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CENTER Speaker characteristics to aim for?

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  • CENTER Speaker characteristics to aim for?

    ​ I've decided to put together a 5.1 in my living room.

    Overkill, but I have to start using all this stuff I build. Right?

    THE GOAL: to fabricate a center speaker based on what surround systems expect out of a center. Range, operation, power compared to the rest of the surround, what center is used for the most (vs. my preconceived notions) I need to know the tricks of the trade in making a center in a 5.1 specifically. Do I need to use only mids and tweeters? Full range? Any filters or XO? That stuff.

    I'm hodge-podging. I know many will not approve. But this is what I am doing so if you don't like it. Move on please. It's my house. I can make it sound good. Buzz.

    Using a 55" wall mounted TV with zero sound enhancements to drop a bunch of stuff in it that I am not using at the moment. To include:

    Pair Main L&R TriTrix MTMTL floor cabinets

    Pair Rear surrounds large bookshelf style two way cabinets with 5" woofers and ribbon tweeters, mounted high on a wall opposing TV pointed down and toward the room center.

    Powered 10" sub of my own creation. Extremely low frequency tickling. Silly ear hair vibrating ****. Probably not legal. And that is 5.1.

    Read no further if this is too low rent.



    What frequencies should they cover and be strongest performers within?

    Should they be tuned louder or softer in a surround mix?

    tips and tricks of the trade?

    (I've Never attempted a "center" without some plans.

    Trouble is choosing center speaker drivers and amplification, power and wiring to fit my existing cabinet. I can't get drivers any bigger than 2.5" before I am pushing it.. How much is too much amplification? How much is adequate? Too little? Are the drivers capable enough? Should I have tried bigger? All those questions you can pretend I have and not answer them. I want advice.

    I am using an HDMI audio splitting device to separate all 6 channels in a 5.1 out to RCA outputs, where they'll each be amplified - except the sub, which is powered. It will follow whatever is ever on the TV input. I do not want a Home Video receiver.They have too many automatic adjustment options that I do not approve of, or understand, So Amplifier for Main L&R. Amplifier for Rear L&R. Amplifier for "center." Powered Sub. 2 stereo, 1 mono, 1 sub plate amp.


    It's a small living room. The room is maybe 15 x 20 with the TV mounted on one of the 15' walls. Cabinet underneath for any gear.

    On either side of that cabinet, as my Left and Right mains: the Tritrix MTMTL powered by a samson 100x2 reference amp that is overkill. I may put a 50x2 Sure amp on them, only because I am afraid of a kid cranking and blowing something. This pair alone would be plenty for the room.

    On the rear 15' wall on either side are bookshelf size two ways mounted high on the walls, neart the corners, pointing down and toward the center.

    The sub is in the corner, to the right of the TV and speakers on the 15' wall,


    And that leaves the center speaker.

    BACKSTORY: I had a soundbar I was working on and aborted for a bunch of reasons, but I salvaged all but the baffle, and it is still a solid cabinet frame that just needs the baffle. And it could be the trick for an amazing center: it's extra long and that may be key. It's longer than your average center. I have put threads on the rear of the cabinet that fit brackets I have for them. Two brackets. One end attaches to the speakers, the other attaches between the TV and the mount on a wall, so the speaker hangs right below the screen on a wall mounted set, like mine. I spent time preparing the baffle in an OAK 1/4" x 4" joined to a 1/4" x 4" birch piece, clamped, and am going to attach to the cabinet, drill driver holes, and trim route around the center. If this works, it will be pretty cool looking.

    This is the dimensions of the center and what I plan to install in it...

    ----- the center (ABORTED SOUNDBAR)

    cabinet salvations. needs some sanding and finishing but is solid.

    *** Should I get FOUR of the Dayton ND64-16 2.5" for the middle section, and wire them all into parallel down to 4 ohms into an amp channel / mono amp?

    I was thinking that since the "center" is one mono channel, I should come up with a creative way to wire these to keep the ohm rating down. Like series into parallel or vice versa.

    Also, I was thinking about the nature of center speakers and what we want them to do. Maybe I am a half layman-moron, but I believed the center was to aid in the stereo panning left to right or right to left, with sound flashing through the center speaker between the main L&R. Second, it seems like the logical choice for most vocal speaking performances to at least be amplified, If for no other reason, than to create the illusion the voices were coming from the screen.

