Announcement

Collapse
No announcement yet.

Parts Express Low cost DIY Home Theater Project

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • Parts Express Low cost DIY Home Theater Project

    UPDATE: This project did finally get finished. However, it is not a low cost HT system. See : "Finally the AC54Alpha Has Life". To match the quality of the finished speakers I just upgraded my Yamaha RXV353 receiver to an Emotive surround processor plus bigger amplifier. The result is astounding but the cost may be prohibitive. That said, I like it.

    I've seen several DIY home theater setups but nothing ready to go from parts easily obtainable sources. Since I'm in the process of building just such a setup I'll post what I have so far with the goal being an un assembled parts list that requires almost no cabinetry (you will have to route speaker holes either with a hole saw or a router) or measuring equipment, just a small place to work and some good DIY common sense. Since the intent is to produce a complete low cost home theater system, including sub woofer, any advice will be welcome.

    Sub woofer goal:
    Sub woofers abound and in HT use are basically a woofer in a box with a separate amplifier. Other than choosing the driver for the enclosure there is little additional real engineering since crossover is dealt with in the amplifier and receiver/processor. However, there is always the voice of experience. Knowing what you don't want is more than half the battle. Sub will be covered in separate posts, assuming this is more than my own personal meanderings. I currently am using a TC sounds EPIC 12" in 3 cu ft ported box tuned around 23 hz and it sounds fine. It's still settling but I do need to rebuild the enclosure to a different shape and reduce it to about 2.5 cu ft to reduce extension in my small room. This is an expensive woofer. A less expensive option would be a TUBA folded horn coffee table. A Fitzmaurice "TABLE TUBA" would be a great low cost 8" sub for HT use and it doubles as a coffee table or ottoman.

    Satellite goal:
    Satellites in a home theater need to be as large as possible to produce as much air movement as possible yet as small as possible to reduce space and wasted transducer size at the same time. The THX, DOLBY, SDDS and DTS are 5 and 7 speaker standards engineered for a multi speaker theater sound system with a crossover point of around 80hz and generally state that no program material lower than 120Hz should go to the satellites. While in the real world things seem to work best when we stay close to this standard there are notable exceptions such as older DVD's with only 2 or 4 channel soundtracks. Thankfully most decoders know how to either turn off the speaker without any input or mix down the side channels through a voice filter to produce a reasonable center channel. With this basic information in hand the goal is to build satellites, including a center channel, that will produce the best quality sound for the least amount of money.

    Parts express has a small array of finished cabinets at reasonable prices. Since this will be a parts-list kit, I'll begin by choosing a suitable woofer and it's complementary enclosure. ... Oh look, I'm already done.

    Woofer choice:
    Visaton W130S 8 Ohm. Chosen for it's cost, reasonably smooth frequency response, power handling and f3 performance. In a quarter cu ft enclosure the visaton easily gets below 80 hz but not so far it's wasted to use a crossover. Measured f3 in a .23 cu ft knock-down cabinet is almost exactly 80hz. It will be slightly lower than that in any of the finished .25 cu ft Dayton Audio enclosures available on Parts Express. This woofer also comes in a 4 ohm version that has a slightly different mid-range profile but it's close enough we could use them in series for a center MTM arrangement with only slight changes to the crossover provided we find a tweeter that will cross low enough to prevent any mid-range issues. A center speaker with a dip at could be a disaster. The FR of each can be seen 8Ohm and 4Ohm

