Thanks Lynn I wasn't considering using the 511 or 811 at all but rather the TPL-150H or something else etc.. It would be a long ways off till I could commit so for now it's just me dreaming away lol..
I beg to differ with you. I had already been doing this technique for many years when Welty, et. al. published their work. I wrote a "Letter" to the AES pointing this out which was also published, but who reads the "Letters". I would also point out that my PhD thesis was on "Low Frequency Sound Field Statistics in Small Rooms", way back in 1981 (34 years ago!). Elements of my approach can be seen in that thesis.
Yeah, it takes a lot of tweaks to make them HIFI enough for most folks, so strictly for 'vintage' systems IME, though the M19's ~1.2 kHz XO is high enough to ~ameliorate the 811's, 511's ~1.6 kHz 'flip'; so on average, it's a pretty flat response at ~75 deg, whereas the larger, longer 511 strongly rises on axis above ~4 kHz, though when Altec switched to the M19's XO near the end of its 'career', it's not so bad.
GM
Cut the front fins out of any of the 311, 511 or 811 horns and they won't have as much diffraction in those horns. I made a composite 311 without the fins long ago, it was night and day different compared to the 311 with fins and coating on the back of those horns.
Can you describe your speaker and the listening space? Is it not bigger than Gary's "BTA"? (Altec 416 is 16" right?). They said "horn is for loading and waveguide is for dispersion", so I believe dispersion is your main purpose? I couldn't find it's benefit for small room, unless you sacrifice nothing for the approach.
Ah, I think I have seen something built into the corners of a room. If that's yours, that's bigger than the Tractix here. May be the room is long or non rectangular open area. But I forget I've seen the detail of the horn. Built that way (removing reflection from surrounding/back walls), it is more than just about horn/WG dispersion (the wall is also the horn extension), it's a no option for me 😀
No problem with closer listening? No HOMs?
The Altec 416 drivers I've owned have been all over the map. None where near the published specs. That's part of the "fun". 🙄
Once I figured mine out and stuck my speakers in the corners, there was no problem getting an f3 of 30Hz. That's real, solid bass. And didn't use much power. They actually needed a -3dB bass shelf when placed in the corners. I was happy, for sure.
On the 1" vs. 1.4/1.5 drivers- just get a better 15". My BD15 are VERY comfortable at 1300hz, which is also very comfortable for my modified and matched selenium d2500ti. A small off-axis dip? Not really a biggie, just another dimension of balancing compromise. It's a 1" throat driver btw, with a small phragm (embossed from factory and further damped with coating by me).
Vuki,
I noticed that there are two different mounting methods for the 15" driver. I wouldn't want to see the second one with the driver mounted from the back like that forming a chamber in front of the driver. I know it looks nicer but the first cabinet with the driver flush mounted would be the preferred method always.
I noticed that there are two different mounting methods for the 15" driver. I wouldn't want to see the second one with the driver mounted from the back like that forming a chamber in front of the driver. I know it looks nicer but the first cabinet with the driver flush mounted would be the preferred method always.
Sure, but 414z (it's 12") can't be flush mounted (or it could be done with lot of effort and some kind of additional mounting ring)...
Are you saying that you can't flush mount the 12" because you already have a 15" hole or because of some reason of the frame on that speaker? If you do have a larger hole for a smaller frame size I can see that you would have to make an intermediate adapter but that would be rather simple to accomplish. With a nice finish it could look integrated with the current veneer finish.
414Z has frame reinforcements around screw holes on the back side of the rim. Look at the pictures of the linked loudspeaker project.
Vuki,
Okay, so you would have to notch the recess to flush mount the frame. Otherwise you would have to have a very deep recess from the back of the enclosure to limit the cavity size you are creating in front of that driver which would cause other problems of a weak section there. I would still choose the front mounting and four small recess cuts for those reinforced sections to fit into. Of course this is only my opinion as always.
Okay, so you would have to notch the recess to flush mount the frame. Otherwise you would have to have a very deep recess from the back of the enclosure to limit the cavity size you are creating in front of that driver which would cause other problems of a weak section there. I would still choose the front mounting and four small recess cuts for those reinforced sections to fit into. Of course this is only my opinion as always.
I have both flush mounted and rear mounted woofers. As long as the rear mount has a radius on the baffle hole edge, I don't see any significant differences in the response. I know that this is not what is traditionally written, but it has been my experience. Of course if the baffle hole is straight sided then the edge diffraction could be an issue, but I have not seen a significant volume effect or otherwise with a rounded edge.
Vuki,
nice speakers there! How large are you cabinets? Ports? The 414-B (GPA) should do ok in 70-150l from what I have seen.
Now I am tending to the autotech iwata 600 horn (instead of the axis-symmetric le cleach or the e-jmlc. It is very compact!
I find these very nice https://www.youtube.com/watch?v=cO2XRVs0VVo
nice speakers there! How large are you cabinets? Ports? The 414-B (GPA) should do ok in 70-150l from what I have seen.
Now I am tending to the autotech iwata 600 horn (instead of the axis-symmetric le cleach or the e-jmlc. It is very compact!
I find these very nice https://www.youtube.com/watch?v=cO2XRVs0VVo
Earl,
That is exactly what I am seeing in the posted photos, a non radius on the straight edged front cavity. As you say this has been talked about forever.
That is exactly what I am seeing in the posted photos, a non radius on the straight edged front cavity. As you say this has been talked about forever.
I hadn't looked at the photos. Yes, back mounting into a straight cut hole would not work very well. The edges need to have a radius. That messes up the veneer of course. The need for a large radius on all edges is why I have never considered veneer - not practical.
Since it was classic driver I aimed for a classic look (sort of).
But, do you have any expirience how audible that difraction issue is really? Because I haven't heard any significant difference between back and flush mounted driver. Even measured fr was almost the same (1dB difference).
@swak
120L tuned to 38hz
But, do you have any expirience how audible that difraction issue is really? Because I haven't heard any significant difference between back and flush mounted driver. Even measured fr was almost the same (1dB difference).
@swak
120L tuned to 38hz