Okay so I haven't exactly been sitting still this afternoon.
As I said earlier, I've been thinking about adding a tweeter, to support the highs. However, given the low budget nature of the speaker, I didn't really want to spend any money on new parts. I looked around my shelf and found a pair of Philips AD 0140/T4 mylar tweeters. I know these are not "good", but I wasn't asking much of them. Mids are handled by the DEW driver anyway, so they'd only support the higher frequencies.
First, I took the Philips AD 0140/T4 tweeters apart.
I found out they use a tiny piece of foam on the dome (hidden behind the plastic faceplate, forgot to take a photo of the stock foam) to dampen some harshness from the mylar dome. The foam turned to pure dust from age. The inside of the dome and the voice coil gap were dirty and dusty. I removed the voice coil and cleaned everything thoroughly. I also attached a new piece of (dense) foam to the dome. These tweeters have a piece of foam in the center of the magnet as well. I rinsed it for a bit and put it back in (straight this time; one of the tweeters had the foam piece in sideways 🤔).
With that part done, I started thinking about how to add these tweeters to the system.
I didn't like the stock faceplate of the tweeter and I didn't really want to cut a hole in the baffle to mount them. I also didn't want to put them on top of the baffle and I didn't want to increase the placement requirements for these speakers (since the tweeter and the full range have different sweet spots) or getting rid of the "ambient feeling" an open baffle creates. But then I remembered my 3D printer... And I decided on making the tweeters firing upwards, with the possibility to make them front-firing if I ever decided to do that.
I launched Autodesk Inventor and I sketched something up.
I wanted a new faceplate for these tweeters. One that didn't block (or protect?) the dome in any way, and preferably one that didn't have the cone recessed as much. It also had to be easily mountable to the existing speaker. So this is what I came up with. The thick part on the bottom is there to support the magnet, and hides a mounting hole as well!
After a mere 3 hours of printing, these came out.
They turned out pretty well! Especially considering this was printed with an Anet A8 from 2018... 😏
The faceplates of these tweeters also hold the mylar dome down. Fortunately, Philips made the start of the threads the same height as the ring that holds the dome in its place. This made designing a lot easier.
After a bit of sanding I mounted the new faceplates to the tweeters.
I was very happy with how this turned out. I know, I know, could have done with a bit more sanding.... 🤐
The original bolts were a bit too short. Fortunately I have a lot of M3 sized bolts laying around. This whole speaker is built with M3 bolts and nuts at this point 🙄. You can clearly see the new foam on the dome, as well as the clean foam inside the tweeter through the dome.
Then I mounted them to the backside of the speaker.
I found one 4,7 uF capacitor in a box of stuff, and sourced another (exact same Audyn cap) from a portable bluetooth speaker I once built. (I replaced it with a 5,7 uF I had laying around, doesn't really matter for that bluetooth speaker anyway). The resistor shown on the picture is removed later on, don't worry. Also, I had to move the handle to the front of the speaker. Oh well.
Unfortunately, I haven't been able to test them yet... 😢
It was getting late and I haven't had the time to set them up again in the living room... I did hook them up to my workbench setup and the sound has definitely improved, but that was from closeby and without any space for the OBs to breathe.
I'll give an update when I get the chance to try this out with some more space. Happy tinkering everyone.
As I said earlier, I've been thinking about adding a tweeter, to support the highs. However, given the low budget nature of the speaker, I didn't really want to spend any money on new parts. I looked around my shelf and found a pair of Philips AD 0140/T4 mylar tweeters. I know these are not "good", but I wasn't asking much of them. Mids are handled by the DEW driver anyway, so they'd only support the higher frequencies.
First, I took the Philips AD 0140/T4 tweeters apart.
I found out they use a tiny piece of foam on the dome (hidden behind the plastic faceplate, forgot to take a photo of the stock foam) to dampen some harshness from the mylar dome. The foam turned to pure dust from age. The inside of the dome and the voice coil gap were dirty and dusty. I removed the voice coil and cleaned everything thoroughly. I also attached a new piece of (dense) foam to the dome. These tweeters have a piece of foam in the center of the magnet as well. I rinsed it for a bit and put it back in (straight this time; one of the tweeters had the foam piece in sideways 🤔).
With that part done, I started thinking about how to add these tweeters to the system.
I didn't like the stock faceplate of the tweeter and I didn't really want to cut a hole in the baffle to mount them. I also didn't want to put them on top of the baffle and I didn't want to increase the placement requirements for these speakers (since the tweeter and the full range have different sweet spots) or getting rid of the "ambient feeling" an open baffle creates. But then I remembered my 3D printer... And I decided on making the tweeters firing upwards, with the possibility to make them front-firing if I ever decided to do that.
