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post #31 of 230 Old 09-09-2017, 11:50 PM
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LLT is simply a ported box. It stands for large, low tuned. This used to be called EBS (extended bass shelf) until someone made up another name for it either because they didn't know the proper name or just felt like renaming a classic concept for some reason. None of these things need abbreviated names anyway, it's all just low tuned ported boxes.

There's a bunch of simulation software that is much better than WinISD, unfortunately a lot of it is no longer available. I use Hornresp mainly, also Akabak, MJK's worksheets (no longer available for sale) and Leonard Audio's TL.app (no longer available last time I checked). These are all worlds better than WinISD, they can show things that WinISD only hints at (like resonances) and stuff that WinISD can't even imagine. The learning curve for all of these (especially Akabak) is quite a bit steeper than Hornresp for a first time user but once you get used to them they are easier and faster to use than WinISD, and of course much more accurate and fully featured.

I have and recommend the UMIK from Cross Spectrum Labs (professionally calibrated) although you can get the same mic at parts express or madisound or from the manufacturer. The few extra dollars is worth the pro cal in my opinion. You can use REW or LIMP as the software for measuring, both are free. I also recommend that you build or buy an impedance jig (woofer tester) to test impedance.

There absolutely is no optimum box size for a given port cross sectional area. You can't tune a 2.75 cu ft box to 9 hz and expect it to perform well, it's going to be a nightmare. You need a better simulator and then you would be able to see the problems this would cause.

Audio physics is pretty simple once you understand it. There's no magic. Resonant strength is all about enclosure size. The box size dictates how much resonant gain you have to play with, the shape and tuning determine what frequency(s) the resonances will fall at. You can't do a whole lot at single digit frequencies with the box size you have chosen. Unless you can get to at least 100 db it's not really worth it to go anywhere near 10 hz, some people say 130 db is where the single digits come alive. No soundproofing will stop that, only thick concrete walls and ground (like a basement or bunker) is going to effectively contain that kind of sound so if your neighbours are not down for that you should probably stick to frequencies that are primarily heard more than felt, like 30 hz and up.

Dual subs will help even out the frequency response, more than 2 subs is even better with the practical limit (diminishing returns) being 4 subs. I also recommend measuring your room gain curve first before building or even designing anything. Once you know what the room does you will know what the sub will need to do.

If you want clean accurate sound the absolute minimum you will need is fully featured dsp and a measurement mic. And if you want to step the game up a bit more you'll need room treatments - the more the better. And ideally the speakers and subs should be designed to be close to the inverse of the room gain curve to get the flattest possible response without dsp.

It appears you are using an off the shelf Dayton crossover with textbook filters, if that is the case your speakers are incredibly poorly designed and you need to study a bit on all aspects of the system. If SQ is your main goal you need to understand the basics of theory and good design and do this stuff properly.

I can help you with all this stuff if you want help.

Post your driver t/s and pick ONE simple ported box design with a single digit tuning that you have already simulated and give me the box and port dimensions. I'll simulate it with proper software and show you the train wreck disaster it really is and why you need proper software especially when designing for extremes.
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post #32 of 230 Old 09-10-2017, 12:58 AM - Thread Starter
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The optimal box and port thing I mentioned was just optimal in terms of efficiently using the available volume, nothing wrt to how good it would sound. I know even the shape of the box and proportions along with volume have effects of which only volume is something I've messed with and trying to provide irregular surfaces inside.

I'll check out the mic, I don't mind spending some extra money if it's something that lasts. Actually just looked it up, $75 for something that's good is no problem! I was afraid it was gonna be several hundred. As for an impedance jig I was actually interested in being able to test speakers entirely for their specs, what do you recommend for that? You are correct, those xovers are generic but they are just placeholders until I have the time to brush up on my xover material. Unfortunately those speakers (in the pictures) are probably not going to be used and I probably won't finish them since I've realized they're not quite what I want for HT. Once I have measuring equipment both for room response and speaker specs I will start messing with DIY xovers. Way back in the day I studied basic electronics in the Air Force.

The receiver I'm really looking at is the Denon X4300H but that's just because of the native 5.x.4 Atmos. Down the road I want to try my hand at what some guys did on here called Zatmos and I figure the .4 as opposed to .2 for Atmos will have more potential. Otherwise I could save quite a bit and get a 5.x.2.

Not sure if you're referencing the 2.5cuft size as something that is hard to do single digit hz with or if you're referring to the 2'x4'x2'. The 2.5cuft I realize is small but that's what I built for the one I've posted CAD and actual build pictures of but again I realized it's no where near optimal for HT. As you said at that size stick to around 30hz which is what it's tuned to.

Anyway the new design that I'm planning on I'm just saying I do not want to go over a 2'x4'x2' DxWxH external dimensions. Actually I want to keep it a bit shorter around 22" because I will only have about 24.75" from the ground to the bottom of the projector screen not counting a border. I won't get into that really but suffice it to say I want to leave a couple inches of wiggle room below the projected image to accommodate whatever comes up.

I probably used the wrong term earlier when I said dual subs, I meant that I plan to have 2 individual subs in the room with each one being a max of 2'x4'x2'. They will go in the front of the room under the projector with a comfortable gap between them to put the receiver and whatever other equipment I need. The projector screen will be AT using spandex so the L/C/R will be behind the screen.

For the DSP I'm hoping that Denon will work well enough, if not what do you suggest? I do plan on room treatments, something I'm researching still. I've read I want 15-25% diffusion and another 15-25% absorption by area. If you have input on that I'd appreciate asking some questions but I'm not sure if those questions need to be in a different forum, let me know.

For the sim lets go with the infinity 1260w - Re:3.59, Le:2.89, Sd:82.3in2, Bl:16.9, Vas:82.96, Cms:206um/n, Mms:222g, Mmd:214, Fs:23.5hz, Qms:6.99, Qes:.41, Qts:.39, Hag:8mm, Hvc:34mm, Xmax:13mm https://eu.infinitysystems.com/tl_fi...260W_PI_EN.pdf

I have slightly different values plugged in because WinISD had conflicts with the published specs. I have - Re:3.59, Le:2.89, Sd:82.3in2, Bl:16.9, Vas:82.69, Cms:206.8um/n, Mms:221.8g, Mmd:214(no idea where this goes), Fs:23.5hz, Qms:6.99, Qes:.412, Qts:.389, Hag:7.9mm, Hvc:34mm, Xmax:13.1mm. Basically when I find it won't save due to conflicts I remove values and let it calculate things but try to remove values so the calculated ones are as close to the published specs as possible.

