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Discussion Starter #1
My Zaph ZD3C Center Channel Project (Working slowly on my 5.1 system.)

I upgraded my house a few months ago and the family room was wired for 5.1 sound with speaker wires provided through the walls in the right places. I have been planning on replacing the existing JBLs that the last owner left in place and update the system a little at a time. I bought the Onkyo 605 this Summer first before anything else and it was a great upgrade from my 30 year old amp. Now I am working on the speaker system.

I have been building speakers using PE enclosures because I do not have wood working tools right now. When it comes time for the front baffle treatment, I need to locate a local wood working shop for the speaker holes and routing to countersink the speaker baffle so that the speaker will mount flush.

I am not a speaker expert but with great DIY speaker plans available including cabinet and cross over designs and knowing enough about electronics to read schematics and put the components of a cross over together, I have been successful in building a few speakers for my personal needs.

In my first speaker project, what I built was based on Dillon Acoustics ‘THE EGO’ (http://www.zalytron.com./HiqKits.htm) using a pair of PE TWC-0.38BK 0.38 ft3 2-way, Curved Cabinet, Gloss Piano Black book shelf speakers, a matched pair of high end HIQUPHON OWII tweeters and a pair of Focal 5 1/4 inch 5W 33211B W-cone Woofer-Mid-bass drivers with a crossover frequency of 2200Hz providing an excellent SPL vs Frequency from 150 HZ to 15K Hz. I chose the cabinet (¾ MDF side and back with a ¾ MDF brace running vertically up the sides and across the top and bottom and a 1 inch front baffle with curved sides to provide a curved interior which provided for better strength and better acoustics by reducing standing waves/resonance. These are now my right and left front speakers in my 5.1 system in my family room.

Tweeters: http://www.ellisaudio.com/hiquphon.htm
Woofer/Midrange: http://www.zalytron.com/Specs/5W3211B.pdf
PE TWC-0.38k: http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=302-711
Crossover was optimized by Dillon for these components.

I desperately needed a good center speaker for my family room 5.1 system so after a lot of research; my current project is the Zaph ZD3C Center Channel Option for his ZDT3.5 system (http://www.zaphaudio.com/ZDT3.5.html). I have bought all the materials and I am coming to that point where I once again have to span the gap of finding a woodworking shop to prepare the front baffle for me. I can’t take it to my last shop because the owner enlisted in the army and was shipped off to Iraq last week. In reading Roman J. Bednarek’s audio innovations web site (www.rjbaudio.com) he presented an idea he used to bypass the need for a router. He uses thin wood or Masonite as a front mounted ‘thick’ veneer covering the front baffle through which he cuts the appropriate holes to fit around his surface mounted speakers. This allows the speakers to become flush to the front of the baffle and after painted would look fine.

I thought ah-ha! This could be my saving grace for my projects since I would like to be able to do everything myself – alright – I don’t make the cabinets but the ones I have bought from PE have been very nice and worth the price and I can cut holes with my jig saw.

Reading a lot of information from this forum and following lots of links, I know that diffraction can occur at the boundary of the speaker frame and the baffle it is mounted on. Roman indicates that the effect of diffraction on the frequency response is a constructive and destructive combination of waveforms that produce dips and peaks in the audible response. The frequency at which these dips and peaks occur is based upon the distance between the edge of the driver diaphragm and the edge of the driver frame so counter sinking the drivers is necessary if you want optimal performance, which I do.

Using Roman’s idea, all I need is a jig saw to cut holes and I am home free. But his solution made me think of an alternative that might be even be easier to reduce the diffraction caused by the driver frame and the speaker baffle.

Here is where I need the experts in this forum to provide some assistance and feedback on my idea. I don’t know if this has been done before but what if I simply surface mounted the drivers on the front baffle and then used thin black felt cut to the same size as the front speaker baffle. With this, I would then cut out each speaker frame hole with scissors and lay the felt over the speakers onto the baffle. The felt could then be glued flat to the surface of the baffle. I might be able to find felt to the thickness I needed or if not, just layer several sheets until the thickness is matched.

The advantages would be that I could precisely cut the felt holes with scissors to exactly mate with the edge of the speaker frame and also match the exact thickness I need to make the entire surface flat. The disadvantage is that it might not look as nice as precisely cut and finished wood baffles but then, while it might look different, it might not look objectionable and from a distance might not be that noticeable.

