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2 hz tuning - pros and cons - Page 6

post #151 of 302
Winisd transfer functions.pdf 26k .pdf file

apparent load.pdf 33k .pdf file

cone excursion.pdf 32k .pdf file

spl.pdf 30k .pdf file



port velocity.pdf 28k .pdf file

maximum power.pdf 32k .pdf file

Here they are. Open them and compare to your graphs. I used 1000 watts as was planned in the beginning.

Good luck,

Robert
post #152 of 302
Thread Starter 
Quote:
Originally Posted by bossobass View Post

What I'm saying is that you either raise the tune to see a real advantage before the signal chain roll off (as the seasoned vets of that sort of alignment have repeatedly said in this thread).

I agree with your entire post except this quoted bit. Post 137 shows clear benefits (assuming your signal chain is at least decent and not too far rolled off down to 5 hz).
post #153 of 302
Quote:
Originally Posted by notnyt View Post

And that is why I have a low frequency HPF. with the rest of the levels high, that ULF causes excursion to skyrocket. It IS there.

Couldn't have said it better!
post #154 of 302
Thread Starter 
Quote:
Originally Posted by Ricci View Post

Fair...forcing the sealed system to be the same in every way when it makes no sense for them to be is fair?

If the sealed system can't achieve the stated goals it isn't the right tool for the job. Simple as that. The stated goal has always been lowest possible frequency at highest possible spl with lowest possible power.

Xmax limited max spl at the lowest frequency desired is the ONLY thing that matters.
Edited by diy speaker guy - 12/10/12 at 9:45pm
post #155 of 302
Notnyt have you ever taken a measurement of the electrical roll off of your signal chain to the subs as it comes out of the amps?
post #156 of 302
Thread Starter 
Quote:
Originally Posted by robertcharles View Post

Winisd transfer functions.pdf 26k .pdf file
apparent load.pdf 33k .pdf file
cone excursion.pdf 32k .pdf file
spl.pdf 30k .pdf file
port velocity.pdf 28k .pdf file
maximum power.pdf 32k .pdf file
Here they are. Open them and compare to your graphs. I used 1000 watts as was planned in the beginning.
Good luck,
Robert

Those are all exactly the same file (at least they were the last time you posted a bunch, all same as each other and the first one you posted separately). What do you want me to do with it? I opened it and looked at it the first time you posted it. As I said you entered almost every single thing wrong. I can't see the t/s you entered but I'm pretty sure you did that wrong too.
Edited by diy speaker guy - 12/10/12 at 9:46pm
post #157 of 302
Thread Starter 
Quote:
Originally Posted by notnyt View Post

And that is why I have a low frequency HPF. with the rest of the levels high, that ULF causes excursion to skyrocket. It IS there.

Of course ulf causes excursion to skyrocket, especially below tuning. All the sims I've posted show that clearly, no one ever said this isn't true. But in this design, it's tuned so low that the drivers will never bottom out before somewhere around 2 hz at the power level simulated, so no need for a hpf.
post #158 of 302
you are seriously twisted. What was entered wrong. I followed protocol just as stated. How did you enter your data?
post #159 of 302
What design are you talking about. You built a square box with a fence post hanging out of it. Not much design there.
post #160 of 302
It is essentially a sealed enclosure.
Edited by robertcharles - 12/10/12 at 9:52pm
post #161 of 302
Quote:
Originally Posted by diy speaker guy View Post

If the sealed system can't achieve the stated goals it isn't the right tool for the job. Simple as that. The stated goal has always been lowest possible frequency at highest possible spl with lowest possible power.

Was this actually stated in this thread? I must've missed it if so. I would argue the "job" is a wasteful one. Either of materials, space or potential depending on how it is looked at. I guess I just don't get the point of gaining a minuscule amount of output in a bandwidth which will likely never be perceivable by increasing the enclosure volume to 3x the size and adding an 8 ft long tube..
post #162 of 302
my kids were doing homework at the time and the files were not saved correctly to the zip file. They are correct now as I saw on the winisd. No one but you is in disagreement here, so maybe you ought to check your graphs. Mine show extreme excursion, Steep rolloff. Extreme port velocity and so on and so on. And if you feed that thing more than a 100 watts down low the driver will go. Guaranteed.
post #163 of 302
Thread Starter 
Quote:
you are seriously twisted. What was entered wrong. I followed protocol just as stated. How did you enter your data?

I entered it correctly. From what I can see you entered power level, tuning, port diameter all wrong and you did not turn on port resonances. Even when I change those your sim still doesn't match mine so you screwed up somewhere else as well, probably t/s entry. Have you noticed that no one has questioned my sims and you are the only one here using WinISD for the first time. What does that tell you? Can you explain why the sims I do in different programs match if I dont' know how to use them?
Quote:
What design are you talking about. You built a square box with a fence post hanging out of it. Not much design there.

