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So, I’ve begun working on 1 of my 2 new builds for MWAF. This is going to be a 4-way design (I mean…why not?) in a moderately sized tower. The main interesting piece of this build is that it is built around an Ultimax 8” subwoofer. So, to start this first post off right, I decided to share some nice 8” flex. Enjoy:
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P.s. – I guess the forum video player won’t play in slow-mo but you can scrub through frame by frame and see these babies flex!
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This is awesome! I actually was thinking about using that ultimax in a build as well. You beat me to it! That thing can move, haha. I can’t wait to see what you end up doing. It looks awesome already.
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I’m excited about it for sure! My only complaint so far is the efficiency… the setup would match so much better if it had about 3 more dB but it is what it is. I tossed around the idea of two per speaker but $$$ and cabinet size just would not allow it.
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Are you using a separate amplifier for the subwoofer? Or are you going to run it as a traditional three way? I have always like Definitive Technology and Golden ear, where they power the sub separately, but you still hook it up via normal speaker wire. There are some advantages to this. One being you have more adjustability of the loudness of the bass depending on seating distance and another, is of course, making the top half of the speaker more efficient. In this case you wouldn’t need nearly as much power to get the top half to an decent listening level. But this comes all at a drawback…cost.
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Well, since these are going to be my Dayton Audio entry for the MWAF speaker building contest, I think I have to run them as a typical single input setup (correct me if I’m wrong). However, that is a good idea for long term setup. Now you’ve got me thinking…
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I am not sure about that. I think it just needs to be the drivers that are Dayton. I don’t think an amplifier would make much of a difference. And assuming you use the subwoofer amplifier variable crossover with volume, you would still hook it up via normal speaker wire. I can ask a few people at PE if you would like.
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Yeah, why don’t you see what you can find out. I could be wrong but I thought only the “open unlimited” could have additional amplification or active crossover/DSP etc… let me know what you find out. I appreciate it!
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These were the rules for 2019. Wish they’d get 2020’s up for those who would like to participate, if there are any changes.
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Yeah, I read those. I take that to mean that speakers with separate amplification will be in the open unlimited category…but maybe I’m wrong.
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That’s my take also. Somewhere else it explains the gear used for the non-powered categories, amp, source, etc.
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The problem that I am having, is you really do not have an active speaker. Granted the subwoofer is active, but the speaker itself is not. And you would still hook it up the same way as a passive speaker. You are probably right that it’ll knock itself into the open unlimited, but I am curious, since none really define this type of setup. But I guess that is exactly what open unlimited says. I’ll still ask an engineer I know at Parts Express that helps run the competition to see if he has run across this or what they would categorize it.
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I am talking with Tim at Parts Express. He suggests sending an email to Tech@parts-express.com to get the question to the correct person.Addendum:More to the point, I found at the bottom of the Rules page the email for questions to MWAF itself: staff@midwestaudiofest.comAlso, to expound on the gear used for driving the speakers during the contest, that is below the audio list on the Rules page as well.
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Here’s the playlist on YouTube for MWAF 2019 . When they update, I’ll compile the new one, if it has changed.
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First of all, great to see you back! I don’t want to hijack the thread, but wanted to get that out there. As far as the competition goes, that stinks. I like the idea of doing a lot of smaller builds with powered subwoofers built in. But I don’t think a lot of them when do real well in the open unlimited class. Although I’ve always been a fan of speakers like golden ear.
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Thanks Nick! Glad to be back, and looking forward to interacting with you guys again.
Agreed, it’s a bummer the way it’s set up but understandable, they’re just trying to keep it fairly easy to distinguish which speakers should be in which class. IMO, some of their classes need to be modified. For instance, the “All Dayton” class should be able to have active and or passive speakers within it as long as all of the drivers are “Dayton”. Also, like you said, the “Unlimited” class is really tough to compete in with smaller speakers. Seems like a sub-division of some type for that class would be a good idea. For those of us who participate, best thing to do is make recommendations to PE, they might listen and agree. They do want it to be a good experience for everyone involved and I’ve always considered them open minded to suggestions.
