the new center channel, I am curious to know how well they go together, or whether the added midrange makes a serious audible difference.

That should cover it,
Austin
 
virtual?

Could you enlighten me on a virtual centre channel. I have never heard of it before and I can't find any posts that clarify.

I was looking at the fostex, and also some audax midranges. Tangband drivers haven't recieved the best reviews from what I read over on the Madisound list and the diyspeakers list, so unless I hear otherwise, I won't use them. Also, I was looking at an MCM carbon fiber woofer (the same one used in adire's Pop), but I don't know how high it extends.

Never used a dome midrange before. Should I consider it? The vifa at PE doesn't look too bad.

Help please,
Austin
 
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Re: virtual?

Austin said:
Could you enlighten me on a virtual centre channel. I have never heard of it before and I can't find any posts that clarify.

It is built into my Dolby Processor -- should be in most if not all. It splits the centre into the left & right channels. Your speakers have to be able to image.

I was looking at the fostex, and also some audax midranges. Tangband drivers haven't recieved the best reviews from what I read over on the Madisound list and the diyspeakers list, so unless I hear otherwise, I won't use them. Also, I was looking at an MCM carbon fiber woofer (the same one used in adire's Pop), but I don't know how high it extends.

The TBs got fair praise on the FR forum... not up to the Fostex thou. I have used the little MCM. It needs its filtering on the top. The FRs can get away with a low order XO (or none at all -- you might find the tweeter mostly superfulous too)

Never used a dome midrange before. Should I consider it? The vifa at PE doesn't look too bad.

These put the XOver right where you want to avoid one.

dave
 
crossover

I was originally thinking about crossing the midrange over at somewhere between 500 and 1000 for the low end and 6000 for the high end, but after looking at my driver options I was considering lowering the 6000 to 5000. It seems that two things will happen with the crossover frequency at 5000 instead of 6000. 1) the center will sound more like the mains, since the tweeter crossover will be closer to that in the mains. 2) The frequency range for speech (which I want the center to do best) will be split more between the midrange and tweeter. I don't know if that is necessarily bad. Maybe it will be even good since less stress will be put on the midrange.

Should I split the speech range between drivers like this? I am thinking 500 and 5000 now for the crossover points. What if I did 1000 and 4000, That would distribute the octaves pretty evenly between the drivers.

Hope the questions aren't too elementary. I have Loudspeaker Design Cookbook on the way, and only $15 on half.com. I expect it to be a big help. Sure would have been nice to have when writing my acoustics research paper on enclosure shapes though.

Thanks again,
Austin
 
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Re: crossover

Austin said:
Should I split the speech range between drivers like this? I am thinking 500 and 5000 now for the crossover points. What if I did 1000 and 4000, That would distribute the octaves pretty evenly between the drivers.

the difference between 4 & 6 K is half an octave so not all the great.

The XO at 500-1000 is a potential problem... i'd push that down to 250 or 300 Hz to keep it out of the midrange.

dave
 
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