Today, I installed the second woofer and wired everything to the Speakon connectors. I could not resist and had a brief listen with just HF and mids and old DSP settings. So far so good🙂 I will try to adjust the DSP tomorrow and listen some more. In direct comparison, I think I like the open back tweeter more.
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A two way variant for AMT-1. I had to reduce the length and mouth area to fit the 90 x 40 patern. It will most probably get secondary flare for the horizontal expansion if it proves to be worth it. In case mids are needed, two 3FE22s will be installed, one from the top and one from the bottom. A pair is more than enough for the planars I am using, no need for extreme SPLs for me.
By the way, even the green prototype has some minimal overlap, so the mids do not need to be used. I made a two way crossover and even though it measures fine (on axis, in room), the three way variant seems to sound better. I hope that the AMT-1 having larger surface will handle the two way better. The mid/bass ports are closer to the throat, but the active surface of the AMT-1 is a bit deeper inside. So it will be a surprise anyway🙂
Yesterday I made an interesting discovery. When walking around the speakers, I said to myself how airy the sound is with a nice semse of space - and I found out, that the tweeter back cover on the green one fell off - it was held temporarily by friction only. Also, my wife, who is a violinist commented for the first time (after hearing the speakers through a stairway and a door since I turned them up a bit one day) how natural the sound of piano is.
So I removed the back cover on the second one and it became even better. The full open backed construction seems to have an interesting effect. It might not be strictly HiFi, but it is very enjoyable.
The theory is that the back wave adds a bit of ambience, which is slightly missing with such large horns in a relatively small room.
Another thing is, that the larger yellow horn seems to sound better overall with its 18" bass - a double bass is really lifelike. The dual 12" on the green horn are missing a bit on the low end. 18" on the horn is impractical, so I want to try a separate bandpass subwoofer with open back with the new round horn being built.
So I removed the back cover on the second one and it became even better. The full open backed construction seems to have an interesting effect. It might not be strictly HiFi, but it is very enjoyable.
The theory is that the back wave adds a bit of ambience, which is slightly missing with such large horns in a relatively small room.
Another thing is, that the larger yellow horn seems to sound better overall with its 18" bass - a double bass is really lifelike. The dual 12" on the green horn are missing a bit on the low end. 18" on the horn is impractical, so I want to try a separate bandpass subwoofer with open back with the new round horn being built.
-if still around and not too tall - you could drag out your Karlson K15. Its always been the winner over any horn I own for bowed double bass. Alternately a cubical K18 could be made like Metro's T15 or so to keep cabinet height to ~24". Open back does add a type of ambiance.
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The K15 is now dedicated as a bass unit to a 2.1 party system. I would have to lay it on its side and I have only one K15 anyway. A U or H frame with optional front chamber would fit better. I plan to experiment with the slot shape, might try a KSlot as well.
But perhaps it is... 🙂 my prediction is that in the future, omni will dominate. It makes so much more sense compared to a beamer. And you just heard one of the reasons why a perfect spherical omni transducer is indeed the holy grail. Nice build!
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For the sake of simplicity, I plan to combine 3D printing and panels with 90 degree edges. The throat attachment barely fits my printer. Hole for the midwoofer will be cut by hand on this prototype.
I´m intrigued!
I run Beyma TPL-150H open back and 8PE21 in OB and have been intrigued by MEH. Will be interested to learn how this works out for you.
I am not sure. I liked the GRS planar in a MEH and my smaller AMT MEH with 3FE22 mids only was fine as well. I was inspired by @xrk971 to try planars and AMTs in MEH and it worked for me as well. I liked the 8PE21 in combination with the small GRS and have another two way with 8" Fane and the large GRS. How would one detect the influence? I have not seen any unusual levels of distortion in the measurements - but I was not looking for them.
By the way, 3 panels out of 4 are cut, the leftover board I had was a bit warped, but in general it looks like it will fit fine together.
@LewinskiH01 Have you seen this thread? https://www.diyaudio.com/community/threads/sirvalences-tpl-150-sb23nrxs-point-source-horn.353508/
By the way, 3 panels out of 4 are cut, the leftover board I had was a bit warped, but in general it looks like it will fit fine together.
@LewinskiH01 Have you seen this thread? https://www.diyaudio.com/community/threads/sirvalences-tpl-150-sb23nrxs-point-source-horn.353508/
Today, I made two woofer mounting plates and a stand. The next step is to mount the plates back to back and measure how the placement of the hole influences the FR - and also the influence of dual wall thickness of the port. The winner will be glued to the horn and the hole through the horn wall will be routed at the correct place.
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