Ha! The um driver's cone is actually quite rigid, when you knock on it with knuckles, it makes a sound sorta like knocking on a door.
Nah, the rew FR isn't averaged, I only move the microphone when I'm taking OmniMic measurements to generate the filters, I switch to REW to measure the "after", just because I think the graphs are easier and prettier (plus I'm lazy and I haven't tried to get OmniMic to display a THD overlay.
Give me about 30 minutes and I'll go measure the THD with rew and with the volume cranked closer to where it was at in the video.
Edit: This is much louder. As it turns out, REW is calibrated by default, as the OmniMic cal file contains level information, whoda thunkit?
Interesting, the FR changes a bit...but at this volume level, both of the doors in this room take off on a little acid trip right around 15 cycles, so I'm not sure if REW is interpreting that as distortion, or changing the response...but nonetheless, this is what the distortion looks like when I'm half a bubble away from flicking the clip indicators on the NU4-6000 that's driving them (on two of it's channels.)
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Oh, and just for fun, here's the shaking cardboard driver!
https://www.youtube.com/watch?v=uxN-usgs25c&hd=1
https://www.youtube.com/watch?v=uxN-usgs25c&hd=1
Don't know what is "organ work". But for audio testing purposes you'd want to be able to control (and to being able to double-check) the exact electrical signal going to the speaker (from the audio test set-up).
Mic locations also matter. Some folks like to see a "near field" sound output in addition to a tire-meets-the-road listener's position. The gold-standard of mic locations requires averaging a few locations because each location has its own random-like ups-and-downs.
There are a number of issues related to how loud you test. A not-too-loud level (but louder than street noises) is just fine for establishing the quality of the design. Loud testing just tells you how loud you can play it or where distortion becomes noticeable or when you'll burn it out.
Looking forward to seeing traces.
Ben
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Well I missed a whole bunch of posts.
Been interesting reading. That's for sure.
As for measurements of my system, well a designer either has to much stuff or none.
I'm in the none stage right now!
Starting next week it will get back into the to much stuff situation again. Have a few commissions to get working on and out of my shop.
I'll post measurements of those.
Been interesting reading. That's for sure.
As for measurements of my system, well a designer either has to much stuff or none.
I'm in the none stage right now!
Starting next week it will get back into the to much stuff situation again. Have a few commissions to get working on and out of my shop.
I'll post measurements of those.
Hi Bach On,
Just a very quick note on testing:
- Do NOT use high power sine wave signals to test your loudspeakers. There is a very high likelyhood that high power sine wave at very low frequencies will damage the woofers. Make sure that there is a high pass (low cut) filter that protects the woofer at the bottom of the frequency range (might already be build in the amplifer, but you have to know, and watch for this).
- Your best test will be listening while driving the speaker with the actual signal that this speaker will be used with, first at lower levels, and than at your normal playing levels. Test the speaker alone, and together with other speakers if that is how you will be using is.
Your subwoofer box is squashed behind other speakers in your organ (pipe?) loft. Your main interest should be what it sounds like in the actual listening area presenting the signal you designed it for under actual listening volume levels.
I see this more as part of the effort of building a musical instrument.
Regards,
Just a very quick note on testing:
- Do NOT use high power sine wave signals to test your loudspeakers. There is a very high likelyhood that high power sine wave at very low frequencies will damage the woofers. Make sure that there is a high pass (low cut) filter that protects the woofer at the bottom of the frequency range (might already be build in the amplifer, but you have to know, and watch for this).
- Your best test will be listening while driving the speaker with the actual signal that this speaker will be used with, first at lower levels, and than at your normal playing levels. Test the speaker alone, and together with other speakers if that is how you will be using is.
Your subwoofer box is squashed behind other speakers in your organ (pipe?) loft. Your main interest should be what it sounds like in the actual listening area presenting the signal you designed it for under actual listening volume levels.
I see this more as part of the effort of building a musical instrument.
Regards,
We have a set of large wooden pipes that are going to be moved. They are currently blocking most of the opening between the speaker chamber and the pipe chamber. The organ tech must move them. So even for testing without the organ, these pipes prevent any practical measurement of what things will sound like out in the Sanctuary where the congregation will hear things.
All I can do is measure the output of the bass cabinet in the small speaker chamber. If these two 15 inch speakers prove inadequate - even with the new port, the next step is to switch to two HT18-18 inch from Stereo Integrity. I can enlarge the speaker openings where the box is.
HT18 18″ Subwoofer | Stereo Integrity
The 4 ohm version of these are on back-order until mid-June. So testing with the 15" Daytons is the plan for now. I remind everyone that the number of times this box will be asked to produce 16 Hz. in a year can be counted on one hand. If we need more volume in the 30-100 Hz. range, we can put some smaller sealed boxes for the 15 inch woofers.
