I'm about to do a build using the Beyma TPL-150 in a WMTMW (not the "H" version, mine doesn't have the waveguide). The tweeter will end up between 2 Scanspeak 18M mids. I've never worked with this Beyma, but I have heard it in a few different builds and generally always enjoyed it. Reviews are all over the place but mostly positive.
Not that I'm trolling or looking to start an argument, more of a good debate if there is one, I'm hoping to get a couple differing opinions here. "Word on the street is" the Beyma will cross as low as 1.2khz, but from what I've read the general consensus is that while the Beyma will play that low, it's best from 2khz up. Is this everyone here's opinion as well? I have a lot of wiggle room using the 18M, I think I can go up to 2.3khz without too much issue.
So, have you used this tweeter? If so, what are your thoughts? Where'd you cross it?
Also, I think the flat face of this tweeter is kinda ugly. An idea I have would be easy to measure, but to try to save me some time I'll ask... I was considering making a 1/2" thick "cover" for the Beyma and trying some different edge treatments on the opening. For example, cut a 1/2" thick piece of MDF, cut an opening (about the size of the tweeter opening in the original faceplate), and use that to "sandwich" the tweeter to the front baffle. This seems fairly simple to do, but I'm curious where I would or should start with either a roundover or a bevel on the actual opening of the tweeter (1/2" R/O, 45 degree bevel, 3/4" R/O..?). And also, is this a bad idea and a waste of time or something I should even try? (Edit) To simplify this question, do you guys think doing this would introduce too much edge diffraction? Not looking to improve performance, just make it look better.
FWIW this will be passive.
Not that I'm trolling or looking to start an argument, more of a good debate if there is one, I'm hoping to get a couple differing opinions here. "Word on the street is" the Beyma will cross as low as 1.2khz, but from what I've read the general consensus is that while the Beyma will play that low, it's best from 2khz up. Is this everyone here's opinion as well? I have a lot of wiggle room using the 18M, I think I can go up to 2.3khz without too much issue.
So, have you used this tweeter? If so, what are your thoughts? Where'd you cross it?
Also, I think the flat face of this tweeter is kinda ugly. An idea I have would be easy to measure, but to try to save me some time I'll ask... I was considering making a 1/2" thick "cover" for the Beyma and trying some different edge treatments on the opening. For example, cut a 1/2" thick piece of MDF, cut an opening (about the size of the tweeter opening in the original faceplate), and use that to "sandwich" the tweeter to the front baffle. This seems fairly simple to do, but I'm curious where I would or should start with either a roundover or a bevel on the actual opening of the tweeter (1/2" R/O, 45 degree bevel, 3/4" R/O..?). And also, is this a bad idea and a waste of time or something I should even try? (Edit) To simplify this question, do you guys think doing this would introduce too much edge diffraction? Not looking to improve performance, just make it look better.
FWIW this will be passive.
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Symmetrical arrangements are going to be a challenge when you're restricted on how low you can go, and when the drivers are not small. Also less choice of slope. Maybe it's not bad that the tweeter is tall but the mids are going to be spread a wavelength even around 1.2kHz.
It would be interesting to see how high you can take that arrangement after some measurements or modelling.
It would be interesting to see how high you can take that arrangement after some measurements or modelling.
I agree, I'm actually looking forward to playing with this just for the learning experience... sort of. I was hoping to avoid a test cabinet because these are so big (lots of MDF), but I think I owe it to this speaker to build one, just in case this tweeter is a bust in this build.
Hopefully I'll get the ball rolling on this build in a month or so. I have a build I'm working on now to wrap up, then I'll get going on this one. I do have all the drivers. I'll try to remember to post measurements here when I have them.
Looking at the factory 18M measurement, and looking at what I can find posted for the Beyma measurements... I'm guessing 1.8k is about where both these will shine. But just a guess. Possibly a notch on the Beyma to pad between 3k and 7k? Or a creative slope? Having 99 db efficiency to play with makes things easier.