    Tweeter choice:
    The goal is to use a tweet that can be easily mounted with nothing more than a 2" hole saw so those are the options I've looked at so far. So far I've debuted 3 tweeters. A Beston RT003 round ribbon, a Vifa BC25SC06 and I'm currently waiting delivery of a Vifa XT25SC90-04 dual ring tweeter for testing. All 3 are below $25 making them ideal for en-masse speaker making. Tweeters are a little more difficult to choose for this duty. There is such a vast array or them available it would take years just to read all the specs. But since this is a low cost goal, cost becomes the initial guideline followed closely by FR extension and third by smooth response. After trying the Beston I gave up before I even mounted it. It requires extensive and tricky router gymnastics to make it fit and seal in 3/4" material and it won't cross low enough to make it usable with the 4 Ohm Visaton in an MTM arrangement so it's a gonner. I toyed with the idea of using it as a topper but gave up on that idea due to cost. I've listened to the BC25SC06 and although it's decent tweeter I think we can do better for the price. The ring tweeters are a new design that, so far, get rave reviews. With an fs below 1K this tweet will easily cross around 2.5K for low power applications assuming it doesn't sound gritty going that low. The BC25SC won't cross at 2K without sounding like it has a speck of dirt stuck in it so it's on the sideline for now. If the XT25SC90 lives up to it's rave reviews it will make an excellent low cost HF driver for this project. Also on the drawing board is one of the new ceramic dome tweets like the Tang Band 25-1719S or its bigger brother the 25-1744S 1" Ceramic Dome Tweeter. Both are near $30 but probably worth it. Anyone having direct experience with one of these in HT use? The comments on the Vifa page make the Vifa XT25 sound a little weak for this application. Generally speaking HT does not drive a speaker for very long at one time. Movies generally have loud passages and lots of dialogue so high power handling is not usually an issue. But, there's nothing worse than having a tweeter heat up and gag in the middle of a long gunfight.

    Crossover:
    As always with my philosophy I'll try a 1st order first and only if It won't work will I go to a more elaborate crossover. Generally speaking I also keep similar orders. If tweet gets second order, so does the woof. My experiments indicate that the more total capacitance and inductance used in a crossover the more phase shift and the less detail and stereo imaging one hears. The BC25 sounded OK with a first order crossover (7.5 mfd) around 4K (1 mh on woof) with an L-Pad to match output but I noticed more than a bit of sibilance. Phase was beautiful with less than 360 deg (270 or so) over the entire spectrum and no woopies except at woofer res. The BC25 also has a hot spot above 10k that is probably not the cause of the sibilance but it certainly adds to it. A second order didn't help and covering the tweet with my hand during voice removes the spitting so either it's an interaction between the tweet and the woof or it's the tweet itself. Those are the reasons I've chosen to try a newer, supposedly smoother tweet.

    Cabinets:
    Dayton Audio/Parts Express has a plethora of cabs of the correct size for this project. Choose a square or tapered .25 cu ft for the front/back and either a .38 or .50 or the MTM. The .38 has slightly less extension but modeling and my testing indicates it would not be overly thick near roll off. It would sound a bit fuller though. A square cab might be better for center channel unless it's going to hang on a wall but then the smaller enclosure will probably sound better due to wall gain. The Visaton W130 extends very flat from 4K down in .23 with a barely noticeable bump before roll off so the .25 finished cabs will be nearly perfect. Add a small single wrap of damping on back and one side of cab and you're set. The only thing I don't like about the finished cabs is the connectors. They come pre-drilled for through-back screw connectors but the connector cups (like PE#260-276) have spring clips and a crossover board mount built-in making them very easy to use. The only issue is the plastic back increasing box losses. I'd like to be able to provide a crossover board PN and components complete with spade connectors that slips neatly into the spring-clip cup. Makes crossover wiring a breeze.

    Thumb is my current test box, comments are encouraged.
    Attached Files
    Last edited by siggma; 09-25-2013, 11:11 PM.
    Tom

    NEW CNC Site http://cnc.trbailey.net/
    My Projects BLOG http://speakers.trbailey.net/

  • #2
    Re: Parts Express Low cost DIY Home Theater Project

    Placing the tweeter on that edge probably isn't optimal, but since it's a test box you could test.

    Comment


    • #3
      Re: Parts Express Low cost DIY Home Theater Project

      If you had to pick which statement was more correct MOST of the time, between:

      a) 1st order crossovers CAN work.
      b) 1st order crossovers NEVER work.