I didn't build anything. Are you still not paying attention? When you simulate something, "design" is an appropriate reference.
Quote:
They won't bottom because it is essentially a sealed enclosure

Whatever you say, boss.
post #164 of 302
Oh, and by the way, how do you know that you did not make a tiny mistake entering data? It had to be me. Well, my cabinets came out exactly like I wanted and I have the tune I could get with the most output. No port or radiator will get that low without potential damage. I bought 2 of these drivers because of the bang for the buck. They will not bang that hard.- period. Do you have any experience at all with vented cabinets. I can't see you insulting me when I have never been insulted on this forum before. All of these guys here in the last 2 days are knowledgable and in agreement. They may be wrong, but that is to be determined later, but, since you do not really have any experience one way or another other than a simulator, I say keep simulating and dreaming- it will work out.
post #165 of 302
Thread Starter 
Quote:
Originally Posted by Ricci View Post

Was this actually stated in this thread? I must've missed it if so.

Yup, a few times. Originally the goal was just to discuss the sim in post 1 but that wasn't working (no one was commenting on the sim) so I asked thjs question in post 10.
Quote:
If the goal is to make a sub with the lowest possible FR that extends well over the highest crossover point you would ever need with no ripple (or at least minimal ripple) and no chuffing in a reasonably sized box (Gjallerhorn size at most), with a minimal amount of power, minimal power compression, and get the most spl possible within a low budget, is this a good way to do it or is there something wrong with the simulation?

And I've repeated that goal over and over.
Quote:
I would argue the "job" is a wasteful one. Either of materials, space or potential depending on how it is looked at. I guess I just don't get the point of gaining a minuscule amount of output in a bandwidth which will likely never be perceivable by increasing the enclosure volume to 3x the size and adding an 8 ft long tube..

Thanks for that. You are in complete agreement on that with almost everyone since post 2. Post 137 shows clear gains though. Your opinion is valid

I would argue that you have more subs and amps than anyone could ever need, so I can see why you think this is a bit silly.

I will admit, the price of extra wood offsetting amp cost is an astute observation and very correct, I was wondering when someone was going to bring that up. I have a pile of free wood though so it's not an advantage for me.
Edited by diy speaker guy - 12/10/12 at 10:21pm
post #166 of 302
Thread Starter 
Quote:
Originally Posted by diy speaker guy View Post

Oh, and by the way, how do you know that you did not make a tiny mistake entering data? It had to be me.

That's because I can clearly see several mistakes that you already made in your inputs - almost every input I see is wrong and I can't even see your t/s data, which is likely also wrong. And because my sims closely agree within different programs (within reason, since they are all calculate different things in different ways). And because I've been simulating things very successfully since before you were a member here. And because I simulate stuff for fun all the time, almost daily. And because I'm fairly sure this is the first time you've used WinISD, based on the questions you've asked.

Do you want a longer list or is that enough? Because there are a bunch more reasons but I don't want to be mean...
Edited by diy speaker guy - 12/10/12 at 10:17pm
post #167 of 302
Quote:
Originally Posted by diy speaker guy View Post

I entered it correctly. From what I can see you entered power level, tuning, port diameter all wrong and you did not turn on port resonances. Even when I change those your sim still doesn't match mine so you screwed up somewhere else as well, probably t/s entry. Have you noticed that no one has questioned my sims and you are the only one here using WinISD for the first time. What does that tell you? Can you explain why the sims I do in different programs match if I dont' know how to use them?
I didn't build anything. Are you still not paying attention? When you simulate something, "design" is an appropriate reference.
Whatever you say, boss.

Have you seen this my man. I spent years designing and building these1000 pound monsters. This is a design. Maybe not what everyone wants or needs, but it is a design, It models exactly like it was designed. No questions.And, if I wanted, it could destroy a good portion of my possessions. But, without a HPF, it could destroy itself. The model worked and was proven correct after the testing. 14.4 Hertz tuning as designed. But I did get different results at many points in time due to bugs in the program learning curve of win isd and just plain not paying attention to small things. You might not ever make a mistake, but in this case you need to have a little bit of something that you can show all these guys in order to prove your point. I could not have just been telling you the thing would look the same and get what I got by accident. I knew it and so does everyone else. The port will compress and it will be no benefit and maybe act like a sealed box and get excursion like a sealed and unload like in my excursion graph. Good luck,



Robert

[URL=http://s228.photobucket.com/albums/ee292/robertcharles123/?action=view&current=3.jpg][/URL]

post #168 of 302
Quote:
Originally Posted by diy speaker guy View Post

That's because I can clearly see several mistakes that you already made in your inputs - almost every input I see is wrong and I can't even see your t/s data, which is likely also wrong. And because my sims closely agree within different programs (within reason, since they are all calculate different things in different ways). And because I've been simulating things very successfully since before you were a member here. And because I simulate stuff for fun all the time, almost daily. And because I'm fairly sure this is the first time you've used WinISD, based on the questions you've asked.
Do you want a longer list or is that enough? Because there are a bunch more reasons but I don't want to be mean...

