Blog Forums Home Theater Starting with my center channel

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    • #9308
      lindelium18
      Member

      So, I built my own center channel a while back and it works ok but in a lot of ways, I made some uneducated choices. So, I’m going to start working on center channel V2.0. I plan on using 2 Dayton 7” Esoteric drivers for the woofers. A single Faital 3” Neo mid driver and a HiVi RT2C-A Planar tweeter for the highs. I’ll let you all know how it’s coming along. 

    • #9315
      123toid
      Keymaster

      Sweet.  Let me know if you need any help with the Eso 7’s.  I will have a pair on hand.  They are very nice drivers.  I like them alot.  I should have my measurements on them out this week.


    • #9319
      lindelium18
      Member

      @123toid

      Yeah, your video talking about receiving the Esoterics and the Corundum made me look at those as options.  

    • #9321
      123toid
      Keymaster

      @lindelium18

      They really are gorgeous and sound really good.  Spoiler alert.  The Eso 7 (what I named the build with the 7’s) are my second favorite bookshelf speakers I have ever designed.  They go down so low and are so clean.  I put these in my living room and played them on pure direct and was blown away by the sound including the bass. My living room is rather small and does accent bass well, but still. Very nice. 


    • #9328
      lindelium18
      Member

      @123toid

      Well, my theater room is roughly 14 x 16 so bass should be pretty solid. I’m looking forward to giving them a run.  I’ve also never used a planer tweeter before either so this will just be all kinds of fun. 

    • #9345
      lindelium18
      Member

       

       

      Well, apparently a short (ish) drive out to parts express was in the cards for today.  I picked up all the drivers for now. I’ll do the crossovers once I have the components in an enclosure. 

    • #9394
      lindelium18
      Member

      Well, I started designing the center channel enclosure in CAD because after looking at the size of the planer tweeter (outside diameter is 7”!!!!) plus the woofers PLUS the flared ports…I wasn’t confident it was all going to fit. Well, after a little hair pulling and a fair amount of cursing, I’ve got something I can work with. The image might look a little strange because I modeled the speakers and the ports as just straight cylinders for a “worst case” scenario. All in all, I think it is going to turn out nice!  Overall outside dimensions are going to be 24.5”w x 13.5”h x 12.5”d

       

    • #9410
      bjaurelio
      Participant

      That tweeter makes your midrange look small. I would be very curious about the polars on that planar. A vertical tweeter mid with woofers as close to center as possible is what you need for a side-ways center. Keep us updated on your progress.

    • #9413
      123toid
      Keymaster

      @lindelium18

      Now that is a center!  About as big of a center as I have seen.  I am interested to see how this goes.  This might sound really nice.  It might even be worth doing a 2.5 way to help with what @bjaurelio is talking about.  Of course, you will know when you design it.  I am very excited to see this.


    • #9414
      lindelium18
      Member

      @123toid

      I’ll be honest, I don’t know what a 2.5 way is. I’m currently planning on doing a 3-way crossover. 

    • #9419
      kevin-kendrick
      Participant

      @lindelium18

      Wish you luck on your build. The first thing I thought when I saw your picture was “Man, I hope he doesn’t leave that woofer in that position for long, not good for the surround. Most drivers now days come with a plastic cover that prevents the surround from being deformed, did the Esoterics not have those?

    • #9425
      lindelium18
      Member

      @kevin-kendrick

      Yeah, they didn’t stay like that for long. Actually, I started woofer break-in right after the picture was taken.  However, the Esoterics did not come with the plastic cover I’ve seen on other drivers. Instead, they are inside a plastic bag and they a foam ring around the outside and then a piece of cardboard on top of that. 

    • #9427
      kevin-kendrick
      Participant

      @lindelium18

      Cool, just looking out for you man. Wouldn’t want to see one of those beauties get messed up.

    • #9502
      lindelium18
      Member

      Lumber was picked up the other day and cut to size but I had to work late last night. Hope to have some baffles cut tonight!  Also, anyone have an opinion on whether to split the airspace between the two woofers or leave it as one bigger space?  The mid is already going to have a sealed enclosure around it and the box is going to have 2 – 2” ports so that won’t be an issue. The only difficulty will be cutting the middle divider around the mid enclosure…  If the general consensus is that it doesn’t make a noticeable difference, I’ll leave it alone. 

