I think I hit a brick wall and am unable "to see the tree in the forest", as we say in German. Maybe one of you can help me out because I'm still pretty new to designing speakers.
Now when WinISD designing this vented enclosure, I already have my "maximum dimensions" for a cabinet measured out, so I know I already have a maximum of 220L to work with. I'd like to use that volume, but don't have to.
When simulating it with WinISD, I enter the driver and vented enclosure and pick "super boom box" to get a nice bump in down low bass, alright. I enter 220L as my volume and play around with a tuning frequency that I can accept.
After having done this, I move on to the bass reflex ports (I want to try 2 horizontal ports, 46cm wide, which is the internal width of the cabinet, and between 5 and 10cm high). I enter this, and it always shows a "1st port tuning frequency" that's at least up in the 400s or 600s....
(While thinking about it, the ports could also be round and on the backside.Either way is fine, I just thought I'd try something "new")
Now to my questions:
Is the "1st port resonance frequency" the first next frequency that will resonante in the vent, but it the main tuning frequency is still the cabinet's tuning frequency?
Is the tuning frequency of the cabinet a distinct concept from the vent, or does one automatically define the other? Because it seems no matter how much I play around with the vent sizes (and lengths), I will need ridiculously large vents to get down to 50-100Hz, if I want to stay in the ~220L volume region with a tuning frequency between 45 and 50Hz. (f3 always stays ~37, which I'm quite happy with).
I know bigger isn't always better and so I have played around with a "smaller" cabinet size of around 150L as some calculators suggest, but according to WinISD, the vents still need to be crazy huge, like 2x 46cm pipes that are 2m long. Rectangular vents are equally ridiculous.
Long story short: How distinct are the concepts "tuning frequency" and "1st port resonance"? Given a cabinet with a volume of 220L and a tuning frequency of 45-47Hz and an f3 of 37Hz, is it "bad" if WinISD tells me the ports need to be ridiculously large and long if want a 1st port frequency as low as the tuning frequency?
Where did I go around the wrong corner, mentally speaking?
Now when WinISD designing this vented enclosure, I already have my "maximum dimensions" for a cabinet measured out, so I know I already have a maximum of 220L to work with. I'd like to use that volume, but don't have to.
When simulating it with WinISD, I enter the driver and vented enclosure and pick "super boom box" to get a nice bump in down low bass, alright. I enter 220L as my volume and play around with a tuning frequency that I can accept.
After having done this, I move on to the bass reflex ports (I want to try 2 horizontal ports, 46cm wide, which is the internal width of the cabinet, and between 5 and 10cm high). I enter this, and it always shows a "1st port tuning frequency" that's at least up in the 400s or 600s....
No, I wanted to try rectangular vents. My plan was to make the front board of the speaker a little too small, so there will be a gap at the bottom and the top of the speaker. Similar to the image I linked
(While thinking about it, the ports could also be round and on the backside.Either way is fine, I just thought I'd try something "new")Now to my questions:
Is the "1st port resonance frequency" the first next frequency that will resonante in the vent, but it the main tuning frequency is still the cabinet's tuning frequency?
Is the tuning frequency of the cabinet a distinct concept from the vent, or does one automatically define the other? Because it seems no matter how much I play around with the vent sizes (and lengths), I will need ridiculously large vents to get down to 50-100Hz, if I want to stay in the ~220L volume region with a tuning frequency between 45 and 50Hz. (f3 always stays ~37, which I'm quite happy with).
I know bigger isn't always better and so I have played around with a "smaller" cabinet size of around 150L as some calculators suggest, but according to WinISD, the vents still need to be crazy huge, like 2x 46cm pipes that are 2m long. Rectangular vents are equally ridiculous.
Long story short: How distinct are the concepts "tuning frequency" and "1st port resonance"? Given a cabinet with a volume of 220L and a tuning frequency of 45-47Hz and an f3 of 37Hz, is it "bad" if WinISD tells me the ports need to be ridiculously large and long if want a 1st port frequency as low as the tuning frequency?
Where did I go around the wrong corner, mentally speaking?
Last edited:
please forgive the double post but: Did I maybe read too much into it? "1st port resonance frequency" is the next frequency that the port emphasizes, apart from the tuning frequency?
aka the speakers tuning frequency is Stage 0, and Stage 1 is then the next?
