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Thread: Dumb audio questions

  1. #1
    Senior Member SEAWOLF97's Avatar
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    Dumb audio questions

    1. suppose a 10 in. LF driver and a 12 in. LF driver have the same rated FR.....

    why does the 12 sound better ? is it because of the added mass/radiating area moving more air ?

    2. Whats up with all these 6.5 in LFs now ? They produce lots of bass. What has changed , letting smaller LFs produce like the older / larger LFs ?

    I have AR powered towers in my HT system and the pair of un powered 8's with powered 8's in the rears produce incredible bass .

    So why are the smaller drivers producing what we used to expect from 8's or 10's ?

    Most forum members don't apparently like the smaller drivers , judging by how many here have 15's and 18's .

    U of Oregon Ducks football = national #2


  2. #2
    RIP 2013 Rolf's Avatar
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    Well, here is a explanation of one question. If a certain 8" woofer has maximum movement of 3/4 of an inc it can move a certain amount of air. If a 6" woofer can move 1,5 inc, it can move more air than the 8". Newer design woofers often have the possibility of a larger movement than older designs. That means the manufacturer can use smaller woofers to give the same bass output than before with older an bigger woofers who can not move so much.

    Of cource one run into other problems using long throw woofers.
    It's really all about music.
    Rolf

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    Senior Member louped garouv's Avatar
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    Quote Originally Posted by SEAWOLF97 View Post

    2. Whats up with all these 6.5 in LFs now ? They produce lots of bass. What has changed , letting smaller LFs produce like the older / larger LFs ?
    in addition to the excursion distance,
    sometimes factors affecting
    this is power handling of the woofer &
    design/tuning of the box itself...

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    OK I'll bite.
    I think your question #1 one needs more data added to get a more specific answer.
    Are both woofers meant to be used in the same way?

    Example: AR woofers are designed for acoustic suspension use in a sealed box where better bass can be achieved in a small box. A typical EV woofer is meant for use in a vented or bass reflex box for bass reinforcement.

    The old AR woofer is really more of a 10 inch (cone area) than the 12 inch EV but the AR will have more bass at the expense of amplifier power.

    What's the 10 and 12 measurment. The frame diameter or the effective cone area?
    Are the 10 and 12 from the same manufacturer with similar designs?
    Are the voice coil diameters the same?
    Are the magnet weights the same or close? (similar Gauss)
    Does one have a longer throw than the other?
    Are both cones made from the same material?
    the same rated FR but do the specs say + - how many db?
    what is the free air resonance of each and are they both in the manufacturers recommended enclosure volumes?

    Question #2 here's how I see this:
    The demand for smaller speaker boxes lead to using smaller woofers. Some manufacturers like Dynaudio for instance have come up with small woofers that can produce good bass in a small box and handle considerable power at the same time.
    A real good small box design with one of the better small woofers can produce enough bass that goes deep enough for some people and if space is limited they are very happy.
    Now if you add more small woofers you can extend the bass response plus add power handling capability at the same time.
    These now towers can then have individual ported "chambers" for each woofer and the footprint is smaller than a large box with a larger woofer in it.
    At some point a quantity of these small woofers, if good ones, will give better bass response and more power handling capacity than one 12 or 15 inch woofer in a larger box.
    But there are factors like impedance when using lots of drivers like that. If they are in series the impedance gets crazy high. If they are in parallel the impedance gets crazy low. Series parallel will work but some might argue that's not correct in a good design.
    "Powered" may be another issue all together because there may be internal EQ to create more bass.
    And as Rolf replied, the smaller woofers have a longer woofer throw.
    IMHO the design quality of the small LF driver has everything to do with how many is needed to do a particular job. Then it's the enclosure design.
    For you ending speculation that forum members don't apparently like the smaller drivers, well I know how I feel.
    Frankly I don't care for the "drone" of a bunch of small drivers using weird cone materials. Give me a big paper or pulp cone any day and I'll live with the cabinet size.
    You said "incredible bass" in referrence to your AR Towers. If I read it correctly it sounds like that was the powered 8's?
    As I said earlier, the powered speakers may have built in EQ or bass boost and "incredible bass" is kind of subjective. Is it a bass peak between 60 and 100HZ or solid bass down to 30 or 40HZ without large peaks?
    Remember jukeboxes with bass? That wasn't real bass.

    Dave

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    Opps. I think maybe I wasn't on the same page with you on the "FR." I looked at it and "frequency response" registered.

