Ports are measured in ^2 not ^3 You have a 7.5in^2 port. High vent velocity is a bad thing.
Hi,
You keep making incorrect statements. There is nothing "perfect"
about equal impedance peaks disregarding the actual alignment.
rgds, sreten.
My apologizes for any incorrect statements.
An electrical engineer friend showed me how to tune a BR using a volt meter, resistor load, signal generator, years ago.
The resistor is in series with the woofer, the volt meter is connected to the woofer; once connected and sweeping with the generator, two peaks and a valley are very noticeable on the volt meter. The valley is the FS, the closer the two voltage peaks the better. I find the first “hump” is the hardest to bring up, typically.
I’m sure this is common knowledge; however I couldn’t find any info on the web.
Is this not the way to tune a BR?
An electrical engineer friend showed me how to tune a BR using a volt meter, resistor load, signal generator, years ago.
The resistor is in series with the woofer, the volt meter is connected to the woofer; once connected and sweeping with the generator, two peaks and a valley are very noticeable on the volt meter. The valley is the FS, the closer the two voltage peaks the better. I find the first “hump” is the hardest to bring up, typically.
I’m sure this is common knowledge; however I couldn’t find any info on the web.
Is this not the way to tune a BR?
@ ODougbo
Hi, your electrical engineer friend wasn't wrong as such, he explained how to tune the box = fb to the driver = fs. That's the classical way of doing things, but there are other ways depending on preferences/limitations etc.
If you find the first hump is the hardest to bring up, you need to tune the box higher.
Regards
Hi, your electrical engineer friend wasn't wrong as such, he explained how to tune the box = fb to the driver = fs. That's the classical way of doing things, but there are other ways depending on preferences/limitations etc.
If you find the first hump is the hardest to bring up, you need to tune the box higher.
Regards
Thanks, didn’t know what I was measuring, but it seemed to make since it is reverse when the speaker is out of the box (the speaker's Fs). My friend did explain that the inherit peak is pushed down and creates the humps once it is in the box and then drew a flat line across it and said, that’s about all you can do.
The Iso box seemed to tune perfectly, but that is my interoperation.
The Iso box seemed to tune perfectly, but that is my interoperation.
Hi,
Nothing is perfect, everything is a compromise, that is engineering.
Your alignment is so way off any sensible classical alignment
you simply cannot apply any classical alignment criteria to it.
Applying "rules of thumb" is not intelligent interpretation.
Why won't you just go off and build a proper box for them ?
And come back and report the consequences ?
Two drivers isobaric in a 25L box tuned to 30Hz versus two
drivers mounted left and right in a 25L box tuned to 30Hz.
The latter will pee all over the former, with bigger ports.
This thread would then be considerably less boring.
rgds, sreten.
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Building new boxes
Seems like were going around in circles, the comments tell me how off they are, and all I heard is chugging lowwwww bass throughout the shop.
Building new boxes, not a bad idea, the speaker bench is empty; you'd have to recommend an optimum port size AND related details.
However, be warned my friend, I did have a 28.4 liter clamshell, it was a powerful sub in a small package ~ the bigger boxes with tunnels are simply better (they have a remarkable “slam” quality).
Construction tip: I used rope caulk (HD) around the side of the box, clamped it off, then added screws, then trimmed with a router. Easy/fast, worked pretty well.
Seems like were going around in circles, the comments tell me how off they are, and all I heard is chugging lowwwww bass throughout the shop.
Building new boxes, not a bad idea, the speaker bench is empty; you'd have to recommend an optimum port size AND related details.
However, be warned my friend, I did have a 28.4 liter clamshell, it was a powerful sub in a small package ~ the bigger boxes with tunnels are simply better (they have a remarkable “slam” quality).
Construction tip: I used rope caulk (HD) around the side of the box, clamped it off, then added screws, then trimmed with a router. Easy/fast, worked pretty well.
Attachments
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... and we are saying, put them in a correctly designed box and you will hear all the bass, not just one chugging low note.
2 drivers isobaric versus 2 drivers left and right (force cancelling)
Hi,
I don't care what box or vent you use to compare them,
as long as its the same, 20 to 25L, tuned to ~ 30Hz.
In reality the normal box would need bigger venting due
to the higher SPL, and probably practically need PR's.
rgds, sreten.
Hi,
I don't care what box or vent you use to compare them,
as long as its the same, 20 to 25L, tuned to ~ 30Hz.
In reality the normal box would need bigger venting due
to the higher SPL, and probably practically need PR's.
rgds, sreten.
