When sound comes out of the back of the speaker does it come out perpendicular to the cone or perpendicular to the face?
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When sound comes out of the back of the speaker does it come out perpendicular to the cone or perpendicular to the face?
Direction is frequency dependent, same as front of cone. Lower frequencies are less directional. Since HF is too short to make the turn in a reflex or too short to flow around a finite "infinite" baffle, my answer is neither.
GM should chime in here, more his area than mine.
I did a test with a 3 x 3 block of 1/2 plywood in a cookie pan of water, as i tapped one corner the waves came off perpendicular to the two opposite sides. I'm betting that the sound comes out perpendicular to the cone. call me corny but it's one way of seeing it. In case your wondering I'm trying to come up with a back loaded horn cabinet design for a winter project.
:D I'm not sure that test holds water.
You are using the force from the speaker to accelerate water. A test with something much lower in mass would be in order.
Regardless sound just plain does not travel in a perpendicular line. An ideal point source has a spherical pattern.
The sound is gonna emanate in a pattern of some sort. Never perpendicular. And you really don't need that info to design a rear loaded cab.
I would suggest looking at successful designs for inspiration, cobble and try works, eventually. Must better to modify existing designs to your needs.
Padding the sides deals with reflections. Just concentrate on the loading itself.
I hear you OG but if you yell hello in a cave and it hit's a wall parrallel to you it will come back. Same with yodelers in the Swiss alps so if you direct the sound in an orderly manner out of the cab instead of letting it rattle around inside you'll reinforce the SPL and eliminate that sound waves bouncing around in a wooden box sound. Here is a couple I'm working on the first one is 40W by 24D by 36H The second one is 48W by 24D by 36H. I reread what you said and I agree that the sound waves expand as they leave the source but only because they are not directed by a hard surface, For instance when people are talking in a boat on a calm lake. Even if they're way out you can almost hear what there saying because their voices are directed along the hard flat surface of the water. By loading do you mean creating some back pressure? Because I would think the basket does that to a degree on the back of the speaker.
Yes, if you yell at a parallel wall it comes back, that still does not mean the sound travels in only one direction.
The box designs you show will work, but won't have anything resembling flat response.
Splitting the horn in two creates two small mouths, to a certain extent LF response is dependent on mouth area . Designs like you show were abandoned some 50 years ago.
A "scoop" like the JBL is a much better idea. You still are gonna have massive phase issues. The response graph is gonna look like a roller coaster. Not so much an issue for a sub, problem for wider range.
http://www.hostboard.com/forums/hbmc...2011/09/71.jpg
If you can blunder thru French have a look here...
Liste des plans
I agree that sound radiates outward, But If you yell at a wall and a person is standing in front of the wall sideways so their ear is pointing towards you your yell will be louder to them than it would be to two people standing on either side of the wall because you pointed your mouth directly at the wall. So your saying 2 small mouths don't equal one big one? I have seen some bass horns and I agree they do get crazy large. My other design was modified A7 cab. see below.
Two small mouths do not equal one big one unless they are right next to each other. You can make small modules where most of the cab front is mouth, and stack them. But separate them and you lose response and efficiency.
We built modded A-7's like that back in the 70's. Again, if you try to use a cab like that wide range your response graph is gonna have peaks and dips like the Himalayas. You can pick a wide peak and use it only at that frequency band...like 40-120 Hz. But as you go outside that band it will get peaky and dippy...
ANY...let me be emphatic...ANY rear loaded horn is gonna be anything but flat due to phase issues between front and rear paths. The design is only used these days as pro sound subs. Like the one I posted.
Wavelength of sound changes with frequency but the horn path length stays the same, so some frequencies will combine, some will cancel.
Designing cabs like that is very intensive, I couldn't do it. I might be able to take an existing design and by "cut and try" improve on it's performance.
Ok just to be on the same wavelength, by flat response do you mean that all the frequency's are coming out at the same volume or decibel? I understand the phase part...I think.
Apparently you never met my ex wife and her two sisters. :DQuote:
Originally Posted by Old Guy
Can someone explain why I would want to build a rear horn loaded enclosure verses a tuned reflex port? Why not horn load both the front and back of the speaker with mirror horns? I've made a sketch. Just need to build a big wood steamer and make some curved plywood. :)
Horn loading the back increases efficiency. Problem is as I have already stated severe phase issues.Quote:
Originally Posted by VolvoHeretic
Quote:
Originally Posted by cradeldorf
You simply misstated the problem is why you got wrong info. In your case two large mouths became one huge one. The effect is drastically increased by proximity just as I said.:D
http://www.hostboard.com/forums/hbmc.../2011/09/1.gifQuote:
Originally Posted by cradeldorf
One pure sound a fraction of a second after the next
http://www.hostboard.com/forums/hbmc.../2011/09/2.gif
Sum of two waves slightly out of phase
Essentially with out of phase issues some frequencies will add, others will cancel. The result is exaggerated peaks and dips. This is why the enclosure can not exhibit smooth response over a wide band.
