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Here it goes. 16 or 8 driver Fountek FE-83 array?

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  • Here it goes. 16 or 8 driver Fountek FE-83 array?

    Hello all!

    This winter I'll build an array. I have 16 FE-83s waiting for an 8 driver per side speaker. But hey, more is better.

    I think.

    So, would you go for a 16 driver FE-83 array? Would it be a "true" array? Better than an 8 driver one? Would a simple column suffice? Would I need to delay the outer drivers?

    One thing I'm worried about is tuning the array. I need an 80 Hz tuning point. With a 55 liter enclosure for 16 FE-83's, I'd need a 7.5" port, 0.75" deep. That's going to look weird...

    Any ideas?
    Line Array: IDS-25 Clone, FE-83.
    2-2.5 Way:
    Zaph Audio's winning entry: ZA5+SB29. - Microliths: RS125+RS28. - Small Bangs: TB W4-1658SB+SEAS 27TBFC/G. - Monoliths: Peerless 830884+SEAS 27TBFC/G.
    3-3.5 Way:Miniliths: SEAS P21/CA21REX+Neo8 PDR+Neo3 PDR. - Megaliths: 2xDayton RS270+2xT-B W4-1337SB+SB29. - ZDT3.5 +: 2xDayton RS180+Dayton RS52+Vifa DQ25. Reflexos: OB 4xDayton RS150 + Neo3 PDR.

  • #2
    Re: Here it goes. 16 or 8 driver Fountek FE-83 array?

    Originally posted by fjhuerta View Post
    ... Would it be a "true" array?...
    Umm, what constitutes a "true" array...
    "Not a Speaker Designer - Not even on the Internet"
    “Pride is your greatest enemy, humility is your greatest friend.”
    "If the freedom of speech is taken away, then dumb and silent we may be led, like sheep to the slaughter."

    Comment


    • #3

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      • #4
        Re: Here it goes. 16 or 8 driver Fountek FE-83 array?

        Originally posted by fjhuerta View Post
        This winter I'll build an array.
        You should read Jim Griffin's "Near Field Line Array Whitepaper" at the link below.
        http://www.audioroundtable.com/misc/nflawp.pdf
        "Our Nation’s interests are best served by fostering a peaceful global system comprised
        of interdependent networks of trade, finance, information, law, people and governance."
        - from the October 2007 U.S. Naval capstone doctrine
        A Cooperative Strategy for 21st Century Seapower
        (a lofty notion since removed in the March 2015 revision)

        Comment


        • #5
          Re: Here it goes. 16 or 8 driver Fountek FE-83 array?

          Each doubling of drivers gains you 3 dB, but soon you reach the point of diminishing returns. Going from 8 to 16 drivers only gains you 3 dB. Halving the impedance gains you another 3 dB.

          In a ported enclosure of 0.1 cu ft per driver tuned to 80 Hz, the f3 will be + 68 Hz. Increasing this to 0.12 cu ft per driver (+ 55 liters for 16 drivers) only lowers the f3 by 3 Hz. Don't even consider trying to reproduce 50 Hz with these drivers as suggested. Count on having to use a sub with this setup.

          The max output the 8 driver array can attain @ xmax is + 114 dB with 96 W in. Is that enough for you?

          Also realize that when you double the array line length, you will need to increase the listening distance. In a standard size room, an 8 or 9 driver array is more than adequate.

          I second the suggestion to read Jim Griffin's "Near Field Line Array Whitepaper".

          Also check out TLAH and SLA on Bill Fitzmaurice's website: http://billfitzmaurice.net/
          Don't worry, if your parachute fails, you have the rest of your life to fix it.

          If we all did the things we are capable of doing, we would literally ASTOUND ourselves - Thomas A. Edison

          Some people collect stamps, Imelda Marcos collected shoes. I collect speakers.:D

          Comment


          • #6
            Re: Here it goes. 16 or 8 driver Fountek FE-83 array?

            As far as the tuning is concerned, the ports can be distributed, meaning that you can use several smaller size ports. It will look better. The calculations for this are simple. Also if you decide to use one of BFM's (Bill Fitzmaurice) designs, they combine line array, transmission line and horn-loading and don't use ports.
            Don't worry, if your parachute fails, you have the rest of your life to fix it.

            If we all did the things we are capable of doing, we would literally ASTOUND ourselves - Thomas A. Edison

            Some people collect stamps, Imelda Marcos collected shoes. I collect speakers.:D

            Comment


            • #7
              Re: Here it goes. 16 or 8 driver Fountek FE-83 array?

