You can see right on the graph that you posted that the graph is showing velocity at the cone. Radiator (net) Diaphragm. Nobody cares what the velocity is at the cone.
Check velocity at the port exit - Radiator (net) Horn mouth - and you will see a dramatically different number for velocity.
And I imagine you should see a noticeable difference in the response graph when changing Re and Bl.
The port isn't difficult at all. It's trivial to just adjust the port to whatever it needs to be.
If you mean "Why is the port so big?", then yes, it is because of the excursion and high power level, combined with the desire to make the velocity slow enough to not cause problems. A single 4 inch port would cause huge chuffing problems and actually cease to function as a port at the power levels you are contemplating. The box would function more like a badly designed leaky sealed box at high power with a small port.
sorry, I did choose the wrong radiator, no need to be a DICK about it guy. this is a place to learn and I did say I haven't done many OD before, calm down
The numbers in bold are the external dimensions, right? If so, and assuming I did all the conversions and other associated math right, this looks ok. Tuning looks to be around 24 or 25 hz and velocity around 24 m/s. 24 m/s is a bit high but it's an acceptable compromise if that's what you want. If you are going to be burping sine waves at tuning it certainly isn't ideal though. I used the t/s specs from the website (same as before), not the ones on the sheet they sent you.
But remember that these t/s specs are probably not right and the ones on the sheet you have probably aren't either, so garbage in = garbage out. Measured specs would probably indicate a higher q than advertised and lead to a requirement for a larger box to maintain similar response. And inductance and any applicable series resistance (wiring) will change things dramatically.
In other words, based on the limited (and probably incorrect) info we have, this isn't a bad sim. But what you will end up with in reality is anybody's guess. I highly advise measuring the t/s specs before you build anything, and adding a small amount of series resistance to the sim to account for real world conditions. I'd also make sure your amp can put out 2000 watts. If it's a car amp and it says 2000 watts on it, it probably can't. There's no use in simulating power you don't actually have. You can get a reasonable estimate of it's real power by finding out what class of amp it is and what size fuse it comes with.
If this is what you want put up a detailed dimensional drawing so I can make sure I'm reading you 100 percent accurately and I'll post up the updated sim later.
Last edited:
Ok here's the last one I'm trying, using a large flared slot-port to keep noise/velocity tame (i'm done)
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
A flared port is not a bad idea but your design has the port very constricted in the middle there. This could cause turbulence problems in that narrow spot. Akabak can tell you what the velocity is at that point.
Also I don't think it's a good idea to sim the bottom half of the box as Nd with a massive throat chamber. That's a large volume with a significant length and a complex shape and ideally it should be simulated in detail as Od. It's too complex for Hornresp but Akabak or TL.app can do it.
Guys i really appreciate all the trouble you are going through for me. I had no idea that this project would get so complicated. I will do some research and see if i can determine the t/s parameters myself, since these all seem to be wrong. I thought i was getting some quality subs. I have read alot of reviews, and nowhere did i see anyone having any problems porting there boxes. Some were even small boxes. I haven't seen any of these boxes or what kind of ports they used. They just say x cuft tuned at x Hz. I will try this box and see what happens. I will try to study up more on box design. You guys must have been at this for years. Thanks again for all off the help.
Don't trust reviews unless you know the reviewer very well and share a lot of common reference points. Most reviewers of products like this haven't got any idea what they are talking about.
There's nothing wrong with putting big bad woofers in tiny little boxes with small ports. But they will not perform as well as they could if designed properly. Same thing as doing the Big 3 wiring upgrade, performance systems perform better if you give them what they need to do the job.
They t/s parameters aren't necessarily "all wrong" but clearly there are 2 sets provided, some info is not included at all, and some of the info is presented in a confusing way that requires some knowledge to sort out. The more pressing issue is that it's not uncommon for manufacturer's specs to be incorrect and this specific manufacturer seems untrustworthy for a variety of reasons. But it is entirely possible that one of the sets of specs could be accurate. I wouldn't count on it though. Ideally, all drivers should be independently tested before use, not just these specific woofers. But personally I wouldn't do anything with these woofers without testing them.