You're welcome!
1. I explained why I used 8" dia. here:
2. Seems like I already explained this elsewhere, but no time to search, so.........the room modes, speaker locations can boost the speaker's low end IF it's tuned low enough to couple with them, i.e. room provides some/all of the baffle step loss (BSC) BW.
BB4 aligment table gives 155 liter box tuned to 50Hz, F3=40,3Hz and +4,5dB of bass boost.
I dont see any point for bigger box, but slightly lower tuning of 45Hz is good idea. It lowers F3 to around 37Hz with more gentle rolloff and with bass boost around +3,5dB.
Iam not using WinISD so I cant give you any tutorial. Iam using Boxsim which has really nice vent calculator inside.
For 155liter box and 45Hz tuning I recommend you round vent 14cm diameter and 2,5cm long. So, all you have to do is make the front board 2,5cm thick and cut a 14cm hole in it.
Just make sure its at least one diameter away from box walls, to avoid boundary effect on tuning.
I dont see any point for bigger box, but slightly lower tuning of 45Hz is good idea. It lowers F3 to around 37Hz with more gentle rolloff and with bass boost around +3,5dB.
Iam not using WinISD so I cant give you any tutorial. Iam using Boxsim which has really nice vent calculator inside.
For 155liter box and 45Hz tuning I recommend you round vent 14cm diameter and 2,5cm long. So, all you have to do is make the front board 2,5cm thick and cut a 14cm hole in it.
Just make sure its at least one diameter away from box walls, to avoid boundary effect on tuning.
Thanks for the input! Yes, I am questioning the volume, too.
Aside from "because I can"
my main point was that I wanted to help the lower frequencies as much as possible.But yes. I'm slowly questioning myself if 220L really are needed.
However:
With 155L (and a tuning frequency of 45Hz) 45Hz has +2dB, highest is 60Hz at +3.5dB and f3 is at 36,5Hz.
With 220-230L (and a tuning frequency of 45Hz), 45Hz sits at 4.4dB, 50Hz even at +5dB, and f3 is still 36Hz. That is pretty much +2.5dB down low across the board. Hmm.
edit: WinISD might help compare it. Thick green line is 230L, thin green line is 155L. Same tuning frequency.
Question to the pro's out here: How much impact does +2.5dB down low have? I've heard 3dB makes a noticeable difference, but does this change down low? Might there be a noticeable difference or is it just "voodoo"? I'd hate to go for a smaller cabinet and miss out on the +2.5dB. However if it can be built smaller without losing much, why not.
Last edited:
Depends a lot on room interaction since down low the room dominates. Anyway, it's not the audible # of dB boost per se otherwise we wouldn't be able to tolerate a large BLH's wide BW 'vent' output!, but the 'ringing' decay (group delay) that can accompany it. When folks began making a 'big deal' out of it on the late, lamented 'basslist' I had no clue at first what they were talking about or why it was such a big deal till I realized that between my normal low tunings (< ~27.5 Hz piano tuning) and/or 'critical' vent damping it had never been an issue as it either had already decayed away enough due to the lower than normal tuning (for the times) and/or been damped down to inaudibility with 'critical' vent damping.
Alright! I'm just rephrasing it to see if I understood your correctly:
On the ond hand, room acoustics dominate more than a few dB here or there, especially down low?
And on the other hand, interferences and decaying sounds (never knew about this, learned something new again) can play a role, but those can be countered somewhat effectively with the click test? Because that's something I already wanted to do as soon as the speakers will be finished!
So long story short, room acoustics and click-testing will play a bigger role than +2.5dB here or there, I guess? If that's the case, I'll seriously consider downsizing the cabinet.
On the ond hand, room acoustics dominate more than a few dB here or there, especially down low?
And on the other hand, interferences and decaying sounds (never knew about this, learned something new again) can play a role, but those can be countered somewhat effectively with the click test? Because that's something I already wanted to do as soon as the speakers will be finished!
So long story short, room acoustics and click-testing will play a bigger role than +2.5dB here or there, I guess? If that's the case, I'll seriously consider downsizing the cabinet.
This is my experience.