Remember that the goal is to blend the pipes and the speakers so people cannot hear the difference. We may or may not be able to achieve that. But that is the hope. tb46 is right: we ARE rebuilding and enhancing a musical instrument. The speakers are only one component of the instrument. We'll first make sure the volume for the manuals (the keyboards) sound good with the pipes. Then we'll gradually bring the pedals online and bring the volume up until we have a balanced blend .
Bach On
P.S. We won't get the sound engine and get things connected until mid to late June. It's also on back-order.
All I can do is measure the output of the bass cabinet in the small speaker chamber. If these two 15 inch speakers prove inadequate - even with the new port, the next step is to switch to two HT18-18 inch from Stereo Integrity. I can enlarge the speaker openings where the box is.
HT18 18″ Subwoofer | Stereo Integrity
The 4 ohm version of these are on back-order until mid-June. So testing with the 15" Daytons is the plan for now. I remind everyone that the number of times this box will be asked to produce 16 Hz. in a year can be counted on one hand. If we need more volume in the 30-100 Hz. range, we can put some smaller sealed boxes for the 15 inch woofers.
Remember that the goal is to blend the pipes and the speakers so people cannot hear the difference. We may or may not be able to achieve that. But that is the hope. tb46 is right: we ARE rebuilding and enhancing a musical instrument. The speakers are only one component of the instrument. We'll first make sure the volume for the manuals (the keyboards) sound good with the pipes. Then we'll gradually bring the pedals online and bring the volume up until we have a balanced blend .
Bach On
P.S. We won't get the sound engine and get things connected until mid to late June. It's also on back-order.
Whatever distinctions can be made between musical instrument uses and music reproduction, in either case you need to know what you are starting with.
For sure, assessing the sound in the organ pipe space is of nearly no value. On the other hand, whatever items are missing now or will be added later is of fairly little influence in terms of the sound in row M of the sanctuary. So if the speakrer box is in place, might as well crank up REW and post the results.
As far as I can figure, "musical instrument" loudspeakers are merely durable versions of HiFi speakers. In the case of woofers, that tends to mean stiffer/stronger suspensions and higher driver resonances. The simulation of, say, a cello, should be a matter of the signal, not the enduring resonances of the speakers; there are almost always of no music-sound value. Likewise for an electric guitar. Not that electronic musicians would necessarily agree with me.
Some people who love traditional live music (meaning, live music on traditional acoustic instruments) are plain puzzled to learn that some people like electronic or even just amplified instruments or voices. I sure know the difference between a singer and a singer plus PA/commercial speaker.
Ben
For sure, assessing the sound in the organ pipe space is of nearly no value. On the other hand, whatever items are missing now or will be added later is of fairly little influence in terms of the sound in row M of the sanctuary. So if the speakrer box is in place, might as well crank up REW and post the results.
As far as I can figure, "musical instrument" loudspeakers are merely durable versions of HiFi speakers. In the case of woofers, that tends to mean stiffer/stronger suspensions and higher driver resonances. The simulation of, say, a cello, should be a matter of the signal, not the enduring resonances of the speakers; there are almost always of no music-sound value. Likewise for an electric guitar. Not that electronic musicians would necessarily agree with me.
Some people who love traditional live music (meaning, live music on traditional acoustic instruments) are plain puzzled to learn that some people like electronic or even just amplified instruments or voices. I sure know the difference between a singer and a singer plus PA/commercial speaker.
Ben
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Looking ahead. If we end up switching to the 18" Stereo Integrity woofers in our original cabinet, the two 15" Dayton drivers I'm currently testing would be surplus. If I bought them and contributed them to the church, we could put them in twin sealed or vented boxes to improve the SPL for the crowd back on Row M of the congregation.
Parts Express suggested a 4.27 cu. ft. vented box for an F3 of 29 Hz. for the Dayton 15" drivers (one per box). Is there a way to tune a box of that volume down to a frequency of 16 Hz.? If so, could any of you who aren't sick to death of this thread suggest port dimensions for such a box?
I'm going over today to do some eyeball and ear cogitating. There is an unused corner in the chamber. The corner is over six feet high. It is not a 90 degree corner, but oddly trapezoidal in shape. I'm going to do some measurements on the space. I MIGHT be able to construct a cabinet to fit this space.
IF I can get it to come up to 4.27 cu. ft. (or larger) with a large enough face, I could stick at least one of those 15" woofers in that corner.
But all such activities will have to wait until I get the new HT18 from Stereo Integrity. I'm just trying to consider in advance possible alternate plans. "Hope for the best. But prepare for the worst."
