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  1. #1

    Arrow I want to build a good reference MTM setup centered around the W4-1320SJ

    Since the Line Array is on the back burner until tax return comes and I can get the drivers I really want, I'm going to move forward for now with an MTM tower build. Im hoping I can get a really good result by adding a few drivers to some of the stock I already have.

    I have a few of these and I really like the midrange clarity on them as well as the W3 version (which I have a pair of sitting here as well)
    W4-1320SJ : http://www.parts-express.com/pe/show...number=264-847

    I haven't seen distortion performance on the W4 bamboo cone, but the W3 version has rising HD from 300hz and down. Of course, it also has 0.5mm xmax as compared to the W4's 3mm That said, I love the sound of these bamboo/paper cones and I think they should make for an interesting project.

    My first order of business would be choosing the tweeter and bass drivers to mate up with these guys. They have a pretty good sensitivity at 89db 1w/1m.

    I have a pair of XT25's coming my way as well. Would they have enough output to keep up with the dual W4's? Other tweeters I have been considering are these:

    BG Neo3PDRW http://www.parts-express.com/pe/show...number=264-735

    HiVi RT1.3 http://www.parts-express.com/pe/show...number=297-412

    AC G2Si http://www.parts-express.com/pe/show...number=276-400


    For bass duties, I really would like to try the Usher 8955A as Ive wanted to for some time. The 7" version tested pretty darn well for FR and HD on Zaphs site, but I'm unsure if one woofer is enough or if I'd need to double up on them. 4 of those could end up stretching the budget beyond what I want to spend.

    Other considerations are:
    Dayton RS270 http://www.parts-express.com/pe/show...number=295-368

    Or perhaps a pair of these-
    Peerless 830634 http://www.parts-express.com/pe/show...number=299-245


    Any other recommendations/thoughts/concerns? Thanks as always for any input offered.

  2. #2
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    Default Re: I want to build a good reference MTM setup centered around the W4-1320SJ

    Quote Originally Posted by captainobvious99 View Post
    Since the Line Array is on the back burner until tax return comes and I can get the drivers I really want, I'm going to move forward for now with an MTM tower build. Im hoping I can get a really good result by adding a few drivers to some of the stock I already have.

    I have a few of these and I really like the midrange clarity on them as well as the W3 version (which I have a pair of sitting here as well)
    W4-1320SJ : http://www.parts-express.com/pe/show...number=264-847

    I haven't seen distortion performance on the W4 bamboo cone, but the W3 version has rising HD from 300hz and down. Of course, it also has 0.5mm xmax as compared to the W4's 3mm That said, I love the sound of these bamboo/paper cones and I think they should make for an interesting project.

    My first order of business would be choosing the tweeter and bass drivers to mate up with these guys. They have a pretty good sensitivity at 89db 1w/1m.

    I have a pair of XT25's coming my way as well. Would they have enough output to keep up with the dual W4's? Other tweeters I have been considering are these:

    BG Neo3PDRW http://www.parts-express.com/pe/show...number=264-735

    HiVi RT1.3 http://www.parts-express.com/pe/show...number=297-412

    AC G2Si http://www.parts-express.com/pe/show...number=276-400


    For bass duties, I really would like to try the Usher 8955A as Ive wanted to for some time. The 7" version tested pretty darn well for FR and HD on Zaphs site, but I'm unsure if one woofer is enough or if I'd need to double up on them. 4 of those could end up stretching the budget beyond what I want to spend.

    Other considerations are:
    Dayton RS270 http://www.parts-express.com/pe/show...number=295-368

    Or perhaps a pair of these-
    Peerless 830634 http://www.parts-express.com/pe/show...number=299-245


    Any other recommendations/thoughts/concerns? Thanks as always for any input offered.
    I've used both the XT25 and RT1.3, and have heard everything else listed but the RS270/Peerless/Usher 8955.