    • #9506
      123toid
      Keymaster

      I would keep the airspace as one with the two woofers.  These are basically acting as one driver, so there is no need to split it and could even be detrimental if done incorrectly.  I would add some bracing though.


    • #9508
      lindelium18
      Member

      @123toid

      That’s what I was thinking and since I was leaning toward leaving it as one, bracing was definitely in the plan!

    • #9513
      lindelium18
      Member

      Baffles and ports are cut!  I’m hoping to start the box assembly tomorrow. 

    • #9518
      123toid
      Keymaster

      That is looking awesome!  Are you running a CNC?  THose are some precise cuts!


    • #9526
      lindelium18
      Member

      @123toid

      No, just a router and a circle jig. Jig does 1/16” increments. It’s pretty nice. Not as nice as CNC but nice none the less! 🙂  The circle centers were laid out with a Woodpecker brand saddle guide which is (potentially) accurate to the 1/32” so that helps too. 

    • #9527
      lindelium18
      Member

      Well, mostly finished assembly tonight (working 2nd shift sucks). Nothing on the box is glued yet except the small internal box for the mid but it’s coming along…

       

    • #9554
      lindelium18
      Member

       

      Not much accomplished tonight unfortunately. I routed out the inset and hole for the terminal cup and apparently I measured wrong. So, I am 3d printing a guide ring so I can use my flush trim bit in the router. Maybe I’ll have a functional speaker tomorrow night?!

    • #9556
      123toid
      Keymaster

      That is pretty sweet.  A good use for the 3d Printer.  I have been considering getting one for the channel to give out files to print off terminal cups, amplifier cases, and even speaker enclosures. 


    • #9559
      lindelium18
      Member

      I have the monoprice mini and, for the price, it is awesome.  They are typically under $200 and work very well right out of the box!  Only down side is print volume. It is 120mm in all directions or a little over 4-1/2”. Other than that, I really like it. I’ve put probably 8-10 spoils of filament through it!

    • #9565
      robbiedh02
      Participant

      I built a center channel out of stuff laying around. No specific measurements just built something. Turned ok okish 

    • #9570
      123toid
      Keymaster

      I was looking at a few.  I am not sure which on e to get.  I would like something with a higher build height, so I could build so cool enclosures, but haven’t go there yet. 


    • #9575
      lindelium18
      Member

      @123toid

      You might think about the Anet A8. It is an open source kit but the instructions out there on the internet is plentiful and you can’t beat if for the price. However, if you’re willing to spend more, I think the Original Prusa is a very solid choice. They come with auto bed leveling and you can add an upgrade to do multi-colored. I’m 95% sure that’s what Hexibase just bought recently. 

    • #9577
      lindelium18
      Member

      As for the center, tonight was not NEARLY as productive as I wanted. I got the ports installed and glued up and the drivers are in the front of the cabinet but I am out of the smaller crimp connectors so I guess it’s back to the hardware store tomorrow!

       

    • #9578
      123toid
      Keymaster

      @lindelium18

      I actually had an Anet A6, but never really got it up and running.  I just got too busy and ended up giving it to a friend who wanted to get into it. I was not impressed with the plastic design either.  So I was considering either a CR10 or and Ender 3.  I do like the idea of auto bed leveling.  That would be a huge plus.


    • #9579
      123toid
      Keymaster

      Those ESO7’s look gorgeous.  Great design!


    • #9581
      lindelium18
      Member

      @123toid

      Yeah, I’m very reluctant to go to bed but 5 hours of sleep with two kids all day is a recipe for disaster!  So, maybe tomorrow I can get a rough idea what it sounds like…

    • #9606
      lindelium18
      Member

      454-9BA8F7E2-B2BE-4133-BC52-58D455724695.MOV  

      Well, I didn’t have time to setup my testing gear but I couldn’t wait any longer to at least hear these Esoteric’s. Um…yeah, they move some air!

    • #9607
      lindelium18
      Member

      I actually have a question for @123toid but anyone can chime in. So, for this specific speaker, in terms of designing the crossover, would you get frequency response graphs from the spot it is going to be installed or from the “best” control location (ie suspended outside etc)?  My first thought was the later but the more I think about it, why not specifically design and calibrate for the room it’ll be in?

    • #9609
      123toid
      Keymaster

      @lindelium18

      This is one of those, there is no wrong answer.  If you know it is staying in that room, then you might want to design it around the room.  However, if you plan on moving it or want the ability to know you’ll have good sound no matter the room, then you will want to design it outside.  Btu really there is no wrong answer here. 

