Suggestions sought on new kit design

Discussion in 'Archived Threads 2001-2004' started by Mark Hayenga, Jul 9, 2001.

  1. Mark Hayenga

    Mark Hayenga Supporting Actor

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    Hi guys,
    I'm in the process of designing a new speaker, to be released as a free kit plan. Since I hope some of you will eventually get to enjoy this, I'm entertaining suggestions on their design.
    The goals I've decided on so far are:
    Flat frequency response
    Low distortion
    Midrange clarity
    Good off-axis response
    High power handling
    Bass extension & output capability
    I'm willing to sacrifice:
    Box size (by which I mean putting up with large cabinets)
    Efficiency
    To this end, I've decided that a three-way speaker would likely be the best option to satisfy these requirements. Presently, I'm thinking about using a Morel MDT-30 tweeter, a Peerless 850108 midrange, and a Peerless 850146 10" woofer
    The tweeter is already decided upon as I've already ordered and tested the pair for this project. I've been eyeing the Peerless drivers largely because of my experience with their excellent 850439 6.5" HDS midbass. The CSX units are very similar technologically to their HDS brethren and have been favorably reviewed by several folks who I trust. Throw in the recent Madisound price reductions and they've got a reasonable amount going for them.
    But that's not to say this is in any way final (save for the tweeters), and I'm very willing to entertain other options or recommendations as to the design of this speaker and/or the drivers chosen for it.
    As it stands, the driver cost per side would be roughly $150, a complete pair with crossovers likely $450. Not cheap, but a reasonable price for a good floorstanding three way. I could also try to make this kit compatible with one of the prefabricated enclosures on the market (ie Madisound Woodstyles or the like) for those without access to extensive woodworking equipment.
    Any thoughts/ideas/recommendations?
    Mark Hayenga
     
  2. Julian Data

    Julian Data Second Unit

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    Hi Mark,
    What will the XO characteristics entail?
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  3. ThomasW

    ThomasW Cinematographer

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    quote: Any thoughts/ideas/recommendations? [/quote]
    Say goodbye to poly and the cone break up modes.
    Say hello to a good Kevlar, Carbon fiber, ceramic driver... [​IMG]
    Just my $.02, (it plus another $2.48 will get you a latte')
    Regards
    Thomas
     
  4. Mark Hayenga

    Mark Hayenga Supporting Actor

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    Hi Julian,
    Crossover design will entail building the actual cabinets, and measuring on the actual cabinets the quasi-anechoic frequency response of the individual drivers (both on and off-axis), their acoustic offsets, their impedance, and their distortion.
    Once all that is done appropriate crossover points will be picked and target acoustic responses decided for each unit. Various crossover networks will be optimized such that each individual driver is appropriately level matched (such that its passband sensitivity matches that of the other drivers) and such that its roll-off(s) match their target acoustic responses. Acoustic offsets will be taken into account and proper phase response (for the type of crossover being used) will be achieved. Once this is done the crossover is emulated via software simulation and the speaker will be actively triamplified for evaluation. Should it not meet with approval, the process is repeated - with possibly new crossover points, different slopes, adjusted output levels of individual drivers, even possibly new cabinets, and so forth until a pleasing unit is simulated via the emulation process.
    Once the crossover has been simulated with good results an actual test crossover will be built and measured to ensure that the simulation was indeed accurate, and that the final result sounds as expected. The final speaker will be measured for on and off-axis frequency response, input impedance, and distortion.
    As for what I'm anticipating in this actual design with the drivers mentioned, based on my experience with Morel tweeters I will likely use a fairly low crossover point between the midrange and tweeter, probably between 2kHz and 2.5kHz. I will also likely use a very steep filter for this crossover, with a 6th order Linkwitz-Riley or an Elliptic crossover very likely (~10th order rolloff slopes within an octave of the crossover, asymptotically converging to 4th order rolloffs as you get away from the crossover point). For the midrange-woofer crossover, I will likely locate the woofer very near the floor and place the crossover point near 200Hz to alleviate floor bounce cancellations (something I've always hated about two-ways). The order of this crossover will be at least 2nd order, and perhaps higher depending on cost analysis (the inductors with higher order filters get real pricey, I can't even remember seeing a design with >2nd order filters between the mid and the woofer, but I'll look into it).
    To accomplish this I will be relying heavily on computer aided measurement and design software, specifically Liberty Audiosuite and LspCAD PRO. For the past year I have been working with two local friends that I met on the basslist to assemble a small audio company, but with all of us working day jobs as hotshot engineers our plans have been put off indefinitely. As such I find myself with access to all the measurement and design equipment we've acquired over the last year, as well resources I have available at UT, and I'd like to do something with it. There's also a little bit of personal pride involved [​IMG] but I'd really like to see and affordable, high-quality kit available 'to the masses' so to speak, for a reasonable sum of money (of which I'd have no financial interest in).
    ------------------
    Mark Hayenga
    www.hayenga.com
    ----------------------
    "Saru mo ki kara ochiru"
     
