lowerFE

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lowerFE last won the day on June 14

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About lowerFE

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  1. Not yet! Far from it actually. There's a lot of DSP optimizations and tricks I need to add on this. But at least right now I can have some fun listening to music as I continue to work on this. I'll be a little less busy for the next month or so, so it is actually great timing to be enjoying the heck out of these things I can't even imagine for you. I've had problems where it only happens at a high enough volume. I'm sure that happens for you too, but for the stuff you work on the volume would be This came in heavier than I expected. It weighs 14.7 pounds each. It's a heavy little sucker, and it always surprises people when they try to lift it. Now I have a silly little idea in the back of my mind to make the next speaker I build as heavy as possible That ATC monitor is indeed amazing. That doesn't substitute measurements though. I have done some measurements, but I don't think they are totally accurate. Soon I will be doing extensive polar measurements on this speaker. Gonna do it really right this time around, but it'll take some time.
  2. Long overdue update. Been incredibly busy lately, so here's a look at the progress I've done with this speaker.I added a preamp board into the speaker. The amplifier needed 2.7V of input sensitivity to reach full output, but my output stage on my Xonar U7 only outputs 1V. This is made from the OPA1642 op amp. The second PCB is for filtering the noisy auxiliary power from the ICEpower amp. The preamp steps up the voltage by 4x. Even though I only need 2.7x, I used 4x to allow spare headroom for the DAC. Now I can finally get full power from the amps and really crank out the SPL.There were many problems along the way. I had a lot of buzzing problems! I had a ground loop buzz problem that took a lot of effort to find the cause, and it was because the RCA connectors were directly mounted to the baffle without an isolator. Even though wood is a terrible conductor, it was enough to cause a very slight hum that was audible since the amp is running full tilt. I had another buzz problem that was extremely peculiar as well, and turns out it was a few screws that were not tightened inside. I had another buzzing problem that was because the rear end of the passive radiator isn't completely flat, so the washers were rubbing each other at high excursions. Another buzz was due to wires slapping the baskets at high volumes. 4 different sources of buzzing, and this has to be the hardest game of whack a mole I've ever played!I did some more tuning of the speaker. I need a really high quality speaker to be used as a reference for this speaker. So I went to a friend's house to use his ATC SCM150ASL's as a benchmark and reference. Before the tuning, while the Reference Mini held its own quite well, the ATC sounded noticeably better in every single metric. The speaker sounds much better after the tuning, and sounds much more similar to the ATC except in the bass. The ATC is a bit bass shy, and I like mine with more bass.
  3. I decided to reread some of the old responses to see if I can have a better understanding of everyone's responses now. I suspect there were things that went over my head when I first read this almost a year ago. I understand what everyone's saying perfectly now. I even got new understanding reading it again now. I was even able to follow SME's math! Thank you everyone who shared their knowledge.
  4. Very impressive results from such a high efficiency, pro style driver. I wonder what is the Cms on the woofer to get such great deep bass and upper bass efficiency. Amazing output from just a 700W amplifier. Looks like the driver had just enough excursion and linearity to produce the 25-30Hz region of highest excursion levels with the given power. Kudos for JTR for coming up with such a high performance subwoofer for such low price. The engineering is obvious to get the most performance possible with modest parts, and that's real engineering skills.
  5. Yes, I just need to add mass to it to drop the tuning. Tang Band has 2 versions of the passive radiator I use, one with 25g Mms and one with 55g Mms. Based on what I'm seeing it looks like I have the 25g version when I thought I got the 55g. I'll just add enough mass until it hits the desired tuning.
  6. I got the speakers yesterday, and I'm grinning uncontrollably as I listen to my speaker. I implemented the crossover and did some rough tuning. Even with no bass (passive radiators tuned too high), the sound quality already greatly exceeded my expectations. The beryllium version of the Scanspeak Illuminator tweeter is 100% worth the 2.5x higher price. I expected minor improvements over the non beryllium version in my previous speaker, but the difference is drastic and immediately noticeable. The tweeter sounds sweeter and more detailed. The Wavecor woofers are a significant upgrade over the Tang Band W4-1720 woofer. I'm hearing a ton of lower midrange detail I've never heard before. The speaker also has much greater dynamics capabilities. Listening to music, especially classical music at high volumes is thrilling. I can't wait to put this speaker through an extensive measurement and tuning session.
  7. I might do that, but that'll be the last resort. The issue is that the noise floor is too high, especially when measuring the rear response for cardioid experimentations. The parking lot I'm using has a few cars driving by every minute, so I'm always crossing my fingers hoping no cars come driving by when I'm doing a sweep Now that's extreme! This will work for speaker measurements, but I have found that when I measure in my front yard my house actually acts as a wall and I can see a dip in the bass region caused by the reflection of the house. Good to hear you're going to do speakers! I think you'll find them to be just a little more complicated than sealed subs .