For arguments sake 3cuft volume, 1 circular port 5" diameter @ 213.19" long with no end correction, 300w power. Feel free to pick something else for the box as that I can plug in easy enough but the infinity I already have the published specs for. I'm in no way saying this is a box I would build or am trying to design though.

Something I asked earlier in the thread that I'm curious about is what happens if the port is designed to have a resonance at the tuning frequency?

What are your suggestions on how to take sound measurements from a sub or speaker without factoring in room gain? Is it as simple as placing the mic very close to the speaker to mitigate most of the room effects? Or do I need to figure out the room gain then subtract it out somehow? I'm just curious to see how to test each piece of the puzzle individually. Would taking a speaker outside for the measurement be a good way by first taking an ambient recording then one with the speaker and find the difference?
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post #33 of 230 Old 09-10-2017, 01:12 AM - Thread Starter
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Here's some updated images. Ignore the weirdness of the sub in the center, had trouble 3D modeling it. The second one is of the crazy port of which I've modeled 2 of them inside since they are mirrors of each other but haven't taken the time to sort out the 3rd one. I'm more or less done messing with them until I can sort out room and speaker measurements and decide if I want to get different subs all together. If I'm going to take on building these cosmetically I want to make damn sure acoustically I know what's going on because these will take TIME to build right and good materials.

So far though that box is roughly around 4.14cuft with 2 modeled ports 3.25"x3.25"x192.75". The volume is already reduced for the 3rd port but it's estimated from the existing 2 ports I've done, obviously it would be slightly different since that port will not be the same configuration as the 2 existing. Anyway I just got carried away with it but ultimately it's more for me to get an idea visually of how I would design the outside if I end up with boxes that big; they're based on the 2'x4'x2' limit. There is a lot of edge profiling that I haven't modeled simply because it would choke Sketchup and regardless of what crazy profiling I can come up with in CAD I will be limited by tools since I don't have a CNC machine to use.

The plywood end grain will follow the edges as you can see in the top left tear drop, I just haven't made them all that way because it involves manually rotating the paint image for each piece! Also the corner tear drops top and bottom would be blended to the face of the box. I might want to do a depression of some kind in the tear drops as well. The edges will just have some kind of round over. The ring around the sub is a bunch of 1/8th inch plywood strips stacked together that would get some kind of compound round over blended to the face of the box. I'm not sure if I'm going to with just the plywood or if I'm going to get some kind of veneer for the non end grain parts or if I would just go with a nicer wood veneer or something completely different. http://www.formica.com/en/us/product...ler-home/09496 http://www.nevamar.com/ (products, nevermar, left side finishes) granite or groovy or whatever, several of them look cool.
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post #34 of 230 Old 09-10-2017, 05:23 AM
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If you are serious about this, then switch to 18" drivers and 8" diameter ports - 12" isnt going to cut it. Also, with only two 2x4x2 enclosures, i would worry less about <10hz and more about 12hz+. You could do two 18" LLTs tuned to ~14hz in that size enclosure and be very solid.

EBS has no guidelines or minimum requirements, LLT does.
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post #35 of 230 Old 09-10-2017, 09:01 AM - Thread Starter
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Steve - I am serious about this but I'm not sure if my 'serious' is the same as yours or others At this point I am going to grab the mic and software for testing speaker and room responses and try to sort out testing speaker parameters instead of going off the published specs. From there I will be able to design more accurately and have a much better grasp on how I want to manipulate things. That will also help me define what is good enough for myself.

I'm not opposed to 18's or LLT enclosures but seeing as how this is not a continuous hobby for me I want to get my information and tools more in order so when I take the time to make a nice looking box and/or complicated build it's not wasted. My hobby is to DIY everything so I get frustrated if I have to do things over and over to get what I want. I still have a projector screen to build, acoustic wall treatments to figure out and build, the regular speakers to design and build w/xovers, Atmos with multiple receivers, custom couch/giant bed, modify my desk bed, build the room for all of this, build a small bathroom and kitchen. Once that's done I'll move on to my 3D printer, laser cutter and possibly a CNC machine. From there I have other projects that I need the 3D printer and laser cutter for. There is also aquaponics/gardening to do.

I did plug in that SI 18 as you described and all looks well except needing a HPF ~7.5hz. Group delay isn't terrible and it's well below 20hz, excursion is good down to 7.5hz and air velocity is around 15m/s peak ~12hz. That's on 300w, starting to think plate amps are not the thing to use and keep seeing people talk about the iNukes. I wouldn't mind going that route but I would want to keep all of the audio equipment on a single 15amp breaker just for convenience. I don't want to have to run new electrical whenever I move.
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post #36 of 230 Old 09-10-2017, 10:22 AM
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As for an impedance jig I was actually interested in being able to test speakers entirely for their specs, what do you recommend for that?
I built my own, you just need a resistor in the 100 ohm range (doesn't matter terribly what the actual value is as long as you can measure it precisely) and a couple of 3.5 mm jack ends that you can cut off old headphones or just cut a 3.5 - 3.5 mm cable in half. The parts will cost you about $2 if you have to buy them but you probably already have this stuff lying around. If you want to get really fancy you can use a couple of alligator clips to clamp to the speaker terminals too. Here's some pics of one that my buddy made, mine is actually much smaller with no case at all, just some electrical tapes around the resistor and solder connections so it just looks like a pregnant wire, it's very small. https://sites.google.com/site/amateu...-impedance-jig

Use REW or LIMP (ARTA) free software with the jig, same software you will use with the measurement mic. Both programs should have wiring diagrams in the manual but it's super simple to wire up. Or you can buy a woofer tester, if you do I recommend the WT2 from Smith and Larson, not the DATS (or whatever they are calling it now) from parts express.

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For the DSP I'm hoping that Denon will work well enough, if not what do you suggest? I do plan on room treatments, something I'm researching still. I've read I want 15-25% diffusion and another 15-25% absorption by area. If you have input on that I'd appreciate asking some questions but I'm not sure if those questions need to be in a different forum, let me know.
I have no idea what dsp your AVR will offer and don't care to look it up. It might be sufficient, it might not. I currently use a Mini DSP 2x4 HD, which might not be the best tool for the job due to filter overshoot in the very low frequencies but it's what I have for now.

We can talk at length about room treatments if you like but I would prefer to talk about the sub first.

Quote:
Something I asked earlier in the thread that I'm curious about is what happens if the port is designed to have a resonance at the tuning frequency?
This is an interesting question, something I've not thought of. There's already a resonance at tuning, the consequence of adding another port resonance at the same frequency will be an interesting phenomenon to observe. The effect will largely depend on the relative phase, q and strength of the resonances. But be aware that the port resonance that WinISD warns about is only the first resonance in a series of resonances that will invade the entire passband if you do this. It could be a workable situation, I'm not sure, but it's definitely something I would never try without fully simulating the effect.

