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Thread: Building my dream system, need lots of advise!

  1. #1
    Member jmpsmash's Avatar
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    Building my dream system, need lots of advise!

    Hi all,

    Before I start, let's start with an introduction and a little history. I have been dabbling with audio on and off for around 2 decades. My mother, of all ppl, is a music lover and an audiophile who got me hooked. My main music category is classical (symphonies/orchestral mostly) and a little jazz and no other genres.

    Over the years going to shows and visiting friends (of friends) there are a couple of systems which really made an impression on me. One is a system with a 2 way, a pair of 2397/375 + 136A housed in a rather large translam cabinet. The bass definition was unreal while the texture coming from the Smith horns were that of a dream, these were driven by a 200W SET amp with a soccer size radio output tube. Another system is a multiway, with 3 horns and 2x JBL 15" and 2x JBL 18" housed in separate pro cabinets, on EACH SIDE. driven by DSP crossver and Crown amps. Playing orchestral music, the scale, dynamics, and at the same time, completely effortless presentation was phenomenal. I couldn't stop smiling for hours.

    While the latter system is too large to be housed in my own home, my dream is to bring the essence of both systems and fuse it into my own dream system.

    With a fair amount of reading and research, I think I have come up with something that is feasible and reasonable in my listening space (20'x20' room).

    I have, as some might seen, started gathering pieces already. I have acquired a pair of 2397 and a pair of 2441. I also recently got a pair of stilll in the box NOS pair of 2123H (just in case I want to do a 4 way), a pair of Fostex T925A (though I am tempted by a pair of 2405 but not sure the condition). These will be driven by a minidsp crossover SPDIF unit that feeds separate DACs and a mix of class D amps (NC400 and Nuprime).

    I have most of pieces already and what is missing is a good woofer and cabinets. I have currently a quad set of Pure Audio Project OB15Neo in open baffle leftover from a previous project but I find them really not up to par when it comes to clarity and definition. there is enough volume and speed but rather woolly in the presentation.

    So in the end, I think I want to end up with:

    Fostex T925A
    2441+2397
    2123H (maybe?)
    2235H

    crossover point is planned to be 5kHz, 1kHz, 250Hz

    I am pretty new to this, and for the 2123H and 2235H I need to build the cabinets. From what I read so far, they need to be 0.5 cuft and 5 cuft respectively.

    I have a few questions...

    Is the plan a sound one? Am I heading the right direction to good sound?

    What I am not sure is the 2123H, do I need it? Can I do away with it and cross at 5kHz and 950Hz? Is that stretching the 2441/2397 and the 2235H?

    I still haven't found a 2235H, what is a reasonable price for it?

    is putting a Fostex in a predominant JBL system heresy? I find it harder and harder to find good condition drivers and buying new might be less headache though a pair of 2405 popped up recently which looked like in good condition. Should I go for those instead?

    I have only build open baffles speakers up till now. There will be quite a lot of learning ahead for the cabinets.

    Anything else I need to know?

  2. #2
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    You are heading the right direction, for shure!

    The JBL 2441/2397 is a great midrange combination and the 2123 a stellar midbass/midrange woofer. I love both of these units!
    Using a 10" midwoofer and building a 4-way or building a 3-way without it is an ongoing discussion on this forum. I havenīt solved this decision for myself yet. I will suspend my ideas on this topic and leave it up for the others....

    The transition between the Fostex 925 and JBL 2397 horn will be a problem. Not so because it is a Fostex, rather because itīs dispersion characteristics wonīt match these of the 2397 horn.
    The Fostex is aprox. 60° if Iīm not mistaken. The 2397 is 140°.... For a smooth transition these should be closer together. That is why I would prefer the JBL 2405 with 120° dispersion. Or the Fostex 825...

  3. #3
    Senior Member Ian Mackenzie's Avatar
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    Your ideas are good.

    The gap is the acquisition of the 2235 woofers.

    Talk to Edgewound at Upland Loudspeaker Repairs about getting old of some woofers or building up some woofers.

    If you go with the dual 2235H woofers try them initially with the Smith Horn.

    The Smith horns 2 inch throat limits diffraction up to 10,000 hertz.

    Cut the Fostex horn over from 8000-14000 with a 3rd order filter. GT recommends a 3rd order high pass filter .

