See third page for the start of the build.
I just ordered 2x Stereo Integrity HT-18D2's! I haven't finished designing the enclosure yet, but it looks like I'm going to be going as low as 20-25hz and as high as 45-50hz. I was able to get a few bandpass enclosures to do that, but then you cant see the speaker, I want the speaker to be showing. I have 2x dual 15" enclosures for 50-120hz.
(I'm not asking for someone to design a box for me, I'm more of posting my progress. But if you want to post a design that's fine too, I might build it if its good!)
Here are some requirements I have:
A Single 18" box can be no larger than 40w x 25h x 30d.
A Dual 18" box can be no larger than 48w x 25h x 36d.
-3dB frequency response of at least 25-40hz. (the deeper, the better)
2v Sensitivity of at least 95dB for a single 18" (half space)
2v Sensitivity of at least 99dB for a dual 18" (half space)
The front of the speaker showing. (If not possible then I will go with a bandpass)
Tapped horns, transmission lines, and bass reflex enclosures preferred.
I used the these TS Parameters (Measured by Data-Bass)
This is a single SI HT 18 bandpass without worrying about the size:
An externally hosted image should be here but it was not working when we last tested it.
There are more pictures and info in these posts:
See this post for the SID18 (revisions 1-3)
See this post for the SID18 (revision 4-7)
See this post for the SID18 (revision 8)
See this post for the SID18 (revision 9-11) and the unboxing of the SI HT 18 D2's
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Just bought one myself, its going in a 24"x 53"sonotube tuned to 16 hertz. Bandpass you say? Good luck with that. 4th or 6th order? The box and ports have to be exactly right or it will sound terrible. If you can pull off the bandpass, they will be loud as hell. Still a little one note ish though. If you want loud and small above all else.
So I can't get anywhere near of what I want without doing a bandpass enclosure. Here are three bandpass designs I experimented with:
Each box is 40w x 24h x 30d
All three are for a single 18"
It was pretty hard to get low enough at the size limitations I have, even though the box is pretty big already.
From left to right in the picture above, here are the frequency responses:
The 2nd and 3rd design are very close with the response. Tomorrow evening I will be doing a 4th design similar to the 3rd design, but with larger ports. I am happy with the frequency response the 3rd design has. I'm now just trying to add 1.5 dB to it to have a solid 96 db sensitivity at 2v. My goal now is to have ~100 dB sensitivity with 2.838v over both speakers.
Each box is 40w x 24h x 30d
All three are for a single 18"
It was pretty hard to get low enough at the size limitations I have, even though the box is pretty big already.
From left to right in the picture above, here are the frequency responses:
The 2nd and 3rd design are very close with the response. Tomorrow evening I will be doing a 4th design similar to the 3rd design, but with larger ports. I am happy with the frequency response the 3rd design has. I'm now just trying to add 1.5 dB to it to have a solid 96 db sensitivity at 2v. My goal now is to have ~100 dB sensitivity with 2.838v over both speakers.
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Those are 6th order designs. I built a couple of those some years ago. MDF with pvc ports. Automotive applications. Be careful how much power you feed the driver, as unless you have it just right, it will unload the driver and destroy itself. You might not even know its happening until the spider tears off. I had much better success with 4th order boxes. Don't let me discourage you though, it will be really cool if you can get it right.
Thanks for the tips! I should be good until 12 hz at the max power Ill give the driver being that the drive has a 30-35 Xmech.
I tried modeling some 4th order boxes, but I was only getting one peak at the low end and too much of a roll off for 40-50Hz range.
I tried modeling some 4th order boxes, but I was only getting one peak at the low end and too much of a roll off for 40-50Hz range.
Thank you tb46, I wasn't sure how to model a BP in Hornresp. I was trying to model bandpass enclosures in Hornresp last night but I couldn't get it right, so I stuck with the Transmission Line software. I will try some more 4th order enclosures tonight. Can you do 6th order bandpass in Hornresp too? Is that what the Ap1 and Lpt is for?
I'm glad you bring this up bjorno. I was about to post about some of the data on the HT18. First, in reply to your findings, Data-bass addressed that there might be a difference in their data:
"SI did mention that this was their production prototype driver and as such it has been beat on and broken in thoroughly so the suspension may be just a hair looser than normal."
My questions on their data concerned the RMS rating. According to Data-Bass the 600w power rating is because of Xmech:
"Indeed Stereo Integrity confirms that the power rating for this driver is based on the mechanical overload not what the coil will handle thermally. They recommend 600w and no more for this driver. The very compliant suspension results in little power being needed to move the driver to full stroke. SI's recommendations for this woofer make sense in light of this and the driver will not make much use of more than 5 or 600w of power without getting into trouble. Depending upon the particular enclosure design more power could possibly be used but careful measurement and simulation would be needed to assess the wisdom of applying more power."
Data-Bass also verifies the Xmech:
"Xmech effectively seems to be closer to 30 or 35mm inward. This was confirmed by pressing in on the cone to the point where the coil touches the back plate."
Being that X-max is only 11.5mm at 30 hz (I will use a 48dB 25hz HPF to avoid the High excursion at low freq.) I wounder what the true RMS of the coil is.
I'm glad you bring this up bjorno. I was about to post about some of the data on the HT18. First, in reply to your findings, Data-bass addressed that there might be a difference in their data:
"SI did mention that this was their production prototype driver and as such it has been beat on and broken in thoroughly so the suspension may be just a hair looser than normal."
