A speaker physics question.

[cradeldorf]

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.

[cradeldorf]

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?

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.

[cradeldorf]

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.

[cradeldorf]

This is a small video of them playing some pink floyd.
Altec604 in Open Baffle.wmv - YouTube

[westend9]

How do those sound Westend?

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.

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?

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'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.
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.

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.

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.
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.

[cradeldorf]

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.

[westend9]

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
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!

[cradeldorf]

Yep it is fun, now to put them back where they sound best, in the Heathkits.

[voice of the theater]

Yep it is fun, now to put them back where they sound best, in the Heathkits.

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):
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......

[cradeldorf]

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.