      The correct answer would be "b". Sorry, but true. Truth of the matter is that a coil won't roll off a woofer's rising impedance, unless you use a Zobel, and THAT's more like a 2nd order since you've got a cap to ground. Also, a tweeter's impedance peak at Fs precludes a single cap delivering any kind of transfer fn that looks like a first order should (with a "shoulder" - or knee, at Fc).
      Last edited by Chris Roemer; 12-20-2012, 06:10 PM.

      Comment


      • #4
        Re: Parts Express Low cost DIY Home Theater Project

        I try not to deal in absolutes except when absolutely necessary. There are cases where electrical roll off is less relevant or even irrelevant and first order crossovers work fine. There are cases where one needs only to protect a driver from spurious amplifier noise to prevent a launch of tweeter bobbins across the room. One will never know without trying. That is the point of existence, isn't it, to try? There is no substitute for personal experience.

        So do you have any personal HT experience you might like to contribute or did you just stop by to pick some nits? The project could use some experience in the form of ideas. Specifically tweeter suggestions in the 1" range that will cross low with the Visaton W130.
        Tom

        NEW CNC Site http://cnc.trbailey.net/
        My Projects BLOG http://speakers.trbailey.net/

        Comment


        • #5
          Re: Parts Express Low cost DIY Home Theater Project

          Originally posted by kmibb View Post
          Placing the tweeter on that edge probably isn't optimal, but since it's a test box you could test.
          Meaning the top edge?
          Yea, it was not a good idea. I was thinking more of getting tweet close to woof than what was on top of it. Originally I was going to mount two different tweets which placed the woof at the bottom of the enclosure. When I removed one I just moved the woof up without thinking. Ah, the value of mistakes is immeasurable.
          Tom

          NEW CNC Site http://cnc.trbailey.net/
          My Projects BLOG http://speakers.trbailey.net/

          Comment


          • #6
            Re: Parts Express Low cost DIY Home Theater Project

            Originally posted by siggma View Post
            So do you have any personal HT experience you might like to contribute or did you just stop by to pick some nits? The project could use some experience in the form of ideas. Specifically tweeter suggestions in the 1" range that will cross low with the Visaton W130.
            Clues to Chris's experience lie in his posting count and join date. He certainly did not stop by to pick nits. A little less defensiveness works better around here.
            -- Doug

            Comment


            • #7
              Re: Parts Express Low cost DIY Home Theater Project

              FYI, this really should be in T T. Interesting project. I am with chris though in that a higher order cross is simply going to work better. It will allow the drivers to integrate much better and protect the tweeter.
              My Facebook audio pagehttps://www.facebook.com/pages/Mosai...3888294?ref=hl

              Comment


              • #8
                Re: Parts Express Low cost DIY Home Theater Project

                Originally posted by siggma View Post
                I try not to deal in absolutes except when absolutely necessary. There are cases where electrical roll off is less relevant or even irrelevant and first order crossovers work fine. There are cases where one needs only to protect a driver from spurious amplifier noise to prevent a launch of tweeter bobbins across the room. One will never know without trying. That is the point of existence, isn't it, to try? There is no substitute for personal experience.

                So do you have any personal HT experience you might like to contribute or did you just stop by to pick some nits? The project could use some experience in the form of ideas. Specifically tweeter suggestions in the 1" range that will cross low with the Visaton W130.
                Chris happens to be one of the friendliest contributors on TT. He often designs crossovers for free, for those less technically inclined. He has also contributed some great designs that are so popular, you can buy the kits on the web. His experience has saved countless members money & time wasted. Feel free to wing it on your own, but don't bash someone trying to help.
                Audiophiles listen to the equipment, not the music.