Hmm, specs say 1 kHz/2nd min., so (4) octaves away (1000/2^4) = 62.5 Hz/-48 dB, ergo can go down to 250 Hz/4th order in theory, though how good it performs remains to be heard.
With a CTC = (18.2+16)/2 = ~17.1 cm, ~34400/4/17.1 = ~503 Hz leaves a bit extra protection, though best to WG load it that's big enough to set it back to the SS's VC vertical centerline allows further EQ protection in the hope that it will keep distortion down to at least -25 dB where we go ~deaf.
Efficiency of course 'drops like a stone' to ~87 dB Vs the SS's 89 dB, but BSC will lower it and power to 20 W max, 40 W dynamic headroom, so still plenty loud for most apps.
With a CTC = (18.2+16)/2 = ~17.1 cm, ~34400/4/17.1 = ~503 Hz leaves a bit extra protection, though best to WG load it that's big enough to set it back to the SS's VC vertical centerline allows further EQ protection in the hope that it will keep distortion down to at least -25 dB where we go ~deaf.
Efficiency of course 'drops like a stone' to ~87 dB Vs the SS's 89 dB, but BSC will lower it and power to 20 W max, 40 W dynamic headroom, so still plenty loud for most apps.
Also, hard to see on the internet sometimes, but hopefully my response didn't come across as snarky, what you posted is exactly what I was looking for (good debate on where to use this tweeter).
I actually talked with Joseph Crowe a while back about possibly doing a horn for this tweeter for me, but it never came to fruition. I never considered using it that low, my fear would be frying the VC (or whatever that's called in an AMT) during a "check this out" listening session if I tried it too low.
Charles, when you say "try that setup anyway" you mean move forward with the MTM using the 18M mids?
I have used the TPL150H extensively in PA work and my good friend also - he uses his with no horn for both PA and home use. I combined mine with Beyma 10" drivers and naturally started with the lowest possible crossover point thinking this would sound best, but finalised at 1.8kHz - it simply sounded better to my ears! Very counter intuitive... With multiple sealed 18" subs they go way louder than one would ever need in a pub setting playing classic rock as I do. In your very low level application I would not be afraid to cross it over at 1kHz, but it might not sound at its best to your ears, who knows? Since we use active crossovers it is so easy to play around with the crossover point - I would suggest you do likewise unless you're a passive crossover design wizard prepared to make many prototypes! These drivers are very robust (as evidenced by one being crossed over at 80Hz in error and surviving a sound check) and you will never, ever hurt them in a domestic setting - your ears will bleed first!
As others have noted, the mid spacing will cause plenty of problems; is there any particular reason you are going for such a difficult multiple driver arrangement?
Regarding the 'kinda ugly' appearance, there is a very strong psychoacoustic phenomenon that not seeing the speakers at all is very positive and powerful. I bought a couple of cheap Chinese full range drivers, slapped them in stainless steel coffee tins with plenty of damping and stuffing - a three-hour build - and hid the setup behind an old army parachute. I demoed them blind to my above hifi nut friend, and after listening for a couple of minutes his quizzical comment was: "... not much bass. You've bought those Quad electrostatics you've been promising yourself haven't you?". Remember that the eyes can easily overwhelm what the ears hear, so don't get hung up with appearance, just hide them!
PS. Beyma TPLs are exceptionally nice sounding drivers, and I struggle to listen to conventional compression drivers now, with perhaps the exception of Radian, which I also use and like.
As others have noted, the mid spacing will cause plenty of problems; is there any particular reason you are going for such a difficult multiple driver arrangement?
Regarding the 'kinda ugly' appearance, there is a very strong psychoacoustic phenomenon that not seeing the speakers at all is very positive and powerful. I bought a couple of cheap Chinese full range drivers, slapped them in stainless steel coffee tins with plenty of damping and stuffing - a three-hour build - and hid the setup behind an old army parachute. I demoed them blind to my above hifi nut friend, and after listening for a couple of minutes his quizzical comment was: "... not much bass. You've bought those Quad electrostatics you've been promising yourself haven't you?". Remember that the eyes can easily overwhelm what the ears hear, so don't get hung up with appearance, just hide them!
