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Murphy Corner Line Array (MCLA)

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  • axes4less
    replied
    Re: Murphy Corner Line Array (MCLA)

    Hi John, I wonder if you could share your experiences/opinions about the 3.5" ND90's off-axis performance in the ranges above 8Khz? I know your project was designed for corner loading, and therefore this wasn't really an issue. But I have a need to improve on my current line array "PA" solutions which are sometimes forced to be used on wide/narrow stages. On another thread I started, I've been discussing this...it began with "what-if" discussions about having side-by-side 2" drivers on convex baffles, and has now evolved to discussing how I might alternate the baffle angles on a single driver array. If however the ND90's off axis performance in the high end is very good, maybe all of that isn't needed. Please share...either by responding here, or on my post. Thanks - Brian
    http://techtalk.parts-express.com/sh...22#post1679922

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  • axes4less
    replied
    Re: Murphy Corner Line Array (MCLA)

    Just wanted to share.....

    I am a full believer, and "user" of DIY line arrays in live band performance. My classic rock cover band in Austin, TX has used this system for more than 5 years now both in large/small indoor clubs and in outdoor venues. A friend also built a pair, and his band does the same. What's also funny...is that someone hijacked a similar posting I put on the Carvin Forum a few years ago, and pasted it over onto the BOSE PA1 Forum, where the thread got plenty of interest, and finally got shut down by Ken Jacob Director and Chief Engineer @ BOSE.
    http://bose.infopop.cc/eve/forums/a/...1971052103/p/2

    Believe everything you read about the benefits of these Full Range driver arrays. I did not rely on corner loading (because as several mention, placement is often not possible like this on many stages), and do run subs with them. Many thanks to John Murphy for sharing his projects and insights. Certainly makes me interested in how much better my solution might be, if I was to invest a few hundred more dollars and try a Version2 using the new Dayton drivers.

    Here also is a small system I built for my daughter and wife, who are teachers. They use it in their classrooms. The kids love using it. It also uses the Full Range NSBs, and would greatly benefit I'm sure with the new Dayton drivers. http://techtalk.parts-express.com/sh...d.php?t=215460

    Leave a comment:


  • bekeys88
    replied
    Re: Thanks John

    Thanks John.....

    Yes, it would be portable and yes... some of the rooms aren't even close to 90 degree corners (and ceilings seem to be an afterthought in some of the clubs!)....
    But I'm still intrigued with the multiple drivers. I'm ancient enough to remember the "sweet 16" project back in the (60's?)... I've got a pretty good set of 12" JBL woofers.... I'm thinking of maybe using 4 of the drivers (or 8?) in a column, (maybe giving them a bit of offset from a 0 degree front) as mid-range & highs.
    While I've got your ear..... If I have the theory correct... I know it would be a waste of power to not cross over if the speaker falls off rapidly at 3.5k, but... it wouldn't hurt anything correct?. And if I just passed over 3K or so through a capacitor to the array... It would at least be simple (power for a musician is no problem... we all seem to have amps with knobs that go to 11).
    I run full stereo (because of the Leslie).. and I'm getting to dang old to haul around the heavy mains anymore. I know there will be a trade-off in sound quality... I'd just like to minimize it as much as possible. Any other thoughts/ideas would be appreciated
    Thanks Again....... cl

    Leave a comment:


  • Ron_E
    replied
    Re: Murphy Corner Line Array (MCLA)

    Can I assume a MCLA would work as a sub-woofer? I'm thinking about putting eight 8" woofers in the front corners of my listening room.

    Ron

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  • John L. Murphy
    replied
    Re: Murphy Corner Line Array (MCLA)

    Originally posted by Ray Tremblay View Post
    Has anyone built one of these yet? Pics?

    Hi Ray,

    So far, besides my own initial prototype pair, only one other person (Geo) has confirmed that they have built them. He gave us a preliminary report but we never got a follow up report or details of the setup.

    I anticipate building a second pair to use as my home theater front mains but I'm hoping to find a source to fabricate the enclosures...so I don't have to cut all those 3" holes again.

    I have construction photos which I have not yet posted but I suspect you want to see pretty finished product photos. My prototypes would not win any beauty contest because they are simply wrapped in black grill cloth. I'll think about it...