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What are your suggestions on how to take sound measurements from a sub or speaker without factoring in room gain? Is it as simple as placing the mic very close to the speaker to mitigate most of the room effects? Or do I need to figure out the room gain then subtract it out somehow? I'm just curious to see how to test each piece of the puzzle individually. Would taking a speaker outside for the measurement be a good way by first taking an ambient recording then one with the speaker and find the difference?
I prefer taking the sub outside with no close boundaries (no walls or large objects anywhere near) and measuring it at at least 2 meters distance. In a pinch you can do extreme nearfield measurements in a room but it gets complicated with enclosures that have more than one sound source (speaker and port are two).

For measuring the room gain curve I recommend using a small sealed sub. First measure it outside if practical and feasible.

To see how the room affects things, next take the speaker inside, put it where you will be placing your sub when it's built and measure from the listening position. Then overlay the two measurements and plot the difference. This is your room gain curve. Data-bass has an article on this - http://data-bass.com/data?page=content&id=80

At that point you can design your sub to be close as possible to the inverse of the room gain curve so you can get the flattest possible response before eq'ing.

Now this is only important if you intend to leave the sub and room setup alone (not change stuff). If you change stuff, even just changing the sub or mic location, all that hard work is for naught. If you plan to move stuff around in the future it might be better to design for general trends in the room gain curve or just design for smooth (not necessarily flat) response so the sub has a good chance of working anywhere.

A bit later today I'll show some sims with the driver and enclosure dimensions that you gave me. You will quickly see that things are not quite as simple as WinISD suggests.
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post #37 of 230 Old 09-10-2017, 10:30 AM
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Also note that if you purchase an AVR the better ones usually come with a measurement mic. That mic might be good enough to use for all your measurements (if it has a jack that will plug into a computer and has it's own power) so you may not need to buy another one.

USB mics are just so simple to use though that the $100 UMIK from CSL is a good deal IMO. You pay a bit more for the pro calibration but I think it's worth it.
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post #38 of 230 Old 09-10-2017, 11:24 AM - Thread Starter
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From Denon "AVR-X4300H features a sophisticated DSP audio processing system that incorporates no less than 4 powerful high speed fourth generation SHARC DSP processors, which together have a combined continuous processing capability of 10 GFLOPS (10 billion floating point numerical computations per second)." "Equipped with the full Audyssey Platinum suite of advanced DSP algorithms, the AVR-X4300H features Audyssey MultEQ XT32 automatic room acoustic correction. With the supplied measurement microphone, MultEQ XT32 analyzes each speaker's output (including the subwoofers) at up to 8 measurement locations and generates precision digital filters that optimize each channel for the correct frequency and time domain response."

"Audyssey Sub EQ HT" "Audyssey Sub EQ HT provides individual DSP tailoring of each subwoofer in a dual subwoofer setup..."

So it does come with a mic, I'll probably hold off on buying a mic until I can figure out if the included one is good enough but otherwise $100 like you said isn't bad assuming it's something that will serve me just fine for years without wanting to upgrade.

Sounds like I incorrectly assumed that an impedance jig would just measure resistance! So it measures the T/S parameters? As for a good meter I'm assuming a Fluke would work? Being an electrician that's typically what I have access to.

WRT to the resonance it was just something I considered since some of these models were not too far from the box tuning already. As an example and it's not very practical, I'm getting 8cuft at 15.09hz with a resonance of 15.09hz but a port that's 20" diameter and 448.2" long! Why do I feel like this is heading in the direction of the principles applied to horns or transmission lines?
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post #39 of 230 Old 09-10-2017, 11:55 AM
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From Denon "AVR-X4300H features a sophisticated DSP audio processing system that incorporates no less than 4 powerful high speed fourth generation SHARC DSP processors, which together have a combined continuous processing capability of 10 GFLOPS (10 billion floating point numerical computations per second)." "Equipped with the full Audyssey Platinum suite of advanced DSP algorithms, the AVR-X4300H features Audyssey MultEQ XT32 automatic room acoustic correction. With the supplied measurement microphone, MultEQ XT32 analyzes each speaker's output (including the subwoofers) at up to 8 measurement locations and generates precision digital filters that optimize each channel for the correct frequency and time domain response."

"Audyssey Sub EQ HT" "Audyssey Sub EQ HT provides individual DSP tailoring of each subwoofer in a dual subwoofer setup..."

So it does come with a mic, I'll probably hold off on buying a mic until I can figure out if the included one is good enough but otherwise $100 like you said isn't bad assuming it's something that will serve me just fine for years without wanting to upgrade.
Might be good enough, you can ask around. I have no experience with AVR dsp or the mics that come with them.

Quote:
Sounds like I incorrectly assumed that an impedance jig would just measure resistance! So it measures the T/S parameters? As for a good meter I'm assuming a Fluke would work? Being an electrician that's typically what I have access to.
Technically the impedance jig does only measure impedance, but it measures it at all frequencies that you specify. Speakers are a dynamic load, impedance changes dramatically through the passband so you need to know what the impedance is at any frequency you want to see it at. Impedance is an incredibly important part of competent speaker design. This is why off the shelf passive crossovers don't work.

The jig can't do anything by itself though, the software is the part that actually shows you the impedance curve and it can also read the impedance curve it generates, perform a few calculations and from that information it can generate t/s parameters.

WRT DMMs, Fluke is more than good enough.

Quote:
Why do I feel like this is heading in the direction of the principles applied to horns or transmission lines?
Because that's EXACTLY where it's heading. In very general terms you could say that a transmission line is simply a ported box but instead of having a separate chamber the whole thing is just a long port with a huge amount of resonances. The de facto standard (among people that know how) is to morph a ported box into some type of transmission line when the ports get too long and unruly. When you start talking about ports that are 450 inches long the frequency response is going to be pretty bad due to resonances all the way through the passband (unless you are VERY careful) and at that point it's probably much easier to just do a tl instead. Transmission lines do have resonance issues too, which can severely limit bandwidth but there are ways around that. Reverse tapered lines with offset drivers and a bit of stuffing can give extremely nice response over a very wide bandwidth but it can be problematic making the terminus large enough with large excursion drivers in that scenario. Then we get into stuff like limited bandwidth tl or tapped horn or some other variant. This stuff is all pretty simple to design if you have the right software.