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Well, the past couple of weeks have been busy…and not with anything I WANTED to do. But, I did get a little work done on these.
I’m hoping that when I put a round over on the port, it resolves my chuffing issue. I mean, it’s only audible at 125 watts or higher on the sub alone so I don’t think it’ll be an issue for now. But if I go the separate amp for the sub route in the future…I may have an issue. Time will tell.
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Looks pretty good so far. Any test video slated for the future?
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Actually, I forgot that I shot some already.
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Holy cow! That surround! That looks pretty awesome. I hope you can get the chuffing worked out. I know that can be a pain to work out.
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Flares, man, flares! 🙂
It’s all about fluid dynamics. Since air is classified as such, the same applies. Chuffing is generally attributed to the violent depressurization and turbulence at the end of the port. Smoothing the transition to open air (and entry to the port) goes a long way toward taming the noise. If that doesn’t resolve the issue, then a larger, longer port is usually the remedy.
Of course, you could always go with a bandpass design…
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Yeah, I’m hoping the round over is going to be enough flare… we will see. Is there any need or benefit from rounding over the internal parts of the port?
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That is a really good question.
The 2 basic camps are:
1. There is no real difference since all that is inside the enclosure.
2. The turbulence inside can be heard through to the outside.
**SPECULATION ALERT**
I am of the thought that if you control both sides of the port, you will reap the best response possible. Smooth in, smooth out. Any diffraction of the waves at either end can carry through to the opposite side. As an example, if you throw a stone into a pond, you create waves spreading out from the impact. If you then throw another stone into the pond in a different area, those waves will intersect the original ones and continue on their own path regardless of the original waves, and vice-versa. So if you reduce the turbulance at both ends, you will ultimately make the port more effective at what it is designed for. And what would it take to round off the edges inside? Not much, and it can only help, imo. Thing is, you’ll have to experiment to find the right amount of round off and if you’ll need a slight extension of the port to compensate (I doubt it.)
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Maybe I missed it? Can you share the information about the size of your enclosure and port? You mentioned hearing chuffing at 12 m/s in a different thread. Something doesn’t sound right about that so I was curious about your vent size and enclosure choice. How much volume did you allow for the sub and what is the height, width, and length of your current slotted vent? I can run the simulation in BassBox and maybe Nick can run it in WinISD to see if everything looks good. Just trying to help if you’re interested in one of us double-checking your numbers.
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Sure, that’s no problem.
Total enclosure is:42”h x 10”w x 12”d
The port is a 2” x 8.5” slot, 34.5” long.
Volume of the enclosure (internal minus the port, the driver and bracing) is currently is approximately about 1.5 cu ft.
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So, the way I see it, as the enclosure sits now. I’m tuned to 28.3hz. And with a 125w plate amp hooked up, she’s a huffin and a puffin from around 20 to 30hz. I don’t know if this video does it justice but here’s what I whipped up real quick:
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Okay…here’s what I’ve come up with. Granted, my simulation is run in BassBox and it’s based on PE’s published specs for the 8″ Ultimax. If you’ve run a DATs sweep, might be better to work with.
Making some assumptions here, guessing you are trying to tune somewhere around 29-30hz. That’s the estimate I’m getting from BassBox based on your vent size and length in the 1.5 cu ft enclosure. Hoping it’s close anyway. BTW, Bassbox is also recommending a smaller vent than you’re using, it’s suggesting a 3.75″ round vent. Your slot vent is equivalent to a 4.75″ round vent. Doesn’t seem like a big difference but the extra size in diameter is increasing your length requirement by 14″.
Anyway, according to the BB software, anything more than 125 watts in your enclosure will be pushing the driver beyond it’s X-max capabilities, but that would only apply to frequencies below 20hz. Without a HP filter, might be an issue on some movies, but fine for most music. The curious thing is, you mentioned chuffing, but it’s not making sense. At 125 watts, with your current vent size, I’m showing vent velocity at 9 m/s. That’s well below what most recommend and it really shouldn’t be making any noticeable noise at that rate. Thinking out loud here, but I’m wondering if the extra length is causing a problem and the vent isn’t actually acting like a Helmholtz resonator but more like a transmission line? Just taking a guess here man, not sure what’s going on but trying to help.
