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Thread: Brociner folded corner horn?

  1. #31
    Senior Member Steve Schell's Avatar
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    Hi guys, really good discussion. I once had an early '50s Jensen Triplex three way system that included that back loaded corner horn and it sounded pretty darn good for something of such reasonable size. Opinions vary about the hyperbolic horns though. Dr. Edgar uses a hyperbolic 35Hz. flare in his Seismic Sub to approximate a 20Hz. exponential flare in the nine foot path length of his design. He does this for the reason indicated in the response graph; low frequency extension. Some have opined that in general a very rapid cutoff will have an attendant rapid phase shift which may sound unnatural. If there is room to use an exponential flare horn of adequate length and mouth size then a more natural sound may result. Problem is that bass horn construction is such a large undertaking that direct comparisons are rarely made.

  2. #32
    RIP 2010 scott fitlin's Avatar
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    Basshorns! MMMM, when done properly basshorn bass is INCREDIBLE!

    BTW, Steve someone was telling me they stopped by your place, and how amazing your stuff sounded!

    scottyj

  3. #33
    Senior Member Beowulf57's Avatar
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    Quote Originally Posted by Steve Schell View Post
    Hi guys, really good discussion. I once had an early '50s Jensen Triplex three way system that included that back loaded corner horn and it sounded pretty darn good for something of such reasonable size. Opinions vary about the hyperbolic horns though. Dr. Edgar uses a hyperbolic 35Hz. flare in his Seismic Sub to approximate a 20Hz. exponential flare in the nine foot path length of his design. He does this for the reason indicated in the response graph; low frequency extension. Some have opined that in general a very rapid cutoff will have an attendant rapid phase shift which may sound unnatural. If there is room to use an exponential flare horn of adequate length and mouth size then a more natural sound may result. Problem is that bass horn construction is such a large undertaking that direct comparisons are rarely made.
    Interesting point regarding the possibility of phase shift with rapid cutoff. I can't say I've heard anything that suggests a problem, but then what would such a phase shift issue sound like in the deep bass? Any thoughts on what sonic characteristics could be identified by the listener as "unnatural"? Perhaps the contribution of the simultaneously forward firing bass masks this possible effect?

    And yes...how to compare? Let's see now where can I put those Klipschorns...?

  4. #34
    Senior Member spkrman57's Avatar
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    Some questions for the horn guru!

    Steve,

    Thanks for chiming in on our thread! I value your input and knowledge of horn design and theory!

    Quote Originally Posted by Steve Schell View Post
    Hi guys, really good discussion. I once had an early '50s Jensen Triplex three way system that included that back loaded corner horn and it sounded pretty darn good for something of such reasonable size.

    Could you comment on the bottom end LF response if you remember from back then?

    Opinions vary about the hyperbolic horns though. Dr. Edgar uses a hyperbolic 35Hz. flare in his Seismic Sub to approximate a 20Hz. exponential flare in the nine foot path length of his design. He does this for the reason indicated in the response graph; low frequency extension.

    I always thought the horn flare was 35hz and Bruce used EQ to extend the bottom LF response.

    I never could see using EQ on a horn for lowering response. Would that not introduce quite a bit of distortion compared to using EQ for a sealed/ported system?

    Some have opined that in general a very rapid cutoff will have an attendant rapid phase shift which may sound unnatural. If there is room to use an exponential flare horn of adequate length and mouth size then a more natural sound may result. Problem is that bass horn construction is such a large undertaking that direct comparisons are rarely made.
    According to Jensen Technical Bulletin No 3 (1952) which I referenced in a website link previously in this thread, the theoretical flare cutoff is 43hz when corner loaded, if they are sidewall loaded, would the cutoff frequency then be approx 86hz using the 40" horn length?

    Thanks from a horn rookie!

    Regards, Ron
    JBL Pro for home use!

  5. #35
    Senior Member Steve Schell's Avatar
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    Hey Scott! Yeah, nothing like giving a woofer a real load to work against rather than having it flail about. Horn loading is a beautiful thing. I get quite a few folks through here, glad to hear the talk is not all bad.

    Beowulf57, I'm not sure what rapid phase shift at 20 or 30Hz. would sound like. Sonically it may be more an issue of loading the driver adequately to prevent an unloaded condition at driver resonance. As I see it the whole point of going to the trouble of building bass horns is to avoid bloated, boomy, out-of-control bass response. Even so, some designers yield to the temptation of placing the driver resonance down around the flare cutoff frequency. This will produce more output down low, but at the cost of some boom. I have always had better results using exponential horns of low cutoff frequency and placing the driver resonance somewhere up higher in the passband where it is swamped by the horn load.

    spkrman57 (two 57s in one thread!), a horn's cutoff frequency is primarily determined by the rate of expansion along its length. The longer the horn path and the larger the mouth, the smoother the response will be down near the flare frequency. This is due to the impedance mismatch at the mouth which causes sudden unloading and reflections that travel back up the horn to affect the driver loading- both positively and negatively depending on frequency and the distances involved. Actually in the case of this rear load Jensen it may be a bit more complicated as backing the cabinet will create a dual rate of flare horn, the flare inside the box followed by the flare of the room corner.

