CSS FR125S for center channel ?

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MCH

Member
2002-03-23 6:41 am
I built a pair of these in the Onken cab (designed by Dave). I've listened to them for a couple of days so far. I'm trying to compare them to my ARdiy's. So far I can't hear anything that really jumps out at me. The only thing that I think is a little different is less sibilance in some female vocals. I'll listen to them for a couple of weeks and then switch back to my ARdiy's. Usually I find this is when the ear notices the difference the most. I find I definitely need my subwoofer to augment the bass. Without the subwoofer the sound is just too flat for my taste.

On to my question. If I build a center channel and utilize say 3 speakers to get a final 8ohm configuration; do I connect it as a pair of parrallels connected to one in series? If so, is the one that is connected in series to the parrallel pair, connected to the positive terminal of one speaker and the negative terminal of the other (in the parallel pair)?

After listening to them, I'll finish them (paint) and post a pic.
 

MCH

Member
2002-03-23 6:41 am
"Why would you use 3 of them for a center channel? "

Good question. I suppose I'm use to center channels in the MTM configuration, I find it difficult to envision 1 speaker for that function. It certainly is more econmical with 1 speaker. I like the look of the 3 configuration. Is this a bad idea for sound? I see lots of line arrays (vertical) that seem to be well thought of. But as for the wiring aspect, is my line of thinking correct?

"How did you place the speakers?"

I have the speakers about 3+ feet from rear and side walls. I'm not saying that there is no bass, just prefer more bass than what is put out by these speakers. Plus I think they would be more efficient (the mid frequencies would be better served) if the lower frequencies were removed from their workload. Personally I feel that most (if not all) systems could utilize a good subwoofer. A subwoofer indepentently is much more versatile, efficient and controllable to suit individual setups. But that is just my personal preferences.
 
I concur with MCH. A subwoofer has more than just one benefit. I built a sealed sub with an active Linkwitz/Riley crossover @ 85 Hz to make up for the lack of low end of my Tannoy Reveal monitors. I plugged the ports of the Tannoys and let me tell you: This is the way to go. I invited a friend over to my house who has a lot of experience with professional recording and found my system to be up to par with the multi-thousand dollar system in his pro studio in terms of sound quality. To sum up the benefits of a sub:

- extended bass
- bass reflex can be avoided
- less movement of the cones of the main speakers, thus better resolution
- room gain can easily be compensated for (provided you can adjust the volume of your amplifiers separately)

By the way, I built a sub amp basend on the LM3886 which I highly recommend for bass if you don't need a lot of power.
 

Landroval

Member
2004-10-14 1:21 pm
MCH said:
"Why would you use 3 of them for a center channel? "

Good question. I suppose I'm use to center channels in the MTM configuration, I find it difficult to envision 1 speaker for that function. It certainly is more econmical with 1 speaker. I like the look of the 3 configuration. Is this a bad idea for sound? I see lots of line arrays (vertical) that seem to be well thought of. But as for the wiring aspect, is my line of thinking correct?

I've always hated the horizontal MTMs. The combfilter effect is very annoying when you move away form the centerline, and I really cant see any benefits in using that config.

If you MUST have an MTM, then I recommend you cut all but the lowest frequencies from the two side drivers and let the center one take care of the mids and highs. You could put the center one in a small closed 3 litre chamber and the two side drivers in a ~10 litre 50Hz reflex with 2nd order lowpass at 100Hz. Or something similar. This way you would actually benefit from the extra drivers.
 
I don't think a horizontal array works the same way as a vertical array at all, and an array of 4.5" drivers running fullrange will run into combing problems. If anything, do what was suggested above and use 2 wr and 1 fr, rolling off the wrs to match baffle step. Really though this compromises the whole idea of a fullrange driver with no crossover to get in the way. I think that with a typical 100hz home theater receiver highpass, and a ported box tuned slightly below the HP frequency, you would have plenty of output from one driver, with much better coherency. Unless of course you have a huge room or listen at extremely loud levels.
 

Landroval

Member
2004-10-14 1:21 pm
morbo said:
If anything, do what was suggested above and use 2 wr and 1 fr, rolling off the wrs to match baffle step. Really though this compromises the whole idea of a fullrange driver with no crossover to get in the way.

The FR doesn't need any x-over in a small closed box. Only the the two WRs should have something to cut the higher frequencies.

morbo said:
I think that with a typical 100hz home theater receiver highpass, and a ported box tuned slightly below the HP frequency, you would have plenty of output from one driver, with much better coherency. Unless of course you have a huge room or listen at extremely loud levels.

I agree. And if you need more power than one FR can give, you should look at real bass drivers to go with it. One FR with x amount of Extremis 6.8 would be one solution for loud listening levels.
 

MCH

Member
2002-03-23 6:41 am
Thanks for all the input.
I think I'll go with 1 driver for the center channel. My question now is the cab design. Is the Aperiodic 4liter style a good choice for this application? The 13 liter mini Onken design that I used for the mains is a tad too large and bulky looking for a center. Laying it on it's side might work though. But I don't know if this is detrmental to the sound.
Also would the Aperiodic integrate with my mains? Keep in mind that these will be utilized with a sub crossed over at a 100hz.
 
I will post a picture of my center channel tonight. Off the top of my head - its 12" wide, 6.5" tall, and 18" deep or thereabouts, with a single shelf brace along the longest dimension. Rear ported, tuned to ~50hz. If I was doing it again, I'd port a bit higher and the box could be either narrower or shallower.
 
Sorry, I thought I'd read somewhere that the specs were the same except for frequency response.

I tried again with WinISD version .44, using the proper FR125S specs, and I got F3= 86Hz and Q=.75

Anyway, a sealed box makes a lot of sense for a center channel when crossed to a sub, don't you think? According to Dickason, "If you cannot get an enclosure resonance from a TL or vented type configuration at least two octaves below the crossover frequency, use a sealed configuration."
 

MCH

Member
2002-03-23 6:41 am
OK. I think I've decided on the cab volumes. I think I'll use the .25 cu.ft (7 liters) for the center . For the surrounds (hang on the wall for my application) I'll use the .15 cu. ft (4.25 liters). I'm sort of lost on all the calculations above; but I assume there seems to be an agreement that these will work fine in the cab volumes I've described.
thx for the input.
 
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