Sims are coming for the design you specified, I'm a bit busy at the moment but they are still forthcoming.

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post #40 of 230 Old 09-10-2017, 12:15 PM
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Bob - personally, i wouldnt fret the details of getting a high quality mic for subwoofer testing. Ive been on these forums for a while and the reality is that the bulk of the diy subs ive seen built do reflect what the simulations predict - it's only when you start reaching the upper limits of what the driver is capable of that things start acting goofy. Build enough 18" subs and you'll never have to reach that point.

Save your money for more drivers.

Also, i wouldnt worry about a 7hz highpass filter. Between the rarity of high amplitude signal that low and the FR rolloff of your bluray player, processor, and amplifier, you have built in protection.
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post #41 of 230 Old 09-10-2017, 12:22 PM - Thread Starter
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Yea no worries, I'm not looking to build this thing any time soon honestly. Need to get the room stuff built first and make one more trip back to Texas to get the rest of my belongings.

One thing I would like to point out is I really like the idea of doing a more 'exotic' design. Whether that is a complicated ABC, TL or horn although I've never attempted the latter 2. In a perfect world the complexity of construction and cosmetic appearance and design are just as impressive as the acoustic qualities. I wish I had pictures of the first sub box I did for my car when I was 17, it was imo extremely impressive as a first build especially considering I had never really used a drill or saw before then and those are the only power tools I used. I made custom panels so the whole thing looked molded to the back end of the trunk (hatchback), had 2 slot ports facing forward with plexiglass tops to see into the ports, plexiglass windows on the top and front of the 1/3 chamber where I built in a box for the amp set at an angle so the front top edge and back bottom edges were flush with the sub box floor inside and had an exhaust fan in the portion below the sub floor. I made a 1/4" thick copy of the stereo shops logo (name surrounded by tribal flames) that I worked at for under the carpet then wrapped it and the inside of the ports with EL glow wire. I actually spent a month building and rebuilding it only to start from scratch because there were so many learning fixes along the way.

I don't expect everyone to be impressed with the construction but I know the design I've shared if I pull that off, someone like my grandpa who is a master carpenter would be able to appreciate the complexity. The pictures may not convey some of the details I haven't taken the time to model.

Anyway I am interested in considering TL's or horns as well but as I said I have no experience designing them or if they would be a good candidate considering my build volume limitations etc. Let me know what you think, it would be nice to have the wow factor in there if it makes acoustical sense as well.
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post #42 of 230 Old 09-10-2017, 12:23 PM
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Bob - personally, i wouldnt fret the details of getting a high quality mic for subwoofer testing. Ive been on these forums for a while and the reality is that the bulk of the diy subs ive seen built do reflect what the simulations predict - it's only when you start reaching the upper limits of what the driver is capable of that things start acting goofy. Build enough 18" subs and you'll never have to reach that point.
While I would tend to agree there are a couple of extremely important caveats.

1. For stuff like single digit tuned resonant enclosures WinISD definitely is not good enough. Especially when using very large enclosure dimensions (wrt wavelengths produced at the top of the passband) and/or very long stroke drivers.
2. OP is not just going to be testing subs - he's already two way speakers. To do that you absolutely need some type of impedance measuring jig and a quality mic. I'm not sure if the AVR mic can be used independent of the AVR or not. If not he will definitely need a mic.
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post #43 of 230 Old 09-10-2017, 12:29 PM
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Anyway I am interested in considering TL's or horns as well but as I said I have no experience designing them or if they would be a good candidate considering my build volume limitations etc. Let me know what you think, it would be nice to have the wow factor in there if it makes acoustical sense as well.
Size is definitely an issue. Transmission line is doubtful unless it's severely tapered towards the open end and horn is just not going to be possible in the space you have dictated unless you use a 6 inch driver (or smaller) and/or change your tuning to 40 hz (or higher). Horns are large for a reason - the size is what makes them work. If you build a horn the same size as a ported box the horn won't have much (if any) advantage over the ported box.

I can show you how to design horns and transmission lines if you like. And tapped horns and everything else. I don't care for complex bandpass boxes though, including ABC. For that stuff you are on your own.
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post #44 of 230 Old 09-10-2017, 12:36 PM - Thread Starter
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Steve - I want to get a decent mic because I plan on doing full range speakers as well, not just subs but I could see your point if I was just looking at subs. Again regarding your point of accomplishing a goal in a way that I could avoid certain issues which I can appreciate it's not really the path I'm wanting to take. I would like to know what's going on as exactly as I can; I'm very detail oriented and a perfectionist. For me it's not just the sound but build design and cosmetics. I like the idea of and take pride in doing things or even just attempting things that require great skill even if it's not the most frugal use of time and money. There are some things I apply that philosophy to but with this project I'm in it to push limits of what usually would not be 'enough'.

Anyway not trying to knock your suggestion, I do appreciate it as I will keep that in mind if my goals and/or focus changes.
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post #45 of 230 Old 09-10-2017, 12:39 PM
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Bob - personally, i wouldnt fret the details of getting a high quality mic for subwoofer testing. Ive been on these forums for a while and the reality is that the bulk of the diy subs ive seen built do reflect what the simulations predict - it's only when you start reaching the upper limits of what the driver is capable of that things start acting goofy. Build enough 18" subs and you'll never have to reach that point.
Don't know where my post disappeared to - I'll try it again.

I would tend to agree with this but with a couple of extremely important caveats.

1. WinISD isn't nearly accurate when simulating large dimensions (compared to wavelengths at the top of the passband) especially with long stroke drivers and long ports.
2. OP has already started into 2 way speaker design. To do that properly you absolutely need accurate impedance and frequency response measurements. I'm not sure if AVR mics can be independent of the AVR but if not OP will definitely need another mic for a variety of different tasks.
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Diy - I only went with ABC because back in the day there wasn't squat on TL's except thoughts and without being able to test, it was a dead end for me. ABC was spelled out and something I knew I could physically build. I know when I looked at more traditional bandpass designs 4th, 6th etc I was not interested but based on how ABC's were explained they sounded like a good deal.

I kind of figured a TL or horn would not be practical for this project but since you mentioned smaller drivers and higher tuning maybe when I get around to the 'full range' speakers we can talk about those designs. I may rig things up so the screen folds up to the ceiling when not in use which would let me appreciate a nice cosmetic build for the full ranges. I've already had a crazy idea for the front speakers to be some kind of curved TL. It would most likely involve a CNC or laser cutter to cut a bunch of slices from the CAD design but I haven't bothered designing much; just a concept. The slices would be to take advantage of the plywood end grain along with more consistent dimensions leaving me with just a ton of sanding.

