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Considering GR AV3s, here come the questions.

Discussion in 'Home Theater Projects' started by Justin Ward, Jan 25, 2004.

  1. Michael R Price

    Michael R Price Well-Known Member

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    Danny,

    Besides the fact that 8" woofers are somewhat cost prohibitive, can you elaborate on the advantages you see in using smaller drivers in a tower format speaker? (I have not had a chance to listen to your larger speakers.)
     
  2. Hank Frankenberg

    Hank Frankenberg Well-Known Member

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    Justin, I just built a pair of A/V-3's. I built a pair for a local customer 2 years ago. The new transmission line design does indeed sound "tight" and "fast" and does go low enough (for me, that is - I augment HT with my Tempest sonosub). Low enough for you? I don't know. If you're young, listen to hard rock and ignore warnings against sustained high spl's (like I did years ago [​IMG] ), maybe not.
    Sitting beside/behind these are a pair of SCH (wwww.speakerpage.com) towers that I built 4 years ago. They are THE best value in a DIY tower, and use an in-house design 8" driver that is quite a performer for the value. It's a 2-way. It won't play "louder" than the A/V-3, but it's a budget DIY and will follow the usual formula of sounding better than commercial speakers costing 3x or whatever the price.
    If you want high accuracy, speed and soundstage, I recommend you spend the extra money on the A/V-3's. I'll try to post a photo link.
    As far as "looks" go, I personally really like the slim, deep A/V-3 tower cabinet, and that DOES mean a lot in the WAF department. Take it from a guy who has tried to sell speakers to people for quite a while and had more than 50% of potential sales shot down by the "wife" who dictated smallest, most unobtrusive speakers possible.
    I won't stick my toe in the hot water of "is a 6" driver speedier than an 8" driver" question...oh no, not me. Quality of design and crossover components are more important than driver diameter.
    I know both Danny and Dan and they both endeavor to put out the best bang for the buck and we need them both in the market to counter the likes of Bose and their marketing millions. Disclaimer: I have NOT heard the KIT281's, but having listened to hundreds of speakers in the last 30 years, IMHO the A/V-3's are the best combination music/home theater speaker I've yet heard, value-wise.
     
  3. ThomasW

    ThomasW Well-Known Member

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    Michael

    There are numerous pacific rim driver mfgrs that spec built drivers (the purchaser can pick and chose from a wide variety of cones, frames, magnets, VC's, spiders, surrounds, etc, etc, for any speaker recipe desired). When purchased in quantity, the cost difference between an 8" and a 6.5" isn't as much as one might think..........

    FYI, there's one internet/mail-order speaker company (a competitor of Danny); that buys raw driver components in bulk, and pays the local high school kids to assemble them..... [​IMG]
     
  4. Hank Frankenberg

    Hank Frankenberg Well-Known Member

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    Now THERE'S an enterprising guy - that'll squeeze the last dollar profit out of the operation. I hope he has good assembly methods docs and has taught the kids "quality at the source". Hmmm...maybe I could get kids to assemble cabinets for me..[​IMG]

    Justin, here they are. Sorry for the poor pic quality. You might think they look "weird", but speaker cosmetics are like any other "look", e.g. cars - it's a personal thing.
    http://www.geocities.com/hankbond1/AV-3.jpg
     
  5. Justin Ward

    Justin Ward Well-Known Member

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    Hank,
    I actually kind of like the look of those AV3s. The wood looks great and the grill helps a bit as well.

    I wish there was someone in my general area that had these speakers and maybe hook me up with an audition.
     
  6. Ronnie Ferrell

    Ronnie Ferrell Well-Known Member

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    Justin,

    I agree! I also think the A/V-3s I've seen before Hanks look kinda awkward. But man Hank, those look really nice. Usually I am a "no grill" kinda of speaker guy. But the A/V-3s do look better with grills. It is amazing how much the grills help to break up the long vertical awkwardness of the A/V-3. I also think the strong grain of the (rosewood?) helps a lot too!


    Great job Hank! The A/V-3s are at the top of my list to replace my A/V-1s this year. The A/V-1s will be retired to surround duty at that point.


    Ronnie
     
  7. MikeSRC

    MikeSRC Well-Known Member

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    Nice pictures Hank. I didn't know you "grew" speakers in your back yard. [​IMG]

    Hopefully, mine will look that good if I ever finish them. Between the holidays and CES, I'm just now getting some time to work on them again.
     
  8. Danny Richie

    Danny Richie Well-Known Member

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    There are numerous advantages.

    Size issue aside, if you want to clean up the sound of a woofer in the upper ranges just relieve it from having to cover the first octave.