It's a difference of position. Doug is happy he's getting bass, the rest of us are more concerned with getting the most/best bass. Doug, this is a place largely by and for technical perfectionists, a wonderful resource to have because we get a lot of expertise here. But if you want to take a halfway solution and call it "good enough", you're in the wrong place. Try Audio Asylum, Audio Karma, or Audio Circle, all of which are less engineer-oriented and more tolerant of sub-optimal solutions, if they "sound good to you".
different ISO box
Thank you for a fresh view, however I don't think halfway is a fair statement, built several these and compared them to many other speakers for about ten years now. The one fellow I passed one along too, is really enjoying it.
I know if some of you fellows heard these, it would a different story and did get support from an engineer that said the "small" port was actually helping out the response.
I would try a different ISO box, enjoy building them and very passionate about speaker builds, etc.
So I really could use the help from the technical folks about a new 25liter build, the port size in particular. I can fine tune it with a generator on the bench, but want to make sure the size /air velocity is correct.
I think the tunnel is the way to go; they seem to handle a little more power. I’d probably go with 10” on the inside (I call them 10” rips). I could turn 90 degrees, up the back if necessary.
Thank you for a fresh view, however I don't think halfway is a fair statement, built several these and compared them to many other speakers for about ten years now. The one fellow I passed one along too, is really enjoying it.
I know if some of you fellows heard these, it would a different story and did get support from an engineer that said the "small" port was actually helping out the response.
I would try a different ISO box, enjoy building them and very passionate about speaker builds, etc.
So I really could use the help from the technical folks about a new 25liter build, the port size in particular. I can fine tune it with a generator on the bench, but want to make sure the size /air velocity is correct.
I think the tunnel is the way to go; they seem to handle a little more power. I’d probably go with 10” on the inside (I call them 10” rips). I could turn 90 degrees, up the back if necessary.
Hi,
Collo's DIY Subwoofer Enclosures Flare-it - Free Speaker Design Software
I guess a slot port could be made into a piecemeal flare of a number of sections.
rgds, sreten.
Collo's DIY Subwoofer Enclosures Flare-it - Free Speaker Design Software
I guess a slot port could be made into a piecemeal flare of a number of sections.
rgds, sreten.
Hehe, you said sub-optimal
Yep, I chuckled while writing it
I don't have to hear it. Nobody does. If you're happy with them, that's all well and good and nobody should tell you you can't enjoy it. But like I say, "It sounds good to me" is not an attitude that catches any fish 'round these parts. That you need help with your next alignment shows that you haven't done any sort of diligence with modeling and testing. In designing speakers, getting the bass alignment right is one of the easiest things and can be calculated using readily available tools. If you like what you've built, that's fine, but don't argue that it's optimized because you like it. That's wrong.
Thanks,
Thanks, never would have found that website. Are you suggesting a flare port vs. a slot?
I was thinking about following a format similar to pic, however, increase the height and length of port size e.g. instead of the 3/4" slot, it could be....say 2", the length would be very long and probably need to be an L or a U.
If the box is to be 20 - 25 liters, I’m guessing it would be a tight fit with a larger port.
If someone can get me going with the cubic inches of the port, I'll fabricate a new box, provide results, pics, etc.
btw, just for fun, adding a pic of the last build, new satellite speakers for the sub.
Thanks, never would have found that website. Are you suggesting a flare port vs. a slot?
I was thinking about following a format similar to pic, however, increase the height and length of port size e.g. instead of the 3/4" slot, it could be....say 2", the length would be very long and probably need to be an L or a U.
If the box is to be 20 - 25 liters, I’m guessing it would be a tight fit with a larger port.
If someone can get me going with the cubic inches of the port, I'll fabricate a new box, provide results, pics, etc.
btw, just for fun, adding a pic of the last build, new satellite speakers for the sub.
Attachments
Oh sure, still have a couple of them left. I wonder if the port size and the box volume will be the same OR the port will size will have limitations due to the small box size.
I guess the port could be a “U” that follows along the bottom, back and along the top.
Btw, Question, How many liters is an 8” woofer equal to?
Btw II, will start laminating 12” square blocks today; two at a time seems to be the way to go (will need 3, 1-1/2” thick pieces).
I guess the port could be a “U” that follows along the bottom, back and along the top.
Btw, Question, How many liters is an 8” woofer equal to?
Btw II, will start laminating 12” square blocks today; two at a time seems to be the way to go (will need 3, 1-1/2” thick pieces).
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