Conceptually, this appears to meet the standard of eliminating the differences in height between the speaker frame and the baffle.

My questions are these:

1. Does anyone see a reason why this would not work?
2. As the surface of the front baffle would now be felt and not hard wood, what effect might this have on the overall speaker performance, if any?
3. Might the absence of visible hard wood on the front side of the baffle, which might also contribute to diffraction, resonance and other negative sound properties, be reduced or eliminated by using the felt?

Right now, I have bought the center channel cabinet from PE (Dayton 1.0 cubic feet gloss black) and speakers but PE is backordered on the RS52 2” Dome Midrange until the end of November so I sit and wait. I have applied tape to the front baffle and drawn the locations of the baffle holes. I used tape to protect the baffles during cutting and routing of my first speakers and have done the same on this one. At least this helps to position and draw for hole cutting. I will go look for felt next weekend and see what thicknesses and stiffness is available.

I also have completed the crossover. I like to hot-glue parts on a piece of Lexan for fitting inside the box.



I tried it out wiring it to my speakers on the table and after listening to a lot of music and test sounds, felt that the balance between the midrange and woofers was not quite right. The woofers were underperforming compared to the mid-range. So I re-read Zaph’s right-up and saw that the woofers are sensitive to the inductor DCR and that the woofer circuit L16 inductor provides variability to the woofers based on its DCR. I had originally used the default 1.5 mh inductor (PE – part 255-426) with a DCR of 0.38 so I looked to see what other inductors were available with a lower DCR. I choose the Jantzen 1.5mh toroidal inductor (PE – 255-804) with a DCR of 0.049. The results were immediately noticeable and very dramatic to my ear and this brought the woofers perfectly into balance with the mid-range. I will have to confirm this again when my RS52 midrange is delivered but I am very happy with this adjustment using the temporary mid-range.

For frequency testing of the speaker setup I used an audiometer testing page (http://www.phys.unsw.edu.au/jw/hearing.html) on my computer to provide input audio at selected frequencies thought the crossover to the speakers. The resulting frequency response range I heard for each speaker (woofer, mid-range & tweeter) were very close to those specified in the crossover response curves in the Zaph speaker plans.

The ND20 sounded smooth and blended nicely but it’s frequency response from PE looked a little ragged so I tried a Tang Band 25-302SH 1” dome tweeter just to see how it sounded. As I went back and forth between listening to the ND-20 and the Tang Band, in the end I decided it was a little too harsh and stuck with the smoother ND-20.

I don’t have sophisticated tools to do this theoretically so I rely on the original developer’s schematics and my ear since the designers have put a lot of time and energy into developing the speaker plans and the person I need to please is me. In this case, however, I felt compelled to experiment to get the balance right (to my ear) between the mid-range and the woofers. In the end, the change I made seemed to be the right way to go. Also, the little ND-20 is perfect for this center channel and combination of speakers.

I like DIY projects but I don’t think I qualify in the same league as you guys but I sure appreciate reading about your projects and skills in ‘creating’ some great speakers.

I don’t know what to do about my sub-woofer needs. I currently have a 10” Athena AS-P4100 which I picked up mail order for about $100.00 6 months ago. It looked like they were going out of business or this was discontinued. I know that I could have done a lot better for twice the price but I needed to fill a hole in my system and this fit my price range. I knew also that I would eventually upgrade this to something better than the $250.00 price range so this filled the bill without over spending. Eventually, I will move this to my office. It seems to work well but I know the stuff that I see being built here is far superior. I think that this would be my next project when my funds accumulate enough. I would like to have an enclosure that is not too big and massive and yet use a 12 inch driver in the $500.00 price range.

Update: PE's delivery date for their Midrange speaker is pushed out to end of December. Rats! I want to finish this. Anyone got a Dayton RS52AN-8 2" Dome Midrange they could part with?


Usil
 

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Congrats on what appears to be a great center channel.I 'm curently in the process of building a pair of Zaphs ZMV5's.I think your idea of using felt is a good one and should work as good as flush mounting.I have done this around tweeters in my pre router days and if you look at a naked Vandersteen you'll see that they do this as well.I would think that that thickness of felt will have some absorbtion at the very highest frequencies but not enough to alter the tonal balance of the system.

Good luck with your build.
 

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Discussion Starter #3
Well, after PE just set the due date for the RS52s ahead to March 2009, they emailed me this morning that they had arrived. I got my RS52 mid-range on the way and I hope to finish this project next week. I will take more pictures when I get the baffle cut and start assembly.