    The mids on the 1320 are really good, and some even call it a full-range driver with the typical lacking top-end performance. Such as this, it will meet all the tweeters you have listed.
    XT25 @ 2.3 kHz, 12dB elec + LCR minimum.
    RT1.3 @ ~2.8 kHz, LR4 acoustic minimum, and easy with LR slopes. I used LR6 at 3 kHz.
    BG3 @ 2 kHz, LR4 acoustic minimum
    AC G2Si @ ~3.5 kHz, 4th-acoustic minimum.

    My vote is with the Ushers, but if you want higher sensitivity, a pair is a must. If you don't mind a little less, padd the 1320's a smidge, and all of the above will likely work and keep up with them.

    Later,
    Wolf

    PS- MAD has the RT1.3 in stock, while PE does not. http://www.madisound.com/catalog/pro...oducts_id=1483
    PPS- be advised the FR plot on MAD's site for the RT1.3 is not the one supplied by HiVi, and looks like the RT1C-A instead. The real plot is much smoother, here:
    Last edited by Wolf; 01-23-2010 at 07:17 PM. Reason: availability...
    "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
    "We don't just make a crossover, we make a statement!" - Lawrence Fishburne for Cadillac

    *InDIYana 2014 event*

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

  3. #3

    Default Re: I want to build a good reference MTM setup centered around the W4-1320SJ

    Thank you Wolf for the very helpful, detailed response.

    Im thinking I will go with the XT25's since I got a nice deal on them and they are already on their way. This will also leave a few duckets in my wallet to perhaps double up on those Usher 8955A's.
    Assuming that ends up being the route I go, would a 250hz LR2 be a suitable cross point between the 8955a and the W4, or would you go a little higher?


    I am still interested in trying those RT1.3's as well at some point (thanks for posting the off-axis plot). Perhaps I'll do another set down the line utilizing them with the W3 bamboo version, or the W4-1337 I have as well. Might even be able to mate them up with a pair of Peerless 830667's I have sitting in the basement...


    -Steve

  4. #4
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    Default Re: I want to build a good reference MTM setup centered around the W4-1320SJ

    Quote Originally Posted by captainobvious99 View Post
    Thank you Wolf for the very helpful, detailed response.

    Im thinking I will go with the XT25's since I got a nice deal on them and they are already on their way. This will also leave a few duckets in my wallet to perhaps double up on those Usher 8955A's.
    Assuming that ends up being the route I go, would a 250hz LR2 be a suitable cross point between the 8955a and the W4, or would you go a little higher?


    I am still interested in trying those RT1.3's as well at some point (thanks for posting the off-axis plot). Perhaps I'll do another set down the line utilizing them with the W3 bamboo version, or the W4-1337 I have as well. Might even be able to mate them up with a pair of Peerless 830667's I have sitting in the basement...


    -Steve
    If you use 250 Hz, the mids will not have any excursion issues, but at that slope, I don't know what the 8955 will be doing. The SS 8545K and the cousin Usher 8945 both I hear use/require a notch to tame a resonance mode in the driver in most cases. I'm not even sure where that mode lies, but that is something to consider that maybe a slightly steeper slope might dismiss unnecessary parts.

    I'll bet the RT1.3 and the W4-1337 would be great together! Add a good woofer, and you might have a Mini-Statement-competitor.... with half the cost in tweeters.
    Later,
    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
    "We don't just make a crossover, we make a statement!" - Lawrence Fishburne for Cadillac

    *InDIYana 2014 event*

    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

  5. #5

    Default Re: I want to build a good reference MTM setup centered around the W4-1320SJ

    Quote Originally Posted by Wolf View Post
    If you use 250 Hz, the mids will not have any excursion issues, but at that slope, I don't know what the 8955 will be doing. The SS 8545K and the cousin Usher 8945 both I hear use/require a notch to tame a resonance mode in the driver in most cases. I'm not even sure where that mode lies, but that is something to consider that maybe a slightly steeper slope might dismiss unnecessary parts.