PS. Beyma TPLs are exceptionally nice sounding drivers, and I struggle to listen to conventional compression drivers now, with perhaps the exception of Radian, which I also use and like.
Yes, exactly that !
I would maybe not make the first try with a nicely built cabinet but some raw prototype. Keep in mind that an AMT does not radiate like a dome but has some inherent vertical beaming which is definitley not bad in an MTM situation.
Regards
Charles
You guys are awesome, this is exactly what I was hoping for 😎
I have played with a couple different AMTs, the build I'm just finishing (a TMWW) has a Mundorf AMT25D6.1 in it. And while I assume both the Mundorf and the Beyma share similar dispersion characteristics being both AMT, I also assumed this Beyma is an entirely different animal.
FWIW, that Mundorf was also a learning experience. If anyone is curious, it's the most laid back, revealing tweeter I've ever used. Seems like those 2 don't go together but that's the best way I can describe it, it's definitely an anomaly for a AMT. Just a pure, amazing tweeter with zero exaggeration, it's like the anti-AMT. To be honest I didn't like it at first, I'm used to a little exaggeration in the upper frequencies that this tweeter just doesn't do, at all. Think of it like an absolutely beautiful girl with no makeup on, if you're used to plastic surgery and makeup on a tweeter, this might not float your boat lol.
I wouldn't say I'm a "passive wizard", but I do know my way around. Thankfully I have a huge stash of caps, resistors and coils so passively I can play around quite a bit to see what I think sounds the best. As far as doing these active, that would probably make the most sense and (can't believe I'm saying this out loud 😛) would most likely sound the best in this scenario. But I want to use these speakers on my main music system, which is passive, plus I like to stretch my brain a bit when it comes to stuff like this just for fun. I actually have some Pascal/Marani plate amps I could use in these, but I'm saving those for a future build.
Thanks Charles! I'll definitely build a test cabinet for this that I can play with and burn in the fire pit when I'm done.
I have played with a couple different AMTs, the build I'm just finishing (a TMWW) has a Mundorf AMT25D6.1 in it. And while I assume both the Mundorf and the Beyma share similar dispersion characteristics being both AMT, I also assumed this Beyma is an entirely different animal.
FWIW, that Mundorf was also a learning experience. If anyone is curious, it's the most laid back, revealing tweeter I've ever used. Seems like those 2 don't go together but that's the best way I can describe it, it's definitely an anomaly for a AMT. Just a pure, amazing tweeter with zero exaggeration, it's like the anti-AMT. To be honest I didn't like it at first, I'm used to a little exaggeration in the upper frequencies that this tweeter just doesn't do, at all. Think of it like an absolutely beautiful girl with no makeup on, if you're used to plastic surgery and makeup on a tweeter, this might not float your boat lol.
I'm using the TPL-150H in MTM with 8" (B&C 8PE21). I was quite reluctant to go there as I had seen recommendations to xo at 2kHz and MTM with such a large tweeter (especially the H version) and large M was a recipe for lobbing issues. My drive towards this was high efficiency: it's an active system where the TPL is driven by a 45-type SET and was hoping the midrange would get close to that sensitivity to use a 2A3 (which I don't currently have; I have a McIntosh MC275 in that role).
In parallel my project went the open baffle direction. It was a very nice improvement for the TPL. The factory small back box seems to be an issue. Even if you don't go OB, I would suggest making a big chamber behind the TPL and have absorbent material. I also installed the 3D-printed notch filter developed by @oneoclock and that was also a nice improvement (it's designed for use with the waveguide, though).
I haven't been as offended by lobbing as I thought I would from modelling this. My ceiling is absorbent, so that might play a role. The TPL has narrow vertical dispersion, so of course if your head goes out of that angle you hear the reduced output. This is not an issue in my setup.