                Comment


                • #9
                  Re: Parts Express Low cost DIY Home Theater Project

                  Originally posted by isaeagle4031 View Post
                  FYI, this really should be in T T.
                  Why TT? This is a project, or is this more a showroom forum rather than an ongoing project forum? I read a few but there are thousands of threads and tens of thousands of comments...
                  Interesting project.
                  I wish someone had done this already when I came looking to build a better speaker. I'm replacing a set of KEF C1 "tangerine" loaded tweet bookshelf speakers. I don't know what they were thinking but I hate that tweeter. Very flat and "unmusical". No timbre.
                  I am with chris though in that a higher order cross is simply going to work better. It will allow the drivers to integrate much better and protect the tweeter.
                  As for crossovers, higher orders are often necessary for decent results but I'm still a minimalist and opinions don't necessarily help the project move along. It sounded like a "hey you're doing that wrong" without even a constructive suggestion, what I characterize as a nit pik. I've been alive probably longer than most people here but that doesn't make me an expert at life nor does it entitle me to make useless comments. I'm not being defensive just practical. I ask for suggestions and get opinionated comments without useful suggestions. The project could use concrete suggestions that help produce a better sounding, less expensive, easier to assemble project. Any suggestions for a low cost tweet that would be acceptable for HT use?
                  Tom

                  NEW CNC Site http://cnc.trbailey.net/
                  My Projects BLOG http://speakers.trbailey.net/

                  Comment


                  • #10
                    Re: Parts Express Low cost DIY Home Theater Project

                    This is a Gallery, meant for pictures and links to writeups and build-sagas. Questions go in TT.

                    The 6dB filters work, but not without LOTS of conjugate shunting filters, and end up usually MORE complex than higher order filters to be optimal.

                    Mods- please move this thread.
                    Wolf
                    "Wolf, you shall now be known as "King of the Zip ties." -Pete00t
                    "Wolf and speakers equivalent to Picasso and 'Blue'" -dantheman
                    "He is a true ambassador for this forum and speaker DIY in general." -Ed Froste
                    "We're all in this together, so keep your stick on the ice!" - Red Green aka Steve Smith

                    *InDIYana event website*

                    Photobucket pages:
                    http://photobucket.com/Wolf-Speakers_and_more

                    My blog/writeups/thoughts here at PE:
                    http://techtalk.parts-express.com/blog.php?u=4102

                    Comment


                    • #11
                      Re: Parts Express Low cost DIY Home Theater Project

                      Originally posted by Steve Henry View Post
                      Chris happens to be one of the friendliest contributors on TT. He often designs crossovers for free, for those less technically inclined. He has also contributed some great designs that are so popular, you can buy the kits on the web. His experience has saved countless members money & time wasted. Feel free to wing it on your own, but don't bash someone trying to help.
                      His experience is good to know, when the time comes for crossovers. Hopefully he'll contribute his expertise. The question was regarding a suitable tweeter for HT use, not whether or not I use first order crossovers. Rather than this becoming a personality thing can we focus on TWEETERS? Specifically for Home Theater use. That includes 4-6 satellites and probably an WTW center speaker. I'm trying to overcome the harsh less-than-musical sound I'm hearing from the KEF C1 set I purchased. Now that I have more experience I realize I need sealed enclosures for satellites or I'll never get good, tight, well time aligned theater sounds. And the question is still open...
                      Tom

                      NEW CNC Site http://cnc.trbailey.net/
                      My Projects BLOG http://speakers.trbailey.net/

                      Comment


                      • #12
                        Re: Parts Express Low cost DIY Home Theater Project

                        Originally posted by Wolf View Post
                        This is a Gallery, meant for pictures and links to writeups and build-sagas. Questions go in TT.
                        Sorry, mods will hopefully move this.

                        The 6dB filters work, but not without LOTS of conjugate shunting filters, and end up usually MORE complex than higher order filters to be optimal.