    The Smith horn may not need a low pass filter.

    Don’t over think the design. Start off with the basics and evolve following extensive listening.

    Get the mini dsp USB mic and download REW for your initial measurements.

    The 2397 should be smooth enough without any additional EQ.

    Use a 12 dB LR filter on the woofer and horn @800 hertz (acoustic slopes) and either apply phase compensation by shifting the horn crossover point or adding delay to the woofers.

    Don’t stress about the beaming of the woofers in the mid range too to start with.

    Once you get this going you can then add the 2123H 10 inch mid cone.

    Crossover at 250- 900 hertz with 12 dB LR (acoustic) slopes and apply phase compensation or delay.

    As l mentioned you will need to measure the drivers individually and the crossover summation in order to get in the ball park. With some work you should be able to get a response +-3 dB from 35-20,000 hertz.

    There are some good enclosure construction references in the Library and the technical references forum.

    Use a suitable protection capacitor on the horn and the Fostex driver.

    Tune the woofers enclosure to 30-34 hertz in 5 cu ft3

    Enjoy your project.

  4. #4
    Member jmpsmash's Avatar
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    Quote Originally Posted by Dr.db View Post
    You are heading the right direction, for shure!

    The JBL 2441/2397 is a great midrange combination and the 2123 a stellar midbass/midrange woofer. I love both of these units!
    Using a 10" midwoofer and building a 4-way or building a 3-way without it is an ongoing discussion on this forum. I havenīt solved this decision for myself yet. I will suspend my ideas on this topic and leave it up for the others....
    Glad to have some reaffirmation that those are good choices! for 3-way / 4-way, that needs to be investigated. If anything, more things to play with! My plan is to build separate cabinets for the 2123H. That, with addition to using active DSP crossover, will allow me to mix in the midrange and adjust the crossovers within seconds and do a proper comparison.

    The transition between the Fostex 925 and JBL 2397 horn will be a problem. Not so because it is a Fostex, rather because itīs dispersion characteristics wonīt match these of the 2397 horn.
    The Fostex is aprox. 60° if Iīm not mistaken. The 2397 is 140°.... For a smooth transition these should be closer together. That is why I would prefer the JBL 2405 with 120° dispersion. Or the Fostex 825...
    What's the effect of having mismatched dispersion? is it for off axis, like i will suddenly lose the highs if i move my head or move around the chairs, or does it also have other effects like interaction with the room? or is it also something that have an effect even on axis?

  5. #5
    Member jmpsmash's Avatar
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    Hi Ian, lots of great info. Let me read through them in detail and understand/digest them one by one slowly and I will reply. Thanks!

  6. #6
    Senior Member Ian Mackenzie's Avatar
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    There is no real time line with diy Audio.

    What matters is you complete your project and achieve the desired outcomes.

    I encourage you to be hands on and do your own investigations. That way you are more likely to achieve your desired outcomes and you will learn as you go.

  7. #7
    Senior Member 1audiohack's Avatar
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    Hi JMP;

    I would skip the 2235's and buy 2216Nd's They are suprisingly inexpensive for a JBL Pro woofer that out performs the 2235 by a wide margin.

    I love old JBL stuff and have 2234's and 2235's currently employed in systems I don't want to modify but when building a system like you are talking about from scratch the 2235's will leave a lot of performance on the table.

    In truth a system like you are thinking, two 15" woofers per side will still be your SPL limiting factor as the 2123 and 2441's will run away from them easily.

    Many people including me (if I have to) run the 2123's down to ≈250Hz but it doesn't play with real authority that low and 200Hz is as low as I ever use them. With really good 15's you can move that crossover up a bit and still keep the goodness the 2123 is known for.

    The side by side wide baffle dual 15 JBL's like the 4350 and 4435 or DD66000/DD67000 have a good solid low frequency presentation that a single 15 just can't match.

    I still think it takes front loaded bass horns to reproduce things like tympanies with true realism but you have to give up about 125 cubic feet of your space to do it right.

    Just a note, my definition of "real" and "loud" are different than most people I know.

    Barry.
    If we knew what the hell we were doing, we wouldn't call it research would we.

  8. #8
    Senior Member Ian Mackenzie's Avatar
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    One of your considerations will be how you stack the enclosures?