I'm gonna work on a drawing of an infinite baffle design, I'll post it up when I get it done, what I really want to do is get rid of the boxy sound that seems to be so common in enclosures.And have a nice clear open sound...only with thundering bass. :/
Edit, Sorry I meant Open Baffle.
I beleive the only real way to do that is with an infinite baffle....... driver mounted in wall/ceiling/floor/etc.Quote:
Originally Posted by cradeldorf
Abe did it and he says their wonderful sounding. Check out this link.Quote:
Originally Posted by Audio_by_Goodwill
http://www.hostboard.com/forums/f700...04-8g-obs.html
Quote:
Originally Posted by cradeldorf
Maybe our definitions of thundering bass are different? Certainly an open baffle is possible, but bass response is their downfall.
I think that thread got messed up in a transfer when the forum changed. The first post or so seems to be gone.
I hope no other threads/posts got messed up or deleted when the forum changed--I really consider the info/history here to be invaluable and some of it is irreplaceable. Anyone else notice any discrepancies/deletions?Quote:
Originally Posted by Audio_by_Goodwill
I've noticed a few that seemed to get chopped up. I think it was the prior change in the forum, not the most recent one. If you notice none of the codes work either.Quote:
Originally Posted by voice of the theater
I've been seeing a lot of this stuff in old posts......... <font size="2" face="Verdana, Helvetica, sans-serif">
Sorry Buddy, I was thinking you were saying in general they won't sound good, Yes I understand the thunder will be down quite a bit from where they are now. But I do wish to get rid of that boxy sound. I don't know if the link I posted is messed up or not but it does still have a lot of good info in it and apparently a lot of others say that after putting the 604's in OB designs they were very pleased with the results.Quote:
Originally Posted by Audio_by_Goodwill
Infinite baffles sound quite good when properly done. I'd want a sub though.
When you say sub do you mean like this 48 "? It's kinda small, I better get 4 :D
Yeah, that one!
You might want to use the backwave of the driver to put out more low frequency sound.Quote:
Originally Posted by VolvoHeretic
http://www.hostboard.com/forums/hbmc...2011/09/75.jpg
Yep, I had a thread bookmarked and it is no longer linked to the same URL.Quote:
Originally Posted by voice of the theater
How do those sound Westend?
I drew this up tonight. It's a 3/4 piece of MDF 24" x 36" with 2x3 frame, it has a 6.5 dia hole that the speaker goes through and has a clamping type of setup so your holding the speaker by the magnet. I wonder how bad the phase issues would be? I'm trying to get them as close as possible and This is about as close as you could physically get them I think. also trying to get the open sound of an open baffle along with some good bass. If anything else it it'll give you a good laugh. :D
That design allows the waves coming off the front and back to meet and cancel each other, turning the "baffle" into a stand.
How about half of an oak wine barrel (used for planters) with the open end facing the wall and the closed end facing forward with the speaker mounted in that?Quote:
Originally Posted by cradeldorf
So, if the horn or port is facing forwards, the sound coming out will have turned 180 degrees and be in faze with the speaker, and facing rewards will be out of faze and requires the sound to bounce off of the back wall 180 degrees to be in faze? How about these speakers with the ports or PR aimed out the sides, are they 90 degrees out of faze?Quote:
Originally Posted by westend9
I dreamt up a folded horn kind of like your picture, but thought of a curved .75? dado slot cut into the sides and gluing three layers of .25? rubber conveyer belting to form pretty, gently curving pathways. I was going to do this to the front and back of the speaker and combine them at the front (which would be the bottom of yours), but the sound would still be out of faze with each other, so...instead of out the bottom, turn the one side another 180 degrees and below and in the same direction of the existing opening?
I built one of my cornball speaker in front of the baffle things and it doesn't sound too bad, I have the second one built I'm just taking a 10 minute break and then I'm gonna get the other speaker out of the old cab and install it. Will be back later with some pics and info on how they sound together.
I took the backs off the heathkit cabs last night and pointed them at the wall, It truly sounded horrible. I moved them close to the wall, far away from the wall...they were just horrible. : / What I'm trying to accomplish is to hook the back wave to the front wave in as short of distance as I can hopefully to reduce the out of phase problem.Quote:
Originally Posted by VolvoHeretic
Ok here's a couple of pics....they sound open that's for sure but I need to work on the bass. I shot some small vids of them in action. I might post one up later depending how it sounds. I think I'm gonna try some sides and top tomorrow. they'll stick out 6 inches from the baffle forward.
This is a small video of them playing some pink floyd.