                        Wolf
                        Ok ok, I got it. They also tend to make it more difficult to hit a crossover target on a less than smooth mid or woof. I'm not a professional at this and I'm looking for tweeter suggestions. Ask me about computers and I'll build one from scratch in 15 minutes but I'm not an audio engineer, just a hobbyist. I'm learning about conjugate filters. The Vifa BC25SC06 for example needs a "conjugate" to tame the top end of its FR. It sounds harsh, especially on digitally reproduced material which includes nearly everything in HT. No vinyl stylus or output matching transformers will ever grace the golden terminals of a home theater speaker.

                        If I seem snooty I apologize.
                        Tom

                        NEW CNC Site http://cnc.trbailey.net/
                        My Projects BLOG http://speakers.trbailey.net/

                        Comment


                        • #13
                          Re: Parts Express Low cost DIY Home Theater Project

                          I'm going to disagree with a few things here. Doesn't mean that I'm picking on you, or being disrespectful... it just means that we don't agree. Disagreements are fine as long as we remain civil towards each other.


                          Originally posted by siggma View Post
                          ...any advice will be welcome.
                          I'm glad that you started off with this statement. Most folks here on TT are happy to offer advice and suggestions.

                          Originally posted by siggma View Post
                          ... Other than choosing the driver for the enclosure there is little additional real engineering since crossover is dealt with in the amplifier and receiver/processor.
                          Sure the active crossover helps, but there are still plenty of other things to address in a well executed sub-woofer design. I would suggest running some simulations to evaluate various tuning options like Ported VS. Sealed VS. Bandpass VS. Transmission Line VS. Passive Radiator, etc...


                          Originally posted by siggma View Post
                          ...Satellites in a home theater need to be as large as possible to produce as much air movement as possible yet as small as possible to reduce space and wasted transducer size at the same time.
                          I had to re-read this one a few times, and I still don't quite get what you're saying. Are you recommending full-size or compact speakers for the rear channels?

                          Originally posted by siggma View Post
                          The THX, DOLBY, SDDS and DTS are 5 and 7 speaker standards ... ... generally state that no program material lower than 120Hz should go to the satellites.
                          Hmmm... Modern receivers typically have Bass management capabilities that allow you to pick the speaker size (Small/Large). This is their way of limiting the amount of bass going to the speaker. e.g. - The tiny 4" woofers in some surround speakers just can't handle the power and cone excursion associated with a full-bandwidth signal. Effectively, it's just a HP filter at about 80 Hz to 100 Hz. Please correct me if I have this wrong... We would normally want all five channels in a 5.1 setup to be full-bandwidth. However, when using small speakers, the bass can be selectively removed by utilizing the bass management's "Speaker Size" options. Does my statement conflict with your statement?

                          Originally posted by siggma View Post
                          (crossover comments) Generally speaking I also keep similar orders. If tweet gets second order, so does the woof.
                          I couldn't disagree more with this statement. Sure it's possible that the electrical slopes end up the same. (e.g. - 2nd order LP, 2nd order HP) But that decision depends on many factors, including phase... both electrical and acoustic. Please don't assume the LP and HP filters will be the same 'order'. If you want the Woofer and Tweeter to integrate smoothly you must pay attention to their phase response at the XO freq. (and for an entire octave above or below the XO freq... sometimes 2 octaves above/below.) If you ignore the drivers' phase, you're destined to spend several weeks in trial-and-error mode without a clear idea of why the woofer and tweeter aren't summing correctly. My suggestion is to obtain some actual measurement data on the drivers, then use Jeff Bagby's Passive Crossover Designer to see the acoustic implications of your filter choices. Sometimes switching to asymmetrical slopes fixes everything. (e.g. - 2nd order LP on woofer, 3rd order on tweeter.) Sometimes it doesn't help at all. My point is: how do you know if you don't look?

                          Originally posted by siggma View Post
                          My experiments indicate that the more total capacitance and inductance used in a crossover the more phase shift and the less detail and stereo imaging one hears.
                          Hmmm... how can I say this without sounding arrogant or confrontational. I don't agree with your experimental results. I think that a well designed speaker system with flat frequency response and good phase tracking between the drivers will produce great sound, regardless of the "total capacitance and inductance" used in the filters. Just my opinion, it's fine if you disagree.