      By the way, looks like those can really move some air!  Seriously though, in my Eso7 build, just TM’s, I had them playing pure direct and I didn’t feel I needed a sub.  Of course, this was in a small room, but I was very happy with them. 


    • #9614
      lindelium18
      Member

      @123toid

      Yeah, I believe that!  I think my f3 is like 33hz or something like that!

    • #9616
      lindelium18
      Member

      @123toid

      Since it is a center channel, and ideally will be there forever, I think I’m going to get my graph in the room. 

    • #9619
      lindelium18
      Member

      @123toid

      In your experience, how different is frequency response reading in room vs. factory?  I just did readings from all the drivers and The Eso’s were pretty different than What Dayton shows…

    • #9621
      123toid
      Keymaster

      @lindelium18

      Typically, Dayton is one of the best with measured response in their frd files and what you receive.  But the Eso’s are not one of them.  I had a nasty peak around 1-1.5khz.  I’ll have to recheck my measurements to be sure.  It definitely was audible.  I used a zobel to get it under control, but you could also use a notch filter.


    • #9622
      lindelium18
      Member

      @123toid

      Heres what I got…

    • #9624
      123toid
      Keymaster

      @lindelium18

      Is that both playing at the same time?  It looks like you are getting cancellation 


    • #9626
      lindelium18
      Member

      @123toid

      Yes. They are wired in parallel. 

    • #9627
      lindelium18
      Member

      @123toid

      Something I should be doing differently?

    • #9632
      123toid
      Keymaster

      @lindelium18

      Take a measurement of each.  If you are getting cancellation, you will see it in those measurements.


    • #9634
      lindelium18
      Member

      @123toid

      Left Esoteric:

       

      Right Esoteric:

       

      Both Esoterics:

       

      All three graphs together:

       

      It does look like I may have a little cancellation but it also looks like the drivers (in this enclosure) has issues between 70-120hz… which, for a center channel, is not good.  So, I’m open to suggestions on my next step… 

    • #9635
      123toid
      Keymaster

      @lindelium18

      You are having one of the same issues I had, which is that hump between 1-2Khz.  You will need to address that with either a zobel or a notch filter, otherwise that will be harsh on your ears at times.  As far as the 70-120hz.  Do you have any impedance measurements?  That will help us see if this is a box issue or a room issue.


    • #9641
      lindelium18
      Member

      @123toid

      Seeing as I do not have a DATS as of yet (come on V3!!!), I don’t have any impedance measurements. Would moving the speaker in the room show enough change?  The room is 14 x 16, currently facing in the 14’ direction. 

    • #9642
      lindelium18
      Member

      @123toid

      Also, in reference to the 1k – 2k hump, I’m crossing over at around 500-600hz with a 2nd order so I don’t think it’s going to be much of an issue. 

    • #9643
      123toid
      Keymaster

      @lindelium18

      There’s a few things you can check. The first is to go to whatever box program you used (ie WinISD) and check for first port resonance. This will be on the screen that informs you of port length and size. See if that is anywhere near your problem area. Second, you can line the inside of the box with an old mattress pad or closed cell foam. If it happens to be standing waves, that should help.


    • #9646
      lindelium18
      Member

      @123toid

      Ok, I double checked winisd and my first port resonance is 1,036hz so I don’t think that’s an issue. Next, winisd shows a flat response down to about 60hz, then about a 1.5db increase to 45hz and then back to 0db at 38hz with an f3 of 33hz and an f10 of 27hz. 

      So, my next step will be lining the inside of the enclosure. I have three basic options. I can go pick up poly-fil. I have enough 1” acoustic foam (the two color stuff you put on walls to trap reflections) or I have enough (probably) Safe n Sound rockwool left over to do that walls with that. Any of those better than any others?

    • #9647
      123toid
      Keymaster

      @lindelium18

      I would use the acoustic foam you have.  Typically for a ported enclosure you don’t want to use loose polyfil, one main reason, is it coming out the ports.  Believe it or not, the main thing I use is cheap mattress toppers I pick up from Walmart.  Sounds kind of silly to some people, but it works great for this and is pretty cheap.  I haven’t done any real tests, but from others that have, supposedly one of the best is recycled denim insulation. 