My questions on their data concerned the RMS rating. According to Data-Bass the 600w power rating is because of Xmech:
"Indeed Stereo Integrity confirms that the power rating for this driver is based on the mechanical overload not what the coil will handle thermally. They recommend 600w and no more for this driver. The very compliant suspension results in little power being needed to move the driver to full stroke. SI's recommendations for this woofer make sense in light of this and the driver will not make much use of more than 5 or 600w of power without getting into trouble. Depending upon the particular enclosure design more power could possibly be used but careful measurement and simulation would be needed to assess the wisdom of applying more power."
Data-Bass also verifies the Xmech:
"Xmech effectively seems to be closer to 30 or 35mm inward. This was confirmed by pressing in on the cone to the point where the coil touches the back plate."
Being that X-max is only 11.5mm at 30 hz (I will use a 48dB 25hz HPF to avoid the High excursion at low freq.) I wounder what the true RMS of the coil is.
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Oliver's BP6 design example can also be modelled in Hornresp as a compound horn - see attachment.
Kind regards,
David
Attachments
Hi David,
Thanks. Yes, I've simulated it both ways. Another neat thing one can do w/ the BP4 is to simulate a nozzle port. Or, maybe something close to the Polk power port. Now, if one could add a little lossyness to that, that would be even nicer. 🙂
Regards,
Thanks. Yes, I've simulated it both ways. Another neat thing one can do w/ the BP4 is to simulate a nozzle port. Or, maybe something close to the Polk power port. Now, if one could add a little lossyness to that, that would be even nicer. 🙂
Regards,
Attachments
Hi David, tb46, and bjorno,
Thanks for the suggestions! It helped me get to my final decision, and helped me model it in Hornresp. bjorno, that is an impressive design! Solid to 16 hz, that would be perfect for an organ. Speaking of frequencies, I listened to about 50 of my Dubstep/Trap/Electro House songs while watching the spectrum analysis. I realized it wasn't as important to get under 30Hz as I thought it was. I knew 20-30Hz wasn't used much, but at first I figured I'd try and get a box that could do it anyways. I decided getting +3 db from 30hz and up was more important then getting down to 25Hz or lower. Also I forgot to add that the final subs will be kept in an 8th space. (Concert walls and floor.)
Sorry I haven't posted in a few days, here's what I've been up to:
The last design (on the right) is the design I'm going with. I still need to tweak the design a little to fit a 36" x 24" grill and recess the speaker 2". With that being said here is the final-ish design specs (some will change slightly):
Name ..................... SI-Descent 18 (SID18)
Driver ................... SI HT 18 D2
Intended use ............. 2xSID18's - Eighth space - Wired at 2 ohms
Half space -3dB .......... 30-85 Hz
Half space 2v/1m ......... 96dB
Intended use -3dB ........ 26.5-75 Hz
Intended use 2v/1m ....... 113dB
Intended use 50v/1m ...... 141db
Size ..................... 37.5"W x 25"H x 37.5"D (after grill mod)
Weight ................... ~200lb
Note the peak in the picture above and how it's evened out after using 2x SID18's and corner loading them.
Thanks for the suggestions! It helped me get to my final decision, and helped me model it in Hornresp. bjorno, that is an impressive design! Solid to 16 hz, that would be perfect for an organ. Speaking of frequencies, I listened to about 50 of my Dubstep/Trap/Electro House songs while watching the spectrum analysis. I realized it wasn't as important to get under 30Hz as I thought it was. I knew 20-30Hz wasn't used much, but at first I figured I'd try and get a box that could do it anyways. I decided getting +3 db from 30hz and up was more important then getting down to 25Hz or lower. Also I forgot to add that the final subs will be kept in an 8th space. (Concert walls and floor.)
Sorry I haven't posted in a few days, here's what I've been up to:
The last design (on the right) is the design I'm going with. I still need to tweak the design a little to fit a 36" x 24" grill and recess the speaker 2". With that being said here is the final-ish design specs (some will change slightly):
Name ..................... SI-Descent 18 (SID18)
Driver ................... SI HT 18 D2
Intended use ............. 2xSID18's - Eighth space - Wired at 2 ohms
Half space -3dB .......... 30-85 Hz
Half space 2v/1m ......... 96dB
Intended use -3dB ........ 26.5-75 Hz
Intended use 2v/1m ....... 113dB
Intended use 50v/1m ...... 141db
Size ..................... 37.5"W x 25"H x 37.5"D (after grill mod)
Weight ................... ~200lb
Note the peak in the picture above and how it's evened out after using 2x SID18's and corner loading them.
Hi Oliver,
Absorbent material can be specified in offset driver and tapped horns. It would get very complicated trying to extend the functionality to other speaker types.
Kind regards,
David
Post #17
Hi David,
I figured as much, it's just one of those things that keeps rattling through my empty head. You do such a great job of improving, and updating your software, so thanks, and no complaints from here. 🙂
Regards,
Hi David,
I figured as much, it's just one of those things that keeps rattling through my empty head. You do such a great job of improving, and updating your software, so thanks, and no complaints from here. 🙂
Regards,
Hi Oliver,
I will have a closer look at what would be required to extend the functionality to other speaker types, but I am not promising anything at this stage...
Kind regards,
David
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