    So I could be all over the place here and only need to rig up something that's full range and matches power with the rest of it.

    Guidance along my obvious lingo and ability here is appreciated. Though I can learn with the best of them, I am trying to pick drivers for this quickly. I have the cabinet pretty much done.



    joined oak and birch to make 1/2" baffle

    pencil outline of cabinet walls


    The idea is this. Take baffle single piece I have made with Oak surface, and attach it to the cabinet. It is too long and wide for the cabinet baffle dimensions, so it will hang off on all sides. I will countersink screws in it, and woodglue, and perhaps clamp to make sure every mm along the edge is in contact with the baffle. Then I'll cut thye driver holes. Hopefully, everything is hole saw standard at this size. If not, out comes the plunge router.

    Thankfully, I can trim the router edges off the baffle, using the cabinet as a pattern guide. I have consulted woodworkers, and gotten this method. I usually do NOT cut baffles this way, but figured I might as well give it a try.


    Feel free to discount my ideas here for your own.

    PARTS: 4x (2 EACH SIDE) , HDMI 5.1 channel; audio splitter into several RCA outputs. HDMI video return to monitor output. Allows for separate amplification for different surround speaker groups.

    I was thinking ND64-4 2-1/2" Full-Range 4 Ohm Part # 295-520 THREE OF THEM across the center of the center

    and FOUR TOTAL (2 EACH SIDE) Dayton CE65W-8 2.5" 4 Ohm full range Speaker Driver Part #285-143

    One input from the HDMI splitter to (2 stereo, 1 MONO amp, 1 Powered Sub) One for the outer GRS sides, one for the Triple ND64, one MONO for the center

    So amp for the center. Mono? Stereo to accommodate the two groups of speakers?

    Amp choice....

    One stereo amp with 1ch to the center 3; 1ch to the outer 4?

    Two amplifiers? One for the center 3 and one for the outer 4?


    alcuin school

    Or with the three center ones I can wire down to four....

    -click to enlarge-

    I'd probably try to use digital amplifiers as small as I could get, hopefully to be able to install right inside the cabinet. I have many VERY small PCB digital amplifiers that, wired correctly, could prove to be a good solution. More recon is needed. I have several 7w/5w max amps, several 24w max stereo amps, many 25x2 w amps. 50x2. a lot of 5x2. There has GOT to be a combo that will work and fit.

    I also have several 2-3 and passive speaker radiators I want to cut and install into the underside of the center as well. Or... possibly some other weird low powered full range I have if my power availability needs to be spread out.

    I'd be welcome to input. I want it. I am not the most creative person in the world. There is lots of elbow room to get creative here.

    Obviously, this wasn't a drawing board, then step by step planned out the way we all like to do it, but such is life.

    Happy to hear what you think about those center speaker driver choices, or recommendations to improve. Perhaps a pad or XO is the way to go if I can isolate some of the 7 speakers lined up in a row for a single channel.

    New at this. Looking for guidance. Don't want to make catastrophic errors.

    More to follow....


    PS not married to any of the drivers. The cabinet, I am stuck with. But I can mess with drivers plenty.​
    Last edited by Spaker; 12-08-2020, 12:43 AM.
    My Studio Music Production Gear:
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  • #2
    EDIT now that I am thinking, and not just going full force working at it....

    Is full range the way to go about this?

    Seems a lot of the commercial Center are two-way with a tweet and a couple small-ish midwoofers.

    Am I totally in denial that I can put this togethe reffectively with a bunch of full range speakers as part of a surround with adequate sub, mains and surround low end?


    And maybe related.... sort of....

    Should I just amplify this thing? Internally? So it can be plugged right into an RCA line out, or even an optical. Then it could double as a soundbar without the surround. That introduces stereo where I might have gone mono though. And probably would be good as far as being packed with full range drivers. Still not sure if any filtering or even minute component addition would benefit this amagmation.
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    • #3
      Yet another option is to throw a bunchg of budget 2.5 - 3" full ranger drivers I have had decent luck with over the years. nothing special. A lot of under 20w Max wattagw. I could fit 8 or more in there depending on if I use the bottom or rear of the cabinet. I was going to put some small passive radiators on the rear for the hell of it. Not really a scientific project. Kind of throwing stuff at the wal to see if it works as far as speaker config and power.

