70liter is net volume
remember to ad driver and port volume
further...
not very much below 70liter will result in a much faster roll off
not much space for errors, and just the bracing could cause that
so I would suggest to go safe, and increase to maybe 80liter nettto volume, and use one 4" port
maybe make it an inch or two longer
if you want it bigger, and longer, maybe a slot port would work better
tinitus
net volume, got it
i can make it up to 100L net.
why make it an inch or two longer? it will lower my tuning and highten my port speed.
80L-28hz- 16,5m/s
100L- 28hz- 19,5m/s
i'd rather avoid slotports to be able to easilie change tuning if nessesary.
best regards
panduro
net volume, got it
i can make it up to 100L net.
why make it an inch or two longer? it will lower my tuning and highten my port speed.
80L-28hz- 16,5m/s
100L- 28hz- 19,5m/s
i'd rather avoid slotports to be able to easilie change tuning if nessesary.
best regards
panduro
Matt
For a flare it's best to have one where the curve is a similar radius to the port- does that mean 4" "out" and 4" up?
they will be used mostly for ht duty- 5db below reference level.
slightly smaller😀?
flaring both indside and outside, got it.
best regards
panduro
For a flare it's best to have one where the curve is a similar radius to the port- does that mean 4" "out" and 4" up?
they will be used mostly for ht duty- 5db below reference level.
slightly smaller😀?
flaring both indside and outside, got it.
best regards
panduro
oscar, yes I need it, but im at a very basic stage right now 🙂
done, running winisd pro now,
question: how much sound "escapes/leakes out" via the port, above the frequency range where there is port gain and therefore alot of port speed?
question two: winisd pro- rear port gain
cant find nothing about it in the help files.
what can i learn of that graph?
My sim tells me: 10hz -16db, 30hz -4db, 170hz -30db
isnt gain suppose to be positive an not negative?
best regards
panduro
done, running winisd pro now,
question: how much sound "escapes/leakes out" via the port, above the frequency range where there is port gain and therefore alot of port speed?
question two: winisd pro- rear port gain
cant find nothing about it in the help files.
what can i learn of that graph?
My sim tells me: 10hz -16db, 30hz -4db, 170hz -30db
isnt gain suppose to be positive an not negative?
best regards
panduro
I don't know where you got the idea that gain cannot be negative. It's like asking "isn't acceleration only supposed to be positive and not negative". Well in physics you quickly learn that there is negative acceleration (deceleration). Same thing with gain, although I don't know if there is a word for it.
Rear port gain is exactly that. Normalized gain (referenced from 0) from the port that connects the rear of the woofer (chamber) to the outside atmosphere.
You may say that you're at a very basic stage right now, but you're not asking "very basic" questions" because the answers to them require modeling/simulation via computer programs. If you want your knowledge to transition from "very basic" to "intermediate", then you need to simulate many many different scenarios and then build and test them to verify the predictions.
Rear port gain is exactly that. Normalized gain (referenced from 0) from the port that connects the rear of the woofer (chamber) to the outside atmosphere.
You may say that you're at a very basic stage right now, but you're not asking "very basic" questions" because the answers to them require modeling/simulation via computer programs. If you want your knowledge to transition from "very basic" to "intermediate", then you need to simulate many many different scenarios and then build and test them to verify the predictions.
Hi all,
of observations:
If the subs are to be XO'd using LR4 at 150 Hz with no localization cues or phantom spreading down to the floor:
I recommend a stuffed OD_ML-TL with a non-stuffed port that do not contribute to easy heard artifacts, i.e. avoiding simple BR boxes with long resonant ports as stands for mains or for stand alone subs.
b🙂
of observations:If the subs are to be XO'd using LR4 at 150 Hz with no localization cues or phantom spreading down to the floor:
I recommend a stuffed OD_ML-TL with a non-stuffed port that do not contribute to easy heard artifacts, i.e. avoiding simple BR boxes with long resonant ports as stands for mains or for stand alone subs.
b🙂
Attachments
OscarS,
i do realize that gain can be negative, this was in the sense that i thought that the port is suppose to give me a +3gaig compared to a sealed enclosure.
thought it was a bad tuning choice that gave me the negative gain. if I tuned the box to 47hz i would get my "promised" gain....
hmm maybe ill understand the rear gain concept later on.
dammit LoL, dont have the time or money to build all those sims🙂.
tinitus,
ill give that some thought to find out if it possible in my design.
Bjorno,
i would very much like to stay vented right know, more than enoughf i dont know about that yet, and theres nothing i know about tl speakers...
my "complete" subwoofer setup wil be 3 12" main subwoofers(acting like one) between the front speakers, one 10" or 12" ported subwoofer in the rear corner and a small sealed 12" subwoofer behind the seating area.
Hopefully i can integrate the subs seamlesly a bit lower than 150hz, the fronts have a -3db at 95hz and a gradual rollof.
can you post a link to pictures of a similar design as i dont really get get the concept?
best regards panduro and thanks for all the answers
i do realize that gain can be negative, this was in the sense that i thought that the port is suppose to give me a +3gaig compared to a sealed enclosure.
thought it was a bad tuning choice that gave me the negative gain. if I tuned the box to 47hz i would get my "promised" gain....
hmm maybe ill understand the rear gain concept later on.
dammit LoL, dont have the time or money to build all those sims🙂.
tinitus,
ill give that some thought to find out if it possible in my design.
Bjorno,
i would very much like to stay vented right know, more than enoughf i dont know about that yet, and theres nothing i know about tl speakers...
my "complete" subwoofer setup wil be 3 12" main subwoofers(acting like one) between the front speakers, one 10" or 12" ported subwoofer in the rear corner and a small sealed 12" subwoofer behind the seating area.
Hopefully i can integrate the subs seamlesly a bit lower than 150hz, the fronts have a -3db at 95hz and a gradual rollof.
can you post a link to pictures of a similar design as i dont really get get the concept?
best regards panduro and thanks for all the answers
vented can give you +3 at tuning but not across the whole bandwidth. It can give more than +3, but +3 was the rule of thumb back in the simple times before easy modeling.
Panduro,
no you don't want a 4"up and 4" out flare that would cause excessive noise at high spl. If you are going with a 4" port diameter a 2" flare radius (meaning a slice of it would look like a 1/4 circle with a radius of 2") is reasonable. your best best if you are heat forming PVC would be to make 2 different "cones" that you could shove the port over while heating it. One would cause the port to slowly taper out from the center of the length and the other would put a short 1" flare at the end. This would be done on the inside and outside of the port. If you could pull that off you would be very please with the result. The minimum cross-section area (pi*r^2) in the center will still accurately predict the tuning if the initial taper is small. Too large of a taper and turbulence occurs in the pipe which is worse than a simple straight port.
-Matt
no you don't want a 4"up and 4" out flare that would cause excessive noise at high spl. If you are going with a 4" port diameter a 2" flare radius (meaning a slice of it would look like a 1/4 circle with a radius of 2") is reasonable. your best best if you are heat forming PVC would be to make 2 different "cones" that you could shove the port over while heating it. One would cause the port to slowly taper out from the center of the length and the other would put a short 1" flare at the end. This would be done on the inside and outside of the port. If you could pull that off you would be very please with the result. The minimum cross-section area (pi*r^2) in the center will still accurately predict the tuning if the initial taper is small. Too large of a taper and turbulence occurs in the pipe which is worse than a simple straight port.
-Matt
- Status
- Not open for further replies.