    With 20 ft wall you will have either woofer enclosures upright or on the sides.
    With that in mind you will want to space the horn centres between 8’ and 10’ feet) apart.

    To start with your listen position (blast radius) will be 10 feet from each horn.

    So the horns will be 5’ (feet) from each side wall.
    The horns will want to be at what ever ear height you intend. Often 39 inches.

    That will dictate the location of the drivers (ideally)

    To avoid that wall of sound pa stack effect you will find clustering the horn / tweeter and woofer driver centres in a close vertical array important particularly if you enjoy classical music as opposed to over produced pop music.

    Barry listens 50 yards from his system (apparently) because he still has his hearing.💭Lol

    This is the problem with high powered systems consisting of multiple woofer enclosures and large horns. Alternatively you sit way back and hear your entire room along with the system. As l said investigate and work out with your enclosure modules what works for you.

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    Quote Originally Posted by jmpsmash View Post

    What's the effect of having mismatched dispersion? is it for off axis, like i will suddenly lose the highs if i move my head or move around the chairs, or does it also have other effects like interaction with the room? or is it also something that have an effect even on axis?
    What you actually hear sitting on your listening position is a mix of sound comming directly from your speakers and sound comming indirectly reflected from walls, ceiling and floor. Thatīs why a frequency response should be smooth on-axis AND off-axis. If your tweeter has a narrower dispersion than your midhorn you will have an uneven frequency response off-axis.
    As explained above, you are listening to a sum of on-axis and off-axis sound in your room. In this case the highs would be overdamped.

    Besides that, a sudden change in dispersion characteristics between individual drivers makes it easy to locate each sound source. The components dont match up well. What you hear are individual compontents, not speakersystem as one unit.

  10. #10
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    Quote Originally Posted by Ian Mackenzie View Post
    One of your considerations will be how you stack the enclosures?

    The horns will want to be at what ever ear height you intend. Often 39 inches.
    When using the 2397 horn and a supertweeter, how would you implement this idea?
    The JBL 4343, 4344 or 4345 monitors mounted the 2405 tweeter right beside the midhorn. Both drivers were located on the same height / ear -height... But Iīm afraid this canīt be done with a horn like the 2397!
    This leaves you up to the decision if you put the 2397 or the tweeter on the ear-height, doesnīt it ?

  11. #11
    Senior Member Ian Mackenzie's Avatar
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    I come back to my final points.

    Don’t overthink the design.
    The OP will need to do practical investigation.

    A thread like this is only a discussion of suggestions and considerations. It is not a white paper about a loudspeaker design. All loudspeakers have compromises and it’s up to the OP to determine which compromises are acceptable to him.

    Btw the DD67000 has the tweeter some distance above the horn. But what does the designer do with the knowledge of the particular characteristics of the horn?

    You have to listen to the drivers to be prepared to do some meaningful measurements. None of this is beyond a diy audio enthusiast. With REW and a USB mic the tools are now accessible.

    Another case in point is the approach Westlake took to their large format monitors.

    The approach of a crossover point at 5000 hertz may actually be a good one depending on what the OP finds and prefers. I heard a horn system with a Fostex horn tweeter in the UK last year. It pays to have an open mind and do the work.

  12. #12
    Member jmpsmash's Avatar
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    I have received my Fostex tweeter and played around with it a little. The issue is that the 2397 is so deep and currently the Fostex and 2397 are driven by the same amp, just a simple cap on the Fostex to make the 5kHz cutoff. I need to get another DAC/amp to add the 4th channel.

    First I put the Fostex at the front of the 2397. The 2397 being so thin there isn't much issue in terms of vertical height. That didn't sound too good image-wise with the time-misalignment.

    Then I moved the Fostex back and the imaging was much more coherent and the sound stage moved back into the rear wall. The issue is that since it is sitting further back, there will be reflection bouncing off the top of the 2397. So maybe I need to raise it up a little. Will try to experiment with that later.

    If I add a separate DAC/amp delay can be added and maybe it will work with the Fostex sitting at the front of the 2397. I will have to experiment with that too.

    I need to do some measurement to make sure they are properly time aligned. Lots of work ahead.

    Interesting that you mentioned DD67000. it has the tweeter horn also sitting back and there is a slope going down toward the lip of the mid-horn. Obviously they cannot add delay so maybe that's the best solution to get time-alignment.

