Triticum Agricolam

Criminally minded people displaying criminal behavior, nothing too surprising. Just imagine what it will be like when the zombie apocalypse comes and these people no longer have their lives supported by the government. Thats going to be an interesting time.

Nice! Glad you got it back!

Have you modeled your enclosure in something like WinISD to see what port velocity you might be getting?

Be sure to get the newest version of WinISD (version 0.7.0.900) its much better. You can get it here: http://www.linearteam.org/download/winisd-07x.exe When you try to enter in the T/S parameters of your sub, you will have a lot better results if you do it this way: 1. Enter Mms and Cms This gives fs. If either is not available, then enter fs and other parameter. 2. Enter Sd, Bl and Re Now, you should get all but Qms (and Qts), Vas. Please note that Vas may not match exactly what is specified by manufacturer, because exact value of Vas depends on environmental parameters. See FAQ. 3. Enter Rms or Qms. Either one will do, although I tend to prefer Qms over Rms, because it can usually be measured in driver measurement procedures. 4. Enter Hc, Hg and Pe. If Hc or Hg or either is available, then enter Xmax and optionally either Hc or Hg if available. 5. Enter number of voicecoils. This procedure is most accurate. Also note that it also calculates true SPL (1W/1m) value. So it might not match the marketing SPL value, which is generally somewhat vague. Not in all cases, though. 6. Correct Znom, if necessary. If there are several voicecoils, then you must be careful when entering parameters in that case, because many manufacturers give Bl in voice coils in series, because it yields double value for Bl against parallel connection. If driver manufacturer gives Qes, Bl and Cms or Mms, then you can check how Bl is specified. For that, you can enter following parameters to calculate Re: Qes, Fs, Mms or Cms and Bl. Connection mode can be changed by changing the combobox selection. The driver editor then converts Bl and Re values accordingly. Equivalently, you can check for Bl by entering: Qes, Fs, Mms or Cms and Re (for desired connection mode). If you enter resistance for parallel connection and get about half of advertised Bl, then you know, that Bl was specified that way. Like in Driver-tab in project window, you'll probably noticed the driver icon in bottom of the driver editor window. you can drag the driver object into some project by just dragging the icon.

If you have the space, more cone area almost always means higher efficiency. I'd use as much as you can properly fit. What makes you think a 4th order band pass (ported boxes are 4th order designs too BTW) is going to get louder than a regular ported box?

Several of my local radio stations boost the bass significantly. I wouldn't be surprised if that's what you are experiencing as well.

LOL, ok. I'm still skeptical and I think your port velocity is going to be too high, but I'm curious to see how your enclosure works out! Keep up the good work with the pictures.

thanks man.. and are you fimiliar with 6th orders? youll see soon enough why it is the way it is;) Yup, in fact I am. I'm just worried you are going to say its that small for "cone control" or something along those lines.

Ain't that the truth!!

Your fabrication skills looks great! It looks like a really fun project. That port looks REALLY small though.

So I'm a little confused by your comment on cone strength, port velocity has no effect on your cone holding together or not.

20 m/s would be more preferable.Of course. The problem I suspect the OP will run into is the balancing act between port area, port length, and tuning. With a low tuning and large port area the port could end up being a mile long, which creates its own problems. Just about every design is compromised in some way. Having a slightly smaller port area will only have a negative effect at max output, which will only be a limited amount of time. If the OP raises the tuning to try to keep the port length reasonable that will effect output at all volume levels.The OP's goals for their system will have to determine just where compromises should be made.

SoundQubed's box recommendations are so generic they are almost useless. It's up to you to decide what frequency response you desire, but in my opinion the 27 Hz tuning looks much more preferable to the 40 Hz one. I would then size your port to be whatever it needs to to keep port velocities under 30 m/sec.

What round port size diameter would you recommend for the 18 to keep port noise down????.... I'll figure out the length when i choose my tuning frequency. Thanks What size box, what tuning, and how much power are you going to put to it? Port noise is a lot more noticeable in a home audio environment vs car audio. You are going to want to make sure your port velocities stay pretty low.

Well, like you said, I'm pretty doubtful there is any merit to what I've seen people do. These same people seem to be very successful in other aspects of their designs and I figured I'd give them the benefit of the doubt until I have more absolute proof of what's going on. Sysnoise looks like some very interesting software, though I have a feeling it is probably a bit out of my price range.

Thank you for the compliment Sencheezy. Yes, I do know how to model. The issue is its a very difficult question to answer with modeling. While I consider myself to be quite proficient with WinISD and Hornresp, neither of those applications can properly model series-tuned BP boxes. Also neither can account for port compression. I'm in the process of learning to use Akabak and have played around with some series-tuned 6th order BP designs in it, but I don't think it can account for port compression either and I'm not good enough with it yet to get any data out that I trust. I think making the rear port undersized is probably a lot like people's silly assumptions regarding 4th order BP ratios. I understand why those are silly, I want to understand if what people are doing with 6th order BP designs is silly as well.

I have a great interest in the science of box design and I've seen several examples around the 'net of folks building high-power series-tuned 6th order bandpass boxes for SPL purposes. One common design theme seems to be to purposefully undersize the rear port, the reason given is for "cone control". This appears counter-productive to me because the frequency where port velocity will be the highest, and thus having an undersized port will have the most effect (whatever that effect may be), is at the tuning frequency when cone excursion is at a minimum anyway. It seems to me all these guys are doing is making a 6th order bandpass that becomes a 4th order basspass with a leaky rear chamber when they turn the volume up. Basically, I think they are doing it wrong. Does what I'm saying sound reasonable, or am I missing something here? I would love to know exactly what's going on with these boxes. If anyone has, or has a way of getting, a high power impedance sweep from one of these boxes in question that would tell me really quick what's happening. A frequency response curve would be interesting to see as well. I also strongly suspect that these series tuned boxes are not tuned to what the designers intend them to be, but that's another topic. Anyway, I look forward to anyone's input on this. I probably should just build a test box and experiment with it myself, but until I find the time to do so I'd love to hear what folks have to say.

Thanks!

Would you mind posting the specs for your box? Bandpass boxes always pique my interest.

That looks like it took a while to cut out! Looks great!

Was your Zv4 in the same box? Just a thought, but if you are tuned to 22 Hz and aren't playing anything with content that low your amperage draw is going to be less. As you get away from your tuning frequency the impedance rises, while your amp will be putting out the same voltage the amperage will be less. Of course if you are using the same tuning and playing the same music as before you can ignore what I just said.

I see, very clever. So do you use polyester or epoxy resin for doing to kerfed bends then? I've been using polyurethane glue for mine, but I'm not sure whether I really like it for that application or not. BTW, thanks for posting all the pictures. You have definitely been an inspiration to me.

What's the reasoning behind drilling the holes in the kerf slots?

that was actually a mistake its 34hz.. The box was professionally built by a very reputable shop.That still doesn't garuntee it's tuned to 34 Hz. If you have a way to measure the tuning I would suggest you do so.

Welcome to the forum!