I launched Autodesk Inventor and I sketched something up.
I wanted a new faceplate for these tweeters. One that didn't block (or protect?) the dome in any way, and preferably one that didn't have the cone recessed as much. It also had to be easily mountable to the existing speaker. So this is what I came up with. The thick part on the bottom is there to support the magnet, and hides a mounting hole as well!
After a mere 3 hours of printing, these came out.
They turned out pretty well! Especially considering this was printed with an Anet A8 from 2018... 😏
The faceplates of these tweeters also hold the mylar dome down. Fortunately, Philips made the start of the threads the same height as the ring that holds the dome in its place. This made designing a lot easier.
After a bit of sanding I mounted the new faceplates to the tweeters.
I was very happy with how this turned out. I know, I know, could have done with a bit more sanding.... 🤐
The original bolts were a bit too short. Fortunately I have a lot of M3 sized bolts laying around. This whole speaker is built with M3 bolts and nuts at this point 🙄. You can clearly see the new foam on the dome, as well as the clean foam inside the tweeter through the dome.
Then I mounted them to the backside of the speaker.
I found one 4,7 uF capacitor in a box of stuff, and sourced another (exact same Audyn cap) from a portable bluetooth speaker I once built. (I replaced it with a 5,7 uF I had laying around, doesn't really matter for that bluetooth speaker anyway). The resistor shown on the picture is removed later on, don't worry. Also, I had to move the handle to the front of the speaker. Oh well.
Unfortunately, I haven't been able to test them yet... 😢
It was getting late and I haven't had the time to set them up again in the living room... I did hook them up to my workbench setup and the sound has definitely improved, but that was from closeby and without any space for the OBs to breathe.
I'll give an update when I get the chance to try this out with some more space. Happy tinkering everyone.
https://www.german-physiks.com/ and https://www.duevel.com/
What about ob corner backwave loading for the sounstage ? 90° room corners.
What about ob corner backwave loading for the sounstage ? 90° room corners.
Funnily enough, the best sound stage ( and tone ) is from some tiny omnis that I made, with a tapering enclosure, they perform way better than they should, I now intend on making floor standers based on the same 40mm drivers in a wow configuration.
Speaking of tiny Omnis, I visited the Linkwitz room at RMAF and I liked his Plutos better than his OB speakers. The Pluto didn't have the same scale, but the tonality and shape of the sound was surprisingly pleasing.
I heard DIY omnis at the Dayton audio festival that were astonishing.
I heard DIY omnis at the Dayton audio festival that were astonishing.
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As goes the conversation, did you notice, you open baffle enthusiasts, a difference in soundstage and 3D imaging between open baffles and baffleless loudspeakers. I am wonderin what is the optimum fhz range to go without enclosure ? 100 hz to 20 k hz ? 80 hz to 5000 hz ? Etc, etc ?
Yep,,,I refer to what I read in the open baffle gallery sticky thread...🙂
... and wonder about open design with corner loaded ( still open loudspeaker at 1m of the corner angle or more because the 90 degree side walls...
... and wonder about open design with corner loaded ( still open loudspeaker at 1m of the corner angle or more because the 90 degree side walls...
I've seen those naked driver projects on the forum over the years. I don't get it. I've tried and they always sound atrocious - a proper baffle does so much good. Hats off to anyone who can make them work.
Seems the use only dsp for the huge amount of linkwitz transform, of course huge xmax and heavy cones and two 18" pushpulled dipole
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LOL, I might be able to dig up a photo.
A few years back I was a judge at the Dayton Audio DIY speaker contest. The other two judges were Jerry McNutt of Eminence and Don Keele of horn and line array fame. We heard a lot of speakers, with the same three music cuts. One cut was a jazz ensemble recoding. One of the builders was showing DIY omins. He make the woofer enclosure and used a modified Walsh tweeter at the top. I've never heard anything quite like it, certainly no other speaker we heard came close. The instruments were placed with an uncanny precision and separation. No smearing of position, no vagueness, they were real and solid and easy to point to. Tight!
Both Jerry and I leaned over to Don, who was in the center, and said something like "Wow, did you hear that!?" Don grinned, nodded and said, "yeah, I know."
Just a pair of tall skinny homemade speakers that had a realistic sonic image like no other we heard. It's one of those things you hear that sticks with you. Were those omnis correct and all the others wrong? Don't know, but I sure wish we could have heard more from those speakers.