Usil
 

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Discussion Starter #4 (Edited)
Re: My Zaph ZD3C Center Channel Project - All Done with Pictures

My Zaph ZS3C center speaker project is completed. After several months waiting for PE to get their backordered RS52 2” midrange dome driver speaker in I can finally complete this project.

Putting the cross-over together. When I tested the cross-over I found that the mid base was a little weak to my ears so I replaced the default Jantzen 15 ga. air core inductor in the woofer circuit with a DCR of 0.38 ohms with a 14 Gauge C-Core Toroidal Inductor with a DCR of 0.049 ohms. I liked this tweak and, to me, it provided a much better blend with the RS52AN-8 mid-range. I also upgraded the capacitors in the woofer circuit to audio grade. I kept these changes in my final assembly.



Here it is in the assembly stage. It does not show but I had the rear holes for the 2 - RS180S-8's champhured to allow more breathing room behind them.



Here it is on the desk for a final check of fit. I had the front baffle holes and routing done by a wood shop for me as I do not have the tools.



Done at last and moved to my family room. As you can see I opted to have someone cut my speaker holes. I will leave the felt experiment for a later project.



A few more views.





A close-up on the shelf.



My front speakers are from Dillon’s Acoustics – The Ego design plans using the Focal 5W4252 and Owl2 speaker design.

My current sub-woofer is an inexpensive, now discontinued 10” Athena AS-P4100 which I bought cheap. My sub-woofer project will be later this year.

I am currently in the progress of designing my rear surrounds.

So, how does the Zaph center channel sound. It is heaven to my ears but I realize any subjective review is just that. I had an old JBL on the shelf being used as a center channel for about 6 months. So this is definitely an improvement. Since it is so high, I positioned it angled down toward the sitting area of the family room. The tweeter is in the lower position as recommended for this project when it is above the TV. I will need some time to listen to it but I have played a number of CDs and tried several movies to see how they sound. The clarity of speech and the separation of the musical instruments is well noted. It certainly is a worthy addition to my slowly growing 5.1 system.

Usil
 

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Very nice, Usil! The new speaker looks great, as does your room. Your center speaker looks higher quality than most of the commercial units I work on. I really like the built-in alcove for the TV and center speaker.
 

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Thanks, the speaker sounds great and I am very satisfied.

The built in alcove is pretty standard on new homes today but they are really unfinished as they are and as you see it. I am planning on a cabinet maker to come in this summer and finish it so it does not look like a mish-mash. Has anyone else done this and have pictures of what it looks like finished? I have a vague idea of what I want there but am still looking for design ideas.

Usil
 

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Great job, it looks fantastic and I am sure it sounds the same. Congrats....:T
 

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I don't know the weight of the speaker but I would estimate it was about 20 to 25 pounds. The total cost for components was about $350.00. Well worth the price. I listened to a lot of center speakers at the local audio shops and this one would easily fits well with the commercial ones at double the price. Plus this was a fun project to do. Nothing like the anticipation of getting everything right and seeing the final project perform well.

Usil
 

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I don't know the weight of the speaker but I would estimate it was about 20 to 25 pounds. The total cost for components was about $350.00. Well worth the price. I listened to a lot of center speakers at the local audio shops and this one would easily fits well with the commercial ones at double the price. Plus this was a fun project to do. Nothing like the anticipation of getting everything right and seeing the final project perform well.

Usil
thanks for the reply. I'm thinking of doing this build or rjb's mtm 2.5 build myself. I'm not a music listener, How is the clarity of voices during home theater use?


I've been reading your sub build and enjoyed it a bit.
 

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Discussion Starter #13
The center channel is a speaker that is generally designed specifically for the TV and Home theater.

Zaph designed the crossover to be optimized as a center channel meaning that it is optimized for voice for listening and clarity's sake for a home theater or TV. Thie Zaph ZD3 design has a different crossover if it is for a right or left front speakers where the crossover setup fully extends the frequency range to the low for this design.

For listening, the listener generally sets the amplifier to optimize for either TV/Theater or music. In both cases, music/Rtside-Lt side stage sounds are divided to the right and left speakers so the center does not need to play the full lower range which is channeled to the rt/lt and the sub.