Hey dude,

I guess you are right. I am wrong, Josh is wrong, Scott is wrong, John is wrong, Bosso is wrong, Mark is wrong, and you are right. You have found something. So, I will truly build your box and I am going to test it the best way I know how. Of course, when it fails, you will blame me. Maybe I will let Josh measure it. I think Josh might be able to be pursuaded to do that for me. Would you believe him if it did not work. Oh, maybe not because he does not have the expertise at measuring port velocity. It might be a great sealed box but 2 Hertz-never.
post #169 of 302
Thread Starter 
I don't think anybody (including all the guys you listed) think this design won't perform as simulated, within reason. Except you. (and maybe Scott) But no one thinks the compromises are worth it, which is a fair and valid opinion.

On one hand I appreciate your misguided attempts to show me how to use WinISD and explain basic acoustic theory to me but on the other hand you are way out of your depth here.

I've wasted almost 2 full days talking to you. No more, ok? I don't care if it's rude to ignore you. It will bother me for awhile but I'll get over it. If this forum has an "ignore" feature I'm putting you on it. If not I'm just not going to read any more of your posts. I simply can't waste any more time on this and you clearly aren't learning anything.

Just be aware that my lack of responses to you in no way means I agree with anything you say.
Edited by diy speaker guy - 12/10/12 at 11:04pm
post #170 of 302
My 2 cents.

Can the concept of a box tuned to 2Hz in order to reduce xmax as you approach that low frequency work? Yes.
Is it worth building? No.
If I wanted to build it just for the heck of it, what would I change? Larger Diameter Port.

Why? Because of port compression.

from the graphs posted it looks like the design acts as a sealed box above 20Hz so for the real world this design may not get you what you are looking for tuned that low.
tuned to 10? might look better, would have to check the graphs to find out.

bottom line is port compression do to air speed is your enemy in all ported designs and you need something like flare it to help with selecting port sizes.
post #171 of 302
Thread Starter 
Quote:
Originally Posted by javi404 View Post

bottom line is port compression do to air speed is your enemy in all ported designs and you need something like flare it to help with selecting port sizes.
.

Showed Flare It results a few pages ago. 10 m/s is the core velocity limit for the vent diameter and the design as shown doesn't pass that until below 5 hz. No compression problem until well below all my supporting electronics are rolling off hard, IOW no compression problem at all.

All ported boxes operate similar to sealed several octaves above tuning, that's not unique to this design.

You could enlarge the port while keeping the same tuning, or tune to 10 hz but either option is going to require a massive port. The entire point of sharing this excercise was to point out that you can use a massively undersized port if you tune low enough that the problems are all outside the usable bandwidth. You might not like this idea (no one else does either) but the simulations show it should work fine.
post #172 of 302
Thread Starter 
Just to let everyone know, this conversation has frustrated me to the point that looking at a pic of these drivers now makes me feel physically ill so I don't think I'll be buying them at all for any purpose. So thanks for that. You (collectively) have raised my blood pressure quite a bit but saved me a bunch of money at the same time. To be clear though, this is not an admission that there is anything wrong with the design as presented in post 1.
post #173 of 302
hi again.

from collo's experimental port site and built into flareit, we know that ports go turbulent (i.e. completely fail to any longer act like ports) when the air speed in m/s is 5 times the port diameter in inches. in this case, that is 10 m/s.

i have attached your simulation with red dashed lines matching up the 10 m/s air speed to the three charts.

in the bottom chart, 10 m/s occurs at 7hz.

moving up to the middle chart, 7hz is right where the port is expected to help lower cone motion. but because below 7hz, the port will completely go turbulent and completely fail, the cone motion will just proceed up as though it were a sealed cab. so no benefit there.

moving to the top chart. again, the port provides less than 1db of gain above 7hz and because the port will completely fail below 7hz, there will be no spl advantage there.

so overall, no advantage to either spl or cone motion vs. sealed.