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Ok let's do a sim. Here's the inputs. All inputs are in metric so I converted them, you can check my math. These are the t/s and enclosure dimensions you wanted me to use. Forget the Xmax and Pmax in the screenshot on the left, I'll set that later. Power for this sim is set at about 135 watts.



Here's the system schematic, the frequency response and cone excursion.
Note that the port is almost as large as the chamber by volume.
The blue trace on the frequency response and cone excursion graphs are the results of a simple sim, the red trace on those same graphs are the result of factoring in estimated effects of lossy inductance. I can point you to volumes of info on lossy inductance but for now you can rest assured that the actual measured response of this sub will be somewhere between the blue and red traces, closer to the red trace. For this reason all subsequent sims will use the red trace model with lossy inductance factored in.
As you can see, this power level causes excursion to reach xmax at the excursion hump above tuning. The excursion spike below tuning can be taken care of with a high pass filter or ignored in design and worked around by just turning down the volume knob when stuff starts to sound bad.



The spikes are dips above tuning are what port resonances look like. The very narrow ones won't show up much, if at all. For example, the spikes and dips that are just one pixel wide won't show up at all so you can round off these spikes and dips mentally a bit to imagine how they will actually measure in real life. The wider parts of the spikes and dips aren't gong anywhere though. This response is actually not that bad because the driver and port are centered on the chamber - it could be made better or worse by moving the driver and port locations around, but because of the small chamber size there's not too far you can move them so you are limited in what you can do by driver and port location.

Here's port velocity and group delay without any filters applied. Note that the higher resonances definitely affect both at frequencies where they appear. Also note that at the lower frequencies it will never actually get that loud as shown as excursion is pushing 60 mm near tuning.



Now let's add a high pass.
Top row - frequency response and cone excursion, dark black trace is with filter applied, light grey trace is without filter
Bottom row - port velocity and group delay with the filter applied



It becomes quite clear that if you do use a high pass filter and keep the sim at this power level, the filter completely chokes off the port resonance. Spl at tuning drops about 12 db, port velocity drops all the way down to about 5 m/s, both of these indicate that the port isn't doing much of anything, the hpf completely castrated the port output.

Whether you use a hpf or not, your output at tuning is going to be limited to about 83 db or a bit lower at 6 hz, any more than that will exceed xmax, with or without the hpf. 83 db at 6 hz won't produce anything at all in terms of audible or tactile output but it may produce a bit of distortion and mechanical noise. Add another fully powered sub and you get 89 db total - still not going to be noticeable except for distortion and mechanical noise.

Also note that the hiphpass filter has caused group delay to rise up almost to the 400 ms mark, not that you will likely notice that at 6 hz.

Now let's compare this design to a comparable sealed box design with the same driver. I pushed the sealed box size up to 154 liters (same size as the ported box was including the port volume) and turned to power down a bit to 105 watts to keep it within xmax.
Black trace is the sealed box, light grey trace is the ported box with high pass filter engaged.
Frequency response and cone excursion shown.



So what did we gain with the ported design? Looks like about 3 db of gain from 6 - 20 hz and then a messy frequency response above 20 hz. And a lot more group delay (if you care about that).


This is what I was talking about - resonant strength is dictated by enclosure size. Your enclosure size (~154 liters, port included) is not nearly large enough to produce much resonance at tuning. So there's only a negligible difference between the ported box and the same size sealed box. As I said before, for single digit tuning I'd move up to at least a couple of 18s and bump up enclosure size to at least 30 - 40 cu ft per driver if you want any real output at tuning.

No matter what box type you choose - ported, bandpass (all types, 4th, 6th, 8th order, including ABC), transmission line, tapped horn, front loaded horn, etc, it doesn't matter, you won't get any more output than this at tuning unless you make the box substantially larger. The more complex you make it the more resonances you will have to deal with in the passband but it won't get louder at tuning no matter what you do unless you increase the box size.

That concludes our simple ported sim. I've got tons more to say about all this but no time right now.
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Diy - I only went with ABC because back in the day there wasn't squat on TL's except thoughts and without being able to test, it was a dead end for me. ABC was spelled out and something I knew I could physically build. I know when I looked at more traditional bandpass designs 4th, 6th etc I was not interested but based on how ABC's were explained they sounded like a good deal.
Transmission line behavior is fully quantified now and easy to sim, anyone can do it, it's easy. Reverse taper, positive taper, straight line, tapped horn, it's all really simple now.

ABC is described in a kind of off hand rule of thumb way. That's no substitute for accurate sims. If you actually simulated some of the stuff you built in the past accurately you might be horrified at the behavior. That doesn't mean it can't sound good in a specific environment but it does mean that if you can sim accurately you can hit goals a lot faster and easier.
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2. OP is not just going to be testing subs - he's already two way speakers. To do that you absolutely need some type of impedance measuring jig and a quality mic. I'm not sure if the AVR mic can be used independent of the AVR or not. If not he will definitely need a mic.
The AVR mike isn't as good quality as the UMIK, and isn't a USB mike. AFAIK, you can't use it for REW. If you can, I'm sure it involves a lot more work than it's worth, the AVR mikes are of variable quality and don't come with any kind of calibration file. The AVR just assumes the mike follows a certain calibration whether it does or not.

I don't know jack about everything else you are talking about, but I can answer that one question.
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The AVR mike isn't as good quality as the UMIK, and isn't a USB mike. AFAIK, you can't use it for REW. If you can, I'm sure it involves a lot more work than it's worth, the AVR mikes are of variable quality and don't come with any kind of calibration file. The AVR just assumes the mike follows a certain calibration whether it does or not.
If it's got a 3.5 mm jack you can use it but the results may be very bad. It almost certainly won't have a preamp (never seen a AVR mic with a power cord) so you will have to measure at very high levels just to get above the noise floor and as you note the quality and accuracy of the mic will be completely unknown unless/until compared against a quality mic.

I used to use an old mic capsule from a computer. While the computer was working I measured lots of stuff against a known standard and the results were accurate so I knew it was a good capsule. After the computer broke I took the capsule out and stuck it in a pen body and wired it to a 3.5 mm jack and continued to use it. With no preamp you have to measure at pretty loud levels though and I was tired of that fragile little thing so when it broke I did not diagnose the failure, I bought a UMIK usb mic.