    I'll bet the RT1.3 and the W4-1337 would be great together! Add a good woofer, and you might have a Mini-Statement-competitor.... with half the cost in tweeters.
    Later,
    Wolf
    Hmm...good to know. I can use an active electronic crossover unit I have to do some testing before hand. No problem with doing a LR4 at that point either.

    Thanks.

  6. #6

    Default Re: I want to build a good reference MTM setup centered around the W4-1320SJ

    So I downloaded, and have been playing with the PCD tool the last day or two mainly just trying to figure it out. Reading, making adjustments, reading more, etc.
    Below I'll post what the project looks like thus far and hopefully some of you fellas will be kind enough to give me some direction and advice. I plan on doing some more reading on loudspeaker design and crossover building as this is all new to me. I got started into the audio hobby years ago through automotive installations, which are a tough nut to crack in their own right because of the extremely unforgiving nature of the environment. Anyway, I'm excited to learn whatever I can along the way here as I build my first (hopefully) decent quality reference set.

    I mostly was focusing on trying to get a smooth frequency response and it looks fairly flat thus far. Who knows what errors or adjustments I'll need to make once you all have a look at it though
    The setup is MTM plus 2 woofers below. Woofers in parallel as they are a lower sensitivity, and mids wired in series.

    Drivers are:

    Tweeter: Vifa XT25TG30-04
    Mids: (2) Tang Band W4-1320SJ
    Woofers: (2) Usher 8955a

    One question I do have is this: I came up with a woofer box volume of 60 liters tuned to 30hz for what appears to be a smoother rolloff with an F3 around 36hz . Does this program take into consideration BOTH drivers as there are two listed in the project page, or does it model PER driver? 60 liters seems small for a (2) 8" driver vented cabinet...

    Anyway, heres the graphs. Looking forward to some feedback. Thanks !



    -Steve






  7. #7
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    Default Re: I want to build a good reference MTM setup centered around the W4-1320SJ

    What's with the 1 ohm impedance on the tweeter?

    Did you enter z-offsets or are the driver's acoustic centers aligned in the box design?

    Did you model the baffle diffraction for the mid and tweet?

    The zobel on the woofer is unnecessary.

  8. #8

    Default Re: I want to build a good reference MTM setup centered around the W4-1320SJ

    Quote Originally Posted by Kapton Planet View Post
    What's with the 1 ohm impedance on the tweeter?

    Did you enter z-offsets or are the driver's acoustic centers aligned in the box design?

    Did you model the baffle diffraction for the mid and tweet?

    The zobel on the woofer is unnecessary.

    You're right...Looks like the impedance for the tweeter is way off...

    I know I set the points correctly when I did used the SPL Tracer...bummmer. Guess I'll have to redo them and relaod those .zma files. Thanks for the heads up.

    As for your other question, I'm not sure how to model for diffraction. Perhaps you can explain?
    The driver vertical offset is 119mm/-119mm center to center from the tweeter to both mids in this model. There is no offset for Z axis depth set.

    Admittedly, I need to do some more reading on baffle step and how to properly compensate for it in this type of design.

  9. #9
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    Default Re: I want to build a good reference MTM setup centered around the W4-1320SJ

    I had a "strange event" with PCD a while back that showed a 1-ish Ohm response curve for my tweet that... was baffling. I tried to replicate the error, but it was not the FRD/ZMA files. While this wasn't so, at least visually in the tool, it was almost as if there was a resistor sitting in the "L" segment of the LPAD, but without one inline. That would generate an anomaly in the impedance curve fo sho. Never happened again...

    Joe.
    New to speaker design? Click here.

  10. #10
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    Default Re: I want to build a good reference MTM setup centered around the W4-1320SJ

    Quote Originally Posted by captainobvious99 View Post
    As for your other question, I'm not sure how to model for diffraction. Perhaps you can explain?