  5. Mark Hayenga

    Mark Hayenga Supporting Actor

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    Say hello to a good Kevlar, Carbon fiber, ceramic driver...
    I definitely agree that there are benefits to the advanced cone materials (we both know of my affection for the Seas mags [​IMG]). Are there any drivers with such in this price range that would work? I'm trying to keep the midrange cost under fifty bucks or so. The Seas alums might work, but I'm actually not that enamored of using them (no cool motor technology [​IMG]).
    One of the reasons I like the Peerless drivers in this price range is I've found them to sound significantly better than other poly drivers I've used/heard in this class (mostly Vifa, Seas) (though the Seas T17/T14 drivers might come close, though I guess they're not exactly poly). We did some sinusoidal distortion tests on those 6.5" HDS drivers, and they performed quite admirably (less than 1% THD from 200Hz to crosspoint (2kHz) in the speaker they were used in). I certainly agree that there's better to be had in the area of midrange clarity with different cone materials, it's the pricetag attached to it that worries me... I'm also hoping that running the bass driver up to ~200Hz will help things out by taking a lot of the stress off the midrange (my last set of two-ways used a full 6dB of baffle step compensation, and sounded lovely, but midbass distortion set in way before the tweeter started to complain...)
    Thoughts?
    ------------------
    Mark Hayenga
    www.hayenga.com
    ----------------------
    "Saru mo ki kara ochiru"
     
  6. ThomasW

    ThomasW Cinematographer

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    Mark
    Although I've never used them, MCM has a woven carbon fiber stamped frame 6.5" (55-1545) $26ea, and a woven kevlar, with phase plug, cast frame 6.5" (55-1585) $52ea.
    Note, my catalog is dated, so the prices are probably slightly higher.
     
  7. Mark Hayenga

    Mark Hayenga Supporting Actor

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    Also, any thoughts on the woofer?
    Thought of another requirement for all drivers: they must be round. The MDT-30 is a wide dispersion tweeter and is significantly affected by diffraction, so things will need to be flush mounted. I don't want first time builders having to hassle with flushmounting non-round driver frames (which nixes one of the other mids I was thinking about, the Focal 4211 [​IMG] ).
    Thomas,
    I'll head on over to MCM and check out those drivers.
    ------------------
    Mark Hayenga
    www.hayenga.com
    ----------------------
    "Saru mo ki kara ochiru"
     
  8. ThomasW

    ThomasW Cinematographer

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    The quick and dirty workaround for nonround drivers is first surface mount them; then using a saber saw cut a masonite plate the shape of the driver frame and glue it to the baffle. This also stiffens and dampens the baffle.
    What's the budget for the woofer?
     
  9. Seungsoo Hwang

    Seungsoo Hwang Stunt Coordinator

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    What ever happened to those Fiberglass SA071(?) drivers you posted pictures of before, the yellow ones?
     