              Originally posted by fjhuerta View Post
              I'd need a 7.5" port, 0.75" deep. That's going to look weird...

              Any ideas?
              Use multiple small ports.
              www.billfitzmaurice.com
              www.billfitzmaurice.info/forum

              Comment


              • #8
                Re: Here it goes. 16 or 8 driver Fountek FE-83 array?

                Thanks for posting Jim Griffin's excellent paper.

                The most important thing, at least to me, is not that the array won't play lower notes (I knew it wouldn't), but that the CTC spacing for the high frequencies will be all wrong. I think I can get to 5 or 6 KHz, tops, without major comb filtering issues.

                Since I'd like to build a line array right the first time around, I'd assume this would mean I'd need some tweeters - maybe 8 ND16's or so per side - which makes the whole thing a moot excercise. The tweeters would be more expensive than the woofers, and I'd still need a sub. I wanted to build a cheap array, but apparently, a full range driver is not the place to start.

                Oh, well. Read and learn!
                Line Array: IDS-25 Clone, FE-83.
                2-2.5 Way:
                Zaph Audio's winning entry: ZA5+SB29. - Microliths: RS125+RS28. - Small Bangs: TB W4-1658SB+SEAS 27TBFC/G. - Monoliths: Peerless 830884+SEAS 27TBFC/G.
                3-3.5 Way:Miniliths: SEAS P21/CA21REX+Neo8 PDR+Neo3 PDR. - Megaliths: 2xDayton RS270+2xT-B W4-1337SB+SB29. - ZDT3.5 +: 2xDayton RS180+Dayton RS52+Vifa DQ25. Reflexos: OB 4xDayton RS150 + Neo3 PDR.

                Comment


                • #9
                  Re: Here it goes. 16 or 8 driver Fountek FE-83 array?

                  Originally posted by fjhuerta View Post
                  Thanks for posting Jim Griffin's excellent paper.

                  The most important thing, at least to me, is not that the array won't play lower notes (I knew it wouldn't), but that the CTC spacing for the high frequencies will be all wrong. I think I can get to 5 or 6 KHz, tops, without major comb filtering issues.

                  Since I'd like to build a line array right the first time around, I'd assume this would mean I'd need some tweeters - maybe 8 ND16's or so per side - which makes the whole thing a moot excercise. The tweeters would be more expensive than the woofers, and I'd still need a sub. I wanted to build a cheap array, but apparently, a full range driver is not the place to start.

                  Oh, well. Read and learn!
                  You could try the Apex jr tweeters only a buck each. They will get you closer to the correct ctc spacing. http://www.apexjr.com/speakerstuff.html

                  Comment


                  • #10
                    Re: Here it goes. 16 or 8 driver Fountek FE-83 array?

                    If I'd like to go that way I'd probably use a more capable driver than the Fountek. The thing is, the Fountek was so cheap I thought I could get away with a line array L:( Now I have 16 of those drivers...
                    Line Array: IDS-25 Clone, FE-83.
                    2-2.5 Way:
                    Zaph Audio's winning entry: ZA5+SB29. - Microliths: RS125+RS28. - Small Bangs: TB W4-1658SB+SEAS 27TBFC/G. - Monoliths: Peerless 830884+SEAS 27TBFC/G.
                    3-3.5 Way:Miniliths: SEAS P21/CA21REX+Neo8 PDR+Neo3 PDR. - Megaliths: 2xDayton RS270+2xT-B W4-1337SB+SB29. - ZDT3.5 +: 2xDayton RS180+Dayton RS52+Vifa DQ25. Reflexos: OB 4xDayton RS150 + Neo3 PDR.

                    Comment


                    • #11
                      Re: Here it goes. 16 or 8 driver Fountek FE-83 array?

                      I am not sure why you would think that the Fountek would be a less capable driver. They are nice drivers and would work fine in a line array. The problem is (always) to find a suitable tweeter that is inexpensive, is small in order to keep lobing to a minimum, yet is able to cross low. All of these requirements are a contradiction in terms. It is relatively easy to find suitable mid woofers, hard to find tweeters that will do the job.

                      Conventional wisdom states that the x-over frequency is the frequency where C-T-C spacing becomes a wavelength. The formula is F = 13500 / D.

                      I have attached a cheat sheet I created a long time ago that I use often as a quick reference.

                      The size of the Fountek driver is + 3.5'', making the suggested max x-over frequency + 3800 - 4000 Hz.

