Mini Earthquake - An 8" Cube of Bass
Some great questions. The one issue with Passive Radiators in WinISD is that it does not predetermine box size or weight for optimal tuning. You really need to mess around with the box size and weights on the passive radiator to figure that out. I notice you are using a woofer, versus a subwoofer. IS this for a speaker project? Or is this to be used as a subwoofer? If this is to be used as a subwoofer, you would be better off to try a different driver. Why don't you give us some ideas of what you are trying to do, so we can better help.
Thanx for your reply!!!
I am trying to build a 2.1 system to connect to my DAW for music production.
I like your idea of using the Lepai LP210PA amp and am trying to incorporate that into my build.
I want to use your design with some slightly larger drivers.
I did not see that there was a difference between this woofer and a similar subwoofer.
I see that I should probably use the Dayton Audio DCS165-4 instead.
Here are the specs for the subwoofer:
Fs 35.7 Hz
Re 3.4 Ohms
Le 1.43 mH
Vas 0.42 ft.³
Cms 0.5 mm/N
BL 9.15 Tm
Xmax 6 mm
Sd 124.7 cm²
I want to insure that I have a system capable of recreating what ever bass response I may use in music production. This is the main and only reason I wanted to use slightly larger drivers. I have no other reason for deviating from your original Mini Earthquake design, which is VERY impressive, BTW!!!
I would like to become more comfortable using WinISD, so I have a bunch of questions that I have yet to find answers to using google:
When I plug all the parameters into WinISD using your initial box volume, on the Box page I see a set Fh value of 87.29 Hz (I understand that with a sealed enclosure this value can be changed by adjusting the enclosure volume or adding weight to the PRs). What does Fh represent (resonant/tuning frequency of the enclosure maybe)? How does this value relate/compare to the F3 value (I come up with and F3 of 72.05 Hz)? Should they be close? Should I try to get them to be the same? I have heard that for deep musical bass response I should tune the box just above the Fs of the subwoofer. Is this correct?
Another question: from what I am seeing after researching online, enclosure volume does not seem to be that important as long as the enclosure is larger than what is considered the 'recommended volume' for the driver diameter. Is this correct?
A few more questions: After plugging in all the parameters and initially using the volume of your design (.198 ft.³ or 5.6 L), the Transfer Function Magnitude graph jumps well above the top of the graph. When I double the volume (.396 ft.³ or 11.21 L) the graph is now on the chart, Fh drops to 64.54 Hz and F3 drops to 55.37 Hz. Is this a good thing? Should I consider increasing the volume even more?
Last question: if I add any weight on the PR tab of WinISD, am I adding that same amount of weight to both radiators?
Sorry for all the questions.
Again, thanx for any and all assistance with this!!!
A couple basic things to note. First just because a subwoofer is bigger, doesn't mean it will go lower. Second, a passive radiator system acts like a ported system. So if you are modeling a sealed cabinet, that will not be accurate. I went ahead and modeled a PR (green), port (red) and sealed (blue) with that subwoofer to show you what I mean.
As you can see using two of the DS175-pr it will only have an f3 of 42hz. However, it will probably be louder and you might make some of the extension up with room gain. Is this closer to what you are looking for?
Yes! Thank you!!!
I created a model using the DCS165-4 with an enclosure volume of .355 (internal volume of a 10 inch cube made with 3/4 MDF) and two DSA175-PR radiators with 40g of weight (I am assuming 40g weight on each PR).
I got an F3 of 42 Hz, and an Fh of 45 Hz.
I found a bunch of your WinISD tutorials on YT and they answered a bunch of my questions.
Still have two more:
1. I used 60 watts as the system input power on the Signal page, as the Lepai amp has 60 watt output to the sub. Is this okay to do?
2. When I check Cone Excursion (PR) for this model, the line peaks above my radiator Xmax. I read that I could actually exceed Xmax by no more than 10%. My model peaks at about 8.6mm at about 40 Hz. Moving towards the lower frequencies the peak decreases a little, then increases up to just over 9mm at 10 Hz.
Would this be an issue?
I also created another model using same sub driver and same enclosure, but with two DCS215-PR 8" radiators.
I got an F3 of 40 Hz, and an Fh of 43 Hz using 50g of weight, with no excursion issues.
I want to take time to thank you again for indulging my effort, here. I know you are busy and I am asking a lot of n00b questions, so...
Hello! New here. Would you recommend this design or your cube-cube for a desktop setup paired with Overnight Sensations and the 2.1 Arylic amp you reviewed recently? This will mostly be to fill out the low end for moderate near-field listening, but I definitely want something that can kick when the housemate leaves and I can crank up my bass-heavy electronic music!
If you would recommend the former... Any 2021 updates you would make to that design? I can definitely spend more on the driver since I'll be using the 2.1 amp in place of the low-pass and plate amp.
Sources are FLAC/Spotify from Laptop > Schiit Modi Multibit or a vintage philips TT > Parks Audio Puffin.
Side note: how will the OS's sound with the Arylic 2.1? I'm coming from a '79 Vintage JVC integrated I found at goodwill for $20 ( removed link ) does a fine job but I think the OS's will benefit from some new components feeding them. Some of the caps were looking pretty bulgy the last time I had it open.
Thanks! Great channel. I've got a whole list of DIY projects in the pipeline now, starting with getting the amp and building a sub!
Honestly, this should probably be a separate topic. But I'll try to answer it. If you have more questions, it would be better to start a new topic and tag me in it.
Having said that, the mini earthquake is great for it's size, but it is still limited in it's size. IF it was me, I would go with the cube cubed. I am not sure, what all I will design for 2021, yet. I will probably do some passive radiator builds, but I haven't decided yet.