    There is no offset for Z axis depth set.
    Jeff Bagby's Frequency Response Modeler will combine the baffle response with your traced frd. Just remember to save the combined response, then use the same program to extract the minimum phase from the file and resave.

    In PCD, the z offsets are positive numbers, indicating that the acoustic center of a recessed or cone type driver is farther away from the reference point(listener). So a 4" mid might be 0.013 and a 8" woofer might be 0.035 (in meters).

  11. #11

    Default Re: I want to build a good reference MTM setup centered around the W4-1320SJ

    Quote Originally Posted by Kapton Planet View Post
    Jeff Bagby's Frequency Response Modeler will combine the baffle response with your traced frd. Just remember to save the combined response, then use the same program to extract the minimum phase from the file and resave.

    In PCD, the z offsets are positive numbers, indicating that the acoustic center of a recessed or cone type driver is farther away from the reference point(listener). So a 4" mid might be 0.013 and a 8" woofer might be 0.035 (in meters).
    And is that measured by the thickness of the frame edge so that the driver sits flush to the baffle or is there another specific method for determining that? Thanks

  12. #12
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    Default Re: I want to build a good reference MTM setup centered around the W4-1320SJ

    Please read these:

    http://techtalk.parts-express.com/blog.php?b=74
    http://techtalk.parts-express.com/blog.php?b=81

    This will help you to understand how to setup the files, and answer your recent Q.
    Later, hope this helps,
    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
    "We don't just make a crossover, we make a statement!" - Lawrence Fishburne for Cadillac

    *InDIYana 2014 event*

    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

  13. #13

    Default Re: I want to build a good reference MTM setup centered around the W4-1320SJ

    Thanks Wolf (and others). The guide pages you have there are a nice help

    Well, I worked out a few of the kinks and made a few changes. This latest graph does not include baffle diffraction simulation correction yet as I haven't decided on the baffle dimensions of the enclosure just yet. That should hopefully be coming shortly though...I just need to wrap my head around how I want it to look cosmetically. I did add estimated z-axis dimensions though as required.

    I did this graph as an active crossover setup as that is likely what I will end up using. I have come to enjoy the flexibility an active crossover setup provides from using them in my car audio endeavors. Some of the mindset behind this is that I can make small tweaks on the fly if I feel its necessary after listening, or if something with the setup changes. Also, an active crossover can be setup to be used on several different speakers so if/when I build more sets beyond this, it will allow me to save money on component costs. Audibly, I havent heard a significant difference between active and passive crossovers so that for me is a moot point.

    I also changed up the crossover points slightly. The latest revision has them set at 200hz and 2500hz, both at LR4. The midranges and woofers are both wired in parallel, and the midranges have a -2db stepdown in gain to level overall frequency response. Some of this may change after all other factors are considered though. Thus far, this looks like it could be a very nice combination. After some modeling of the woofer enclosure/volume, it looks like the box modeler likes a 30hz tuning with appx 40 liters of airspace for the Usher's. This yields an F3 around 36hz. What I don't know, is if the program is modeling that for ONE driver or two which is what i have in the main page of the simulation. Ive got to think its for a single driver as WinISD was showing closer to 75 liters for a pair.

    Anyway, here are the current graphs...any thoughts/comments/suggestions thus far? The total impedance looks too flat. What am I missing here?








  14. #14
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    Default Re: I want to build a good reference MTM setup centered around the W4-1320SJ

    Your system impedance appears to be flat at about 1 ohm. I would hope that is a mistake....

    And- your woofers are a whole meter away from the tweeter??

    Wait a minute- There aren't any xover values in that sim!!! I think you missed something somewhere....
    Later,
    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
    "We don't just make a crossover, we make a statement!" - Lawrence Fishburne for Cadillac

    *InDIYana 2014 event*

    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

  15. #15
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    Default Re: I want to build a good reference MTM setup centered around the W4-1320SJ

    It was a little too blurry for me, but looking at it, you just explained why it has the ultra low system impedance. Without the xover values set, all the drivers are being run in parallel, generating the low 1 ohmish response.