    Dave

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    Senior Member SEAWOLF97's Avatar
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    Quote Originally Posted by DaveV View Post
    You said "incredible bass" in reference to your AR Towers. If I read it correctly it sounds like that was the powered 8's?
    As I said earlier, the powered speakers may have built in EQ or bass boost and "incredible bass" is kind of subjective. Is it a bass peak between 60 and 100HZ or solid bass down to 30 or 40HZ without large peaks?
    Remember jukeboxes with bass? That wasn't real bass.

    Dave
    here's it specs

    it's great for HT , but I dont find them "very musical",,,(now there is a subjective opinion) , and I cant even tell you exactly why, except they are fatiguing after long music sessions

    The four-way P428PS from AR is a floor standing tower speaker which utilizes a built-in, rear firing powered subwoofer for low frequency reproduction down to a rumbling 28Hz. The slim profile front houses a 1" polycarbonate tweeter, a 5" Uni-cone midrange, and a separate 8" woofer. The rear 8" subwoofer is powered by a 120 watt amplifier.
    Available in Black or Cherry woodgrain.
    SpecificationsDriver Complement8" Rear Subwoofer powered by 120 watt amplifier, Separate 8" Front Woofer, 5" Uni-cone Midrange Wave Guide 1" Polycarbonate Tweeter Magnetically ShieldedEnclosure DesignFrequency Response28Hz-20KHz +/- 3dBSensitivity90dB @ 2.83 Volts/MeterCrossover FrequencyRated System Power120 Watts RMSRecommended Amp. Power20-350 Watts RMSNominal Impedance8 OhmsEnclosure Dimensions41 1/2" x 9 1/2" x 11 1/2"Weight65 lbs.

    U of Oregon Ducks football = national #2


  7. #7
    Senior Member edgewound's Avatar
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    In your example you have a dedicated subwoofer.

    In essence, now you're biamped....that gives you something on the order of 6dB more efficiency over a passive system.

    That just in addition to the fact that the subwoofer was specifically designed for that task.

    Back in 60's, who ever heard the term "subwoofer"? Two full range, passive speakers were expected to do all the work that today's multi channel, multi speaker HT systems can do...

    Thing is....it's not necessarily always better....lots of electronic tricks to pump up the bass to "incredible" levels.
    Edgewound...JBL Pro Authorized...since 1988
    Upland Loudspeaker Service, Upland, CA

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    Quote Originally Posted by SEAWOLF97 View Post
    why does the 12 sound better ? is it because of the added mass/radiating area moving more air ?
    The result depends on a thorough design.

    But a smaller cone with enlarged excursion will unevitably have more intermodulation dissortion.
    Another aspect that may be considered is the power frequency response. What is the max SPL at 28 Hz?
    Quote Originally Posted by Steve Schell View Post

    Speaker engineer Tom Danley recently made an outdoor recording of July 4th fireworks. It contains phenomenal low frequency information, and may give you a better indication of how well your sub is working. This one is best played at low levels the first time through, while watching for excessive woofer excursions. He has made this recording available as a free .wav file download here:

    http://www.danleysoundlabs.com/knowledge%20baSE.htm
    ___________
    Peter

  9. #9
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    Yeah, really, who'd want one of these dumb things with its stupid 8" and 6.5" drivers? Couldn't they wedge a big paper cone in there somewhere?
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    Oops! I guess I would.

    Fortunately I got a bunch of big amps.
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  11. #11
    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by SEAWOLF97 View Post
    1. suppose a 10 in. LF driver and a 12 in. LF driver have the same rated FR.....

    why does the 12 sound better ?
    First off, two drivers with exactly the same ratings may sound entirely different. This is true even if they are rated by the same company. If they were rated by different companies then measurement techniques and standards also enter into he conversation.

    Second... the 12" sounds better? Define better sound.

    I don't mean to be difficult, but your premises are so open and wide it would take pages to discuss the all of the possible differences and possibilities.

    If you are wondering why a modern 8" system may seem to have more bass than a vintage 15" system... it is likely that it actually does not... but the older system produces so much more midrange that it appears to produce less bass or it produces a less mellow tone, to use vintage vernacular.

    In absolute terms a typical vintage 15" woofer will produce a greater amount of energy at say 30Hz than any 8" woofer unless that 8" woofer is a dedicated sub with in excess of 1" of cone travel... even then the vintage unit may beat it out. This said, unless you are a system designer the performance of a driver in absolute terms is pretty much irrelevant... the spectral balance is how you will perceive it's performance.


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