    • #9650
      lindelium18
      Member

       

      Well @123toid , this is getting pretty frustrating…  This is both woofers, after adding the acoustic treatment. It is virtually identical to the measurement without treatment…  I’m not sure what do do at this point…

    • #9651
      123toid
      Keymaster

      It would appear to be a problem with the room, which you’ll want to fix with you room eq of your av receiver. It’s the reason the room equalizer is on your receiver. Unfortunately none of us have the perfect room. Or at least I should say not many of us. O of the ways to test if it’s your room is to take measurements from different distances. First start out as close as you can to the speaker without touching it. Then keep backing it up until you see the null. If it


    • #9652
      lindelium18
      Member

      @123toid

      I’ll do that again tomorrow (forgot to save those results or take pictures) but I did about 1.5 ft, and about 6 feet. All three graphs looked almost identical…

    • #9654
      123toid
      Keymaster

      @lindelium18

      Definitely do an up close measurement, that will give you an idea if it is the speaker.  Having said all this, I’m not sure it is as big of an issue as it looks like on the graph.  Our ears don’t hear sharp dips like that.  What you may want to do is change the smoothing of your graph to ERB.  ERB is one of the measurements that will give you a more accurate representation of what the speaker will actually sound like to your ears.  It is definitely worth a look.  Of course, the final test is to listen to some material and see if you hear the loss as well. 

      I should mention at 1.5 feet you are getting a lot of room in your reading from about 500hz and below. 


    • #9657
      lindelium18
      Member

       

      Graph is the measurement yesterday from 3 feet and then the measurement from the picture. Again, almost identical.  Normally I’d agree about the peaks and valleys being virtually inconceivable but this is a 10db swing over like 30hz within the male vocal range.  But at this point, I don’t even know what to think… for a half second, I thought maybe it was my mic but if I play the two tones at the peak and valley, it is definitely an audible difference. 

    • #9658
      lindelium18
      Member

      @123toid

      could it be the small amp I’m using to drive the test?!  That just came to me as an option that I’ve been ignoring.

    • #9684
      123toid
      Keymaster

      @lindelium18

      It is doubtful it’s the amp, but it always could be..  One might assume it is the driver, but since I also have this driver and have finished a design with it, I know that is not the case.  So if your up close measurement still looks off (ie it is not the room), then there’s only two possibilities that I can think of.  Either you do not have enough bracing or you have a small air leak.  What does your bracing look like?  If you do not want to do an up close measurement, you could always try another speaker int he same location to see if you are getting a similar dip.  If you are, then it is the room/location. 


    • #9692
      lindelium18
      Member

      @123toid

      bracing is ok but not extensive.  Is there a good way to determine where more needs to be?  As for any possible air leaks, I’ll double check that. 

    • #9693
      123toid
      Keymaster

      @lindelium18

      The general rule of thumb is every 12 in needs a brace.  That is a generalization though.  You can try a knock test.  If your hear it resonate you need more bracing there.  If you get a solid thud, you may not.  Looking at your speaker, I probably would have a window brace on each inside of the woofer and three brace in between those two going the width of the center (down the middle).  I typically round over the insides of the braces as well.  You can see a version of what I do here: https://toidsdiyaudio.com/community/diy-speakers-diy-speakers/the-uglies-tower-and-surround-build-log/#post-376

      I probably should have added some vertically, but I didn’t this time.


    • #9695
      lindelium18
      Member

      @123toid

      Just when I thought I could put the router away…  ok, I’m not sold on my issue being either of these problems but I’m out of ideas so what the heck, right?  I’ll get to fabricating some bracing soon but I guess I’ll check all the seals first. 

    • #9697
      lindelium18
      Member

      @123toid

      When will the response graphs for the Esoterics and Corundum be coming out?  

    • #9698
      123toid
      Keymaster

      @lindelium18

      Just to clarify, I am not saying it is either of those things.  I still think it is most likely your room.  However, I just reread something of yours and think there is something going on with your measurements.  Your measurements nearfield and farfield should not look identical.  Am I understanding you correctly and you are saying that one of these is right next to the cone and one 3 feet away?  

      Is this just one Eso 7 playing or both?  Where are you taking this measurement from?  Mid tweeter?  A typical nearfield and farfield measurement would look something like this.  

