I did listen to it in mono for an hour or so. I really like how the 8PE21 sounds - even with the roll off at ca 200 Hz, I really like the upper midbass and lower mids, the large front horn "midbass kick" is definitely not missing. I am not so happy with the compression driver - but it might be also due to the missing low end. I definitely need to install the 18" bass driver, at least without a back cover. It might be worthwhile to try a 12" or 15" instead and limit the low end to ca 80 Hz, where the bass horns would take over. Also, the performance on the top end really makes me consider building the next prototype with an AMT - either the large Heil (cool, but dificult to mount) or the GRS PT6816 (it worked really nice in my smaller 2 way "Kallax" synergy, but might be too low sensitivity for this large one).
I realized I had a Scan-Speak R2604/833000 ring radiator tweeter with a custom 3D printed plate with 1.4" exit. It measured pretty fine with large 1.4" horns, so I will actually try it on this MEH, too. I do not expect much, it will need lots of EQ to compensate for the horn boost - but that should result in lower distortion at its lower end and a low crossover point - at the cost of sensitivity - and hopefuly a nicer top end as well, at least at low volumes.
Attachments
I was able to do some quick measurements and listening with the R2604 tweeter. Adding a low shelf ca -5 dB at -4.5 kHz made the response surprisingly flat, crossover was actually easier than with the CP755Nd. The sound at normal listening volume (measured ca 90 dB at the seat) was also more natural. The Beyma kind of disappointed me - I liked it really as a part of the 12XA30, but there it uses a higher crossover point. I will still keep them, maybe I can find some good use for them.
Anyway, the little ring radiator tweeter does surprisingly well. It cannot keep up with the mids. I can really imagine it in a smaller two way, lower efficiency synergy (like this one https://www.diyaudio.com/community/threads/synergy-attempt-without-compression-driver.286679/). So it is a keeper, but not for the large horn.
I got bored of listening in mono so I pulled my old small AMT + 2x3FE22 MEH and set up the DSP quickly and did listen to a few tracks.
Even with the lousy and cluttered setup (see the pic) with bass roll off starting at 200 Hz on both sides, both did their job well - and that is "disappearing" sonically. Some live tracks were actually spooky, with the singer "being there" just in front of me - like with a pair of nice full range speakers, but with a much wider sweet spot.
I wonder, how important is it to have the mids and bass in a MEH placed symmetrically...
Unfortunately, I forgot to save the measurements, so I will measure and tune a bit again before trying out the small planar driver.
Anyway, the little ring radiator tweeter does surprisingly well. It cannot keep up with the mids. I can really imagine it in a smaller two way, lower efficiency synergy (like this one https://www.diyaudio.com/community/threads/synergy-attempt-without-compression-driver.286679/). So it is a keeper, but not for the large horn.
I got bored of listening in mono so I pulled my old small AMT + 2x3FE22 MEH and set up the DSP quickly and did listen to a few tracks.
Even with the lousy and cluttered setup (see the pic) with bass roll off starting at 200 Hz on both sides, both did their job well - and that is "disappearing" sonically. Some live tracks were actually spooky, with the singer "being there" just in front of me - like with a pair of nice full range speakers, but with a much wider sweet spot.
I wonder, how important is it to have the mids and bass in a MEH placed symmetrically...
Unfortunately, I forgot to save the measurements, so I will measure and tune a bit again before trying out the small planar driver.
Attachments
I replaced the sofisticated EVA foam stand for the box pro Achat 112 active PA sub from Thomann. It is a very nice subwoofer , perfect for 40-200 Hz band. I think I will buy a second one, it sounds and measures really well and is nice and compact.
Now the frankensystem starts being really enjoyable. I must say I really like the ring tweeter in the large horn. I hope the small planar and DCX464 will be at least as good. The smaller AMT horn would maybe need also a gentle slope reducing the HF, it seems to be a little too much pronounced at times. And surprisingly, the AMT does not measure as flat as the R2604, because it did without a horn.