                      I agree with the Apex Jr. tweeters and was going to suggest the same thing. Steve has 2 different cheap small tweeters for sale. The cost is about the same. You will find them at the bottom of the linked page.

                      There are a trade-offs with these:

                      The small grey one is woefully inefficient, though that becomes less of an issue in line arrays. The fs is high. Form factor is small, which will help lobing.

                      The black square tweeter is made by Samsung. Efficiency is much higher. Fs is lower. It is a little larger, which means more of a lobing issue. I actually prefer this one over the smaller one.

                      Understand that there are 3 different C-T-C spacing issues here:

                      1. Spacing between the mid woofers.
                      2. Spacing between the tweeters.
                      3. Spacing between the mid woofer line and the tweeter line.

                      Please understand that if playing a purely sinusoidal tone of a certain frequency, lobing becomes very prominent. Playing music content with wave forms of many varying frequencies, lobing becomes much less of an issue and much less notable than pure theory would indicate, especially at the higher frequencies. So I believe even the Samsung tweeters will do fine here.

                      If you have never built a line array, go for it using these components. I believe that you will be pleasantly surprised.
                      Attached Files
                      Don't worry, if your parachute fails, you have the rest of your life to fix it.

                      If we all did the things we are capable of doing, we would literally ASTOUND ourselves - Thomas A. Edison

                      Some people collect stamps, Imelda Marcos collected shoes. I collect speakers.:D

                      Comment


                      • #12
                        Re: Here it goes. 16 or 8 driver Fountek FE-83 array?

                        How about running them full-range ala Roger Russell?!? Little EQ on the top end and you ought to have a very nice sounding array.

                        I hope to do the same but planning to have them running open baffle with bass support.

                        Regards,
                        Rich

                        Comment


                        • #13
                          Re: Here it goes. 16 or 8 driver Fountek FE-83 array?

                          Originally posted by rmeinke View Post
                          How about running them full-range ala Roger Russell?!? Little EQ on the top end and you ought to have a very nice sounding array.

                          I hope to do the same but planning to have them running open baffle with bass support.

                          Regards,
                          Rich
                          As stated before, you should not run these above + 4000 Hz, unless you don't mind substantial lobing issues!
                          Don't worry, if your parachute fails, you have the rest of your life to fix it.

                          If we all did the things we are capable of doing, we would literally ASTOUND ourselves - Thomas A. Edison

                          Some people collect stamps, Imelda Marcos collected shoes. I collect speakers.:D

                          Comment


                          • #14
                            Re: Here it goes. 16 or 8 driver Fountek FE-83 array?

                            Originally posted by thekorvers View Post
                            As stated before, you should not run these above + 4000 Hz, unless you don't mind substantial lobing issues!
                            I don't ' think' you'll have lobing issues with a full range driver array but comb filtering above 4khz and a drastic need to either eQ boost above or shelve below. There will be beaming above 8khz though and pretty aweful off axis response horizontally.

                            ......so I suppose yea, I agree a Fullrange driver line isn't the best direction. But there are those new dayton planar/ribbons that are pretty cheap......

                            http://www.parts-express.com/dayton-...6-ohm--275-083

                            Under a $100 for an 8 per side array.

                            If this were my project, here's what I'd do with those Founteks. I'd build a tower with two rows of four of the Founteks with 4 of those Dayton ribbons in the middle crossed at 5khz or so. The narrow dimensions of the ribbon are ideal for such an alignment and will have near point source and excellent horizontal response.

                            I'd put this all over a pair of silver flute 8" wool cone woofers ported to 40hz and crossed at 250hz first order. That would be my inexpensive big boy speaker! Lol

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                            • #15
                              Re: Here it goes. 16 or 8 driver Fountek FE-83 array?

                              Originally posted by Mayhem13 View Post
                              I don't ' think' you'll have lobing issues with a full range driver array but comb filtering above 4khz and a drastic need to either eQ boost above or shelve below. There will be beaming above 8khz though and pretty aweful off axis response horizontally.

                              ......so I suppose yea, I agree a Fullrange driver line isn't the best direction. But there are those new dayton planar/ribbons that are pretty cheap......

                              http://www.parts-express.com/dayton-...6-ohm--275-083
                              Actually I meant to say comb filtering all along. Don't know what happened there. Had not seen those Mini Planars before. Interesting, will have to check those out.
                              Don't worry, if your parachute fails, you have the rest of your life to fix it.

                              If we all did the things we are capable of doing, we would literally ASTOUND ourselves - Thomas A. Edison

                              Some people collect stamps, Imelda Marcos collected shoes. I collect speakers.:D

                              Comment

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