A few years back I was a judge at the Dayton Audio DIY speaker contest. The other two judges were Jerry McNutt of Eminence and Don Keele of horn and line array fame. We heard a lot of speakers, with the same three music cuts. One cut was a jazz ensemble recoding. One of the builders was showing DIY omins. He make the woofer enclosure and used a modified Walsh tweeter at the top. I've never heard anything quite like it, certainly no other speaker we heard came close. The instruments were placed with an uncanny precision and separation. No smearing of position, no vagueness, they were real and solid and easy to point to. Tight!
Both Jerry and I leaned over to Don, who was in the center, and said something like "Wow, did you hear that!?" Don grinned, nodded and said, "yeah, I know."
Just a pair of tall skinny homemade speakers that had a realistic sonic image like no other we heard. It's one of those things you hear that sticks with you. Were those omnis correct and all the others wrong? Don't know, but I sure wish we could have heard more from those speakers.
Here is what I said in my article at the time:
https://www.diyaudio.com/community/threads/midwest-audio-fest.170305/post-2245052
You can go completely baffleless all the way. But for woofers you need to use brute force.
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Thanks for the input adason.
Did you reduced also the Betsy baffle below the Neos ?
I am trying to understand what is the more efficient bandwidth for open design...
Some noticed odd things for instance when the mids are open baffle but not the tweeter, etc...
Is there also a good trade off for the mid-bass area (80-200 hz) ? Also open or baffle less there VS sealed or cardioid ? I know one can go 100% baffle less or open baffle but is there a diminushing return point (frequency) where the sonic improvement is not noticeable anymore vs others loads ?
Did you reduced also the Betsy baffle below the Neos ?
I am trying to understand what is the more efficient bandwidth for open design...
Some noticed odd things for instance when the mids are open baffle but not the tweeter, etc...
Is there also a good trade off for the mid-bass area (80-200 hz) ? Also open or baffle less there VS sealed or cardioid ? I know one can go 100% baffle less or open baffle but is there a diminushing return point (frequency) where the sonic improvement is not noticeable anymore vs others loads ?
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Hi Adason,
Interesting design. Is the other sidewall (where the woofer baskets are visible) missing or maybe clear? Two woofers aligned 90deg like that would make about zero bass on the speaker mid/tweeter axis due to OB cancellation.
Interesting design. Is the other sidewall (where the woofer baskets are visible) missing or maybe clear? Two woofers aligned 90deg like that would make about zero bass on the speaker mid/tweeter axis due to OB cancellation.
Theoretically thinking minimal/nobaffle is the best thing, least interaction from speaker structure to sound of all loudspeaker systems I've managed to figure out, in other words perfect acoustics. Assuming crossovers happen at long enough wavelenght so that diffraction is not an issue on any of the "ways" for their pass band, except for tweeter because there is nothing to crossover to and it is unavoidable. In this kind of system a particular way is acoustically small on its pass band and at null of the other ways. Purest thing as it is nothing but the drivers, easiest and cheapest build because there isn't any.
Similarly, a system with some or big baffle could be made, crossing over before diffraction, but now the SPL capability is limited as the transducer is relatively small to its pass band because we have the structure that makes diffraction lower in frequency lowering the pass band of the particular way. This simple reasoning makes the baffle unnecessary cost and trouble, just use biggest drivers naked.
Trade-off is there is probably 4-way system so some cost and complexity with amplification and crossover and probably benefits dedicated listening space where the back radiation and directivity can be utilized best, but all these would happen and benefit any open baffle or multiway speaker in general so nothing bad. There is gonna be some structure to suspend the thing upright somehow so its probably complicated to build well in reality though. Reality usually bites, but at least reasoning upon loudspeaker systems a naked multiway OB with DSP would make excellent loudspeaker system for home use, unless it is not dedicated listening space 🙂
Similarly, a system with some or big baffle could be made, crossing over before diffraction, but now the SPL capability is limited as the transducer is relatively small to its pass band because we have the structure that makes diffraction lower in frequency lowering the pass band of the particular way. This simple reasoning makes the baffle unnecessary cost and trouble, just use biggest drivers naked.
Trade-off is there is probably 4-way system so some cost and complexity with amplification and crossover and probably benefits dedicated listening space where the back radiation and directivity can be utilized best, but all these would happen and benefit any open baffle or multiway speaker in general so nothing bad. There is gonna be some structure to suspend the thing upright somehow so its probably complicated to build well in reality though. Reality usually bites, but at least reasoning upon loudspeaker systems a naked multiway OB with DSP would make excellent loudspeaker system for home use, unless it is not dedicated listening space 🙂
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