I have tried xo from 2kHz and have been lowering it. I'm at 1.3kHz now and will try 1.2 and probably 1.1kHz as well. My digital xo are NT2 for now, but that is to be explored too. My preference for lower xo might be driven by my preference of the 45+TPL sound vs 8PE21+MC275 sound. Dunno. I really like the sound! At some point will probably also experiment with the TPL without the waveguide. Right now my attention is more focused on figuring out my midbass.
@mattsk8 what made you pick the Scanspeak 18M for this design? Down the road I might look into replacing the 8PE21 so would be interested in your choice.
In parallel my project went the open baffle direction. It was a very nice improvement for the TPL. The factory small back box seems to be an issue. Even if you don't go OB, I would suggest making a big chamber behind the TPL and have absorbent material. I also installed the 3D-printed notch filter developed by @oneoclock and that was also a nice improvement (it's designed for use with the waveguide, though).
I haven't been as offended by lobbing as I thought I would from modelling this. My ceiling is absorbent, so that might play a role. The TPL has narrow vertical dispersion, so of course if your head goes out of that angle you hear the reduced output. This is not an issue in my setup.
I have tried xo from 2kHz and have been lowering it. I'm at 1.3kHz now and will try 1.2 and probably 1.1kHz as well. My digital xo are NT2 for now, but that is to be explored too. My preference for lower xo might be driven by my preference of the 45+TPL sound vs 8PE21+MC275 sound. Dunno. I really like the sound! At some point will probably also experiment with the TPL without the waveguide. Right now my attention is more focused on figuring out my midbass.
@mattsk8 what made you pick the Scanspeak 18M for this design? Down the road I might look into replacing the 8PE21 so would be interested in your choice.
From the above it seems you aren't using protection caps with the TPLs, and wanted to pick your brain on this. I use paralleled caps to reach 37uF for protection, and wonder if these generic caps in the signal path are degrading the sound. So buy better caps or remove the caps altogether? It's an active system so the amp driving the TPL should never see low frequencies. However when I connect the amp to a midrange driver without caps I can hear a low volume thump upon turn-on or turn-off. With a regular multi tester in between amp and midrange driver I measured 8mA on turn-on and 22mA on turn off, but of course I don't know the frequency range of the noise.
What would you suggest?
Unfortunately it wasn't a very scientific reason, I already had all but 2 of the 18m drivers for this build. I was going to do a TMWW, which I still could, but I wanted to try a WMTMW. I still need to get 2 more 18m mids to make this happen.
My original plan for the Beyma was to use it with an Acoustic Elegance 8" midrange in an active build, but I decided to use a Faital Pro HF10AK instead on that build.
This has been my experience as well, lobing is not the "speaker building train wreck" it seems to be.
Years ago I won a pair of Eminence Beta 12 drivers as a door prize at a DIY speaker event. I remember thinking, "what in the world am I going to do with these?", because I was coming from fairly cookie cutter builds at the time (typical MTM, TM- 6.5" woofer with a 1" tweeter). I've always loved SPL and sound quality, so I decided to roll the dice and use them as mids in a hybrid active/passive 3 way using a Selenium D220 tweeter and a Dayton 390HO sub. I did a passive filter from the mid to the tweeter, ended up with 3rd order at 1.7khz. (I did the mid>tweeter passive because I only had 2 amps at the time, I used a DBX Driverack for the woofer to mid).
This definitely broke some lobing rules, but I was very pleasantly surprised at how that did not show up in the polar response, and to me and everyone that listened it sounded phenomenal, even without any EQ. That was actually a really fun speaker, was stupid loud and a riot to listen to, I'll even say it's one of my favorite builds to date. I ended up selling it to my buddy to fund another build so I do still get to listen to it on occasion (so do his neighbors haha).
The Beyma does seem like it's a very robust tweeter, but I personally wouldn't use any tweeter in an active scenario without a protection cap. I know that sucks from a "purist" standpoint because you're supposedly dirtying the signal with a capacitor, but those Beyma tweeters are pretty spendy and one signal problem from your DSP could send them up in smoke.
