Passinwind
I know nothing.
- Dec 3, 2003
- 23,077
- 46,033
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- Designer/Toaster Tech @ Passinwind Electronics
I've used the calculator in WinISD, which is in something like the Utilities section IIRC.
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Avatar SB112 - port tuning too high?
- Thread starter bobcruz
- Start date
I've used the calculator in WinISD, which is in something like the Utilities section IIRC.
Alright, here are the pix. The first pic shows the cabs with original grills, port plugs and original flat black paint in the remaining duct. Looks gray and dusty as I said. The second pic is with the wheat grill and satin paint in the duct. The picture makes it look like I didn't go far enough with the satin paint, but from any normal angle you can't see the gray stuff or the unpainted back wall of the cabinet. The third pic is a closeup of the plug, with the thin carpeted cover over the plug. From the outside all you see is black carpet. I can't show the material behind the plug but anything that gives you an airtight plug will work. For example, a plywood rectangle wrapped in rubber tape as a gasket would work.
A good point from bobcruz on the tuning. I'd neglected to take into account the shelf port/wall lengthening effect and the box may indeed be tuned a bit lower rhan I'd originally thought. My ear would likely still consider his mod an improvement.
WinISD does have a screen for inputing all the driver measurements but I've never actually used it. I've always just taken a diameter measurement where the frame comes through the inside of the baffle and a measurement across the back of the magnet. Average those two and use that as the diameter to figure volume of a cylinder using however far the driver sticks inside the box as the depth. It's pretty close. There's also a geometric shape called a "conical frustum" that's pretty close to being a speaker, plus it just sounds cool.
In any case, coming within a few cubic inches on a 2cu.ft. zone is enough to get the tuning right and put you in the "no audible difference" zone.
WinISD does have a screen for inputing all the driver measurements but I've never actually used it. I've always just taken a diameter measurement where the frame comes through the inside of the baffle and a measurement across the back of the magnet. Average those two and use that as the diameter to figure volume of a cylinder using however far the driver sticks inside the box as the depth. It's pretty close. There's also a geometric shape called a "conical frustum" that's pretty close to being a speaker, plus it just sounds cool.
In any case, coming within a few cubic inches on a 2cu.ft. zone is enough to get the tuning right and put you in the "no audible difference" zone.FWIW, WinISd can sometimes be a little off on shelf ports. Some discussion of it in this thread http://www.talkbass.com/forum/f15/cab-building-question-about-shelf-port-length-823673/
The link in there to this port calculator Link Removed puts that 64L box size, figuring 15" W x 2" H worth of port area at 7" deep between 55 and 56 hz. The 7-1/2" x 2" half of it, also 7" deep it calculates as 42hz. If you call it a "slot port", the numbers go much deeper, enough that it doesn't make sense.
The link in there to this port calculator Link Removed puts that 64L box size, figuring 15" W x 2" H worth of port area at 7" deep between 55 and 56 hz. The 7-1/2" x 2" half of it, also 7" deep it calculates as 42hz. If you call it a "slot port", the numbers go much deeper, enough that it doesn't make sense.
Just for a sanity check, does 500 in^3 seem about right for the volume of a 3015? It's about as near as I've been able to come. Doing math on an Eminence recommended cab suggested closer to 400 in^3, but I don't really trust either calculation.
KO
KO
OK, I got my 112 cab and I am thinking about this mod.I notice that at higher volumes my low C and C are on the edge of farting out.I don't have any extreme EQ settings. This subject is completely confusing to me still. The question I have is:
If I plug half of the port and that will extend the frequency range lower, will that not put more stress on the woofer?
At the same time I was also thinking that if less air can escape the cabinet( because the port is now only half the size) wouldn't make the cabinet tighter sounding?
So for a 5 sting bass If I want a clear yet punchy sound all the way down to the low B is this mod worthwhile?
If I plug half of the port and that will extend the frequency range lower, will that not put more stress on the woofer?
At the same time I was also thinking that if less air can escape the cabinet( because the port is now only half the size) wouldn't make the cabinet tighter sounding?
So for a 5 sting bass If I want a clear yet punchy sound all the way down to the low B is this mod worthwhile?
Peavey's big ferrite magnet Black Widow 15's state occupying a volume of 200-220 cubic inches when front loaded. 500 cu.in. I would think in excess, more like an 18 with a deep basket.
First, make sure your cab is fully broken in, which loosens the suspension around the woofer and allows it to travel farther/more easily for deeper bass. If you still have the issue, plugging half the port can help. It stresses the woofer less to have deeper port tuning because the port is increasing output at lower frequencies. The same amount of air can blow through the remaining port, but it will move faster due to the smaller port area (think of rapids in a river). If that air moves too fast it can create turbulence and distortion known as "chuffing" but when I modeled the woofer in WinISD, a cabinet design program, WinISD said the remaining port was sufficient to prevent chuffing at a full 250 watts. The woofer would run out of excursion and distort (fart out) long before that happens. So by all means try the plug--it's reversible and won't do any harm.
You mention "full 250 watt". I don't have the 250 watt Neo in the cab, I have the regular 500 watt speaker. The cab is 4 ohm and I'm powering it with the Eden WT 550.Does that change anything as far as the porting goes?
By the way, how long does it take for a speaker to be fully broken in? Does it need to be broken in at high volumes or is playing it at softer volumes also going to do the trick?
By the way, how long does it take for a speaker to be fully broken in? Does it need to be broken in at high volumes or is playing it at softer volumes also going to do the trick?
Sorry, I didn't know you guys had the non-neo speaker. I didn't model that one so I can't say whether it has the little bump at 80 Hz that my change in port tuning reduced or whether the port air speed gets too high at higher wattage.
