# Center Channel on the Cheap



## Rubus (Dec 30, 2013)

I recently replaced the 6 1/2" kevlar drivers and the Hiquphon tweeters in my Fried C/4 loudspeakers. One of the old tweeters was destroyed by little fingers but the other is fine. The 6 1/2" drivers need the center black spots glued back on but I think they sound fine. I could simply build a third C/4 with the old components and use that for my center channel. I'm not convinced it would handle the low end of the center's responsibilities. Perhaps a second 6 1/2" driver would boost the low end. I have the drivers for a Mid-bass Tweeter Mid-bass speaker. How do I design the box and crossover for a MTM transmission line center channel speaker? Thanks


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## Mike Edwards (Mar 10, 2011)

Rubus said:


> I recently replaced the 6 1/2" kevlar drivers and the Hiquphon tweeters in my Fried C/4 loudspeakers. One of the old tweeters was destroyed by little fingers but the other is fine. The 6 1/2" drivers need the center black spots glued back on but I think they sound fine. I could simply build a third C/4 with the old components and use that for my center channel. I'm not convinced it would handle the low end of the center's responsibilities. Perhaps a second 6 1/2" driver would boost the low end. I have the drivers for a Mid-bass Tweeter Mid-bass speaker. How do I design the box and crossover for a MTM transmission line center channel speaker? Thanks


you'd need to get diagnostic equipment and measure your drivers ... measure them in certain sized boxes and create a crossover from scratch, measuring after each time. unless you COMPLETELY mimic the original speakers boxes and carefully reverse engineered the crossover. 

crossover's are tricky things and you can't just toss some generic one in there. they change based on box size, type of speaker (ported, sealed, etc) and the placing of the driver in relation to the woofer vs. the tweeter etc.

I mean if you're up to the task and are interested in the fun of it, then by all means go ahead. otherwise I would honestly suggest using a proven design for a DIY speaker


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## fusseli (May 1, 2007)

Agreed, it would be a "performance risk" to try this haphazardly. If you insist on proceeding I would suggest duplicating the original crossover and calculating the smallest enclosure for acceptable (80Hz) bass performance. You would not be guaranteed the original frequency response, and turning an MTM speaker on its side would only get you about +/-10degrees of good horizontal response in the best scenario.


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## Rubus (Dec 30, 2013)

Thanks Mike and fuseli,
I do think I'm in a fortunate position to build a center channel speaker with drivers that I currently own. As a matter of setting the bar, at the very least I could replicate the Fried C/5 and call it my "center channel". The C/5 has a frequency of 60 Hz to 22 kHz and can be driven by a 25 to 200 W amp. If it had a flaw as a center channel, it would be at the low end. As a main speaker, its the top dog but it is designed for using with bass enhancement, in my case the Fried O/4's. What is the difference in bass requirements between the main and center channels? Am I fretting over nothing? The question for me is can I improve with an extra driver. The C/5 is trapezoidal, I could glue two of them together at the top, turn the whole thing on its side and call it my center channel. I could either replace the tweeter, or just plug the hole on one side. Would that be a waste of time?


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## fusseli (May 1, 2007)

Almost all of the time, a center is playing human voices. So the bass requirements are not high by any means. If a center can at least get down to 100Hz or a little lower, it should be easy to seamlessly integrate it to the sub.


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## Rubus (Dec 30, 2013)

I'm convinced, another C/5 will be my center speaker. What do you mean "integrate it to the sub"?


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## Mike Edwards (Mar 10, 2011)

Rubus said:


> I'm convinced, another C/5 will be my center speaker. What do you mean "integrate it to the sub"?


he means crossing it over so that the sub picks up where the speaker leaves off (basically the low pass filter on your receiver should do that for you)


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## Rubus (Dec 30, 2013)

I had not planned on adding a subwoofer to the center channel. My mains have subwoofers and I do intend to build a dedicated subwoofer, but not one linked to the center speaker. My C/5 would be it.


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## Mike Edwards (Mar 10, 2011)

Rubus said:


> I had not planned on adding a subwoofer to the center channel. My mains have subwoofers and I do intend to build a dedicated subwoofer, but not one linked to the center speaker. My C/5 would be it.


are they actually SUBwoofers on the mains? or just woofers??? (subs go to MUCH lower frequencies than woofers do, which would technically make it a 3way speaker.....tweeter, woofer, subwoofer)

the reason we say "blending with the subs" is most people use dedicated subwoofers run on their own power systems for the low frequencies and have them take the 80hz and below frequencies (ish, you can adjust higher or lower according to taste) while the speakers, mains and center do 80hz and above (ish)


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## Rubus (Dec 30, 2013)

My front speakers are two way C/4's that sit on top Fried O/4. The O/4 is advertised as a subwoofer with a response down to 23Hz.


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## Rubus (Dec 30, 2013)

Hi Mike,
When I play a movie with a 7.1 system, I have eight signals going to eight different speakers. If the signal going to the center channel has contains a lot of bass and the center speaker doesn't reproduce bass well, having mains with great bass won't make up for the deficiency. It seems to me that the center speaker has to cover its base.


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## Paulcet (Jun 18, 2013)

No, I don't think the center channel has any bass material in it. The audio channels are separated by what you need to hear from that location, but when it comes to low frequencies, it is hard to tell where they are coming from. That is why most HT systems have just one subwoofer channel. (The .1 in 7.1) So you don't need a "Center Subwoofer".


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## fusseli (May 1, 2007)

Exactly. A center only needs to play as low as the lowest of human voices (mid 80s), any extension below that is more or less wasted. The mains and/or subwoofer in the system handle the bass, not the center.


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## Mike Edwards (Mar 10, 2011)

what these two said. usually a center doesn't carry a lot of bass and the mains will take care of your LFE needs


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## Rubus (Dec 30, 2013)

Thanks,
I have to say the system works! I was looking for a decent center channel on the cheap and I believe HTS has given me that. In general I would conclude that if someone had subwoofer-satellite mains, they should consider another satellite for the center channel. its time to tune the table saw. Great blog.
Paul


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## RTS100x5 (Sep 12, 2009)

Rubus said:


> I recently replaced the 6 1/2" kevlar drivers and the Hiquphon tweeters in my Fried C/4 loudspeakers. One of the old tweeters was destroyed by little fingers but the other is fine. The 6 1/2" drivers need the center black spots glued back on but I think they sound fine. I could simply build a third C/4 with the old components and use that for my center channel. I'm not convinced it would handle the low end of the center's responsibilities. Perhaps a second 6 1/2" driver would boost the low end. I have the drivers for a Mid-bass Tweeter Mid-bass speaker. How do I design the box and crossover for a MTM transmission line center channel speaker? Thanks


Just use this or similar MTM box with a finish of your liking....

http://www.parts-express.com/dayton-audio-mtm-075bk-075-cu-ft-mtm-speaker-cabinet-gloss-black--302-740

crossovers

http://www.parts-express.com/cat/assembled-passive-crossovers/308?N=13282%204294967118%204294967060&Ne=10166&Nrs=collection()/record[endeca:matches(.,%22P_PortalID%22,%221%22)%20and%20endeca:matches(.,%22P_Searchable%22,%221%22)]&PortalID=1


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