Hi Lewis,
This is because the fundamental design and architecture of the Transmission Line software is quite different to that of Hornresp 🙂.
Kind regards,
David
I thought I finished the final design. But, it will take just over 2 sheets of 4x8 wood, and the slight changes I did raised the f3 to 40hz. It is 3 dB louder, but I definitely need it flat until 35Hz. A good 25% of the songs I have go down that low.
Name ..................... SI-Descent 18 (SID18)
Driver ................... SI HT 18 D2
Intended use ............. 2xSID18's - Eighth space - Wired at 2 ohms
Half space -3dB .......... 39-97 Hz
Half space 2v/1m ......... 99 dB
Intended use -3dB ........ 35-85 Hz
Intended use 2v/1m ....... 116 dB
Intended use 50v/1m ...... 142 dB
Size ..................... 37.5"W x 24"H x 37.5"D
Weight ................... 215 lb
I do like how it looks, but I am going to move the sub to the left and combine the ports to make one. This will lessen the wood needed, and make it easier to make a longer port. At this point I might as well design a tapped horn too.. (don't quote me on that)
Name ..................... SI-Descent 18 (SID18)
Driver ................... SI HT 18 D2
Intended use ............. 2xSID18's - Eighth space - Wired at 2 ohms
Half space -3dB .......... 39-97 Hz
Half space 2v/1m ......... 99 dB
Intended use -3dB ........ 35-85 Hz
Intended use 2v/1m ....... 116 dB
Intended use 50v/1m ...... 142 dB
Size ..................... 37.5"W x 24"H x 37.5"D
Weight ................... 215 lb
I do like how it looks, but I am going to move the sub to the left and combine the ports to make one. This will lessen the wood needed, and make it easier to make a longer port. At this point I might as well design a tapped horn too.. (don't quote me on that)
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.
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Post #19
Hi David,
Thanks for taking a look at it. At the moment it is still difficult to simulate back-loaded horns, it seems that most of them depend on proper placement of damping material for optimization. Looking at the plans for e.g.: the Fostex family of BLH fullrange speakers it is almost comical to which extent anything from lightly fluffed wool to rocks is used to alter the native response of the enclosures.
Anyway, I hope to be able to keep on checking in to follow your program advances. I'm having to take care of a bunch of business, and other problems at the moment (tomorrow it's a bone scan in the Hospital), so I may or may not be around as much as previously during the next few weeks.
Best Regards,
Hi David,
Thanks for taking a look at it. At the moment it is still difficult to simulate back-loaded horns, it seems that most of them depend on proper placement of damping material for optimization. Looking at the plans for e.g.: the Fostex family of BLH fullrange speakers it is almost comical to which extent anything from lightly fluffed wool to rocks is used to alter the native response of the enclosures.
Anyway, I hope to be able to keep on checking in to follow your program advances. I'm having to take care of a bunch of business, and other problems at the moment (tomorrow it's a bone scan in the Hospital), so I may or may not be around as much as previously during the next few weeks.
Best Regards,
Post #23
Hi abcdmku,
I like the looks of your enclosure, but 🙂 , every symmetrical (dual duct) box I have designed uses more wood than an equivalent single duct enclosure.
Regards,
Hi abcdmku,
I like the looks of your enclosure, but 🙂 , every symmetrical (dual duct) box I have designed uses more wood than an equivalent single duct enclosure.
Regards,
I did try a tapped horn, didn't work out too well. I'm not sure what to call the design I ended up doing. It's like a tapped horn or maybe like a scoop, but acts more like a bass reflex. Anyways here are the specs and pictures:
(I've been forgetting to add the revision number in the name)
Name ..................... SI-Descent 18 R11 (SID18-11)
Driver ................... SI HT 18 D2
Intended use ............. 2xSID18's - Eighth space - Wired at 2 ohms
Half space -3dB .......... 27.5-90 Hz
Half space 2v/1m ......... 96dB
Intended use -3dB ........ 25-78 Hz
Intended use 2v/1m ....... 112dB
Intended use 50v/1m ...... 140db
Size ..................... 37.5"W x 25"H x 37.5"D
Weight ................... ~165lb
(I've been forgetting to add the revision number in the name)
Name ..................... SI-Descent 18 R11 (SID18-11)
Driver ................... SI HT 18 D2
Intended use ............. 2xSID18's - Eighth space - Wired at 2 ohms
Half space -3dB .......... 27.5-90 Hz
Half space 2v/1m ......... 96dB
Intended use -3dB ........ 25-78 Hz
Intended use 2v/1m ....... 112dB
Intended use 50v/1m ...... 140db
Size ..................... 37.5"W x 25"H x 37.5"D
Weight ................... ~165lb
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.