Here's some specific things to look up. Google "port compression" (this is the major factor in this discussion), and while you're at it you might as well look into "power compression". Search for "how to test t/s parameters" and "ARTA jig" if you don't have lots of money or just look for "woofer tester" if you have some cash to spend. Ask your friends if they have a woofer tester you can borrow. And for boxes like these I would upgrade to a better simulation program. I use Hornresp, MJK's Mathcad worksheets, Akabak and TL.app. You've seen screenshots of 3 of these programs in this thread. They all have specific strengths and weaknesses, all are free except MJK's ($25) and they are all fairly easy to use once you get the hang of it. Akabak has a fairly steep learning curve though.
Last edited:
I don't see the velocity at the pinch point being an issue in the real world, one of my similar project enclosures using an Eminence 4015LF reaches 48.7m/s at the pinch and 21.71m/s at the mouth (sim'd) there is NO port noise in the completed design.
This is my final go (for real this time) I've been sitting here half the day playing with this, if you decide to build it I'm sure you'll be happy with the results.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Def_Const
{
S1 = 635.28e-4; |Horn segment 1 throat area (sq m)
S2 = 899.22e-4; |Horn segment 1 mouth area and horn segment 2 throat area (sq m)
S3 = 819.42e-4; |Horn segment 2 mouth area and horn segment 3 throat area (sq m)
S4 = 635.28e-4; |Horn segment 3 mouth area and horn segment 4 throat area (sq m)
S5 = 702.80e-4; |Horn segment 4 mouth area and horn segment 5 throat area (sq m)
S6 = 708.94e-4; |Horn segment 5 mouth area and horn segment 6 throat area (sq m)
S7 = 687.46e-4; |Horn segment 6 mouth area and horn segment 7 throat area (sq m)
S8 = 650.63e-4; |Horn segment 7 mouth area and horn segment 8 throat area (sq m)
S9 = 297.69e-4; |Horn segment 8 mouth area and horn segment 9 throat area (sq m)
S10 = 570.83e-4; |Horn segment 9 mouth area (sq m)
L12 = 46.60e-2; |Horn segment 1 axial length (m)
L23 = 13.90e-2; |Horn segment 2 axial length (m)
L34 = 30.80e-2; |Horn segment 3 axial length (m)
L45 = 6.70e-2; |Horn segment 4 axial length (m)
L56 = 7.30e-2; |Horn segment 5 axial length (m)
L67 = 11.50e-2; |Horn segment 6 axial length (m)
L78 = 6.90e-2; |Horn segment 7 axial length (m)
L89 = 51.70e-2; |Horn segment 8 axial length (m)
L910 = 48.40e-2; |Horn segment 9 axial length (m)
Sd = 545.00e-4;
}
|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|Network node numbers for this offset driver horn system:
| 0-Voltage-1
| |
| Radiator(1)-5-Driver--Radiator(2)-6-Driver
| | |
| 8-Segment-9-Segment-10-Segment-11-Segment-12-Segment-13-Segment-14-Segment-15-Segment-16-Segment-17-Radiator(3)
|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Def_Driver 'Driver'
Sd=545.00cm2
Bl=8.32Tm
Cms=1.70E-04m/N
Rms=11.31Ns/m
fs=27.77Hz |Mmd = 185.88g not recognised by AkAbak, fs calculated and used instead
Le=0.50mH
Re=1.50ohm
ExpoLe=1
System 'System'
Driver Def='Driver''Driver 1'
Node=1=0=5=10
Driver Def='Driver''Driver 2'
Node=1=0=6=12
Filter 'HP1'
fo=29Hz vo=1
{b4=1;
a4=1; a3=2.613126; a2=3.414214; a1=2.613126; a0=1; }
Radiator 'Diaphragm'
Node=5
SD={Sd}
Label=1
Radiator 'Diaphragm'
Node=6
SD={Sd}
Label=2
Waveguide 'Horn segment 1'
Node=8=9
STh={S1}
SMo={S2}
Len={L12}
Conical
Waveguide 'Horn segment 2'
Node=10=9
STh={S3}
SMo={S2}
Len={L23}
Conical
Waveguide 'Horn segment 3'
Node=11=10
STh={S4}