      The nearfield would be much smoother.  As you can see this is the room, I mention in my videos that sucks bass out.  You can see that at 3 feet away.  But the nearfield measurement takes away all the room, so you can see what the speaker plays without room interaction.  This is why your measurements don’t makes any sense.  At 3 feet, the room will have some influence on the speakers response, that will not occur nearfield.  So I think we should focus first on your measurements to see what the disconnect is, before we try to fix anything else.   


    • #9699
      123toid
      Keymaster
      Posted by: @lindelium18

      @123toid

      When will the response graphs for the Esoterics and Corundum be coming out?  

      Here is a graph of thhe Eso 7’s and Peerless.  Keep in mind, that this was done in the same room that kills bass and I had not added the port in yet.  But here is a teaser.


    • #9700
      lindelium18
      Member

       @123toid

      Ok, first off, thanks for the teaser!!  Second, yes, those two nearly overlapping graphs, one is from 3’ and the other is almost touching the woofer. They were both still playing but I figured at that distance, it wouldn’t matter (plus I’m tired of screwing and unscrewing and I’m trying not to destroy the mdf screw holes). Regardless, if they should look THAT different, I have an issue. I didn’t really want to drop the coin on an omnimic setup but I am thinking that is going to be needed… got any PE coupons laying around? 😉

    • #9701
      123toid
      Keymaster

      @lindelium18

      I completely getting the unscrewing and screwing portion of it.  A tip, you maybe want to use in the future is to run each individual drivers wire out through the ports.  That way when doing the crossover design you test multiple crossover combinations without having to continue to unscrew and screw the speakers in.  

      It shouldn’t really matter at that distance.  It is weird.  I am not sure it is your microphone.  Is that am EMM6?  I do have some coupons laying around.  I’ll upload them later.  I am curious what your sweep settings are in Rew and if you are running any gating.


    • #9708
      lindelium18
      Member

      @123toid

      No, it is a behringer model. The mic then runs through a Scarlet 2i2 interface via XLR and then into the computer via USB. The output goes out the headphone jack of the PC, into a small Chinese amp and into the speaker.  I’ll look into the sweep settings when I get home. I am not super familiar where that setting would be but I’ll see what I can see. I know I ran a single sweep and I think it was at 256k resolution. I think it was like a 5.5 second sweep. 

       

    • #9709
      lindelium18
      Member

      @123toid

      I remembered you did a video on the omnimic vs umik-1 so I went back and watched it again. I think I’m going to pick up the Umik due to $$$. Full disclosure, I picked up my current mic from an auction site so I’m not even sure on its accuracy. At least if I get the umik, I’ll have a fresh starting place and see what kind of results I get. 

    • #9713
      123toid
      Keymaster

      @lindelium18

      I completely understand that.  There is a big difference in price.  And it isn’t really justified unless you are doing this a lot.  I still prefer the Omnimic, but I used a Umik-1 for years with no complaints.  It sounds like a wise decision.  Something does seem off.  I wish I lived closer, I would just bring the omnimic down so we could a better idea of what was going on.  

      I will mention that typically, you run a fast sweep for frequency response (aka 128).  The longer sweeps are good for distortion and other measurements.  This really shouldn’t make a huge difference but something to keep in mind.  


    • #9714
      lindelium18
      Member

      @123toid

      I realize this is just an iPhone recording, but it still provides a perfect example of what the graph is showing. The biggest dip is 68hz to 91hz. Here is a video where I play those two tones back to back and change nothing else.

      495-3126FF6D-1A00-48C1-8185-98AA83C2232F.MOV

       

      I was thinking measuring equipment until I remembered that this dip is audible. So, now I’m back to having no clue what to do. 

    • #9715
      lindelium18
      Member

      Well $h!t 

      @123toid

      wanna hear a funny story?  I’ve been pulling out my hair because NONE of this makes sense. Well, I’m sitting here, at 2:30 in the morning, checking connections on the Scarlett and I completely unplug the usb cable. Then, I notice that REW is still picking up readings…while the interface (and ultimately the mic) is unplugged from the system!  Ummm…WHAT?!  Then I realize, at that moment, I am an idiot. I have a Blue Yeti for recording vocals every once in a while. Anyone want to take a guess what is hooked up and has been getting my tests..THE ENTIRE TIME?!  After I change the input in REW, which just said “default,” to Scarlett, everything started working properly. 🤯  Now, I’m WAY too tired to play around at this point, but here’s the curve with the mic about 3” away:  

       

      I’m going to bed and pretend all of this never happened!