Here are some good threads on breaking in speakers:
http://www.talkbass.com/forum/f15/sound-generators-breaking-speakers-800276/
http://www.talkbass.com/forum/f15/do-i-need-break-new-bass-cab-743193/
Good luck!
Here are some good threads on breaking in speakers:
http://www.talkbass.com/forum/f15/sound-generators-breaking-speakers-800276/
http://www.talkbass.com/forum/f15/do-i-need-break-new-bass-cab-743193/
Good luck!
Do does that mean this mod does not apply to the regular speakers?I never crank up the WT550 as loud as it will go anyways.Could there still be a sonic benefit to plugging that hole for me?
OK I did it. So far I'm only playing through the cab in my room. I'll be taking it to a rehearsal on Wednesday.
What I notice so far is that the cabinets seems less bassy. I don't mean that in a negative way, It seems clearer and more defined yet still punchy. Maybe even more so. I can always add a little more low end from my amp if I need it.
I did notice that in a band situation the setting that sounded good to me at home was too bassy and not punchy enough. On rehearsals I had to take off some of the deep lows and ad a little bit of 300 hz. Could have been because the cab was pretty close to a wall.
I'll find out how the cab does with the modification. My second cab is in the rehearsal room and it is still stock so I'll be able to AB them.
At this point I cannot say if the mod is an improvement or not. All I can say there's a clear difference. I'll know more on Wednesday.
What I notice so far is that the cabinets seems less bassy. I don't mean that in a negative way, It seems clearer and more defined yet still punchy. Maybe even more so. I can always add a little more low end from my amp if I need it.
I did notice that in a band situation the setting that sounded good to me at home was too bassy and not punchy enough. On rehearsals I had to take off some of the deep lows and ad a little bit of 300 hz. Could have been because the cab was pretty close to a wall.
I'll find out how the cab does with the modification. My second cab is in the rehearsal room and it is still stock so I'll be able to AB them.
At this point I cannot say if the mod is an improvement or not. All I can say there's a clear difference. I'll know more on Wednesday.
I had the modded cab on a rehearsal a couple of days ago. It sounded different didn't seem to move as much air but the tone was not bad.
I now have both cabs in front of me in my room and I'm A/B testing them. As much as I would like to say the modification is an improvement, I don't like it.
I notice a lack of warmth in the modded cabinet and a more pronounced high mid nasally sound quality that is not pleasant to my ears. So what really appealed to me about the cabinet went away after the modification. I'll play around with the two cabs some more but most likely I will remove the plug. Too bad I did a really nice job fitting it super tight. I was really proud of myself
I now have both cabs in front of me in my room and I'm A/B testing them. As much as I would like to say the modification is an improvement, I don't like it.
I notice a lack of warmth in the modded cabinet and a more pronounced high mid nasally sound quality that is not pleasant to my ears. So what really appealed to me about the cabinet went away after the modification. I'll play around with the two cabs some more but most likely I will remove the plug. Too bad I did a really nice job fitting it super tight. I was really proud of myself
I had the modded cab on a rehearsal a couple of days ago. It sounded different didn't seem to move as much air but the tone was not bad.
I now have both cabs in front of me in my room and I'm A/B testing them. As much as I would like to say the modification is an improvement, I don't like it.
I notice a lack of warmth in the modded cabinet and a more pronounced high mid nasally sound quality that is not pleasant to my ears. So what really appealed to me about the cabinet went away after the modification. I'll play around with the two cabs some more but most likely I will remove the plug. Too bad I did a really nice job fitting it super tight. I was really proud of myself
That sound difference is to be expected. Listen to it at a gig, mixed in with the band, listening from 20 ft. out or wherever your audience is. It'll sit nice out there. It follows the barband thing of "what sounds nice and full/bassy up close is too muddy/indestinct out in the room" and, "what sounds a little too midrangey/shy in the bass up close sits nice out in the room".
Sort of a "can't have your Kate and Edith too" scenario.
Maybe I'm getting more selfish as I'm getting older. If I have the choice of having it sound good where I can't hear it or have the killer tone where I'm standing, I'd go for the latter.
Most of the gigs I'm doing these days are smaller venues where volume is a concern so having the tone the way I want it on the band stand ( If there is a bandstand) will make it less tempting for me to crank it up more than I should.
So yes, you are probably right about the cab sounding better far away but if it sounds good to me where I am, I'll play better.
If the tone gets too muddy I could also dial back the bass a little which might accomplish the same thing, right?
I'll play with the cabs some more. I have them set up side by side in front of me.I'll swap them to see if the location has something to do with it. I doubt it but I'll do it anyway.
Most of the gigs I'm doing these days are smaller venues where volume is a concern so having the tone the way I want it on the band stand ( If there is a bandstand) will make it less tempting for me to crank it up more than I should.
So yes, you are probably right about the cab sounding better far away but if it sounds good to me where I am, I'll play better.
If the tone gets too muddy I could also dial back the bass a little which might accomplish the same thing, right?
I'll play with the cabs some more. I have them set up side by side in front of me.I'll swap them to see if the location has something to do with it. I doubt it but I'll do it anyway.
Perhaps there's an in-between? Block 1/2 of the areas you have blocked now. This would require a run of plywood, perpendicular to the bottom of the cab, port height, front to back. May get a nice sound in both places, and again, reversible.
The original 55-56 seems too high to me, although the 1/2 blocked 42hz is low enough to get reduced bass to the point it might not be enjoyable for the player. Not modeling it or anything, perhaps a 1/4 or 1/3 blocked setup would put it in the mid to upper 40's? Enough to get some "oomph" for the player but not "boom the room". You're really in an area there where it comes down to taste and you personal uses of the cab. 56 is the high extreme, 42 the low extreme.....sort of...depending on you ear.