I did an active 3 way build for my sister using the Hypex FA503 amps. She's using a Bluesound Node 2 as a preamp, optical from Bluesound to amp. The amps have an auto-on feature so she would leave them switched on. One night, for absolutely no no reason they started playing this horrendous, digital shrieking noise fairly loudly, so she unplugged the speakers. Without that 33uF protection cap, I'm pretty sure that would've smoked both of the SS 6600 tweeters. I never did figure out why the Hypex amps did that, they've never done it since and they seem to work fine. But she does switch the amps off now instead of using the auto feature.
Obviously I enjoyed your post lol, sorry for the mess of quotes but I'm pretty sure this is the last one... Do you know the dimensions of the cabinet I should try for it?
Interesting you brought that up. I mentioned that Mundorf I used, and that is the dipole version. I initially tried that as a dipole in that build, and I felt like it was too sterile sounding so I made a cabinet for those, then lined the inside, right behind the tweeter, with microfiber I cut from towels. It actually improved the response of the tweeter, BUT... I also mentioned I didn't think I liked that tweeter when I first heard it because it was too laid back- I attributed the laid back sound to the dipole and I think I was wrong, it's just the nature of that Mundorf tweeter. For the record I've fallen in love with that Mundorf since, I just had to get used to it.
Either way, if I did consider using the Beyma as a dipole, I think I would switch from WMTMW over to a TMWW, just because I'm not sure how much dipole effect I would get from that Beyma playing thru a 17" deep tunnel out the back pf the cabinet. But as a TMWW, I could just make a mount above the midrange, use no back or tunnel at all on the Beyma and have a true dipole. Anyone here have an opinion about that?? Try it open back, playing out the rear thru a 17" deep opening? Or do a TMWW?
Open is fine if you want that. I think it's a little drastic as an approach to a problem with a box. I know that boxes can sometimes seem like they have a problem that won't be fixable.. but it can be a matter of finding a way to integrate it, then the 'sound' goes away.
Hello!
Size behind the TPL: maybe about 1 or 2 liters, with the back wall away enough to allow for absorption of the back wave. I had planned on doing this with loose fiberglass and a bit more dense fiberglass towards the back wall, but ended up going the OB path. Size is probably not too important as long as it's significantly deeper than the factory plastic box. I envisioned a back chamber the depth of the cabinet. I'm not settled on the OB vs boxed solution, mostly driven by midbass, but if I were to go boxed I would use a large chamber behind the TPLs and use them without the factory chamber.
My TPL-150H is open back in MTM with the two 8" mids are OB as well. The MTM assembly is on a flat baffle sitting atop the midbass section.
Interesting you mentioned the AE TD8! I'm considering AE dipole woofers as upgrade for my midbass and have also thought about the TD8 for midrange. How would you describe the sound differences between the TD8 and 18M?
I hear you re protection caps. I guess I'll have to spend on quality caps 🙂
Size behind the TPL: maybe about 1 or 2 liters, with the back wall away enough to allow for absorption of the back wave. I had planned on doing this with loose fiberglass and a bit more dense fiberglass towards the back wall, but ended up going the OB path. Size is probably not too important as long as it's significantly deeper than the factory plastic box. I envisioned a back chamber the depth of the cabinet. I'm not settled on the OB vs boxed solution, mostly driven by midbass, but if I were to go boxed I would use a large chamber behind the TPLs and use them without the factory chamber.
My TPL-150H is open back in MTM with the two 8" mids are OB as well. The MTM assembly is on a flat baffle sitting atop the midbass section.
Interesting you mentioned the AE TD8! I'm considering AE dipole woofers as upgrade for my midbass and have also thought about the TD8 for midrange. How would you describe the sound differences between the TD8 and 18M?
I hear you re protection caps. I guess I'll have to spend on quality caps 🙂