    • #9720
      123toid
      Keymaster

      @lindelium18

      Haha, that makes sense!  And your response looks very similar to mine on the Eso7.  That has happened to me before, but it was the laptop microphone instead.  A dead giveaway typically is if you move the microphone closer or further and the spl stays the same.  😀   I am glad it got figured out.


    • #9723
      lindelium18
      Member

      @123toid

      Yes, it was a very “facepalm” moment. I’m planning on having measurements for all the drivers tonight so I can start the crossover. 

      Quick question though, I did a quick 6 foot measurement and I had a big dip in the bass section. I don’t remember what frequently but if I have to take a guess I would say it’s probably around that 70 hz mark like the previous measurements. Obviously, it’s from the room… Anything I can do to help with that?

    • #9745
      123toid
      Keymaster

      @lindelium18

      This is where DSP and room correction become your best friend.  Unfortunately there isn’t much you can do passively.  But really, this is why room correction was invented in the first place.  Because, no one really has the perfect room.  Bass especially is really susceptible to this since the waves are so long.  You could try to move your center channel, but I am guessing that is probably out of the question.  If that is the case, you will need to DSP it from there.   Of course, so,e of this is dependent on where you plan to cross over the center.  If you are crossing over at 80hz, it might not be a big deal.  But if you are crossing over at 50hz or just playing it full-range, then I’d take care of it actively in your amplifier.


    • #9748
      lindelium18
      Member

      @123toid

      Yeah, I haven’t figured out yet where I’m going to highpass the woofers yet but I know I’m going to die to some Xmax issues. As for DSP, I’m not entirely sure how much I can do with my receiver. I’m going to have to look into it. It is a Denon AVR-X4300H which supports Atmos so I’m hoping it will also have some DSP functionality. If it doesn’t, is there a piece of equipment I could put in between the amp and speaker to adjust the signal?

    • #9758
      123toid
      Keymaster

      @lindelium18

      You would just use Audyssey to DSP for your room.  If you don’t use Audyssey, you should be able to fine tune via a graphic EQ and use your microphone to see the changes.  But Audyssey typically does a pretty good job.  You can always check it later after it has run.


    • #9766
      lindelium18
      Member

      Well, crossover is done. Curve isn’t perfect but it’s good enough for me. Now…what to do with the exterior of this behemoth…

    • #9803
      lindelium18
      Member

      Well, I lied. I have listened to the center channel now for a few days and it just sounds a bit…muffled.  Which, going back and looking at my frequency response, kind of makes sense. The mids drop about 3db and then I’m ok from about 1k-3k but from there up it dives far too quickly. So, I’ve re-tweaked in PCD and I think the l-pad on the tweeter was too aggressive, so I’m changing those resistors. Also, I raised and spread the band of the mid a bit. Finally, I stretched the woofers out a bit more as well.  I’m hoping to run out and get the 6 new components this weekend. 

    • #9805
      cap
      Participant

      from speaker designers and designs, I’ve noted that a slight rise up to 10kish and a slope back down past 10k tends to be most desired for avoiding muffled audio

    • #9806
      lindelium18
      Member

      @cap

      Yeah, on my second crack at it, that’s what I’m shooting for. Attempt #1 was almost the opposite of that and it is definitely audible. Currently, I am moderately underwhelmed. I’m hoping this resolves the current status of my whelmed-ness. 

    • #9840
      123toid
      Keymaster

      Is that response with all the drivers hooked up?  I don’t mind people who do a sloping down response.  Typically that is done in an anechoic chamber so it becomes flat in room.  But some even like it sloping down in room.  It’s really a personal preference.  But 20db down, is pretty excessive.  It also looks like 200hz and below have about a 5db rise, which can muffle sound.

      One last question. I notice the rise in 1-2Khz.  Since I am pretty familiar with the Eso 7, they typically have a rise there.  I know you are crossing over before that, but I am wondering if there is some inter modulation distortion going on there.  IE the ESO 7’s are affecting that response.  You could add a zobel after the ESO 7 crossover to see if that takes care of that.  If that is going on, you will get much more clarity from doing this.


    • #9841
      lindelium18
      Member

      @123toid

      Yes, that is all drivers, in the room, from about 18” or so. I’ll definitely look into a zobel on the 7’s. I think it has one currently.  I’ll look at what my tweaks were/are and see. However, since I currently have a sick kid laying on me, it may be a bit. 😒🤮

    • #9854
      lindelium18
      Member

      Well, due to a very awesome wife, I actually made it out to PE today.  Hoping to work the revised crossover the next few nights!

