Conference napalm::commusic_v1

I am also interested in speakers. I didn't get any response to my speaker review
note, but I think they are critical to live performing and studio mixdown
monitoring. The goal of that note was not to say "my speakers are better and
cost more than yours", but to compare sound quality (subjective) vs. price and
make us more aware of the variety available. Stores like E.U. Wurly tend to
get locked in to one brand/vendor and you don't really get a side-by-side
comparison in the store. If you go to a home stereo shop, they have walls full
of different sizes and brands and you can switch during a song to compare. It
might be hard to compare in a notes file though. Some bands bi-amp or tri-amp.
Some use stacks, others use stands. You need a large van and many strong young
bodies to haul this stuff around. I am interested in what makes good speakers
sound good, and how to carry as few as possible.

Without getting into the math, here are some factors I think might pertain..

1. Internal cross-over filter quality
2. Speaker cabinet design
3. Room acoustics
4. Speaker positioning, they sound better to me up on stands
5. Volume level, some speakers don't get going until they are driven hard
6. speaker design, this includes cone material, windings in voice coil, etc.
7. impedance matching, 8 ohm, 4 ohm, 2 ohm should be matched to power amp
8. horns vs. tweeters
9. phase relationships, this relates to room dimensions and speaker positioning

The volume of air moved is only a small part of this complex issue. It's more
a question of how accurately and efficiently the speaker transduces the
electrical signal into air waves which move our ear drums.

Let's hear from the speaker design hackers.

Dave

    I think the reason the 15"-18" 'bin' bass boxes sound better is
    primarily due to the box design and attention paid to crossover
    points. Generally smaller, 8" class speakers are in hermetically 
    sealed boxes, or have marginal porting.
    
    Boxes made specifically for bass have an internal volume matching
    the resonant frequency of the speaker (as nearly as possible),  
    plus a port area equal to that of the speakers' surface area.. 
    the column of air leading from the back of the speaker to the port 
    is of a length so that when the vibration emerges from the port 
    it is in phase, reinforcing the air movement off the front of the 
    speaker cone. Can you say 'bass reflex' ? I knew you could.
    
    So as apparent volume is a function of air moved, I will say that
    a box with multiple 8" speakers, correctly designed and with the
    appropriate crossover points, would give bottom end volume equal
    to another bass bin with larger speakers, given approx. equal 
    speaker area.

    karl

    
    It is true that multiple smaller drivers will "push as much air"
    as a single larger driver, and their resonant frequencies will interact
    and sum together to assimilate a larger driver, but not in a
    predictable linear fashion. The 'esteemed' doctor will admit this
    himself because they sell an active equalizer with the 801 to add
    more bottom electronically. That to me is a kludge.
    
    The problem is, there is no single driver made by anyone that will
    have extended bass response and high efficiency. So cabs that go
    way down, and have that fat bottom, just won't pump up the volume
    as loud as one that doesn't, assuming the same number of drivers
    per cab. You have to make a tradeoff. Horn loaded bins have very
    high efficiency, but don't have the extended low end of a ported
    cab.
    
    Thiel-Small small signal parameters are the design guidelines that
    are used to closely match the driver to the cabinet. When you have
    achieved this match, the cabinet is known to be "optimally tuned".
    The parameters of the drivers are sometimes printed in the lit with
    the driver, but they can be measured with the proper equipment.
    
    This is a great topic.
    
    CdH
    
    

    I know I'm gonna get yelled at for saying this, but you don't want
    a lot of small drivers to "assimilate" (i.e., absorb) a large driver,
    you want them to "simulate" (i.e., behave the same way as) the large
    driver.
    
    len.
     

    
    Len,
    
    I knew that. I wanted to see if you'd catch that. 8^) 8^) 8^)
    
    Thanks for the English lesson 8^) 8^)
    
    CdH_who_only_got_B's_in_English
    
    

    < Note 1170.3 by TWIN4::DEHAHN >
>    It is true that multiple smaller drivers will "push as much air"
>    as a single larger driver, and their resonant frequencies will interact
>    and sum together to assimilate a larger driver, but not in a
>    predictable linear fashion. The 'esteemed' doctor will admit this
>    himself because they sell an active equalizer with the 801 to add
>    more bottom electronically. That to me is a kludge.

    Sorry, Chris. the Bose 801/901s need active bass EQ because the
    box is a) sealed (no port/bass reflex effect, b) TINY, only about 
    2 cubic feet. For ANY speaker to respond well below 100 cycles it 
    needs correct port area and phasing and at LEAST 7 cubic feet.    
        
>    The problem is, there is no single driver made by anyone that will
>    have extended bass response and high efficiency. So cabs that go
>    way down, and have that fat bottom, just won't pump up the volume
>    as loud as one that doesn't, assuming the same number of drivers
>    per cab. You have to make a tradeoff. Horn loaded bins have very
>    high efficiency, but don't have the extended low end of a ported
>    cab.