  13. #13
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    This is what I have cobbled together. More work to be done but I am already in love with the sound... well, anything 1kHz and above at least.

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    Quote Originally Posted by 1audiohack View Post
    Hi JMP;

    I would skip the 2235's and buy 2216Nd's They are suprisingly inexpensive for a JBL Pro woofer that out performs the 2235 by a wide margin.

    I love old JBL stuff and have 2234's and 2235's currently employed in systems I don't want to modify but when building a system like you are talking about from scratch the 2235's will leave a lot of performance on the table.

    In truth a system like you are thinking, two 15" woofers per side will still be your SPL limiting factor as the 2123 and 2441's will run away from them easily.

    Many people including me (if I have to) run the 2123's down to ≈250Hz but it doesn't play with real authority that low and 200Hz is as low as I ever use them. With really good 15's you can move that crossover up a bit and still keep the goodness the 2123 is known for.

    The side by side wide baffle dual 15 JBL's like the 4350 and 4435 or DD66000/DD67000 have a good solid low frequency presentation that a single 15 just can't match.

    I still think it takes front loaded bass horns to reproduce things like tympanies with true realism but you have to give up about 125 cubic feet of your space to do it right.

    Just a note, my definition of "real" and "loud" are different than most people I know.

    Barry.
    Hi Barry,

    you are really trying to "poison" me. Just 2 months ago I have visited a friend who has a pair of 15" and a pair of 18" on each side in some huge JBL pro cabinet. The amount of speed and ease coming from the low end was unbelievable and totally keeping up with the stack of horns sitting above. Unfortunately, I will have to get a divorce first before I can pull that one off.

    This is the first time I have heard of the 2216ND-1. I did some research but so far they seem to be unobtainable anywhere. I can't find too much discussion on them, is it because they are less available? I would love to try them if I can find a pair. I always thought the 2235H is the best but wouldn't mind if there are better.

    and let's not get into front loaded bass horns. where i live, the room itself will cost 100x the price of the horns...

  15. #15
    Member jmpsmash's Avatar
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    Quote Originally Posted by Ian Mackenzie View Post
    Your ideas are good.

    The gap is the acquisition of the 2235 woofers.

    Talk to Edgewound at Upland Loudspeaker Repairs about getting old of some woofers or building up some woofers.

    If you go with the dual 2235H woofers try them initially with the Smith Horn.

    The Smith horns 2 inch throat limits diffraction up to 10,000 hertz.

    Cut the Fostex horn over from 8000-14000 with a 3rd order filter. GT recommends a 3rd order high pass filter .

    The Smith horn may not need a low pass filter.

    Don’t over think the design. Start off with the basics and evolve following extensive listening.

    Get the mini dsp USB mic and download REW for your initial measurements.

    The 2397 should be smooth enough without any additional EQ.

    Use a 12 dB LR filter on the woofer and horn @800 hertz (acoustic slopes) and either apply phase compensation by shifting the horn crossover point or adding delay to the woofers.

    Don’t stress about the beaming of the woofers in the mid range too to start with.

    Once you get this going you can then add the 2123H 10 inch mid cone.

    Crossover at 250- 900 hertz with 12 dB LR (acoustic) slopes and apply phase compensation or delay.

    As l mentioned you will need to measure the drivers individually and the crossover summation in order to get in the ball park. With some work you should be able to get a response +-3 dB from 35-20,000 hertz.

    There are some good enclosure construction references in the Library and the technical references forum.

    Use a suitable protection capacitor on the horn and the Fostex driver.

    Tune the woofers enclosure to 30-34 hertz in 5 cu ft3

    Enjoy your project.
    Thanks. I plan to do some detail measurements of each individual drivers. I have obtained the Fostex, the 2241/2397 and the 2123H already. I still need to put together a cabinet for the 2123H. Right now all they set sitting on is just a front/open baffle and they make sound but not optimal.

    I will read up on box design and building as well.

    I am still looking for the 15". There are a couple pairs of 2235H on ebay. one pair has a mismatched looking cones and no surrounds, the other pair has really dodgy looking surround replacement job. both will end up around $800. Luckily I didn't decide on them as now Barry got me into looking for a pair of 2216ND-1

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