Thanks for the input.
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post #51 of 230 Old 09-10-2017, 02:35 PM - Thread Starter
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That ported box looks like a mess! Beyond the FR nastiness there are 2 more peaks in the port velocity and group delay around 35hz and 65hz which are the only ones that would be in the range I'm looking to run these. 65hz is still way above what I want to run them at if playing a 10-100hz sweep from a signal generator is any indication. I think I would cut these off somewhere between 35-50hz as I would like the front mains to get down to at least 40hz if not a bit lower. I just don't expect the mains to be a huge source of air movement, just good SQ.

So the question goes back to optimal design class for the build envelope I'm ok with. For arguments sake if I did want to use more room the only place I would be comfortable doing so would be behind the screen which is essentially the back 10" of the box where I could go vertical a bit. I need to leave room for the mains to go and while I don't plan on tiny satellite speakers all around I'm also not planning on full towers. Something like the Statements Monitors look nice but I'm in no position to dump that kind of money on that, maybe when I get back to work but honestly if I'm looking at almost $1k for a pair of speakers in just drivers and xovers I want to design them myself. What I'm getting at is I expect the mains to be medium sized. Not sure on 2 way or 3 way and I understand in theory the goal is a single full range driver with no circuitry. The build envelope I imagine for the mains is 12"x12"x24" WxDxH or smaller, sealed or ported or other. Only time I see this changing is if I attempt that crazy picture I posted but that would be for a living situation where the room is wider and I wouldn't have speakers and subs competing for the same footprint on the floor.

I'll start digging into the software you suggested for modeling. The added work of ported for that little bit of gain with all of the non linearity is not worth building. The only thing I feel might be an issue wrt sealed SI18's is the roll off and room gain not combining enough to get flat although Unretarded posted a decent looking graph for them sealed iirc.

One observation and correct me if I'm wrong but it looks like the first peak that WinISD doesn't show is due to the port resonance of ~32hz and the second peak is due to twice that frequency so if the port resonance was higher would that mean the ported response would be much cleaner in the desired range?
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WinISD .7.x with simulate voice coil inductance and use transmission line model for ports, looks more similar at first glance. I had this but wasn't using it because I didn't realize the added options did this.
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post #53 of 230 Old 09-10-2017, 03:18 PM
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That ported box looks like a mess!
Yes but due to box losses the spikes and dips won't look so bad in reality. And a bit of stuffing might help too. Transmission lines look somewhat similar in response too until you use all the tricks to smooth the response. The ABC boxes you've built in the past probably have response somewhat similar looking to this wild looking sim.

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Beyond the FR nastiness there are 2 more peaks in the port velocity and group delay around 35hz and 65hz which are the only ones that would be in the range I'm looking to run these.
That velocity peak at 65 hz is very narrow, most of it won't even show up in real life. An educated guess would suggest that you could round it off so it peaks around 5 m/s and the whole top part of the spike will completely disappear. The 35 hz spike is quite a bit wider so it won't change much in real life, just chop the top 5 m/s or so off the top of the spike.

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65hz is still way above what I want to run them at if playing a 10-100hz sweep from a signal generator is any indication. I think I would cut these off somewhere between 35-50hz as I would like the front mains to get down to at least 40hz if not a bit lower. I just don't expect the mains to be a huge source of air movement, just good SQ.
Just be aware that the "punch" and "slam" in the bass is way up around 80 hz and higher, so mains like you have now aren't going to cut it down to 40 hz. What are those drivers, maybe 4 or 5 inch?

Quote:
So the question goes back to optimal design class for the build envelope I'm ok with. For arguments sake if I did want to use more room the only place I would be comfortable doing so would be behind the screen which is essentially the back 10" of the box where I could go vertical a bit. I need to leave room for the mains to go and while I don't plan on tiny satellite speakers all around I'm also not planning on full towers. Something like the Statements Monitors look nice but I'm in no position to dump that kind of money on that, maybe when I get back to work but honestly if I'm looking at almost $1k for a pair of speakers in just drivers and xovers I want to design them myself. What I'm getting at is I expect the mains to be medium sized. Not sure on 2 way or 3 way and I understand in theory the goal is a single full range driver with no circuitry. The build envelope I imagine for the mains is 12"x12"x24" WxDxH or smaller, sealed or ported or other. Only time I see this changing is if I attempt that crazy picture I posted but that would be for a living situation where the room is wider and I wouldn't have speakers and subs competing for the same footprint on the floor.
Designing your own mains is going to be a trip. First download Jeff Bagby's PCD (passive crossover designer). The entire program is contained on a single Excel spreadsheet. It works best with Excel 2003 if you have that. Open up that spreadsheet. Know that you will have to measure the impedance and frequency response of your speakers, create .frd and .zma files from those measurement, input those files into the spreadsheet and only then can you start designing the speakers. Take a look at the spreadsheet and let me know if this is something you want to do or if it seems a bit too much at this point.

In theory the goal is absolutely not to have a single full range driver with no circuitry, unless you can find one that's WAY better than anything currently on the market. A single full range driver is either going to have massive issues with max spl or with beaming and all full range drivers have problems with frequency response. As Toole states, on axis frequency response is king but off axis frequency response is a very close second. The only way to get smooth off axis response is with more than one driver. Woofer and horn tweeter combos do off axis and high spl exceedingly well but they tend to be large and will likely cost more than Statements. Dome tweeters on a flat baffle will cause excessive "tweeter bloom" which is a major cause of a "bright" sound even if the frequency response on axis is flat - unless you use them outside in which case the off axis response isn't a factor at all.

Having your mains in a sealed box will tend to make it much easier to cross over to the sub in a proficient manner. With ported mains the impedance is swinging all over the place and can cause issues trying to get a proper match through the crossover region.

Quote:
I'll start digging into the software you suggested for modeling. The added work of ported for that little bit of gain with all of the non linearity is not worth building. The only thing I feel might be an issue wrt sealed SI18's is the roll off and room gain not combining enough to get flat although Unretarded posted a decent looking graph for them sealed iirc.
Hornresp is what I used for the sims I showed. I don't think you will be able to find MJK's worksheets at all anymore and I don't think TL.app is available anymore either. Akabak is WAY to complicated for you at this point, it's something to get into once you have Hornresp under your belt. Akabak is entirely script based and doesn't show a schematic so you REALLY have to know what you are doing and be confident in your work.

Check out PCD for mains design as I previously mentioned. Speaker Workshop will also work, I've heard, but it's a lot harder to use than PCD.

Room gain will depend entirely on the room you are using. Is it small or large? Concrete walls or vinyl siding on 2x4s? Sealed airtight or open to the entire house? All of this will affect your room gain curve and it really needs to be measured. It's entirely possible to have flat response with sealed boxes down to near 1 hz if you have the right drivers, the right size box, an airtight concrete bunker underground. The max room gain boost is 12 db/oct as frequency decreases, you can't get more than that but you can definitely get less. Room gain will start at a frequency dictated by the room dimensions, usually starting around 30 hz or so and increasing gain as frequency decreases.

