Grimberg, I took a look at your the 7pi frequency response and it looks like you have the mid bass and upper bass covered well so you could look into using a Dayton HE for it's deep bass. Maybe go with a 15" to keep up with your pi speakers.
Since the 7pi is horn loaded you could also look into horn loaded bass, BFM makes some good plans and Speakerhardware has flat packs for them if you don't want to the do all the cuts. One option might be to buy a Eminence Lab12, this driver works well in sealed and vented enclosures and also works in the BFM THT bass horn. You could try the sealed or ported first and if that isn't enough bass, build the horn.
Since the 7pi is horn loaded you could also look into horn loaded bass, BFM makes some good plans and Speakerhardware has flat packs for them if you don't want to the do all the cuts. One option might be to buy a Eminence Lab12, this driver works well in sealed and vented enclosures and also works in the BFM THT bass horn. You could try the sealed or ported first and if that isn't enough bass, build the horn.
I'll try the RSS390HE-22 in a vented box. Can you point me to resources that will help in calculating the box internal volume and port diameter and length? I have read about on-line calculators but have no idea which one is reliable.
Grimberg, I mainly use WinISD and hornresp. WinISD is easier to use, hornresp is for more complex boxes. There are tutorials for both on youtube.
this is the recommended enclosure from Parts Express:
Vented (home theater/music): 5.6 cubic ft. (gross internal, including driver and ports) tuned to 22 Hz, with a 2 x 4” diameter x 30” long flared vent, for an f3 of 22 Hz (may have port chuffing at high output)
I simmed it in WinISD and it looks pretty good. 5cu ft net, 22hz tuneing, F3 22hz, 5"x17" port
Vented (home theater/music): 5.6 cubic ft. (gross internal, including driver and ports) tuned to 22 Hz, with a 2 x 4” diameter x 30” long flared vent, for an f3 of 22 Hz (may have port chuffing at high output)
I simmed it in WinISD and it looks pretty good. 5cu ft net, 22hz tuneing, F3 22hz, 5"x17" port
That is helpful, although I don't know how to fit a 30" vent in a 22.5h x 21w x 20.5d box. Is it OK to bend it at 90 degrees?
thats why I did a 5" x 17" vent in my sim. If you can go straight and keep the end a few inches from a wall, that is best, otherwise a bend is fine
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I had seen that box suggestion in the speaker's Q&A section at parts-express.com and wanted to know how to address the long port issue. I missed the part where you had already resolved it, quite elegantly.
Two of these would be great, really great output for a reasonable size box and should keep up with your coaxial 15's. Some will say you may get chuffing with the 5" vent but I've found that with music it rarely happens and when it does it's so loud it does not matter much. ymmv
I don’t know all the details of your build but…
…is 20-22hz F3 a project goal?
Is smaller vented closure better?
Per PE, The Dayton RSS315HFA-8 12” models to 20hz per Bass Box pro in a vented 4.63 cu ft closure.
It may not match the RSS390HE-22 sensitivity/ efficiency or power handling specs as I have not compared them.
@Shrub0: Does that line up w/your experience or anyone else’s modeling? Asking for me as I have a pair on the way to supplement my towers from about 40hz to cutoff. My towers do very well in-room to the low 30s.
Best to ya, and thanks. Tony
…is 20-22hz F3 a project goal?
Is smaller vented closure better?
Per PE, The Dayton RSS315HFA-8 12” models to 20hz per Bass Box pro in a vented 4.63 cu ft closure.
It may not match the RSS390HE-22 sensitivity/ efficiency or power handling specs as I have not compared them.
@Shrub0: Does that line up w/your experience or anyone else’s modeling? Asking for me as I have a pair on the way to supplement my towers from about 40hz to cutoff. My towers do very well in-room to the low 30s.
Best to ya, and thanks. Tony
After downloading WINISD I created an entry for the Dayton Audio RSS390HE-22. When I tried to use it in a project it failed validation. Can somebody tell me what did I enter wrong?
Isn’t chuffing the equivalent of a resistor limiting output either frequency specific (near cutoff) or overall?
Sorry I neglected in my earlier reply to help those offering advice: my towers are 3-ways & actively XOd
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Did you have a subjective commentary on the bass quality and musicality of the B&C driver? Thanks!
Chuffing is when, due to air moving through the port above a certain speed, the air movement becomes audible.
When designing a speaker with a port, the volume of air is used as resistance on the movement of the cone of the driver. Pressure can be measured in dB or Pascal, where 120dB equals 20 pascal, which is around 0.0029007548 PSI.
So, box volume and port length and size directly cause the air to act as a resistance block, but it will be moved, both out of and into, the box. By varying port size and box size, it changes the speed at which the air moves through the port and whether or not at that speed the air moving is audible. When it is audible, it is called chuffing.
Normally, as a rule of thumb, 17m/s is the threshold commonly strives for at which the air passing is not audible.
I think WinISD uses 15m/s as a maximum air speed. I try to keep my ports <10m/s.
A series tuned bandpass enclosure (BP6S) can get away with a higher speed on the low side port. The high side port should mask the high air speed of the low side port.
A series tuned bandpass enclosure (BP6S) can get away with a higher speed on the low side port. The high side port should mask the high air speed of the low side port.
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To achieve that low of speed, the port would have to be extremely long, if doing a straight port. A way around that would be to, if not choosing a band pass or passive radiator, use flared ports, which can drastically reduce the velocity of the air, allowing for shorter ports while remaining below the audible threshold. How to calculate the effect of a flare can be found from different sources. I've never got the flare function in winisd to work, though. Maybe the version i downloaded or a corruption or something.
But the math to find the effect can be done longhand, so long as you find an equation you trust regarding velocity of air with the flared port.
The B&C is kind of a cross between the Magnum and the Lab. It has pretty good midbass impact and also good deep bass extension and power. However the magnum does better with midbass and the lab with deep bass.
The B&C has a clean and fast decay, I believe partly due to it's dual spiders and high suspension loss.
Invalid link, but here's a comprehensive tutorial that includes how to input driver specs: WinISD – a beginners tutorial | Midwest Audio Club