    Everything in this area is again, full of compromises. You give up one area to get gain in another.

    You can't expect a large heavy mass woofer to pound out bottom end and be forced in and out of its gap and still be able to handle subtle details in upper vocal regions without giving up a lot.

    Most home theater systems have one thing in common. A sub woofer. Many high end audio systems use them too.

    If a sub can handle from 50Hz or so and down what do you need your main speakers to cover? Everything up from there wouldn't you say?

    This is where smaller driver can have advantages. With smaller masses to move, less stored energy and inertia, less air to have to accelerate, loaded in a way that causes impedance to rise as frequency decreases, drivers that physically won't play low, smaller lower inductance voice coils that generate much less back EMF, etc.

    You gain a lot of speed, ability for detail, extended upper end, etc.

    If crossing a woofer off to a tweeter in the 2kHz to 3kHz area I want a woofer that plays smoothly and without break up into the 6kHz range.

    This minimizes the number of components that have to be put in the signal path, which minimizes shifts in phase, minimizes smearing from the use of additional components, allows money to be used for high quality parts instead of more parts, can reduce addition inductive reactance from needing additional coils, etc.

    The result, well just read what people in this thread alone have said.

    Hey Hank, nice looking speakers man. Really nice work as usual! And thank you for passing on your views regarding the performance of our products. You to Ronnie and Jake.

    Also in regard to driver size. I best sounding, most controlled, cleanest hard hitting, lowest distortion bass I have ever heard was from a speaker that uses 4" woofers.
     
  9. Michael R Price

    Michael R Price Well-Known Member

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    OK, thanks...
    A few questions though, if you have "less air to accelerate" and "less moving mass" doesn't that also mean less sound produced? Isn't SPL a function of the overall force the driver exerts on the air regardless of size? (So a woofer with twice as much air to accelerate, would only need to accelerate that air half as much, in order to produce the same sound.)
     
  10. Danny Richie

    Danny Richie Well-Known Member

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    Is one tweeter louder than another because it moves more air?

    You need not push a lot of air to make a loud noise. Many speakers can play fairly loud and move little to no air at all, horns, planar's, electrostat's...

    You can create a loud sound by hitting an anvil with a hammer and move little air.

    You can also push a lot of air and not make a lot of noise.

    Just wire one woofer out of phase from the other. It still pushes the same amount of air but one sound cancels the other.

    Get the picture?
     
  11. ThomasW

    ThomasW Well-Known Member

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    Yes one tweeter playing louder than another, is a direct function of it displacing more air.

    Planars loudspeakers have a HUGE Sd. Therefore it's not necessary for the radiating elements to move all that far in order to displace a large amount of air.

    Horn based speakers move a lot if air, if they are playing loud

    When one hits an anvil with a hammer, one hears the sound because shockwave resonating off the anvil is displacing air. If the sound is loud a lot of air is being displaced

    Anytime air is displaced, a sound is made. How loud that sound is, is a function of how much air is being displaced.

    Yes unfortunately everyone probably 'gets' the picture.... [​IMG]
     
  12. Danny Richie

    Danny Richie Well-Known Member

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    Michael, backing up a moment, what you said or what you are getting at is also correct depending on the frequency range covered.

    In a pistonic range sound pressure level does go hand in hand with the ability to move air.

    In higher frequency ranges air is not pushed or displaced. It is excited. Like my example of hitting an anvil. I said it moves little air not it moves no air (Thomas).

    Planars do have a lot of surface area and it does take what looks like very little movement and adds it up to equal quite a bit due to the large Sd, but it is still displaces a very small amount of air. It can excite a lot of air though.

    Horns (compression drivers) get increased output from controlled directivity (compression). It keeps excited air focused in one direction.

    Its just like turning a sub-woofer to the wall. It didn't displace any more air but picked up SPL from coupling with the wall (compression).

    Now back to the original subject matter regarding smaller drivers used in the A/V-3 and giving this some context:

    The transmission line loading of the A/V-3 utilizes the back wave of the drivers as well as the front wave and sending it out in phase with the front wave.

    Kind of like Sd of the front and Sd of the back combined, because it takes advantage of the woofers moving in both directions.

    So actual Sd is not only 29.5 sq in., that the drivers are themselves, are but also 21.125 sq in. from the transmission line minus some loss to the efficiency of the t-line itself.

    It's like a 5.25" woofer times about 3.5 (per speaker) instead of times 2, at some frequencies.
     
  13. Michael R Price

    Michael R Price Well-Known Member

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    Danny,
    While we're on the topic, what would motivate one to choose transmission line over a vented alignment or vice versa? It seems a port does the same thing you describe about increasing effective driver area around Fb. (There's also a transmission line alignment for the Kit281 and no one seems to build it.) Thanks for taking the time to provide these opinions, by the way. You really don't have to... I've just been curious.
     