    The other problem is that he is misinterpreting the distance to be in inches and not meters. You can spot this on driver responses when they have the strange repeating humps.

    Joe.
    New to speaker design? Click here.

  16. #16

    Default Re: I want to build a good reference MTM setup centered around the W4-1320SJ

    Quote Originally Posted by Wolf View Post
    Your system impedance appears to be flat at about 1 ohm. I would hope that is a mistake....

    And- your woofers are a whole meter away from the tweeter??

    Wait a minute- There aren't any xover values in that sim!!! I think you missed something somewhere....
    Later,
    Wolf


    They were crossed over using the active filters on the other side of the page that isnt visible. Crossover points are 200hz and 2500hz, both LR4.

    Im not sure what the deal is with the summed impedance graph there... If you look at the individual impedances they look normal. Perhaps something got a little goofy with the program in the summed Z window? I'll try starting it from scratch again with the same zma and frd files and see if it was just a fluke. Doesnt make sense that it would come out like that

    As for the woofer spacing... I like the look visually when the woofers are vertically offset from the mtm a bit. In this case, I'm shooting for about 12" or so spacing between the bottom mid and the first woofer. That would put center to center spacing of the bottom woofer to the tweeter at about 35" if I get everything else about as compact as I can. In this model, the distances are closer to 40" CTC with the driver spacing used.
    Im not solid on enclosure size/shape just yet as I'm still learning and playing around with the Baffle Diffraction Simulator to see what effects are caused by the various positions of the drivers and the baffle characteristics.

  17. #17

    Default Re: I want to build a good reference MTM setup centered around the W4-1320SJ

    Quote Originally Posted by joekraska View Post
    It was a little too blurry for me, but looking at it, you just explained why it has the ultra low system impedance. Without the xover values set, all the drivers are being run in parallel, generating the low 1 ohmish response.

    The other problem is that he is misinterpreting the distance to be in inches and not meters. You can spot this on driver responses when they have the strange repeating humps.

    Joe.
    Does the active crossover filter section, when used, not generate a proper summed impedance curve in the window or am I missing something ?

    As for the driver distances, they appear as I expected.
    The mids are 0.119 / -0.119 meters (4.685" CTC spacing from tweeter)
    The woofers are 0.742 meters and 1.015 meters from tweeter CTC spacing, appx 29" and 40" respectively.

  18. #18
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    Default Re: I want to build a good reference MTM setup centered around the W4-1320SJ

    Quote Originally Posted by captainobvious99 View Post
    Does the active crossover filter section, when used, not generate a proper summed impedance curve in the window or am I missing something ?
    Hmm. Don't have it in front of me to try. The 1 ohm impedance is a sign that something is off, but I haven't tried it with active xover, so don't know.

    As for the driver distances, they appear as I expected.
    Well, it was a little blurry to me, so if you know it's meters, I'll assume you got it right.
    New to speaker design? Click here.

  19. #19
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    Default Re: I want to build a good reference MTM setup centered around the W4-1320SJ

    I guess if you're amping/xovering separate, the impedance is a non-issue, as they will be independent.
    Later,
    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
    "We don't just make a crossover, we make a statement!" - Lawrence Fishburne for Cadillac

    *InDIYana 2014 event*

    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

  20. #20

    Default Re: I want to build a good reference MTM setup centered around the W4-1320SJ

    Quote Originally Posted by Wolf View Post
    I guess if you're amping/xovering separate, the impedance is a non-issue, as they will be independent.
    Later,
    Wolf
    Makes sense. Thank you.


    Next up will be enclosure/baffle design. I think I'd like to try something a little bit different than the standard boxy enclosure. I'll try to work on some sketch-ups and see what I come up with.

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