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.
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.
Blimey, and I thought WinISD to design a sealed box that suited this driver (I've bought four) was hard enough!
Will be interesting to see the outcome, that is a lot of output if it plays how it models 🙂
Will be interesting to see the outcome, that is a lot of output if it plays how it models 🙂
how do you plan to load these to achieve 8th space? I ask because the curve is a bit more wild in half space.
That is a back loaded horn.
They are similar to a BR but the port is a horn and loads the driver in a different way.
They can go quite low if designed so.
Your coupling chamber is a little oddly shaped with the step from the full driver diameter to maybe half of that, but it is a classic back loaded horn.
Go to quarterwave dot com to learn more about that type of design.
Scroll down to 2nd blue link.
That is Martin J. Kings website, the author of many famous Mathcad design sheets for speaker enclosures.
Dave
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Its capable of almost 5db more output than a similar sized vented box... but the vented will go down to 17 or so hz, and play nicely above 70hz.
MemX - Yeah it took awhile to get it right! I had some help from people on here too as you can see from the previous posts on this thread. Stick around I'll be posting more pictures of the build!
Shadydave - Oh yeah I forgot about back loaded horns, I've read the "Transmission Line and Back Loaded Horn Physics" and "Horn Physics" articles before. I'll need to look into the "Design of a Back Loaded Exponential Horn" article though.
sine143 - I originally was just going to go with a vented box, but I decided I rather have the extra 5dB for 25-70Hz. I don't really need anything lower than 30Hz for music. (95% what I use the subs for) Also, I have 2x dual 15s that will cover 70-120Hz maybe higher.
I plan on using this corner:
Shadydave - Oh yeah I forgot about back loaded horns, I've read the "Transmission Line and Back Loaded Horn Physics" and "Horn Physics" articles before. I'll need to look into the "Design of a Back Loaded Exponential Horn" article though.
sine143 - I originally was just going to go with a vented box, but I decided I rather have the extra 5dB for 25-70Hz. I don't really need anything lower than 30Hz for music. (95% what I use the subs for) Also, I have 2x dual 15s that will cover 70-120Hz maybe higher.
I plan on using this corner:
An externally hosted image should be here but it was not working when we last tested it.
The biggest issue I'm seeing is that the SI 18 doesnt reach xmax till about 90/100 volts at 4 ohms.... where as its voice coil is rated for 600 rms (although as per databass, this rms rating may be more a reference to its mechanical limits in a sealed or vented enclosure), or about 43 volts sustained sine wave. Pushing this thing to xmax (In a horn enclosure, which helps control excursion above fc) above 25hz is potentially to put it DEEEP into power compression, and potentially damage the voice coil, especially if hitting it with 100 volts.
I know you've already built/cut your wood (and made a very nice model for your enclosure, GREAT WORK!), but heres a pair of FLH of similar size (425liters) compared to your BLH, both shown at 90 volts. The BLH does support a lower hipass (21hz 18 db/oct BW filter) vs the FLH pair ( 24hz 18db/oct bw filter), but since both of these are well out of the intended pass band, the result is still similar.
Black is your horn, grey is FLH. both compared in eighth space as per your spec. It likely took me longer to layout the picture in photoshop than it did to make the sim for this (fold is a different matter entirely).
I know you've already built/cut your wood (and made a very nice model for your enclosure, GREAT WORK!), but heres a pair of FLH of similar size (425liters) compared to your BLH, both shown at 90 volts. The BLH does support a lower hipass (21hz 18 db/oct BW filter) vs the FLH pair ( 24hz 18db/oct bw filter), but since both of these are well out of the intended pass band, the result is still similar.
Black is your horn, grey is FLH. both compared in eighth space as per your spec. It likely took me longer to layout the picture in photoshop than it did to make the sim for this (fold is a different matter entirely).