I am beginning to think about building another prototype, slightly smaller, so that all parts fit my CNC, using smaller mids (3FE22s) and 10-12" bass drivers to get the symmetry and relieve the tweeter a bit.
Now the frankensystem starts being really enjoyable. I must say I really like the ring tweeter in the large horn. I hope the small planar and DCX464 will be at least as good. The smaller AMT horn would maybe need also a gentle slope reducing the HF, it seems to be a little too much pronounced at times. And surprisingly, the AMT does not measure as flat as the R2604, because it did without a horn.
I am beginning to think about building another prototype, slightly smaller, so that all parts fit my CNC, using smaller mids (3FE22s) and 10-12" bass drivers to get the symmetry and relieve the tweeter a bit.
Attachments
So I did some measurements (quick and dirty, in room). Yellow is with the R2604, red is with the PT2522 (with open back, different scale). With a bit more EQ work, these can be made very similar. The only drawback of the PT2522 is the narrow dip at 7.5 kHz - I do not know where this could come from. Most probably it cannot be heard anyway. It seems that the open back gives some more ambience to the sound, I quite like that. In general, I prefer the planar. The next plan is to work a bit on the smaller AMT synergy (the left one) EQ and maybe try it out with open back as well. Now it seems to be a bit laid back.
I did some measurements around the large horn to find out how much the asymmetry matters and where is a good place to measure. It looks like aready some 50 cm out of the horn, the asymmetry does not matter. But that will be proven only when full polar measurements are made.
The waterfall looks really clean on the PT2522, I need to make some distortion and phase measurements. The Clio Pocket is really good, although a bit user unfriendly.
I did some measurements around the large horn to find out how much the asymmetry matters and where is a good place to measure. It looks like aready some 50 cm out of the horn, the asymmetry does not matter. But that will be proven only when full polar measurements are made.
The waterfall looks really clean on the PT2522, I need to make some distortion and phase measurements. The Clio Pocket is really good, although a bit user unfriendly.
Attachments
It is pretty cool that I start noticing stuff in the recordings I have never noticed before. And I also start noticing, how badly some of my favorite music is recorded.
I have mixed feelings about the open back tweeter. It definitely adds something to the sound and I like what it does - the added ambience/reflections are fine. I only have a sort of guilty feeling that it is too much of good, like three sugar cubes in a cup of coffee.
I have mixed feelings about the open back tweeter. It definitely adds something to the sound and I like what it does - the added ambience/reflections are fine. I only have a sort of guilty feeling that it is too much of good, like three sugar cubes in a cup of coffee.
These are definitely not headphone like even with the closed back tweeters (edit: I think this is because of the placement - not a typical stereo triangle here). I will print a back enclosure to test as well. Maybe I will end up with some sort of back wave management - by wall treatment or some sort of diffuser mounted to the back of the tweeter.
I've become convinced the headphone like sound, which I've heard too, is the result of a relatively narrow horizontal pattern.
Like 60 degrees or less, especially if it's a rather larger sized horn.
By 90 degrees H, I haven't heard any headphone effect, even with 4 ft wide horns.
And my current bestie, a 75x60 also 4ft wide, has a very, very open sound.
I know to never say never, but i don't think I'd ever add any ambience speakers to them..(once 75 degrees or wider)
If anything, I've been reducing ambiance somewhat, by strengthening the stereo central image via LCR matrix strategies.
(Good ole preferences, huh?)
A good point. Both test horns are around 80 degrees horizontal.
There is one thing I do not like that much with the long planars - and that is narrow vertical beam. Luckily that only means that I need to position them in the correct height or tilt them a bit. The smaller horn is 30 degrees vertical - as long as I can see the whole AMT, the sound does not change much. In the large one (65 deg V), I can already hear (and measure) some narrowing.
There is one thing I do not like that much with the long planars - and that is narrow vertical beam. Luckily that only means that I need to position them in the correct height or tilt them a bit. The smaller horn is 30 degrees vertical - as long as I can see the whole AMT, the sound does not change much. In the large one (65 deg V), I can already hear (and measure) some narrowing.