SMo={S3}
Len={L34}
Conical
Waveguide 'Horn segment 4'
Node=11=12
STh={S4}
SMo={S5}
Len={L45}
Conical
Waveguide 'Horn segment 5'
Node=12=13
STh={S5}
SMo={S6}
Len={L56}
Conical
Waveguide 'Horn segment 6'
Node=14=13
STh={S7}
SMo={S6}
Len={L67}
Conical
Waveguide 'Horn segment 7'
Node=15=14
STh={S8}
SMo={S7}
Len={L78}
Conical
Waveguide 'Horn segment 8'
Node=16=15
STh={S9}
SMo={S8}
Len={L89}
Conical
Waveguide 'Horn segment 9'
Node=16=17
STh={S9}
SMo={S10}
Len={L910}
Conical
Radiator 'Horn mouth'
Node=17
SD={S10}
Label=3
27 m/s at the pinch point shouldn't be a problem.
The only issue here is that you put a high pass filter in there, and if OP doesn't have a hpf it won't work as simmed. What's the velocity at the pinch point and the port exit without the hpf? And why is the hpf so aggressive? Did you use the hpf to control the velocity? It's way more aggressive than you needed to control excursion below tuning. I'd back it off until the excursion peak below tuning is as high as the peak above tuning, there's no need to set it any higher in frequency than that. A hpf set too high erodes spl at and slightly above the tuning frequency.
This does bring up a good point though, designs should be simmed with the hpf in place if one is going to be used. (Mine didn't have a hpf.)
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
One final issue I just noticed.
I can see you are running your sims at 47.43V. OP doesn't have that much power.
OP said he has 2250 watts. 2250 watts into a .75 ohm load is 41.08V.
47.43V would be 3000 watts.
So you could crank that power down 750 watts to reflect the situation better. That will reduce velocity and excursion but unfortunately it will also bring down the spl level in your sims too.
I can see you are running your sims at 47.43V. OP doesn't have that much power.
OP said he has 2250 watts. 2250 watts into a .75 ohm load is 41.08V.
47.43V would be 3000 watts.
So you could crank that power down 750 watts to reflect the situation better. That will reduce velocity and excursion but unfortunately it will also bring down the spl level in your sims too.
The 4th order part is appropriate, the frequency it was set at was not. In your excursion graph in post 32 (graph #17) the excursion peak below tuning was much lower than the one above tuning. That indicates the hpf was set at a higher frequency than necessary. I like the way you did it in post 34 much better (graph #32 specifically).
But like I mentioned, too much power.
Last edited:
You guys are just amazing. It will take me a week just to figure out those charts. Looks like a complicated box to build. I do have a hpf built in. The amp is a powerbass xta2250. It is alot easier to set than my jl audio 500/1. It took me forever to figure out what all of those knobs and switches do. Lol. I will study all of this, its alot for me to take in. Again, thank you for all of your hard work on this.
This isn't splitting splitting hairs. All these details are important.
These drivers are $550 each (MSRP) and wood isn't cheap either. OP is making a significant investment here. If we are going to submit simulations at all I think we have a responsibility to make sure they are as accurate as possible.
here is the design with cut-sheet and diagrams
instagater212
well his amp does not state 0.75 ohm stable, in my experience most people don't sim at the driver RE
I did post the Akabak script, you are more than welcome to change it
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.