  6. #36
    Senior Member Beowulf57's Avatar
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    Thanks for the insights Steve. I haven't noted much "boom" down low, as the room resonances higher up in the mid-bass (say around 160-180Hz) are more prominent. I'm intrigued with the actual result of the corner loading continuing the horn flare particularly when the output is from a split 2-section horn and is augmented from the front-firing woofer. Frankly the physics and audio math necessary to figure out how this horn actually performs is beyond me, though Figure 2. in the PDF I posted in post #28 does show the interference effect you have mentioned around the flare cutoff.

    If Jensen is specifying the flare cutoff at 43Hz (which has a wavelength of around 26'), I think this must be using the additional flare of the room walls?

    Almost as if the entire cabinet is a loading chamber feeding the throat of a 1/2 horn formed by the room corner? I say 1/2 as the top of the horn is open with only the sides and bottom in place (walls and floor). Though I may be way off base (bass...) here as I don't know how much loading a horn has when one of the 4 walls is absent? However, the Klipschorn seems to work this way. I'm interested in your thoughts on the audio physics of this, since once you are out into the room or in another room, one has the impression of the whole room loading the driver. I recall as a child that my father was playing around one day and cranked the system up full with pipe organ music...he cracked open a window in our den and closed the door to the room before he stepped out into the street. I could have sworn the pipe organ was the whole house as a loading chamber playing for the outside world.

  7. #37
    Senior Member jcrobso's Avatar
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    You have right on the nose.

    Quote Originally Posted by Beowulf57 View Post
    Thanks for the insights Steve. I haven't noted much "boom" down low, as the room resonances higher up in the mid-bass (say around 160-180Hz) are more prominent. I'm intrigued with the actual result of the corner loading continuing the horn flare particularly when the output is from a split 2-section horn and is augmented from the front-firing woofer. Frankly the physics and audio math necessary to figure out how this horn actually performs is beyond me, though Figure 2. in the PDF I posted in post #28 does show the interference effect you have mentioned around the flare cutoff.

    If Jensen is specifying the flare cutoff at 43Hz (which has a wavelength of around 26'), I think this must be using the additional flare of the room walls?

    Almost as if the entire cabinet is a loading chamber feeding the throat of a 1/2 horn formed by the room corner? I say 1/2 as the top of the horn is open with only the sides and bottom in place (walls and floor). Though I may be way off base (bass...) here as I don't know how much loading a horn has when one of the 4 walls is absent? However, the Klipschorn seems to work this way. I'm interested in your thoughts on the audio physics of this, since once you are out into the room or in another room, one has the impression of the whole room loading the driver. I recall as a child that my father was playing around one day and cranked the system up full with pipe organ music...he cracked open a window in our den and closed the door to the room before he stepped out into the street. I could have sworn the pipe organ was the whole house as a loading chamber playing for the outside world.
    The whole room becomes part of the horn!
    When I walk from my living room through the dinning room at the far end on the dinning room the bass is just something to feel, coming from my JBL loaded "K" horns. With corner horn speakers the longer the walls are from the corner the better the bass. The effect of the room loading of the horn is something to feel.

  8. #38
    RIP 2010 scott fitlin's Avatar
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    Quote Originally Posted by Steve Schell View Post
    Hey Scott! Yeah, nothing like giving a woofer a real load to work against rather than having it flail about. Horn loading is a beautiful thing. I get quite a few folks through here, glad to hear the talk is not all bad.
    BAD TALK? No, what this guy had to say was that looks are deceiving, and that your horn system made instruments and vocals sound UTTERLY real, which is something the vintage horn stuff was known for. He was also taken by the magnet wire, and your tube amps, and HOW YOU CAN GET SO MUCH OUT OF SO LITTLE!

    I must admit, I love the way your horns look, I lust for them! And the one thing I REALLY want to hear, is YOUR midrange! From everything I have read that you post, I get the impression that part of your philosophy is IF THE MIDRANGE AIN'T RIGHT NOTHING ELSE WILL BE, EITHER!

    The vocals and instruments sounded UTTERLY real! That's the tell, for that to happen, you have that special midrange.

    My dad has a huge home in Austin, and while I was visiting dad asks me what kind of speakers do I think he would like, so we go online, looking for your stuff, I show him pics, I tell him THIS IS THE DEAL! Here comes my mom, takes one look at the horns, and starts doing the "SCOTTAREYOUOUTOFYOURFUCKINGMIND" dance! Dad was intrigued by the field coil operation, and being that our bumper cars motors are field coil DC motors we have MORE than a hint of understanding about the principles of operation. Dad says he vaguely remembers big speakers with all kinds of wires, I mean he was born in 1937, so even when he reached ten or twelve years old, there was stuff like that still in use! Then, we look at pictures of the old RCA stuff, and he says YEAH, THAT I DO REMEMBER! There was alot of Altec stuff, and also RCA, and you know, I was never into audio like you, but, I remember RCA!