    Uh, many of the Voice of the Theatre boxes are BOTH horn loaded
    AND have an in-phase port (bass reflex to me). The bigger the 
    box/horn/port, the less amplifier power is required. My father 
    worked for Conn Organ in the early 1950s. They used to make bass 
    enclosures for amphitheaters and stadiums. He tells me of one 
    enclosure that held two 15" Jensen drivers, 25 cubic feet internal 
    bass reflex, with a folded front horn that was 12 FEET SQUARE at
    the mouth. They hadda ship it on a flatcar. When installed, it 
    literally cracked the foundations of the auditorium (I forget where). 
    The amplifier ? A 50-watt Marantz tube amp. 

karl

    >When installed, it 
    >literally cracked the foundations of the auditorium (I forget where). 
    >The amplifier ? A 50-watt Marantz tube amp. 

    Just from the weight, no doubt.
    
    >karl
     
    Edd

    
>   The bigger the box/horn/port, the less amplifier power is required.
    
    
    Sure, but don't you then introduce slewing problems and therefore
    harmonic distortion? 
    
    Those big old Voice of the Sewer speakers weren't known for fidelity.
    For bass players, it's may not be much of a problem (?). I personally
    like kick drums and floor toms to have some definition to them (Thump!
    instead of flump!).
    
    Why not use large tuned ports? I have an old article describing
    an 11' chamber in a relatively small box. Requires more power (no
    front horn) but it has a clearer sound.
    
    Not that I have anything against horns. 
    
    /pjh

    
    I guess I better check up onmy 801 lit when I get home. I could
    swear those two round ports in the front of an 801 are for cabinet
    tuning.
    
    I also beg to differ about your 7 cubic foot minimum for bass response
    under 100Hz. The subwoofers I designed, built, and use in my 2500
    watt system are 6 cf and are flat to 40Hz and have a -3db point
    at 23Hz. All it takes is the proper driver, and proper tuning of
    the enclosure. I used straight forward Theil-Small.
    
    When I was comparing horn loaded cabs to ported, I was comparing
    just that. Combination cabs like the VOT have their own set of
    problems.
    
    Those mega-sized VOT speakers are still in production. The biggest
    ones are about 15 feet by 6 feet with the extensions, and use two
    15" drivers. They are ported as well as horn loaded (obviously).

    CdH
    

    > The subwoofers I designed, built, and use in my 2500 watt...
      
    2.5 KILOWATT !?!?!?! 
    
    You can't draw that much on a wall socket- it requires a 30 ampere
    service at 110V, or 15 amps at 220V.  Does your amp have an electric-
    range wallplug?
                   :-)
    
    I take it you sacrificed efficiency for a low roll-off point?
                   :-) :-)
    
    Yes, Bose 801's have a pair of very small ports, with tuning plugs.
    Kind of like Soviet rocket boosters (semi-plugged nozzles).
    
    

    
    Has anyone seen the EV's with 4 18"s aimed up, down, and at both
    sides, and the sound comes out the front???
    
    I heard them, and they are loud and powerful.
    
    I was thinking about making a portable bass amp cabinet with 6 10"s,
    aimed up, down, and at every side, like a cube.  since bass is
    allegedly non-directional, this should work, right?? 
    
    Tell me why it won't.
    
    Ashley

    I don't know if it will work or not, but....
    
    Since bass frequencies exhibit lots of non-directional tendencies,
    what do you feel you have to gain by pointing the speakers towards
    every which way?
    
    It also seems to me that you'd want to isolate each speaker in the
    cabinet to keep them from cancelling each other out.
    
    Edd

    
    The EV system is the MT-4 and uses what they call "maniofold
    technology". Each driver is loaded into a plenum which exits in
    a port. The rear of each driver is open. The plenum is designed
    so that the sound exiting the port is in phase with the sound leaving
    the rear of the driver. It's capable of *** 138 db ** from 40Hz
    to 400Hz or so. The matching upper cabinet is 3way with a 'manifold
    loaded' low mid and horns for highs and tweeters. I think it was
    designed for flown arrays, not floor standing.
    
    Re: 2.5KW
    
    Somewhere in here is a short description of my big system, but it's
    a 4-way 2.5KW (actually 2.4KW at present) custom designed system
    using Altec Lansing components exclusively. Response is from 23Hz
    to 22Khz +/- 3db and has a maximum output somewhere around 124db,
    although that's the limit of my meter. Big, heavy, old-tech, but
    loud. BGW and Crown amps, mostly Rane electronics. At full tilt
    it will draw 60 amps, but you power engineers should know that it's
    not steady state, so a 30 amp breaker does just fine. There's also
    a lot of amplifier headroom built in.
    
    CdH