Quote:
One observation and correct me if I'm wrong but it looks like the first peak that WinISD doesn't show is due to the port resonance of ~32hz and the second peak is due to twice that frequency so if the port resonance was higher would that mean the ported response would be much cleaner in the desired range?
A shorter port will have resonances starting at a higher frequency, but once they start, everything above that frequency is going to be a mess. Resonances like this are called "harmonic resonances", you can research the term if you like, all resonant enclosure have a series of harmonics. Usually with normal ported boxes the box and port are small (compared to wavelengths being produced) so you can more or less trust WinISD. But when any dimension starts to get long you really need appropriate software to map out the resonances.

But yes, if you can push the first resonance up outside the passband it's smooth sailing.

With a straight port all you can do to raise the resonance is make it shorter (which will also mean making it narrower, which will in turn raise the port velocity) or use large flares, in which case you can make the middle part narrower and decrease the overall length of the port. There's a few port tricks you can use to make the first resonance higher and/or make the resonances behave. We can get into that more if you like, but like I said, unless you are prepared to increase your box size substantially there's not much point.

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post #54 of 230 Old 09-10-2017, 03:20 PM
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WinISD .7.x with simulate voice coil inductance and use transmission line model for ports, looks more similar at first glance. I had this but wasn't using it because I didn't realize the added options did this.
Attachment 2280666
That's a lot better than not using those features but it's still not accurate.

Learning a more fully featured program like Hornresp will pay off in ways you can't even imagine yet. What you've seen so far is just the tip of the iceburg.

If you MUST use WinISD at least make sure you understand what Ql and Qa are and set them appropriately. If you don't do that you can't even compare WinISD sims to anything else. There's also Qp to consider but I don't think WinISD factors that in. Most simulators just assume no losses, which is fine if you understand how losses will affect the behavior.
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post #55 of 230 Old 09-10-2017, 03:46 PM - Thread Starter
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Haven't read your last 2 reply's but wanted to put this up.
Pink - Sealed 1.5cu 300w w/options (sim VC induc., TL model for ports)
Green - 2.5cu 31.27hz 300w w/no options (this is what I saw in WinISD .5 alpha and designed off of)
Blue - same box w/sim VC induc.
Teal - same box w/TL port model sim
Orange - same box w/both options
Sorry I forgot to change the labels to white when I changed the background to black but left is 10hz and the rightmost line is 200hz then jumps down to 100hz then down in 10hz increments.
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I think I lucked out at least on the FR part so far simply because I was tuning higher; first port resonance at ~280hz. With both options enabled it actually smoothed out the corner hump and brought the extension out a bit to almost 25hz before it starts really dropping. Looking at group delay it peaks around 26ms @ 20hz. Excursion peaks above tune 10.75mm @ ~34hz, excursion limit 13.1mm @ ~19hz, port velocity peak 15.5m/s @ ~19.5hz.

I threw in another one to model the top end of the ABC at 58hz and port velocity peaks 25m/s @ ~53hz which makes sense for what I remember hearing. Excursion above tune peaks @ 6mm @ ~63hz, delay 22ms @ ~54hz. All in all looks good except the FR looks like a right triangle peaked at ~57hz +9db over the 31.27hz.

Now I'm interested to measure it to see if it's dual tuned or infinitely tuned between the tune and 1.9x.
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post #56 of 230 Old 09-10-2017, 04:11 PM - Thread Starter
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Yea they are 5.25's but originally they were just supposed to be midranges. I'm sure I can reuse them in the surround sound somewhere but I'm not sure if they'll go in the mains.

The ideal speaker was just to say that in a perfect world which I know doesn't exist there would be one driver capable of 20-20khz without sacrifices or needing electronics to color it. Usually we end up with at least a 3 way if you count the sub and then 4 way if the mains are 3 ways but I know it gets more complicated to add drivers with their own personalities, electrical/electronic needs and room effects.

Regarding the mains that's a down the road thing and I will probably tackle that after the subs since I have a better handle on the subs so it would be faster for me to get that squared away. Regardless of looking at the xover spreadsheet I can tell you I am interested, I highly doubt there is anything contained in a spreadsheet that scares me. I use Excel regularly to sort through things and I program in it as well. As far as math goes I've taken several calculus classes and some calc based physics. If I ever decide to finish school I'll be majoring in electrical engineering but I haven't had the stability or the right situation to go to school for more than a year in one sitting with several years between.

This newer WinISD does have Qa, Ql, and Qp but I have no idea what that is and the help file is for the older version which didn't include these. Not saying I won't check out HornResp but I was curious about this since I had installed this and remembered seeing these different options.

When you're talking about increasing the box size are you referring to the 2'x4'x2'? To me that's a pretty large box already! Not sure how I'm going to move these things around by myself if it's ported and uses 2 full sheets of plywood per box!

One thing I do know is I would prefer to design things to be flat in their response with the exception of the subs which I would like to design them around a pretty typical or easy to expect amount of room gain. This way when I move I have a more consistent baseline to work off of and just take what correction I can get from the DSP. Maybe one of these days when I buy a home and I'm done moving around for work I'll design around the room specifically.
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post #57 of 230 Old 09-10-2017, 04:15 PM
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I threw in another one to model the top end of the ABC ...
You can't do that, the box is a complex unit and it acts as a complete sum of it's parts. You can't just simulate some small part of it and expect the results to be realistic in any way.

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Now I'm interested to measure it to see if it's dual tuned or infinitely tuned between the tune and 1.9x.
If you use the proper software to sim it, the sim will tell you exactly how it will behave. No need to build and measure just for curiosity. I can pretty much guarantee your sims are not accurate in any way, that's not how it will behave. Sim it properly or build it an measure it, you'll see.
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post #58 of 230 Old 09-10-2017, 04:23 PM
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Yea they are 5.25's but originally they were just supposed to be midranges. I'm sure I can reuse them in the surround sound somewhere but I'm not sure if they'll go in the mains.
Those are designed as woofer, not mids. There are much better choices for mids. They are perfect for what they are designed for though, making low spl woofer bass in a small box.