    • #9903
      lindelium18
      Member

      Well, I almost hesitate to tell you all this because it’s a pretty silly mistake but hopefully I save someone from the same issue. I used REW to get actual FRD measurements from each driver. Well, there are two woofers in my speaker so I just got one measurement for both speakers, hooked in parallel. However, when I loaded the drivers into the crossover designer, I used the factory ZMA file.  Anyone see an issue here?  The crossover designer was acting like I had an 8 ohm load, when actually I had a 4 ohm load. So, when I was trying to extend the upper frequency of the woofers, it was telling me to use an inductor 2x too big and a capacitor 2x too small… 

      So, after realizing this error and changing the components once more (luckily I already had some that were close enough), this is my final (probably) result.   

       

      @123toid you were right. My 1k – 2k rise was (is) coming from the woofers but at this point, there’s very little chance I’m going to change it since I’d have to change the components not only on the woofers, but also the mid. 

    • #9904
      Elliott
      Participant

      @lindelium18

      I’m afraid I dont know I can help you with that problem but if you ever do a centre channel redesign I recommend putting the tweeter slightly higher than the woofers that way you get less cross talk. This helps with many aspects of the sound such as with sweet spots and so on.


      Elliott Dyson – Elliott Designs (YouTube) – 3rd year MENG Student
    • #9905
      lindelium18
      Member

      @diyaudiphileelliottbridge

      Absolutely and thank you for the input. Unfortunately, due to the overall size of the tweeter and my height limitations due to the projector screen coming down, that is literally, as far apart as possible. 

    • #9906
      Elliott
      Participant

      @lindelium18

      Fair enough then, if you ever get more space a 3 way is the best way to disperse a centre channel with the woofers either side, the mid centre bottom and the tweere centre top.


      Elliott Dyson – Elliott Designs (YouTube) – 3rd year MENG Student
    • #9907
      lindelium18
      Member

      @diyaudiphileelliottbridge

      Just to be clear, you do know that that is how I have mine setup, right?  It’s just that the planar tweeter has a 7” diameter. It makes the 3” mid look tiny. 

    • #9908
      Elliott
      Participant

      @lindelium18

      I am very sorry, none of the images have loaded in for me. Great design choice. You know your stuff! 😉


      Elliott Dyson – Elliott Designs (YouTube) – 3rd year MENG Student
    • #9909
      lindelium18
      Member

      @diyaudiphileelliottbridge

      Ha ha, I don’t know if I’d go THAT far. Plenty of my mistakes in just this build alone are too well documented for me to say “I know my stuff” but I truly do appreciate the input.  If I had to do it over again, I’d probably choose a different tweeter. This one specifically did not measure like the factory specs which was disappointing. I may exchange it for another of the same and see if I just got a dud but I’m getting close to the return window… 

    • #9910
      Elliott
      Participant

      @lindelium18

      What tweeter is it? I’ll have a look for you. 


      Elliott Dyson – Elliott Designs (YouTube) – 3rd year MENG Student
    • #9911
      lindelium18
      Member

      It is the HiVi RT2C-A Planar tweeter from Parts express. Factory test shows relatively flat from about 6k up to 18.5k and about 1db drop to 20k. My results have a big 9db drop from 9k to about 14.5k. Then about a 3db rise and fall from 14.5k to 20k. 

    • #9924
      Elliott
      Participant

      @lindelium18

      Unfortunately if those were more spiked then it could be they were filtered out when doing the graph smoothing which they all do. You can see how much they smoothed it out next to the graph.


      Elliott Dyson – Elliott Designs (YouTube) – 3rd year MENG Student
    • #9961
      123toid
      Keymaster

      @123toid you were right. My 1k – 2k rise was (is) coming from the woofers but at this point, there’s very little chance I’m going to change it since I’d have to change the components not only on the woofers, but also the mid. 

      It’s up to you, but if you have a 10uF cap I would try to replace the 5.6 with a 10, I think that will help your rise.  If you don’t have a 10, you could put two 5.6 caps in parallel to give you an 11.2uF just to try. 