  10. Mark Hayenga

    Mark Hayenga Supporting Actor

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    Seungsoo,
    Those are also in the works. I have the drivers for that project here already, and hope to begin work on them sometime in the next few weeks. I've already begun working with John on crossover plans for guys who 'just can't wait' [​IMG] using Steve Sedmak's Clio measurements of the drivers, but without having a completed speaker here for me to test these designs are really only starting points for people to tweak on their own (as well as serving to highlight some new ideas I've been playing with for ultra low cost yet effective crossovers). That kit will be aimed more at the budget market (along the lines of the Bang! or Pop! kits from Adire). I'm shooting for a driver + crossover cost of under $150 for a pair of two-way MTMs, versus a likely driver + crossover cost of $450 for the kit being discussed in this thread.
    Thomas,
    Again, fifty-ish bucks. We played with the 850146 and it was fairly impressive, used in an isobaric setup w/passive radiator. But, I've no experience with its competition so it's still up in the air. I'm also thinking of going sealed on this project, something with a sub 50Hz Fc if possible, to reduce crossover interactions with the box-loading induced impedance spikes. I need to find some way to export impedance data from T/S sims so I can start playing with ideas for LF alignments and crossover points before buying drivers or deciding on bass alignments... I played with some measured data we took on various bass drivers and tried to implement a decent lowpass crossover (such as if they were a woofer in a three-way), and as I tried to push the woofer lowpass crosspoint below 200Hz the woofer impedance spikes became very troublesome (stupid voltage division). I figure going about stuff this way might prevent any "Doh!" or "Argh!!" events later on when developing the woofer lowpass (and maybe even the mid highpass... ooh, more stuff to think about).
    I'm not even building stuff yet and this three-way is interesting . Sweet [​IMG]
    BTW, the MCM page was kinda skimpy on the details on those mids. Do they get a better write-up in the print catalog?
    ------------------
    Mark Hayenga
    www.hayenga.com
    ----------------------
    "Saru mo ki kara ochiru"
     
  11. ThomasW

    ThomasW Cinematographer

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    Mark
    6.5" woven carbon fiber, FR 30-6Khz no plot just the numbers, 8ohm, 86db, 1.357" VC, 17.7oz magnet, Qts.39, Vas 1.14 cu ft, Fs 32Hz.
    6.5" woven kevlar, FR 100-14Khz, 94db, 8ohm, 1.25"VC, 29.9oz magnet, Qts.55, Vas.23, Fs 111Hz.
    That's all, I think they will provide complete T/S specs on request
     
  12. Hank Frankenberg

    Hank Frankenberg Cinematographer

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    Mark, tell me more about your hate for two-ways. My experience is that they're the best-sounding D-I-Y's I've heard (I've built seven bookshelf and two tower 2-ways). That said, my caveat is value for the money. Not just one less driver per side to buy, but also simpler, less expensive crossovers. Also, passive crossovers are a big constraint to accurate reproduction, so I believe you have to have a great crossover design with high-quality (expensive) components to do a three-way right.
    Don't discount a non-round driver. Since this is your higher-quality design, I think D-I-Y'ers would put up with routing the flat areas if the result is better sound than with similarly-priced round drivers.
    What T-S parameters would you like in your mid and wolf? I'll check my source.
    Lastly, I would definitely listen to the counsel of Thomas. Go for it - sounds like a great project. You're getting so good, UT will probably give you that EE degree after only three years [​IMG]
     
  13. Mark Hayenga

    Mark Hayenga Supporting Actor

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    Aww, c'mon Hank, you know I don't hate em [​IMG] They're all I've spent the last year or so on, and their simplicity is definitely a plus to achieving with a pleasing system - I've tried to talk many a DIYer into taking that route for that very reason. But after working on a half dozen or so two ways with Scott and Jonathan this past year, and picking up lots of knowledge from them in the process, two-ways are getting too easy. I'm also starting to become more nit-picky about the areas in which they don't do so well, namely power handling and distortion, and especially midrange clarity at high levels. Floor bounce/dip is also another shortcoming that not everyone thinks about (until they have a problem with it), which can be fixed with a three way design.
    I did a lot of thinking about large, two-way MTM's and TMM's before deciding the only way I was going to achieve the output and distortion levels I want is with a three-way. I really want something that can impart the proper scale to music, as well as fidelity.
    The three non-round drivers I'm considering are the HDS version of the CSX mentioned, the 5.25" Audax aerogel, and the Focal 5NV4211. Scott's got the 6.5" aerogel in a two-way that I'm plan on listening to before any decisions are final, and I need to look into those MCM drivers Thomas mentioned.
    As for the bass driver... I've no real T/S specs in mind, it just needs to work in 70L or less, with a voltage sensitivity of 87dB or so. Shooting for an f3 anywhere from 30-40Hz, vented or sealed (again, I just need to assemble a list of quality drivers and consider the trade-offs involved with each. The mental conception of this design is still 'in the works'). I also need to look into acoustic loading considerations before deciding on a woofer, having it at a floor boundary might introduce some issues.
    PS - I also plan on releasing the two-way I emailed you about as a free kit in the near future, so there will be a two-way available for folks who want to go that route.
    ------------------
    Mark Hayenga
    www.hayenga.com
    ----------------------
    "Don't worry, Oburi will be home soon..."
    [Edited last by Mark Hayenga on July 10, 2001 at 03:00 PM]
     