      Still interested in the nature of "center" in general.
      My Studio Music Production Gear:
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      • #4

        The center channel from my experience watching movies needs to be responsive, loud and clear from around your sub crossover point (say 60 ~ 100 Hz) to around 16K or more as your hearing sensitivity dictates.

        The majority of the action and human voice dialogue will be coming from this center channel speaker - high sensitivity/low distortion is what I think is important.

        A horizontal array of smaller drivers could work for this with a tweeter in the center.

        OK - I'll let the experts/more knowledgeable finish up here.

        Good luck and keep us posted.


        • Spaker
          Spaker commented
          Editing a comment

          I can make this happen with what I have on hand. And it will sound good in the room, guaranteed.

        • Steve Lee
          Steve Lee commented
          Editing a comment
          Don't forget to line that box and very lose-fill it with something like pillow stuffing as needed to tame resonances which will increase detail/intelligibility otherwise you will hate it. Post pics too.

      • #5
        PM this guy and buy his spare Tritrix MTM kit. Best center between two Tritrix is a Tritrix.


        • Steve Lee
          Steve Lee commented
          Editing a comment
          Great call, djg - but I don't think he has the vertical room for it if I understand his original post.

        • Spaker
          Spaker commented
          Editing a comment
          See post below regarding TriTrix MTM. Can't. Being hung under TV mounted high on wall.

      • #6
        Most critical when not using an AVR with any EQ is that the "voicing" of the center be the same as the mains. About the only way to do that is for them to be the same, which you have deemed impossible as you have some old sound bar cabinet. If using an AVR, it can eq the center to be closer to the mains if they are reasonably close. So, optimum is what you don't have, and that would be an MTM upright the same as your mains. Trust me on this, when a voice moves across the soundstage and the tone changes, you will hate it.

        Now, for your plan, if you must, a matching tweeter is a must. Full range drivers have very ragged response and fall off way before a tweeter. By full range, they really mean voice, not music. They can (some of them) make decent midranges. Getting tiny full range to go deep enough to match your mains crossover to the sub may not be possible. With enough of them, they may have enough x-max to eq the bass down to 80 or so, but not easy. If the sub is directly below them, then crossing @ 110 is OK. which tiny FR drivers can do if you have enough to push enough air.

        There is no way to provide direct guidance on tuning the crossover for the center to try and match your mains. I would not take that on myself. Even with identical drivers, it is sometimes hard to get the center voicing right as the surrounding reflections are different. I had some Paradigm mains and the "matching" center running a Rotel AVR with no eq. Horrible. Sold the center. My current HT uses the same Dayton /Seas but as the center is an MTM ( not D'Apolitto aligned as it is horizontal) where the mains are single in-wall flush. It took several tries to get the voicing where you can't detect the source. I am not sure I have it there yet. Even with my Anthem AVR. It's eq only goes up to 3K so the crossovers are different.

        Seriously, I would reconsider your plan and make a MTM center matching your mains. Providing you cross them over to the sub all at the same frequency, 80 Hz maybe, then the TL cabinet is not really doing anything for you and you can make the center ported or sealed depending on the drivers. Now what you wanted to hear.


        • #7
          A sealed Tritrix is 8" deep. Eight inches. And you could make it shallower by making it wider.

          Click image for larger version  Name:	Tritrix10ltrsealed.gif Views:	0 Size:	57.7 KB ID:	1458444


          • Spaker
            Spaker commented
            Editing a comment
            I know. I have a pair on stands. If you remember, I said this had to be hung under the TV using a soundbar mounting kit that attaches to the TV mount. The Tritrix MTM would not only look ridiculous up there, it would rip the entire setup to the floor.

        • #8
          So nobody wants to just let me salvage this thing into a center? Not allowed, eh?

          I can make a TriTrix MTM. I probably will someday. I already have the baffles cut for them. I already have a little bit of many projects. That's part of the point.

          I am getting rid of drivers new in boxes and salvaging an aborted soundbar attempt.

          2.5" to some 3" drivers will fit in this soundbar attempt I aborted when I wasfirst making these.

