Hi All_1, that looks great. Did you use Hornresp to come up with this design?
Some FEM simulations are in this case only interesting to see if we can use this for example for the effect of stacking and/or the effect of the folding of the horn sections. 95 (if not 99%) in this case can be done with Hornresp and in my mind you have taken my Hornresp printscreens as a starting point and did go from there (iterating between Hornresp and 3D), but I don't know if we are on the same page 🙂.
Some FEM simulations are in this case only interesting to see if we can use this for example for the effect of stacking and/or the effect of the folding of the horn sections. 95 (if not 99%) in this case can be done with Hornresp and in my mind you have taken my Hornresp printscreens as a starting point and did go from there (iterating between Hornresp and 3D), but I don't know if we are on the same page 🙂.
I used hornresp for approximate design, since I am not 100% sure how to correctly input completely accurate parameters in 3d model to hornresp (because of folding and corners). I used path lenghts from centre of segments and then calculate areas with formula (71.6cm x other dimension), it should be quite close, will post hornresp data asap. For start I used yours and welter's input screens, didnt match it completely (lenghts and area of horn segments), but got similar response
Yes, as I said, I want to get 3d model right first, then will start building it and make measurements in large open space. I have CNC available so it should not be a problem. Will keep thread updated with progress and then share final plans with community. Primarly looking for support and advice from experienced horn designers since it's a quite complicated and large design.
I don't know if the compression ratio at the throat is too much for this driver: Sd / S1 = 4.23.
- Maybe others know what maximum ratio makes sense for a high-output (and robust) subwoofer using this driver.
- It could be the 'real' S1 value is a bit higher due to the front chamber volume.
I believe realistic S1 is quite a bit higher as driver is mounted on 18mm thick plywood and center of driver is located about 240mm offset from S1, weltersys used even lower value than me for S1. Sw115 is definitely a very robust driver from my experience.
Looks very similar to my result - simulation without offset
Do you think there is room for improvement?
What do you think about compression ratio?
Do you think there is room for improvement?
What do you think about compression ratio?
Compare it to this, an 18" in a DSL box with a 22.5" exterior height:
The high powered BC 18" can take pretty high compression ratios..
Do we know the height of S2 in the DSL enclosure? I'm quite sure TD used an offset driver model to create that enclosure.
For modeling purposes, 21" would be the interior width.
For modeling purposes, 21" would be the interior width.
I would change the Hornresp model now to Offset Driver (OD) as well and try to mimic the start of the horn section of the DSL sub, since the performance benefits from a high compression ratio.
Unfortunately you have to divide your horn sections again because the first section is used for the offset part.
The frontal chamber volume of 3000cc is a rough estimate (don't know how I came up with it 🙂 ), but it's wise to check/calculate that ...
Unfortunately you have to divide your horn sections again because the first section is used for the offset part.
The frontal chamber volume of 3000cc is a rough estimate (don't know how I came up with it 🙂 ), but it's wise to check/calculate that ...
In most of my models,
Ltc = Sd
and
Vtc = Sd x 1.905cm (0.75in).
Those numbers represent the driver's mounting panel.
Ltc = Sd
and
Vtc = Sd x 1.905cm (0.75in).
Those numbers represent the driver's mounting panel.
When I take a closer look at your current design, the compression ratio probably already equals that from the DSL sub (more or less)?
If BP1Fanatic and you come to the same result, there is maybe some finetuning left, but this is what you can achieve in this size of enclosure.
If BP1Fanatic and you come to the same result, there is maybe some finetuning left, but this is what you can achieve in this size of enclosure.
The BC218 has a 30" exterior dimension, the height of S2 is 28.5".
The mouth exit areas appear to have laminated the plywood to 1.5".
21" wide by 28.5" high is a HUGE S2!
S2 = 3,861.28cm2...that can't be right unless you are stating that S2 equals the mouth.
I'm referring to S2 being the middle of the driver in an offset driver model.
S2 = 3,861.28cm2...that can't be right unless you are stating that S2 equals the mouth.
I'm referring to S2 being the middle of the driver in an offset driver model.