    • #9964
      lindelium18
      Member

      @123toid

      Yeah, I actually decided to basically just start all over. I found a work around for my measuring error on the woofers so I re-designed the crossover for all three and re-used any components I could (not many unfortunately). I also took the tweeter back to PE for an exchange and see if I get the same thing.  Sounds perfect, right?

      Well, PE forgot to put one of the inductors (a big 5.5 mH) in the bag. Crap!  Well, they said they’d ship it to me for free.  Ok, patience isn’t my strong suit but ok… Then it got worse. I went to test the new tweeter before heading off to work. Guess what… dead on arrival. I hooked up another speaker just to be sure it wasn’t on my end and it was fine. So…back to PE to return this one and pick up my inductor. Unfortunately I can’t get back out there till next week probably. As the world turns I guess…

    • #9969
      123toid
      Keymaster

      @lindelium18

      Lol, ah the joys of speaker building.  If you want to send me over the raw frequency response and impedance when you take the measurements, feel free.  I’ll mess around with them to see if I can help the crossover design for you.  Or help you out if you get stuck in an area.


    • #9971
      lindelium18
      Member

      @123toid

      Just checking, is there a way to get impedance besides DATS?  Otherwise, I’d be happy to send them over to you just to see what you come up with (at your leisure of course). Once I get the new tweeter, I’ll get a new response from it and send them over. Where should I send them?

    • #9972
      123toid
      Keymaster

      @lindelium18

      There’s other ways to capture it, but you need a device like Dats to do it.  So, no.  You should be able to attach it here.  Just make it a rar/zip file or something equivalent and attach all the files on here.  If not, I’ll PM you my e-mail.  But if you put them on here, others might also be able to chime in. 


    • #9974
      tvor-ceasar
      Moderator

      If you have a computer, Audacity, and a good amp you trust as your reference amp, then you could use this method.

      http://sound-au.com/tsp.htm

      As a matter of course, I suggest most people here take a gander at this whole site. So much goodness to absorb.

      Use Audacity to create a slow sweep and take note of where the impedance starts to rise, peaks and flattens back out, then you can plot them and use Word or some other type of program that does graphs to plot up the curve.


    • #9976
      123toid
      Keymaster

      @tvor-ceasar

      Cool. I didn’t realize that was an option. That’s why I love this forum!


    • #9977
      tvor-ceasar
      Moderator

      We are not “All Knowing”, but as a collective, we know A LOT. 😀


    • #9980
      tvor-ceasar
      Moderator

      Then watch this video  by HexiBase and it’s follow up, then the one labeled Measuring Woofer Break-in. Lots of T/S formulae there and how to use them.


    • #9982
      123toid
      Keymaster

      I forgot about this one.  BUt this guy shows you how to built your own Dats module for pennies on the dollar. 

      https://www.avsforum.com/forum/155-diy-speakers-subs/1340740-lilmikea-s-diy-impedance-measurement-jig.html


    • #9984
      imcokeman
      Participant

      Well I just spent a little time reading schematics and posts about that impedance tester, and the lilmike mic.  I don’t really have any projects in mind that I need to make these, but I wouldn’t be surprised if I end up ordering some parts anyway haha.  I feel like I’m close to starting down a slippery DIY speaker slope.  Still have a car to wrench on as a project though.  

    • #9985
      tvor-ceasar
      Moderator

      I know I’ve seen something like the LilMike box in the past. You’re talking 10-20 years ago, at least, so don’t expect a pinpoint from me. I do know I was contemplating doing a computer hookup via either Serial Port or Parallel Port. Would have been the 386 or the Win98 computer, both ran QuickBasic which would have accepted the inputs. 

      Hrmmm…


    • #10046
      lindelium18
      Member

      Im not sure “hurray” is even close to what I shouted when I finally got a respectable frequency response to come out of this center channel!  The lows are there. (Most of) the highs are there! Vocals sound good and forward. And it even hits low too. I’m happy enough with it at this point (I’m not opening this thing up…ever) that I started finishing it; which is a pleather wrap in black. Once that is all wrapped up (see what I did there) she will be finished. Then, a short hiatus waiting for my DATS V3 and hopefully a response from hexibase before I start on my next two projects…entries for MWAF 2020. 

    • #10053
      lindelium18
      Member

      Fully finished. Grill cloth matches the room. Held on by magnets.  For never doing it before, I’m happy with the pleather wrap!  Thanks to everyone for their help along the way, especially @123toid

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