          Maybe my question should have been: "What is the center channel typically used for?"
          Then I would have just chosen appropriate drivers, full range vs. 2-way, mono vs. stereo. oye.)


          I figured I would get replies like:

          "cast a wide net and focus on frequency range XX - XX."
          "Install at eye level. Power it with about 1/4 the wattage as the main L or R gets."


          I really did say if you don't like this, don't worry about it. I know this is not by the book, but I think it can work with the setup I have.

          Just, if you have any advice on how Center channels are usually utilized, a frequency range perhaps, and even a comparison to their power capabilities compared to main / surrounds.

          It would be sweet to find a formula like:
          If Max Volume of Main Ch is 100W, Center Max Volume should be 30W. Center should XO at 250Hz and 7500Hz with a single tweeter.

          That is the kind of info I am looking for, even if it's ballpark. This is Kids and tweens and teens and downloaded crap and bootleg movies and god knows what else the hooligans are playing..

          I am just killing time here, have this thing from an aborted project and stuff lying about. Didn't mean to offend any purists or anything.
          My Studio Music Production Gear:
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          • djg
            djg commented
            Editing a comment
            Maybe do some reading.


          • Spaker
            Spaker commented
            Editing a comment
            Oh I know what the articles and books say. What do the builders say?

            If you think I am using one source, or blindly doing as some persuasive writer mentions, you are incorrect.

            I have built and torn down these systems for a lifetime. I am just curious as to what the builders say.

            Some have direct answers to a pretty direct set of questions.
            Some have a complaint about something or other.
            Some assume this is a child, or the mind of one.
            And some are ballsy enough to feign charity, graciously impart their brand of wisdom, and then sit and wait for the endless thanks and praise. Those people... they need help.

        • #9
          Center channel is of no use for stereo music. It is decoded for video and will contain the majority of voice. If you had a really really good setup with great imaging, you would not need the center. I got away without one for years when I had a well "treated" environment, mains not too far, and pinpoint imaging. ( 4.1) Very few can achieve that unless in a dedicated room and if going through all that, might as well! But my current room, shared guest and HT is not a good imaging setup, so the center is imperative to bring the action to the screen.

          Formula: Mains to sub@ 80 unless you have a very good reason. Kind of a HT standard. HP 4th order @ 20 to prevent excessive cone excursion from effects and garbage. Again unless you have a very good reason. My living room music only is crossed @ 60.
          Crossover from mid to tweeter is totally dependent on the drivers. My living room are 1800 LR-4 acoustic, 2nd and 3rd hybrid electrical. My HT mains are 2200 LR-4 acoustic, 3rd electrical. My center is 2000 LR-4 electrical. No simple formula.

          If you know your drivers, you can put the model in WInISD and play with different "signal" parameters to see what wattage gives what cone excursion and what SPL. No set formula. Totally dependent on the drivers and the cabinet alignment. For instance, just modeled my desktops as I am going to re-box them. If I tune them for an Fs of 80, with the 1.5mm X-max, they wil peak @ 88 dB with 2 Watts. Plenty for my desktops. But in my HT, I want around 95dB peak. Speaker design is engineering. To do it right, understand the physics and do the math.


          • #10
            A center does exactly the same thing as the L/R speakers do, which is to reproduce everything above the crossover from the subs, say 80Hz or so. Some 75% of the above subwoofer frequency content comes from the center, so by no means can you think of it as secondary to the L/R mains. When the volume goes up, as in action scenes, the mains are called upon to handle more content than the center, but only then. One of the most common mistakes I see with HT systems is very large mains used with very small centers. A 4:3 size ratio of mains to center is reasonable, a 2:1 ratio is not.


            • #11
              IF it has to fit tiny woofers, then I think something like 4 ND65-8 wired series/parallel (to total 8ohm) with a simple LowPass using a 2mH coil and 17uF cap could work along with the DC28FS-8 tweeter using the same HighPass as the TriTrix MTMTL followed by an Lpad to tame it down to match the ND65's.....this sim's pretty close to the Tritrix before accounting for BaffleStepLosses (which I'm hoping will be minimized by wall-mounting), so I think it might get somewhat close matching aside from being about 9db less efficient watt-per-watt which you should be able to make up for by adjusting the channel's volume.