                          Now with all of that said, let's remember that different opinions are what make the world go 'round. Don't take my comments as criticism, they are merely another person's point of view... based on my own experiences with this kind of stuff.



                          Originally posted by siggma View Post
                          So do you have any personal HT experience you might like to contribute or did you just stop by to pick some nits?
                          Whoa... I would suggest a slightly different 'tone' if you want people here on TT to help you. Geesh.
                          ~Marty

                          Baby Eidolons
                          Sapphos
                          Cables (Post #54)
                          Other speakers (Post #21)
                          Design Thoughts (Posts: 6,10,13,33,35)
                          Boundary Augmentation
                          Dispersion/Interference

                          Comment


                          • #14
                            Re: Parts Express Low cost DIY Home Theater Project

                            Originally posted by ReissM View Post
                            I'm going to disagree with a few things here. Doesn't mean that I'm picking on you, or being disrespectful... it just means that we don't agree. Disagreements are fine as long as we remain civil towards each other.
                            Sounds like you disagree with nearly everything I wrote, which is fine. I'm pleased to see you feel free to express your opinion, but you don't want others to have the same freedom? I stand by what I said, his comment sounded like a nit pic, to me. It was off topic and not particularly helpful. The topic is building and designing a home theater system, not opinions about crossover design or opinions about opinions. I'm not offended by what he said nor do I disagree but so far out of almost a dozen posts not one of you kind folks have provided any useful suggestions or comments about the actual topic. Clearly there is more going on here at Tech Talk than my one sentence comment to someone else. I feel like I stuck my head in a hornets nest. Maybe this isn't the best place or time to ask for help.

                            Disagree about phase if you want but I also stand by the fact that the more inductive or capacitive reactance placed in the signal path of any signal processing system, the further out of phase will be the output. Whether that summed output is in final phase is relative to the different path's the signal takes on it's journey, and the individual reactance placed in each path. Inductors and capacitors produce reactance by releasing stored energy out of phase with the original signal causing reduction in output at differing frequencies until they are eventually able to store nearly the entirety of the signal, preventing nearly all of it from passing. They also distort the signal in the process of storing it and nothing on Earth can change that. A stereo image is produced by the relative arrival time of one channel compared to the other. Adding components to the signal path of a stereo system will alter it's phase characteristics and therefore it's ability to accurately reproduce a stereo image. Therefore, to me it seems only logical that the fewer components the better. I think it logical to use same slope crossovers where possible diverging only when a different slope produces more correct phase and/or FR at the output.
                            Last edited by siggma; 12-20-2012, 09:18 PM.
                            Tom

                            NEW CNC Site http://cnc.trbailey.net/
                            My Projects BLOG http://speakers.trbailey.net/

                            Comment


                            • #15
                              Re: Parts Express Low cost DIY Home Theater Project

                              Originally posted by siggma View Post
                              Sounds like you disagree with nearly everything I wrote, which is fine. I'm pleased to see you feel free to express your opinion, but you don't want others to have the same freedom? I stand by what I said, his comment sounded like a nit pic. It was off topic and not particularly helpful. The topic is building and designing a home theater system, not opinions about crossover design or opinions about opinions. I'm not offended by what he said nor do I disagree but so far out of almost a dozen posts not one of you kind folks have provided any useful suggestions or comments about the actual topic. Clearly there is more going on here at Tech Talk than my one sentence comment to someone else. I feel like I stuck my head in a hornets nest. Maybe this isn't the best place or time to ask for help.
                              With respect sir, I thought his comments were right on topic. It wasn't until I re-read your post for the third time that I realized the only question you asked concerned tweeters. Probably Chris, like I, assumed your early comment that "any advice will be welcome" meant that any advice was welcome. Sorry 'bout the confusion. -- Doug

                              Comment

                              Working...
                              X