Hoping Nick will take the time to run the simulation also, curious what his thoughts will be. Best of luck!
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A 18hz high pass is planned but since that calls for a 2,500 uF capacitor, I haven’t bought that yet. I originally had a 1” vent (I think it was something like 13” longish) and I could hear chuffing even under my test amp. So, I made the vent bigger (and obviously longer) to try to compensate. It is weird the BB is saying port velocity is only 9 while winisd said something like 12-14 I think…
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2500 uF cap, well I’ve got several of those laying around, just kidding. You can probably buy a MiniDSP and actively high pass cheaper than building a 18hz passive filter. Which sub amp are you using, surprised it doesn’t have a HP filter option?
That is strange the m/s isn’t matching. I’ll go back and double check the T/S parameters to make sure I loaded them all correctly.
Do you have a DATs? If so, have you confirmed the port tuning of the enclosure?
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Sadly I do not have DATS. I’m still (im)patiently waiting for my V3 to come in. Yeah, I haven’t checked anywhere besides PE but I think a 500 uF cap is like $9… and I’ll need 5 for each speaker. For MWAF, I’m not going to use an additional amp so that I can enter them into the DAYTON category. So, it kind of depends on what I’m going to do with them after MWAF to determine what I need to buy for the low end high pass. That’s the other reason I haven’t purchased anything thus far. I think the next step is going to be round everything over and then move on. I’m hoping to get a DATS next month. Then I can start playing around with it and start getting some more accurate numbers.
edit: actually, I just looked and madisonsound has 1000uf caps for less than $9 and 500uf for around $6 so $25 or so for a 18hz highpass. But then again, I’m going to have to look at winisd and see at what wattage they say xmax will be an issue. I may not need it at all for MWAF. Then I can look at maybe dropping the coin on a pair of Dayton 250w plate amps with DSP. But at $180 each…that’s a lot of coin.
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Darn, was really hoping you’d have the DATs. Thought I saw something the other day on the TT Forum about the new version being in stock very soon. Hope they’re bringing enough in to cover the demand, it would stink to be waiting and then see them go into an “Out of Stock” situation right after they land.
Personally, I wouldn’t worry about the HP filter for MWAF, they’re not playing anything music wise that that will create an issue for that woofer.
A couple of your videos including the last one you posted are showing up as “Invalid”. Nothing happens if I click on them to play em. Maybe it’s a setting on my computer though, since no one else has said anything. Anyway, best of luck on the rest of your build. We’ll have a chance to meet face to face at next years MWAF, hope to see you there.
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A couple of your videos including the last one you posted are showing up as “Invalid”. Nothing happens if I click on them to play em. Maybe it’s a setting on my computer though, since no one else has said anything. Anyway, best of luck on the rest of your build. We’ll have a chance to meet face to face at next years MWAF, hope to see you there.
If I use IE on my computer here at home, it says Invalid, while chrome will either show a video or a sound player. Chrome on my phone shows everything.
I’d love to make MWAF and meet some of you guys in person if possible. We’ll see if the old knees hold out. (Replacements would be great before then! Don’t think PE has anything for that. LOL)
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Haha, I don’t think they do. Not unless you want to march to the beat of a different drum (I mean driver). 🙂
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Some of the videos I shot at 240 frames to try to get the slo-mo woofer porn for you guys but it seems the player in the forum is not a big fan of that. That might be your issue. Good luck with the knees!
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well, despite my best efforts to screw this thing up…we are making progress! Still not 100% on whether not to add an amp for the sub but I’m leaning toward yes. Kind of sucks because I probably wouldn’t have bought just Dayton drivers but it is what it is. I went ahead and ordered 2 amps and power supplies from Banggood and we will see how it goes… Once I get the amp in and can get some measurements, I’ll start the crossover.
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Your progress is looking great! I can’t wait to see how the crossover goes!
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You could always convert it to a different video format! 🙂
Elliott Dyson – Elliott Designs (YouTube) – 3rd year MENG Student
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