  8. Thank you! And yes, lots of DSP tinkering and measurements next. I'm trying to find good spaces to do measurements, and that's proven to be difficult. There is an outdoor parking lot which is great for ground plane measurement, but the asphalt surfaces ruins the measurement accuracy above 500Hz or so. Measuring at an indoor basketball court is fantastic, but they are really reluctant to let me use it, and when they do, it is at most for 1.5 hours, which isn't much time at all. I only have 3 hours worth of booking time lined up, and I need a lot more than that, especially for cardioid experimentations.
  9. Wrapping up! Pictures don't do justice, but there it is!
  10. Good suggestion. I think I'll take it! . I'm just planning ahead. Look at the date on the first post of this thread to give you an idea how long it takes. The size is a real problem with waveguides. The only other solution I'm aware of is through gradient systems and DSPs to manipulate phase, but efficiency takes quite a hit even compared to standard monopole, let alone waveguides. One nice thing is that the waveguide on the tweeter will allow the speaker to play a lot louder before straining. This should be interesting, a small speaker that can also play really loud. I'm thinking I should take this one slowly to spread out the fun. There has been a number of innovative speakers coming out just in the past 2 years, and I've been learning a lot and taking cues from them. I can probably incorporate more improvements as well. I hope I will have all of the things that make a big improvement to a speaker's sound quality in the next speaker, which are controlled directivity, increased headroom with waveguided tweeter, and better amplifiers (I think I have a way to fit Hypex NCores). I'm not too worried about things that make little differences like better DAC's or amps, or even drivers since I'm already at the top and any driver improvements will likely be small.
  11. From what I've seen, a ~5.5" waveguide can be made to hold its directivity to at least 2000Hz, which should be low enough for my purposes, hopefully. The fun of this project is to try to achieve the seemingly impossible. The goal isn't as unrealistic as you may think though. What I'm trying to do is a radiation pattern no wider than 180 degrees from 200Hz and up through a cardioid configuration. I want this so the speaker is radiating only forward from 200Hz and up so there would be little sensitivity to the distance to the front wall due to baffle step loss. In my opinion this is important because the amount of BSC drastically changes the sound of the speaker since it affects such a wide band for a small speaker. The distance to the front wall is going to affect <200Hz, but a rise <200Hz sounds pleasant, so it's not really a problem. As frequency goes up, the directivity of the midrange is going to slowly rise. There's nothing I can do to narrow it to constant directivity. Then, up to a point, the midrange directivity will match the waveguide, and that's where it will be crossed over to the tweeter. The question then becomes what kind of a pattern do I want on the waveguide? The SEOS waveguide may be the "easiest" to source, but the 90 x 40 pattern may be a just a little too narrow, especially for nearfield use. I may want something like a 120 x 60 waveguide, but right now that's just wishful thinking because it's not like small waveguides are readily available in many models (hint, there are none). Ideally I'd like a constant directivity of say 120 degree from 200Hz to like 10000Hz, but that may actually be impossible on such a small speaker if reasonable SPL capability is also a goal.
  12. Yeah that's a concern I had as well. However, I somehow managed to narrow the dispersion on the midrange and tweeter to a 135 degree pattern for 1.5 octave around the crossover point. If I can get that on this speaker, then it would match the directivity of the rest of the range. I need to measure (and listen) carefully to make a decision. The waveguide will take care of this problem in the next speaker.
  13. Oh man, I'm screwed. This is no longer the ultimate small speaker. While doing research about getting cardioid radiation in a speaker, I realized just how important controlled directivity is for a speaker's performance in room. You can put the best speaker in the world, put it in a room and the room is going to mess up the sound. The key is to reduce room interaction by controlling directivity and more direct sound to the listener. This speaker has a very wide dispersion pattern, which means almost maximum room interaction. I can make the 100-400Hz area to be cardioid, and maybe even to ~1000Hz if I do well, but above that the speaker is omnidirectional. I am envisioning a design with the primary advantage of obtaining controlled directivity for almost the entire range. It will be cardioid from low midrange to hopefully fairly high up in the midrange band, then a waveguide will control directivity for the tweeter. This speaker should be much less susceptible to the room and sound quite a bit better in a room. While I know it should doable, I have no idea how to do some of the things, like where to get a small waveguide, yet. There goes another year of my free time and a lot of money. Or maybe I should just check myself into Audioholics Anonymous
  14. Very interesting. However, I find it sort of hard to believe that these are all the improvements there are to the driver. What about inductance? It's not so low no improvements can be made by any means. That stereo integrity 6.5" is very interesting. I actually may have a use for a really high quality shallow 6.5" woofer. That makes a design I'm thinking of possible, which is bad, because that means another year of my free time will be gone! However, modeling that woofer shows rather poor output in a small sealed enclosure, about 2dB less for the same power than a 6.5" woofer from Audio Technology with the same T/S parameters as the 5.5" I ordered. I'm not sure why, maybe the high Fs?
  15. Thank you. It took a while to find that special exotic veneer, but 100% worth it. Right now I'm working on getting controlled directivity via cardioid radiation like the Kii Audio Three and this is really frigging hard and I'm also running low on free time