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Lost in Bass - Thanks for the kind words, but no need need to call sine143 a thread hog, I appreciate feedback (if its not signal in my speakers haha!). I am an art major so I like when my stuff is critiqued. It shows people took time to understand where I'm coming from and what I'm going for.
sine143 - I REALLY like that design! Now the question is, can it be folded up nicely in a 37.5 x 37.5 x 24" box 😱? That was the issue I was having with the tapped horn and the SID18-R8. Because the SID18-R7 worked how I wanted but used too much wood and the speaker was sicking out. After I got it to all fit, it didn't perform as I wanted anymore, it works well for a 40Hz BP though! Oh and about the x-max/power rating. You can see the voice coil, they use a good size wire. WAY thicker than the MCM 18s I have which take 50v no problem. (Keep in mind they are 8 ohm) I'll post pictures once I'm done building for the night.
sine143 - I REALLY like that design! Now the question is, can it be folded up nicely in a 37.5 x 37.5 x 24" box 😱? That was the issue I was having with the tapped horn and the SID18-R8. Because the SID18-R7 worked how I wanted but used too much wood and the speaker was sicking out. After I got it to all fit, it didn't perform as I wanted anymore, it works well for a 40Hz BP though! Oh and about the x-max/power rating. You can see the voice coil, they use a good size wire. WAY thicker than the MCM 18s I have which take 50v no problem. (Keep in mind they are 8 ohm) I'll post pictures once I'm done building for the night.
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In that case Al, I think you of all people should appreciate the benefit behind my proposed design. I've double the usable bandwidth, significantly flattened response, flattened phase anomalies (albeit added about 10ms of group delay down around 30hz), picked up almost 15 db of output in your precious "Kick Drum" area, all while maintaining the same net volume, and compromising very little in added excursion.
If kept to 50v (around the RMS value of the driver, and the proposed usage level for OP) it can easily be run without a hipass (with excursion peaking at a mere 17 mm at 25 hz, decreasing below that. It uses a low compression ratio (2.42:1) so little worry of cone damage as well. the only place where it loses ANY output (about .5db) is between 30 and 40hz.
The back loaded horn will require a hipass regardless of the 50v input (no sealed rear chamber for excursion control below Fc), A lot of its smoothness in passband also relies on the smoothing of response when adding more horns to the stack (a phenomenon which IM *pretty* sure only occurs with FLHs, although as modeled with hornresp is attributed to all designs), AND the added smoothness from corner loading.
hell, givin the 50v drive input into the SI, even our little friend the LAB 12 can almost match output down to 30hz in that sized package (FLH) without exceeding xmax (this isnt a shot abcdmku, just a observation).
a single cab, half space comparison is more telling in reference to the above mentioned points (before the lab12 bit).
As far as the fold goes... I dunno. I'm absolute rubbish at it (learning still). Your cad work is actually quite inspirational, you art degree paid off 😀
If kept to 50v (around the RMS value of the driver, and the proposed usage level for OP) it can easily be run without a hipass (with excursion peaking at a mere 17 mm at 25 hz, decreasing below that. It uses a low compression ratio (2.42:1) so little worry of cone damage as well. the only place where it loses ANY output (about .5db) is between 30 and 40hz.
The back loaded horn will require a hipass regardless of the 50v input (no sealed rear chamber for excursion control below Fc), A lot of its smoothness in passband also relies on the smoothing of response when adding more horns to the stack (a phenomenon which IM *pretty* sure only occurs with FLHs, although as modeled with hornresp is attributed to all designs), AND the added smoothness from corner loading.
hell, givin the 50v drive input into the SI, even our little friend the LAB 12 can almost match output down to 30hz in that sized package (FLH) without exceeding xmax (this isnt a shot abcdmku, just a observation).
a single cab, half space comparison is more telling in reference to the above mentioned points (before the lab12 bit).
As far as the fold goes... I dunno. I'm absolute rubbish at it (learning still). Your cad work is actually quite inspirational, you art degree paid off 😀
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IF willing to give up about 1 db of sensitivity below 40hz (which, at this voltage in, can be eqed back considering the gobs of excursion headroom left), and increase compression up to 2.61:1, you can reduce the FLH size to 380 liters, almost a solid 1.5 cubic feet less sim volume.
If you want to take a crack at folding it I'd be stoked to see your results 😉
If you want to take a crack at folding it I'd be stoked to see your results 😉
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