  14. Hank Frankenberg

    Hank Frankenberg Well-Known Member

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    Justin, Ronnie, Mike and Danny, thank you very much for the compliments. I put lots of hours into cabinets, including my secret sauce oil finish and working it in down to 1200 grit. Those are the best finish I've done to date - very smooth, but not glossy and NO polyurethane. The veneer is Rosewood, BTW (surprise![​IMG] ).
    After I harvested them out of the backyard, I took a photo inside. I'll get it on my geocities site and post a link to it.
    Michael, I bet the main reason people aren't building the T-Line version of the 281's is the greater complexity. The new A/V-3 cabinets have a lot more MDF parts to cut and mount than the prior version. There's debate over whether the additional complexity and therefore cost, is worth it.
    Uh-oh, I hope I didn't start something. The jury is instructed to ignore the last statement of the witness:b
     
  15. Danny Richie

    Danny Richie Well-Known Member

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    I haven't seen the plans, but what might scare many off from building it would be increased complexity in building it or an increase in size.
     
  16. RichardHOS

    RichardHOS Well-Known Member

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    I have to agree with Thomas here. The physics are essentially cast in stone. There is certainly a frequency/SPL relationship for a given displacement, but that doesn't negate the fact that air is still displaced at higher frequencies.

    Quite true. The SPL/displaced air/frequency relationships are relevant only at the measured position. When you extrapolate back to the source, you must take into account the radiation pattern, which will vary depending on the speaker design (dipolar, line source, point source, horn loading, etc.). The example of a subwoofer being horn loaded against a wall or corner is a good one.

    With your anvil example, you would find that the total surface area of the anvil + its amplitude of surface vibration (excursion) will perfectly predict the SPL (at the anvil's resonant frequency) at a given measuring point in space using an omnipolar radiation model.

    And yes, for a given diaphram diameter and mounting arrangement, a tweeter playing louder than another at a given frequency is also displacing more air due to increased excursion. There is naturally a trade off to using higher SD and lower excursion to achieve a given SPL at a given frequency. Doppler distortion, cone breakup, beaming and lobing error, harmonic distortion,... some get better and some get worse as you reduce excursion and increase surface area.
     
  17. ThomasW

    ThomasW Well-Known Member

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    Richard,

    Thanks............ they've invented "new math" since I was in school, but they've yet to create "new physics" :wink:

    Hank,

    Speakers look very nice. How much do you fertilize and water before they're ready for harvest? [​IMG]


    Interesting....since it's of course physically impossible to increase the measured area of a cone, (Sd), after it's been manufactured.
     
  18. Hank Frankenberg

    Hank Frankenberg Well-Known Member

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    Thomas, thanks! I wish you could see them in person. I'll try to post a better photo. Brian's been trying to get me to go with a better web host so I can post higher res photos, but I've managed quite well to procrastinate.
    My secret garden of delights requires rainwater and Tibetan Yak poop fertilizer to grow speakers.
    I just returned from our cryogenic lab and you'll never guess what the lab coat guys have done! Yep, sound waves with no excursion[​IMG] You read it here first.[​IMG]
     
  19. Danny Richie

    Danny Richie Well-Known Member

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    Your right Thomas. The measured surface diameter doesn't really increase. It is the effective use of its movement that increases output, which is "like" having greater Sd since positive pressure is being created by its movement in both directions not just movement in one direction.

    Do I need to thank you for the help?

    I sense only a get even attitude from you due to exchanges that we have had in the past.

    If you feel you have a score to settle just say so. Pick your subject matter and position, but make it something worth while, something that some benefit can come from.

    Pointless nit-picking a post over senseless issues are of no value.

    Then pick your forum. I don't think this is the place. Preferably for me not in a place where you have the power to simply close down the thread if things don't go your way.

    Or maybe something like this is not at all what you want but would rather avoid. Even better for me. I would just as much prefer to not have any more exchanges with you. You have only been adversarial.
     
  20. ThomasW

    ThomasW Well-Known Member

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    Danny,

    The chronology of events at the beginning of this thread are........

    1)Someone inquired about A/V3's
    2)someone posted about Adire 281's
    3)12 posts later, you post questioning the speed, accuracy and high end extension of the 281's
    4)I post a link to a review of the 281's
    5)you then chose to address me directly, and bring up a thread I posted some 1-1/2yrs ago, on a different forum.
    It does give one cause to ponder

    Enough is enough..............

    Ciao,
    Thomas
     

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