I have Seas FA22RCZ in stuffed transmission line. Pipe is 2 meters long. At first, last 30cm of the pipe was unstuffed. After a month I added the rest of stuffing. Hornresp sim showes some 1dB difference, but I could hear it. Less bass, but deeper and with better definition.
Small difference, but I like that more, so I left the full stuffing.
So, if I could hear 1dB, than I guess 2,5dB will make noticeable difference.
But, larger box has sharper response peak, so transient response is less accurate.
I have Seas FA22RCZ in stuffed transmission line. Pipe is 2 meters long. At first, last 30cm of the pipe was unstuffed. After a month I added the rest of stuffing. Hornresp sim showes some 1dB difference, but I could hear it. Less bass, but deeper and with better definition.
Small difference, but I like that more, so I left the full stuffing.
So, if I could hear 1dB, than I guess 2,5dB will make noticeable difference.
But, larger box has sharper response peak, so transient response is less accurate.
Right, i.e. up to +9 dB in a corner........... indeed, everything 'rings' at some frequency (it's how they measure distances to other galaxy, etc.) and pipes are 1/2 WL resonators based on its total internal acoustic mass, so can 'ring like a ten penny nail struck with a ball-peen hammer' when sufficiently 'excited' .
.
Understood in that 'critically damped' always costs me a bit of bass gain......... but caught out again in that I was responding to this earlier post: https://www.diyaudio.com/community/threads/new-12-full-range-fane-12-250tc.246746/post-7508064
Thanks for all the replies, guys! MDF is bought and brought home, already cut to the needed sizes. I'll only be able to work on the speakers for a few hours every weekend, so progress will be slow but steady.
Concerning the vent... Would it be stupid to go with a 19cm diameter (~7.5 inches)? WinISD says the length should then be 12.5cm, (~5 inches).
(Box volume will be 158L with 45Hz tuning frequency)
I could also go with a 15 or 16cm diameter for the vent (5.9 and 6.3" respectively), but.... why not go crazy?
Is there a tipping point where there's "too much vent area"? Port velocity will be low either way with 3m/s for the 19cm diameter, and 4.2-4.7m/s for the 15 or 16cm one.
My goal for the speakers is not incredible balance, equality and precision.
With those Fanes, I want straightforward and somewhat over the top fun. Goofy looks with a big vent play into that, as far as I'm concerned. But is there a "logical" reasons not to go overboard?
With a 19cm diameter, the length would still be capped at 12.5cm, which is like only 27% of the total internal depth of the cabinet.
Concerning the vent... Would it be stupid to go with a 19cm diameter (~7.5 inches)? WinISD says the length should then be 12.5cm, (~5 inches).
(Box volume will be 158L with 45Hz tuning frequency)
I could also go with a 15 or 16cm diameter for the vent (5.9 and 6.3" respectively), but.... why not go crazy?
Is there a tipping point where there's "too much vent area"? Port velocity will be low either way with 3m/s for the 19cm diameter, and 4.2-4.7m/s for the 15 or 16cm one.
My goal for the speakers is not incredible balance, equality and precision.
With those Fanes, I want straightforward and somewhat over the top fun. Goofy looks with a big vent play into that, as far as I'm concerned. But is there a "logical" reasons not to go overboard?
With a 19cm diameter, the length would still be capped at 12.5cm, which is like only 27% of the total internal depth of the cabinet.
Last edited:
Good question! Can some pros maybe explain?
I'm building cabinets for the Fane's right now, however I can only make some progress on the weekends because work is taking up a lot of time right now.
I was looking into treating the cones with some mod-podge to slightly dampen the response and make it more linear to additionally fine-tuning it with an equalizer.
I'll revise the above a little: with passive filters, most of the time that's what people do, as it's almost (not entirely) impossible to boost practical output with passive filters. Hence the infamous parallel RL 'baffle step compensation' (aka low pass shelving filter) inserted in series with many single-driver system setups. In many cases, it's not necessarily baffle-step itself that it's being used to EQ, although it can & is, but naturally rising response trends also. With active filters, you have freedom to cut or boost as you see fit. Power-handling is identical in both cases, so much of the time, people tend to kick the LF up as it's a narrower region to modify & they'll often make some compensation for room modes etc. in the process, although this in itself can be taken too far if you're not careful.