Quote:
Regarding the mains that's a down the road thing and I will probably tackle that after the subs since I have a better handle on the subs so it would be faster for me to get that squared away. Regardless of looking at the xover spreadsheet I can tell you I am interested, I highly doubt there is anything contained in a spreadsheet that scares me. I use Excel regularly to sort through things and I program in it as well. As far as math goes I've taken several calculus classes and some calc based physics. If I ever decide to finish school I'll be majoring in electrical engineering but I haven't had the stability or the right situation to go to school for more than a year in one sitting with several years between.
It's not hard and you don't need to know any math. The issue is that there's SO MUCH to consider that first timers frequently look at the spreadsheet, see how much there is to good design, buy a set of commercial speakers and find a new diy hobby. But none of it is actually difficult and you won't be doing any math at all.

Quote:
When you're talking about increasing the box size are you referring to the 2'x4'x2'? To me that's a pretty large box already! Not sure how I'm going to move these things around by myself if it's ported and uses 2 full sheets of plywood per box!
2x2x4 is plenty big enough for a 30 hz sub but it's not going to cut it for a single digit tuning frequency using only a single 12 inch driver. It won't put out enough output at 6 hz to be of any use at all. This is why people keep telling you to consider 18s, bigger boxes or a higher tuning.

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One thing I do know is I would prefer to design things to be flat in their response with the exception of the subs which I would like to design them around a pretty typical or easy to expect amount of room gain. This way when I move I have a more consistent baseline to work off of and just take what correction I can get from the DSP. Maybe one of these days when I buy a home and I'm done moving around for work I'll design around the room specifically.
That's fine. As long as you have a goal things are a lot easier.
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post #59 of 230 Old 09-10-2017, 04:56 PM - Thread Starter
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I'm not opposed to going to those SI18's as I've said before they look really good at least in WinISD sealed. I'm also not set on a particular tuning frequency either. I guess we could start to narrow down what's realistic considering I don't want to go any larger than 2'x4'x2' external, I do plan for 2 individual sub/box setups, I currently have 300w Yung plate amps but I'm not opposed to grabbing something different yet not super expensive; maybe an inuke1000 to power both. There is a little wiggle room on power but again I want to keep the receiver, amps etc. all on a single 15a breaker. So with that in mind I'd like to see what's reasonable for low and go from there. Getting to 20hz I think is a good expectation and lower would be nice for when movies have it.

I'm watching a tutorial on hornresp, getting sidetracked because this guy was saying it assumes your sub is flush mount to the wall and doesn't really consider boundary effects. He's referencing an Excel boundary effect calculator by Bagby?, his mic sucks so it was hard to understand him.

I went with those woofers because I figured I could use the plate amps to filter for the woofer but I wouldn't get them crossed very high so I wanted the mid to go lower to meet the plate amp xover. I get it though and I experienced some of this once I had it built, nice ideas but turned out to not be the execution I wanted. Anyway I figure since from what I've read they're not bad drivers both the woofers and tweeters for the money that I can reuse them as something in the surround sound. Whether that's the center, heights, Atmos, rears I'm not sure. I have planned on ditching the generic xovers.

As for getting scared and finding another hobby probably not My hobby is hobbies in general but I never stick to one thing. I've yet to come anywhere close to what I'd like to accomplish with speakers though and even when I do it will just become a skill that's saved for when I decide to make use of it again. For me I DIY everything I can pretty much.
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post #60 of 230 Old 09-10-2017, 05:28 PM
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Originally Posted by MeltManBob View Post
I'm not opposed to going to those SI18's as I've said before they look really good at least in WinISD sealed.
Yeah they look great until reality sets in. WinISD is not considering lossy inductance, that will change things a lot, but not as much as the room will. Lossy inductance presents as a loss in motor strength compared to what the t/s would suggest, in this case it's probably about 30 percent. That changes things a lot.

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I'm also not set on a particular tuning frequency either. I guess we could start to narrow down what's realistic considering I don't want to go any larger than 2'x4'x2' external, I do plan for 2 individual sub/box setups, I currently have 300w Yung plate amps but I'm not opposed to grabbing something different yet not super expensive; maybe an inuke1000 to power both. There is a little wiggle room on power but again I want to keep the receiver, amps etc. all on a single 15a breaker. So with that in mind I'd like to see what's reasonable for low and go from there. Getting to 20hz I think is a good expectation and lower would be nice for when movies have it.
I'd say 15 hz is a nice practical goal considering your constraints, but it's up to you. Powering your entire system on a 15 amp breaker shouldn't be a problem, with low tunings or making a sealed sub play low, you won't use a whole lot of power. My most recent sim was 135 watts for the ported, 105 watts for the sealed.

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I'm watching a tutorial on hornresp, getting sidetracked because this guy was saying it assumes your sub is flush mount to the wall and doesn't really consider boundary effects. He's referencing an Excel boundary effect calculator by Bagby?, his mic sucks so it was hard to understand him.
Yeah I did that tutorial and forgot to delete it. It was a first pass to see what what was involved in creating a tutorial, I just started talking with no script and recorded it. I realize it sucks really bad but at that point I also realized that I really dislike making tutorial videos - and I would have had to make at least a dozen more to cover the basic features of Hornresp. I really should delete that piece of crap.

Hornresp does consider boundaries but only insofar as it assumes the sound source is flush mounted IN the boundary, not in front of the boundary. This is probably more technical than that tutorial needed to be and it's nothing you need to worry about, but Bagby's Diffraction and Boundary Simulator spreadsheet is a good source of info, and it can be used to create aspects of .frd files that can be used in his PCD spreadsheet, estimate room gain, etc. Bagby's spreadsheets are on point.

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As for getting scared and finding another hobby probably not My hobby is hobbies in general but I never stick to one thing. I've yet to come anywhere close to what I'd like to accomplish with speakers though and even when I do it will just become a skill that's saved for when I decide to make use of it again. For me I DIY everything I can pretty much.
I've been semi serious about this hobby for 10 years and I knew nothing when I started. Now I know more than most of the guys I used to learn from. It takes dedication - a lot of time, a lot of research and a LOT of playing around with a capable simulator. But if you put in the time you can become better educated than most of the engineers that make commercial products. It's not like the old days - all the info is out there and readily accessible and computers have made the learning curve a lot less steep - you don't need to know math anymore at all. The software is fantastic and mostly free and the accessories (dsp, measurement mics, impedance jigs) are stuff that were not available at all (for a realistic price) 30 years ago. It used to require a college level math education and an expensive tone generator and other electrical parts just to measure t/s and design a simple box. Now you can do all that stuff with a computer, $2 in parts and 10 minutes.

The first step is to get the proper software. Ditch WinISD and download Hornresp. Get PCD, ARTA, REW. I'll list a few others as we go along that you will need. None of this will be difficult if you can follow simple directions.
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Last edited by diy speaker guy; 09-10-2017 at 05:34 PM.
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