I find that these are very clear and do not have trouble with voice or present a muddy sound making you say 'what was that he just said... like my wife and I used to do with the old speaker I used. This is a credit to the crossover design, speaker selection and the fact it is a three-way speaker.

As I said before, this has proven to be a great design. I have been listening to them for many months every day and they meet my every expectation.

Usil
 

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The center channel is a speaker that is generally designed specifically for the TV and Home theater.

Zaph designed the crossover to be optimized as a center channel meaning that it is optimized for voice for listening and clarity's sake for a home theater or TV. Thie Zaph ZD3 design has a different crossover if it is for a right or left front speakers where the crossover setup fully extends the frequency range to the low for this design.

For listening, the listener generally sets the amplifier to optimize for either TV/Theater or music. In both cases, music/Rtside-Lt side stage sounds are divided to the right and left speakers so the center does not need to play the full lower range which is channeled to the rt/lt and the sub. btw, I appreciate your take on output of your build as it convinced me to do this.

I find that these are very clear and do not have trouble with voice or present a muddy sound making you say 'what was that he just said... like my wife and I used to do with the old speaker I used. This is a credit to the crossover design, speaker selection and the fact it is a three-way speaker.

As I said before, this has proven to be a great design. I have been listening to them for many months every day and they meet my every expectation.

Usil
I'm slowy gathering the parts. There's some question I have about the crossover design, I don't understand the red resistors in the diagram. Maybe i'll have to reread the writeup again as if I haven't, hahahaha.

Usil, If i got further questions on this build(especially the crossovers schematic) could you help me out, but its a project 3 month down the line.
 

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Discussion Starter #15
If you have questions let me know. The red resistors in the diagram are not purhased or installed resisters rather they are the natural resistance of the inductors components you use in the crossover build. The cross over is a sensitive electronic component and you have to take the resistance values of the inductors into consideration as they can impact the overal operation.

Read the write up again. I printed it out and studied it for a long time before I started the project or bought any components. Then just build it as he has indicated and you will be fine.

Usil
 

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Usil from your experience/usage of the ZD3C, does this build play well at low volumes as to clarity or does it need mid to high volume gain to shine?

My system will be strictly for HT usage and would use this CC with future Modula MT's build for front L/R and currently owned small surrounds. I hope it matches well but I really want clarity for the CC as you have described.

thank you in advance for you take on this
 

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Discussion Starter #17
I don't know if you can get any closer to your understanding of what these sound like in a discussion. These have been built by many using them for home theater with satisfaction. You will simply have to try the build. I can tell you that I have observed no negtatives with this design at any volume.

I have been there at this point where a decision has to be made and all you can do is review all the comments from all the builders. At some point, you just have to go for it. This is a proven design by someone who knows what he is doing and he has been kind enough to share his designs in the public domain.

Usil
 

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Usil,

I'm still in the process of gathering the parts for my build and the major get right now is the crossover parts within a month and half.

As I view your pics I noticed that the interior of the cabinet is lined with carpet pad, is that correct? I've checked out Whispermat and P.E.'s sonic barrier and they are way expensive for my taste(shipping costs to Hawaii is the deal killer). From reading Zaph's build instructions I don't remember him stating any stuffing material to use. I've read for sealed enclosures you'd stuff it with polyfil(or something like that) and for ported enclosures you'd use sonic barrier/whispermat on the interior walls. I'm thinking since the Zaph ZD3C is a sealed enclosure fiberglass from HomeDepot would do. Currently I have the Energy Take 5 CC and openned it up and found its filled with an inch thick of pink fiberglass, of course its a small sealed box and there's not much room in there on the rear panel(as it has the crossovers) to attach any type of mat
 

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Discussion Starter #19
I use carpet pad to deaden the wood to make it neutral. This prevents the box from acting as a sound conduit or to resonate at certain frequencies. There are other materials and as you said they are costly which is why I use 1/2 inch carpet pad attached using spray on contact cement.

For my sealed speakers like the center channel, I also use a polyfil stuffing. I follow others recomendation on this and I modify amount based on trial and error or in other words what sounds best to me. Fiberglass is supposed to be good in sealed boxes but I like to avoid handling it.

If you do a search on this you will find many opinions but the good thing about DIY is you can try for yourself to see what the effect is.

Good luck with your build.

Usil
 

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I have been "shopping" for a DIY center channel to go a long with my Natalie P's. You have done a very nice job making this system shine. The finished product turned out very nice.

Kyle
 
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