    Regards,

    John

    Leave a comment:


  • John L. Murphy
    replied
    Re: MCLA use pro-audio (PA application)

    Originally posted by bekeys88 View Post
    Another post referenced the suitability of using these for a small club PA (for vocals & keyboard). I'm looking to try & duplicate what Bose has done with their L1 system. This design looks like it should do it. Question: Since portability is an issue, what would be the minimum # of driver's I could get away with and still get the line array effect (I'm looking to try and get equal volume levels regardless of where one stands in the room.... or at least thats what Bose is claiming the L1 does). In my case, the cabinets would be stacked (using the minimum speaker concept) for bigger venues (and at the small venues the "extra" columns might be used as monitors on their side in the front of the stage.
    Thanks....... great info by the way.........

    Hello bekeys88,

    As a permanent installation in a small club with parallel ceiling and narrow wall at the front I think they would do quite well. The higher the SPL required the higher you would want to set the -3 dB corner. The sound coverage about the room would likely be very even without blasting the folks in front.

    As a portable system you may not be able to place them in the corners as you would like. Also, for a performing artist, the room-of-the-night may not even have its ceiling parallel to the floor. I expect there would be a lot of variation in the bass output from room to room for starters. You would want some flexibility in voicing. The MCLA EQ would be no more than a starting point.

    In order to get the "infinite" line array effect of the MCLA you would need enough drivers to cover about 90% of the floor to ceiling distance. I would keep the drivers tightly spaced. Stacking multiple smaller arrays would be the best way to keep it portable and adaptable to each room.

    Regards,

    John

    Leave a comment:


  • Ray Tremblay
    replied
    Re: Murphy Corner Line Array (MCLA)

    Has anyone built one of these yet? Pics?

    Leave a comment:


  • bekeys88
    replied
    Re: MCLA use pro-audio (PA application)

    Another post referenced the suitability of using these for a small club PA (for vocals & keyboard). I'm looking to try & duplicate what Bose has done with their L1 system. This design looks like it should do it. Question: Since portability is an issue, what would be the minimum # of driver's I could get away with and still get the line array effect (I'm looking to try and get equal volume levels regardless of where one stands in the room.... or at least thats what Bose is claiming the L1 does). In my case, the cabinets would be stacked (using the minimum speaker concept) for bigger venues (and at the small venues the "extra" columns might be used as monitors on their side in the front of the stage.
    Thanks....... great info by the way.........

    Leave a comment:


  • John L. Murphy
    replied
    Re: Murphy Corner Line Array (MCLA)

    Originally posted by oodesigns View Post
    Thanks John for the information

    One Question about the "Behringer Ultra-Curve Pro DEQ2496." my better half would like to know if the rack mounts can be taken off as she thinks they do not look good, if not I will have to look for a small 1 unit high case.

    I checked my unit and the rack mount ears are part of the chassis...so no, they are not removable (unless you want to look inside the chassis).

    Regards,

    John

    Leave a comment:


  • oodesigns
    replied
    Re: Murphy Corner Line Array (MCLA)

    Thanks John for the information

    One Question about the "Behringer Ultra-Curve Pro DEQ2496." my better half would like to know if the rack mounts can be taken off as she thinks they do not look good, if not I will have to look for a small 1 unit high case.

    Leave a comment:


  • John L. Murphy
    replied
    Re: Murphy Corner Line Array (MCLA)

    Originally posted by oodesigns View Post
    Hi, John

    thanks for the information I will be anaylizing it more carefully.

    My room is pretty small about 360cm * 270cm - I based in the uk where the rooms are not big!.

    One thought I had off the top of my head was to angle the speakers at greater than 45 degrees towards the center of where I will be (standing or sitting) .

    The way I thought was to base the cabinet on a pipe which can be rotated, or would the completly destroy the whole concept.

    plus as I am sooo close to the speakers would it be helpful to phase correct each driver based on my location, this would occur a cost of a electronics per speaker (ie active time alignment - with a small amp per speaker - this might be a bit nuts but then a system with 25 drivers per unit is quite over the top any way).

    It sounds like nice intimate setup for listening to music!

    You would want to place the arrays in the narrow corners of the room 270 cm apart. For my 45 degree enclosure the axis of the two enclosures would cross at 135 cm from the front wall. The equilateral triangle setup would place you back (.866 x 270 =) 234 cm from the front wall. Your room would seem to be a good candidate for the MCLA.