    He was reading though, had his attention!
    scottyj

  9. #39
    Member originaltubino's Avatar
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    I've got a pair of those giant Imperials

    Quote Originally Posted by spkrman57 View Post
    Here's more Jensen info/data I found useful while researching:
    http://aafradio.org/audio/Jensen_G-610_triaxial.html
    Nice link! I have a pair of these beasts in my basement, and it is quite amazing what they can do with JBL LE15B drivers (and with Tannoy dual concentrics, and with Altec 515E's ...) Even with crazy-loud and crazy-low bass making objects dance off the shelves, the cones will have extremely low excursion -- so they sound remarkably clean over the rest of the frequency range. I also have Tannoy GRF-R's, which are a considerably smaller version of the giant Jensens (30 cu ft: 5' tall x 3' wide x 2' deep). With a crossover at 800hz and the HF done with a 2" compression driver on Yuichi horns (which I got from Woody on this forum!), it's a truly remarkable two-way.

    A friend of mine was inspired by my pair to build his own, and I recently heard the TAD 1601a in there. Impressive.

  10. #40
    RIP 2010 scott fitlin's Avatar
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    You must have a really sweet sound. I like the bottom end from these kinds of cabinets, punchy.

    You liked the TAD in that kind cab? I think the TAD 15,s make outstanding low end, and have a very clean sound. I use the 1603,s in Altec VOTT horns, and am thinking of upgrading to the 1601B, it is JUST hideously expensive.

    I dig those 15,s too!
    scottyj

  11. #41
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    Quote Originally Posted by scott fitlin View Post
    You must have a really sweet sound. I like the bottom end from these kinds of cabinets, punchy.

    You liked the TAD in that kind cab? I think the TAD 15,s make outstanding low end, and have a very clean sound. I use the 1603,s in Altec VOTT horns, and am thinking of upgrading to the 1601B, it is JUST hideously expensive.

    I dig those 15,s too!
    I'm the friend with the 1601, it didn't load the horn to quite the extent the LE15B did but it DID load it enough to offer some punch. We only recently dropped them in there and it was impressive with some room for improvement in some areas but a very clean yet punchy presentation.

  12. #42
    RIP 2010 scott fitlin's Avatar
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    For me, the TAD 1603 deals with the extreme amounts of low end in todays digital music. I found the 1603,s tightened up the bass for me as well as offering prodigious low frequency. It is a flatter response than my old Altecs, and not as midrangey as the altecs were, but for todays music, that turned out to be good.

    I also find my speakers, as always has been the case, are amp sensitive. And Crown is what I prefer on them, and they sing.

    They do work thats for sure.
    scottyj

  13. #43
    Senior Member spkrman57's Avatar
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    After re-reading your post many times.....

    Steve,

    I think I was getting ready to make a mistake in using a driver in my horns that have a Fs of 40hz (JBL 2225).

    Now after reading your post over and over again enough times for my feeble brain to understand what you are trying to say, I'm going to use my JBL D131(reconed w/2202 conekits). They have a Fs of 70hz without being broke-in!

    I ordered the cork gaskets for them from edgewound(Thanks Ken!) and after my windows get installed(next week or so), I'll get new baffleboards cut and install the D131/2202 drivers and get them broke in and see how they sound.

    If the horn has a theoretical horn flare frequency of 43hz and I have a driver with 70hz, how low will the horn reproduce the bottom LF response?

    Thanks, Ron


    Quote Originally Posted by Steve Schell View Post
    Some designers yield to the temptation of placing the driver resonance down around the flare cutoff frequency. This will produce more output down low, but at the cost of some boom. I have always had better results using exponential horns of low cutoff frequency and placing the driver resonance somewhere up higher in the passband where it is swamped by the horn load.
    JBL Pro for home use!

  14. #44
    Senior Member Steve Schell's Avatar
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    Spkrman57, my way of doing things is definitely the path less traveled, and YMMV. One can surely obtained the widest bandwidth in a given volume using a driver whose resonance is down around the flare frequency. I am primarily after clarity and transparency to the source, and suppressing resonances is the way to go IMO. It is hard for a driver to slavishly follow the signal if it is trying to go nuts at its resonant frequency at the same time. If you try it both ways you might at first be seduced by the extension of the low Fs driver, but eventually come to prefer the clean sound of the high Fs driver. With a finite horn (all of them) the response achieved never quite makes it to the flare frequency, though I would expect you'll get good response to 50Hz. or so.

    Re: Bruce's Seismic, he does employ several dB of EQ boost on the low end to flatten response to 20Hz. Not my way of doing things, though its hard to argue with the big grins on the faces of those leaving his demo rooms at shows.

  15. #45
    Senior Member spkrman57's Avatar
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    Sometimes I know better, but have to hear it from someone else to believe it!

    Thank you Steve for once again educating us!

    I will also explore the issues that occur using the "sidewall" position that Jensen indicated is possible in the technical note No. 3.

    I'm guessing that the horn will lose some LF response without the full corner-loading. But I will be interested in trying it out anyways when the time comes. I have to do these projects in my bedrooms as they are the only rooms with usable corners right now!

    As soon as windows get replaced the project will continue along!

    Thanks, Ron
    JBL Pro for home use!

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