  14. Hank Frankenberg

    Hank Frankenberg Cinematographer

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    Okay, go for the SPL's young man! I want to hear more about floor bounce/dip (some other time). You might look at this 8" woof - it's the one in my 2-way towers:
    http://speakerpage.com/S08911.htm
     
  15. Dan M~

    Dan M~ Second Unit

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    Mark,
    Have you posted over at the Madisound board? Dennis Murphy and the rest dispense some good advice on two and three way cross-overs and recommended drivers. There is some "net noise" going on over there right now, but if you ignore those posts you can get some VERY good help from the regulars.
    I highly recommend those guys (gals?).
    -Dan
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    -Dan M~
    My Small Collection
     
  16. Scott Quick

    Scott Quick Agent

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    I can personally, very highly recommend the Peerless 850146 10" driver. I'm familiar with it in a 3.3ft^3 with rear mounted port alignment with acoustic foam inside for eliminating standing waves... I've come to prefer this over Acousta-Stuff or fiberglass stuffing for ported alignments. The best sounding *ported* woofer I've EVER heard.
    As for the midrange, its a little over budget, but the Morel MDM-55 is a great dome mid, and the Peerless has a good enough response to cooperate with a high frequency rolloff (say ~600Hz 2nd order).
    I'd also like to recommend the Seas P17/REX 6.5" for midrange. The Xmax isn't all that impressive, but using a 200Hz+ xover point as you stated would probably be adequate for a design... I'd probably go to ~300Hz personally. It has a much better midrange section than the Vifa P17, however the Vifa has a much better bass section... there are always trade offs [​IMG]
    I've come to prefer Seas fabric domes over Vifa also. Seas tends to have a better mix of "airyness" and "sweetness." The 27TFF or the Excel T-001 would be my recommendations.
    Hope this helps and doesn't throw too many wrenches in the pile [​IMG]
    Good luck, and please keep us updated!!
    Scott
     
  17. Mark Hayenga

    Mark Hayenga Supporting Actor

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    Hank,
    Thanks for the driver rec's. As for working for Bose, they're going to have to make a heck of an offer to get me away from AMD [​IMG]
    Dan,
    Frequent lurker at the Madisound board, and chatted with Dennis a time or two via email. I haven't posted there yet, but I likely will before I decide on a midrange.
    Scott,
    Thanks for the review! I think I'm going to go ahead and finalize the 850146 as the woofer for this project. $63 for that woofer is a tremendous bargain given that, for a reasonable improvement over it, it looks like I'd have to go with a Scan-Speak or Lambda (and that isn't happening within this budget...)
    We also favor the Seas tweeters (specifically the 27TFFC) over the Vifa softdomes (D27TG-35, -45), but when it comes to power handling and detail I haven't found anything that tops the Morel MDT-3x stuff without jumping to uber-expensive tweeters. They cost a little more, and tend to have a little 'bite' if you're not careful with the crossover design, but done properly can be quite smooth sounding.
    Now all I have to do is figure out how having a side-firing woofer at the floor boundary will going to affect its measured sensitivity, then pick my mid with that in mind... hmmm...
    ------------------
    Mark Hayenga
    www.hayenga.com
    ----------------------
    "Don't worry, Oburi will be home soon..."
    [Edited last by Mark Hayenga on July 12, 2001 at 01:37 PM]
     
  18. ThomasW

    ThomasW Cinematographer

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    If you're going to use a side firing woofer, then the "mid" better go solid to 50Hz for use with a 100Hz XO point. Otherwise you'll have a hole in the response curve [​IMG]
     
  19. Scott Quick

    Scott Quick Agent

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    Double ditto what ThomasW just said... I didn't realize 'til just now that you wanted to do a side firing configuration. If this is the case, I think you'll probably want to move up to an 8" or have a really steep rolloff for the 6.5" HDS Peerless. I don't think it'll handle the "high power" very well being crossed over at 100Hz. Just my $.02
    HTH,
    Scott
     

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