    There is no reason not to experiment with the angle of the enclosure in the corner. Basing the enclosure on a pipe makes sense. Note that you may well end up with a different enclosure volume per driver which would affect the required corrective EQ.

    For a similar pipe enclosure design see Darren Kuzma's line array project using a 4 inch pvc pipe as the enclosure:

    http://www.partsexpress.com/projects.../Kuze3201.html

    Considering the reflected images of the arrays in the floor and ceiling I don't think it is desirable to apply delay to any of the drivers. I actually tried the experiment of delaying the signal to drivers in my MLA8/16 arrays back in the 1980s. I never found a delay configuration I liked better than the un-delayed array. For example, if you attempted to focus the array at the listening position each reflection of the array would be miss-focused and spoil the whole plan. Likewise with amplitude tapering the array; each reflection would also be tapered messing up the whole tapering arrangement.

    Let us know how your project progresses.

    Regards,

    John

    Leave a comment:


  • oodesigns
    replied
    Re: Murphy Corner Line Array (MCLA)

    Hi, John

    thanks for the information I will be anaylizing it more carefully.

    My room is pretty small about 360cm * 270cm - I based in the uk where the rooms are not big!.

    One thought I had off the top of my head was to angle the speakers at greater than 45 degrees towards the center of where I will be (standing or sitting) .

    The way I thought was to base the cabinet on a pipe which can be rotated, or would the completly destroy the whole concept.

    plus as I am sooo close to the speakers would it be helpful to phase correct each driver based on my location, this would occur a cost of a electronics per speaker (ie active time alignment - with a small amp per speaker - this might be a bit nuts but then a system with 25 drivers per unit is quite over the top any way).
    Last edited by oodesigns; 08-19-2010, 12:57 PM.

    Leave a comment:


  • John L. Murphy
    replied
    Re: Murphy Corner Line Array (MCLA)

    Originally posted by Chris Roemer View Post
    I think on some boomboxes there's a "Wide" switch that must throw (only) the tweeters out of phase to "spread" the sound. It's not right, though.

    Chris

    In this case oodesigns might need a "narrow" switch to try to compensate for the wide placement. It occurs to me that a partial blend to mono might help but even that would not help the case of a centered vocal which is sucked to the side too rapidly as you move off axis of too widely spaced speakers.

    It actually sounds like oodesigns has just adequate separation to achieve an equilateral triangle listening setup. That should not be too wide.

    Thanks for the comments Chris.

    Regards,

    John

    Leave a comment:


  • John L. Murphy
    replied
    Re: Murphy Corner Line Array (MCLA)

    Originally posted by auracle View Post
    Hi John,

    Just curious if you've had the chance to experiment with sound absorbing materials on the walls adjacent to the line arrays to see what impact it might have on imaging, tonal balance, and a sense of depth.

    Having experimented a fair amount myself with line arrays, I agree wholeheartedly with some of your earlier observations about the actual percentages of direct/reflected sound in point source configurations versus line source. Given the comments I've read in various places, I think this aspect of line arrays is one of the most overlooked - concentrating the source of excitation in one place in most real environments produces greater contrast in both reflection time and intensity - often making reflected energy more noticeable.
    auracle,

    No, actually I have not experimented with absorbers in the room at all. The room is fairly live but with a pleasing sound that I actually allow to leak into my acoustic guitar and vocal recording tracks. So I have not felt a need to tame any reflections up to this point.

    Regards,

    John

    Leave a comment:


  • John L. Murphy
    replied
    Re: Murphy Corner Line Array (MCLA)

    Originally posted by oodesigns View Post
    Hi, I am new to this group...

    I am intrested in making these also... but I have the same issue as another member, i quote:

    "I've had the MCLA's running for 4 days now but my first impressions have not been that great, mainly because of the distance between corners in my room. My corners are 17 ft. apart along my front wall, and my listening position can be 12 ft. max back from the front wall. As a result I'm getting too much separation between the left and right channels.

    In the MCLA article, I can't see where John mentions anything about optimum spacing between speakers. I don't have any experience with using equalizers. Would optimum equalization settings minimize this problem?"

    In my case I have no choice but to have the speaker further apart than I will be sitting. Will this make this design reduntant? or using could using other features of the equalizer help.

    Leave a comment:

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