.....

noah, by transition frequency, i meant the point where the air transitions from behaving like a compressible gas to more like an incompressible gas. that is the only thought that i had on why there would be a cutoff frequency where turbulence is no longer a function of frequency in the port.
Edited by LTD02 - 12/11/12 at 3:54am
post #174 of 302
it might be interesting to send the guy who developed that software a note to include an algorithm that transitions the model from ported to sealed in the simulation when the port air velocity exceeds the critical threshold of complete turbulence, not just chuffing, but complete turbulent overload.

thiele and small did not include exceeding port turbulence thresholds in their equations.

i hope i'm not increasing anybody's blood pressure. it was an interesting idea and discussion.
post #175 of 302
Quote:
Originally Posted by LTD02 View Post

hi again.
from collo's experimental port site and built into flareit, we know that ports go turbulent (i.e. completely fail to any longer act like ports) when the air speed in m/s is 5 times the port diameter in inches. in this case, that is 10 m/s.
i have attached your simulation with red dashed lines matching up the 10 m/s air speed to the three charts.
in the bottom chart, 10 m/s occurs at 7hz.
moving up to the middle chart, 7hz is right where the port is expected to help lower cone motion. but because below 7hz, the port will completely go turbulent and completely fail, the cone motion will just proceed up as though it were a sealed cab. so no benefit there.
moving to the top chart. again, the port provides less than 1db of gain above 7hz and because the port will completely fail below 7hz, there will be no spl advantage there.
so overall, no advantage to either spl or cone motion vs. sealed.

.....
.

Exactly what I've been saying. Cut everything below 7Hz and look at what is left. Virtually no difference at all.

The gains in the simulation are not really there at high power because the 2" vent can't cope without compressing and going turbulent. What you might gain is what is shown above 7Hz which is next to nothing.
post #176 of 302
Quote:
Originally Posted by diy speaker guy View Post

Please reread post 1, especially the simulations. This design does not effectively eliminate any useful gain from the port. It wastes a lot down low, but above 3 hz or so and up until 10 hz the port is contributing significantly...Do you have any specific questions?

It's already been covered, but all I am asking is why tune so low, when you can tune an octave or more higher and get a lot more benefit from the port, without "wasting" as much. Efficiency is what you're going for, so why not increase your efficiency and tune to 5, 6, or 7hz?

I'm not gonna ask a 5yr old to help me move, I'll ask a 20yr old to get more benefit/help from them. Same with the port, I'll tune a little higher to get more benefit/help from it.
post #177 of 302
Quote:
Originally Posted by diy speaker guy View Post

Post 137 shows clear gains though.

They are not real though. Simulations are only as good as the data entered and the complexity allowed. At 1w or maybe 10w the simulation would be valid. At the maximum power levels and frequencies used the port will not produce the output shown. There is no possibility. Even 8 and 10" heavily flared ports with 15 to 20x the area compress a little at the air speeds shown.
Quote:
Originally Posted by diy speaker guy View Post

Your opinion is valid
I would argue that you have more subs and amps than anyone could ever need, so I can see why you think this is a bit silly.
I will admit, the price of extra wood offsetting amp cost is an astute observation and very correct, I was wondering when someone was going to bring that up. I have a pile of free wood though so it's not an advantage for me.

I'm not arguing against being frugal and getting the most out of your money. This just isn't the way to do it IMHO. If you are going to make room for extra large enclosures and pay more for the materials. (Yes I understand that you have free wood, but not everyone does.) don't you want a return on investment from that? For a moment let's assume that the 2" port somehow can produce it's contribution without issue and all of the gains in the simulation are still there at full volume. Do you think it would give a better experience than a simple sealed system? Would you be able to tell under blind circumstances if someone plugged the port? Keep in mind all of your gains are below 7Hz. I am confident you would never be able to tell a difference. If you cannot then what are the big enclosures and ports for?

If I had free wood and wanted to get maximum potential out of a couple of drivers on the cheap I would forget about everything below 10Hz right at the outset.
post #178 of 302
Indeed they are, which is why I have ascertained that a 2,000 foot long, 22" wide vent tube would be sufficient to tune a large (300 liter) box to 2hz, using a typical 18" driver... with zero port-related issues. It would need to be an external port and feature a 180-degree bend, so it vents right next to the woofer itself instead of three or four blocks away. Makes sense because the wavelength of a 2hz tone is 562 feet.
Quote:
Originally Posted by Ricci View Post

They are not real though. Simulations are only as good as the data entered and the complexity allowed. At 1w or maybe 10w the simulation would be valid. At the maximum power levels and frequencies used the port will not produce the output shown. There is no possibility. Even 8 and 10" heavily flared ports with 15 to 20x the area compress a little at the air speeds shown.

Edited by imagic - 12/11/12 at 10:00am
post #179 of 302
Well they told Christopher Columbus that the world was flat, and the Wright Brothers that they would never fly, so OP, if you truly believe in your simulations (and clearly you do, even when very knowledgeable people tell you that it is waste of time) I say build it and prove them wrong if you are that confident.

Nothing ventured, nothing gained.
post #180 of 302
Quote:
Originally Posted by ack_bk View Post

Well they told Christopher Columbus that the world was flat, and the Wright Brothers that they would never fly...
Because clearly this is on par with those two discoveries / inventions. wink.gif
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