Bach On
Parts Express suggested a 4.27 cu. ft. vented box for an F3 of 29 Hz. for the Dayton 15" drivers (one per box). Is there a way to tune a box of that volume down to a frequency of 16 Hz.? If so, could any of you who aren't sick to death of this thread suggest port dimensions for such a box?
I'm going over today to do some eyeball and ear cogitating. There is an unused corner in the chamber. The corner is over six feet high. It is not a 90 degree corner, but oddly trapezoidal in shape. I'm going to do some measurements on the space. I MIGHT be able to construct a cabinet to fit this space.
IF I can get it to come up to 4.27 cu. ft. (or larger) with a large enough face, I could stick at least one of those 15" woofers in that corner.
But all such activities will have to wait until I get the new HT18 from Stereo Integrity. I'm just trying to consider in advance possible alternate plans. "Hope for the best. But prepare for the worst."
Bach On
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Hi,
You could use 2 drivers in a Isobarik configuration, which means the box could be half the size. So a driver first thought to be unsuitable in a certain sized box, might now work. Plus suitable drivers could benefit from the reduced volume.
For eg, this could be in a Reflex or sealed box. 24db HPF @ 12Hz, & some EQ ?
Also the drivers could be mounted Push/Pull to reduce THD
You could use 2 drivers in a Isobarik configuration, which means the box could be half the size. So a driver first thought to be unsuitable in a certain sized box, might now work. Plus suitable drivers could benefit from the reduced volume.
For eg, this could be in a Reflex or sealed box. 24db HPF @ 12Hz, & some EQ ?
Also the drivers could be mounted Push/Pull to reduce THD
I get about 65.5" (!) for 16hz in 4.27 cubes using a 6" port. 28" if you went down to a 4" port.
That I couldn't tell you. With 1 driver and the cabinet pretty far away from the listeners, I wouldn't imagine it would be a concern, especially considering any frequencies and volumes where it might be a factor will also come with loud higher pipes, I'd think "meh."
I'm sure someone will be along with crazy maths to show just how terrible the chuffing would be, so it might have to be one of those things you try.
Hi Bach On,
You just divided your original box by a factor of 3, and you still want to maintain the same low frequency tuning.
Zero D is spot on in Post #533, use the drivers isobarically, and you'll still need a very long vent, e.g.: 6"I.D. x 53.5"long for a port mouth velocity of 17m/sec. In addition to the 120.9 L [4.27ft^3] for V_net you'll also need 24.8 L for V_port; these are net values, so add wood and drivers.
Now you are definitely in passive radiator territory.
Regards,
You just divided your original box by a factor of 3, and you still want to maintain the same low frequency tuning.
Zero D is spot on in Post #533, use the drivers isobarically, and you'll still need a very long vent, e.g.: 6"I.D. x 53.5"long for a port mouth velocity of 17m/sec. In addition to the 120.9 L [4.27ft^3] for V_net you'll also need 24.8 L for V_port; these are net values, so add wood and drivers.
Now you are definitely in passive radiator territory.
Regards,
I went into the speaker chamber today at the church. No sound testing, but lots of measuring and eyeballing. First, the chamber is very full. The six Allen HC12s do occupy a substantial amount of the territory. But the problem is the big bass box. It's shape doesn't fit the available area.
Try to picture this. There is a full-sized door that swings out into a room (actually the nursery). We use a ladder to enter the chamber. This box is so big it practically blocks the door. Yet there is remaining space in the chamber.
Continue to picture things. To the right of the door in the chamber there is a triangular area. It was created to work around some structural items of the building. Try to get these dimensions: the corner is 30 inches to the right from the door frame. So there is a wall of 30 inches deep and roughly 74 inches high. Another wall meets it at roughly a 45 degree angle. That is the rear corner. That wall is 45 inches wide and 74 inches high. There is an open area that could to accommodate a wall 30 inches wide and 74 inches high.
Thus, there is room for a triangular shaped cabinet (as viewed from the ceiling and looking down). The big box is using part of this triangular space - but not all of it. The excess of that box is in the way of people movement (and sound too) in that area of the chamber. It's a good box, but it's simply the wrong shape for the available space.
I need to build a triangular cabinet to fit into this space and take out the rectangular box. The floor footprint would be a right triangle. Two sides of 30 inches and one of 45 inches. Depending on the height I can build a box with a volume that could be roughly equivalent to the rectangular box. Or I could create multiple triangular shaped boxes stacked one over the other.
I'm not crazy about not using the big box. But the geometry is wrong for it.
Here's where things are headed in the drivers. I currently have two 15" woofers in the big box. I'll be getting at least one 18" woofer in June. I could build a larger triangular box and put the two 15" drivers in it. Then I could make a slightly smaller box and put the 18" driver in it - when the driver arrives. These could easily fit in this triangular area. As someone climbed from the ladder into the chamber, the speaker cones would be on the right - pointed into the center of the chamber.