Altec604 in Open Baffle.wmv - YouTube
Using a 4" Fostex driver, the FE126e, they sound sublime, especially through the midrange. Using a lightweight cone and a huge magnet is one of the better ideas, I'm thinking. This is pretty much the same construction as our Altec's, a paper cone, limited excursion, and a beefy magnet structure, everything on a smaller scale.Quote:
Originally Posted by cradeldorf
I'd urge you to experiment with any kind of horn to see the effect. The lowest frequencies don't have to presented with a lot of directivity because our hearing doesn't break down that information with as much directionality. A bear grunt in a cave was enough information, probably. ;)Quote:
Originally Posted by VolvoHeretic
My experience tells me that making a front horn opening is almost more difficult to bring good results than having a rear or side-opening mouth. I'm sure users of the A7 can shed light on the front horrn and reflex chamber in that cabinet.
The Fostex BLH I built is a design by Ron Clarke, dubbed the A126. He has designed horns for other drivers, as well. In the picture below you can see the added sand-filled deflectors behind the horn mouth. These are used to diffuse the sound from the horn mouth.
http://www.hostboard.com/forums/hbmc...2011/09/76.jpg
http://www.hostboard.com/forums/hbmc...2011/09/77.jpg
http://www.hostboard.com/forums/hbmc...2011/09/78.jpg
You're probably going to get more bass by having the frame even with the baffle. I messed around with IB speakers enough to know that they're not for me. I'm pretty much a basshound and the IB design doesn't help my cause. Horns, on the other hand, can add a pleasant spike to the lower end.Quote:
Originally Posted by cradeldorf
Since I built the large MLTL's that GM designed, I can't go back to horns or BR anytime soon. Have you looked at the 6moons article about their 604 collaboration? Here
I seem to remember that GM had a major hand in the design of that speaker, too, but wasn't credited as he should have been.
I did read the article on 6 moons about the 604 cab. I thought there was more people around here than just GM who didn't get credit. Greg's a good guy that's for sure. I got some other things I'm gonna try with this OB design before giving up and going back to the Heathkits. I need something to play with winters coming. :)
Understood, about winter coming, a man needs projects for the indoors:Thinking:Quote:
Originally Posted by cradeldorf
I obviously don't know the whole story about the 6moons project but thought the cabinet design might be good if you have the room.
Good on 'ya for the OB experiments. On the Decware forums, there was a lot of experimenters with the OB design, adding wings, trying different baffle arrangements, quasi BLH additions, etc.. AFAIK, that part of the Decware Forums is lost to posterity. From my little goofing around, it seemed a larger baffle and moving the driver to anything but a midpoint of the baffle, resulted in a better presentation. This may not follow for the 604 so your experiments may turn up a better combo. Best of luck, experimenting with sound is too cool!
Yep it is fun, now to put them back where they sound best, in the Heathkits. :D
I'm not sure I understand exactly what you're describing as a "boxy" sound, but I think I have a general idea of what you're referring to. It may be something that can be fixed by things like (or a combination of):Quote:
Originally Posted by cradeldorf
1) speaker placement i.e. the difference between how they sound on the floor compared to how they sound sitting on stands/elevated off the floor which also puts the drivers at ear level. Keep in mind you can experiment with this before "committing to building speaker stands/risers" by propping them up on blocks (as long as they're solidly supporting all four sides of the bottoms of the speakers of course). You may very well be surprised at the difference in sound of the speakers being elevated compared to sitting on the floor (the only way to know which position if any gives you less or no boxy sound is to try both). Another possible factor related to speaker placement may be how near or far you have them from the corners of your room and/or how close you have them to the wall that's directly in back of them. Sometimes moving them just a few inches closer to the "back wall" or farther from that wall (or just a few inches closer to the corners of the room or farther) can make a surprising difference in sound.
2) EQ You may find with a little trial and error with an equalizer you can eliminate what you're referring to as a "boxy" sound. In my experience, most vintage Altecs I've owned don't require that you add much if any midrange EQ, but you may find an equalizer setting (possibly just adding some of the higher frequencies and probably the lower bass too) may "open up" your sound--and possibly if EQ experimentation is combined with speaker placement/elevation experimentation.
3) Crossovers I think you've mentioned that you have two sets of crossovers (an original set and a GPA set) and I'm aware you have two different models of 604. Maybe a little experimentation there might help as well--for example trying the original crossover with one 604 and the GPA with the other and vice versa or trying both old and both new and seeing which fit your system (referring to your entire system--drivers, cabs, amp, EQ, source, acoustics/room, etc.) the best. Keep in mind, the original crossovers probably need new caps if you want to give them a fair audition/comparison. Also, an active crossover might be worth experimenting with if these other variables aren't the "culprit" or as I mentioned, any combination of these three things (for starters). Just thinking out loud, for whatever that's worth......
The nady is toast, I bought a Kenwood eq. tonight off ebay $55.00 After putting them back together I couldn't get them to sound for crap, and I had both the gain knobs at 0 then I noticed that the left side lights weren't going as high as the right side ones so I upped the gain to the 3/4 mark for that side and the speakers came right into tune. I've read up a lot on them since I started suspecting it was bad. I wont toast the next one, if it isn't already.
I have the entire parts list and schematics to build new N-1500 crossovers. Thanks to Mr. Markwart, and Abe. :)