              I think the woofer's would ideally be grouped tightly together hugging each side of the tweeter, and an internal box volume of 2.5liters with a 1.5inch-diameter X 10inch long port should let it reach a little under 80hz up around 100db (before BStep losses) at about 35watts.

              Not sure how bad the lobing from four woofers will be, but at least the crossover point is somewhat low thanks to the DC28 tweeter.

              If you can fit 3inch woofers, then a pair of DMA80-4 woofer's (series for 8ohm) using the same 2mH and 17uF LowPass might work for less money and a tighter center-to-center distance and maybe a hair more headroom. They'll prefer a slightly larger 4liter internal volume for the box, along with something like 1.5inch diameter X ~4inches long port to let it reach down to ~80hz F3.
              Last edited by LOUT; 12-08-2020, 09:32 PM.
              My first 2way build


              • Spaker
                Spaker commented
                Editing a comment
                Zero woofers. This IS NOT a soundbar. It is only a center channel that I am putting into the frame of a soundbar I had made and didn't like. There are a couple different kinds of 2.5" full range speakers wired together in series and parallel configurations to keep it to 4 ohms.It is long and thin and mounted under the TV. It hangs off a bracket attached to the TV wall mount. There is a Subwoofer in the corner, the two main speakers are Tritrix MTMTL Left and right of the TV. There are two rear speakers, mounted in the back of the room, high up almost to the ceiling, but pointed down and to the middle of the room.

                So it's a 5.1 in a 16 x 21 room with a flatscreen hung pretty high up on one of the 16' walls. Subwoofer to the right of the TV in the corner. Under TV is a cabinet with video games and stuff. On either side of cabinet are the TriTrix MTMTL pair.

                The trick will be, as I see it now, to filter out anything below, say..... 160 and let the subs handle it. And anything above... maybe, 16kHz, let the tweeters take over. That will be the trick. Once I can get that to happen, I can rest.

            • #12
              What HDMI to RCA audio extractor are you using?
              Does it know how to pick out Left/Center/Right/Lsurround/Rsurround audio or is it just taking the regular stereo signal and splitting it out?
              My first 2way build


              • DeZZar
                DeZZar commented
                Editing a comment
                I kind of doubt it. Unless its a powered device that is able to interpret PCM Bit Stream etc (i.e. an actual surround sound processor) I'm not sure how something would passively extract multi channel audio from a HDMI cable. Not my area of expertise though.

              • Spaker
                Spaker commented
                Editing a comment

            • #13
              Just assuming that you do end up with the five proper channels of audio through this splitter then the basic answers to your questions:

              - the audio sent to a centre channel is as expansive in frequency range as any other channel. Movie tracks will dedicate voice and any sound effects intended to come from the front middle to the centre channel. Music and other effects is generally sent to the fronts with residual effects, sounds intended to come from the back, ambient sounds and echos dedicated towards the rear channels.

              - a centre channel should basically be full range (at least sub-crossover all the way up). As others have mentioned, ideally it is the same as the front speakers, or at least using the same drivers/top end.

              Does it matter that it isn't the same speaker? Does any of it matter? At the end of the day, as you highlight, it is entirely based on what you are happy with.

              The reason it's ideal for them all to be the same is so that you are presented with an equally voiced sound stage. At the very least just make sure they all play at the same level. You'll have to play around with gain etc to get this right without a proper receiver. But again, if even that doesn't matter to you, dude ghetto up anything you want!

              Will sound come out of the speakers you've suggested?....yes. Once they are up and running you'll either be happy as can be OR if you aren't - refer the above reasons.


              • #14
                Originally posted by Spaker View Post
                I do not want a Home Video receiver.They have too many automatic adjustment options that I do not approve of, or understand
                Is this based on the idea that the presence of these features degrades the audio quality in some way?

                IF it is man, I just have to point out a glaring irony of avoiding a proper home theatre receiver on the basis of audio quality whilst at the same time trying to create a theatre from a combination of spare parts.

                But I said - sound is going to come out and you will either love it or not.


                • #15
                  He's experimenting and learning - it IS the best way to learn, IME . . .


                  • DeZZar
                    DeZZar commented
                    Editing a comment
                    Absolutely. Its my daily modus operandi!! :P