Any sage observations or caveats?
Bach On
Try to picture this. There is a full-sized door that swings out into a room (actually the nursery). We use a ladder to enter the chamber. This box is so big it practically blocks the door. Yet there is remaining space in the chamber.
Continue to picture things. To the right of the door in the chamber there is a triangular area. It was created to work around some structural items of the building. Try to get these dimensions: the corner is 30 inches to the right from the door frame. So there is a wall of 30 inches deep and roughly 74 inches high. Another wall meets it at roughly a 45 degree angle. That is the rear corner. That wall is 45 inches wide and 74 inches high. There is an open area that could to accommodate a wall 30 inches wide and 74 inches high.
Thus, there is room for a triangular shaped cabinet (as viewed from the ceiling and looking down). The big box is using part of this triangular space - but not all of it. The excess of that box is in the way of people movement (and sound too) in that area of the chamber. It's a good box, but it's simply the wrong shape for the available space.
I need to build a triangular cabinet to fit into this space and take out the rectangular box. The floor footprint would be a right triangle. Two sides of 30 inches and one of 45 inches. Depending on the height I can build a box with a volume that could be roughly equivalent to the rectangular box. Or I could create multiple triangular shaped boxes stacked one over the other.
I'm not crazy about not using the big box. But the geometry is wrong for it.
Here's where things are headed in the drivers. I currently have two 15" woofers in the big box. I'll be getting at least one 18" woofer in June. I could build a larger triangular box and put the two 15" drivers in it. Then I could make a slightly smaller box and put the 18" driver in it - when the driver arrives. These could easily fit in this triangular area. As someone climbed from the ladder into the chamber, the speaker cones would be on the right - pointed into the center of the chamber.
Any sage observations or caveats?
Bach On
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Hah, triangles! I just happen to have a couple of those as well, but they're for 12s...and they're only tuned to around...oh, I think 27 hz? or so. They do work really well though, and in the corners, they take advantage of corner loading. They could EASILY be made taller for more internal volume, and a lower tune.
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Ready, fire, aim.
The time alignment of various organ voices is always off-beat**. You could put the enclosure at some distance from the pipes and other speakers. Long cables are no issue if they aren't too small in gauge.
Essentially, you want a good corner to snug into. That outweighs most other considerations... except maybe appearance. The rest is simply careful carpentry and volume of the box... and to disguise the box as a heat radiator or coat rack.
In fact, maybe you could make an "infinite" baffle*. Enthusiasts on this forum, esp. the keen simulators, sometimes forget that an enclosure is a "necessary evil" for occasions when an infinite baffle is not possible. Except for horns (AKA impedance transformers), there's nothing beneficial about resonant boxes, even leaky sealed boxes.
Instead of more "the cowboy saddled his horse and ran off in all directions..." why not just sit your box as close to a corner as you can and see what output you've created. That's likely to tell you more about sound in the pews as dozens or well-meaning sim posts.
Ben
*just cutting a hole in the access door to your organ pipe space to mount the driver (or any other convenient piece of wall) might give you all the "enclosure" you'll ever need. If that doesn't work out, just replace the door.
**one of the greatest glories of organ building is the rank of "State Trumpeter" reed pipes under the far-end rose window of the St. John the Divine in New York. Great sound... you can almost count the seconds till the full blast reaches you.
The time alignment of various organ voices is always off-beat**. You could put the enclosure at some distance from the pipes and other speakers. Long cables are no issue if they aren't too small in gauge.
Essentially, you want a good corner to snug into. That outweighs most other considerations... except maybe appearance. The rest is simply careful carpentry and volume of the box... and to disguise the box as a heat radiator or coat rack.
In fact, maybe you could make an "infinite" baffle*. Enthusiasts on this forum, esp. the keen simulators, sometimes forget that an enclosure is a "necessary evil" for occasions when an infinite baffle is not possible. Except for horns (AKA impedance transformers), there's nothing beneficial about resonant boxes, even leaky sealed boxes.
Instead of more "the cowboy saddled his horse and ran off in all directions..." why not just sit your box as close to a corner as you can and see what output you've created. That's likely to tell you more about sound in the pews as dozens or well-meaning sim posts.
Ben
*just cutting a hole in the access door to your organ pipe space to mount the driver (or any other convenient piece of wall) might give you all the "enclosure" you'll ever need. If that doesn't work out, just replace the door.
**one of the greatest glories of organ building is the rank of "State Trumpeter" reed pipes under the far-end rose window of the St. John the Divine in New York. Great sound... you can almost count the seconds till the full blast reaches you.
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