I'm in deep you know what and in way over my head. I got the wife telling me "I thought you said these were going to be the best speakers we ever had".
Any way I did some playing around. Without taking the baffle off, I stuck my fingers in the port hole and knocked of the tube. Instantly I heard more bass but still not as much as the one in the make shift enclosure. I then laid the box on its side and now it has almost the same bass as the other.
I guess its something to do with the woofers being near the carpeted floor and probably my only way to salvage this project is to add a second DA175 down low as some have mentioned.
Maybe its something to do with the room its in. My house is a raised ranch and the system is in the main part of the house consisting one big area 32ft X 30 ft, which is the living room. dining room, kitchen and front foyer. It also has cathedral ceilings.
Tony
Any way I did some playing around. Without taking the baffle off, I stuck my fingers in the port hole and knocked of the tube. Instantly I heard more bass but still not as much as the one in the make shift enclosure. I then laid the box on its side and now it has almost the same bass as the other.
I guess its something to do with the woofers being near the carpeted floor and probably my only way to salvage this project is to add a second DA175 down low as some have mentioned.
Maybe its something to do with the room its in. My house is a raised ranch and the system is in the main part of the house consisting one big area 32ft X 30 ft, which is the living room. dining room, kitchen and front foyer. It also has cathedral ceilings.
Tony
Ya you've been around the block.
Think I have the same BKprecision (an oxymoron) aka Circuitmat Function generator and eons ago and had the same Fluke77 (sold to my boss when upgrading to an 87 back in '90.) Next soldering station ought to be a Hakko, blow away both the Unger and Weller stations by a mile. Can't read the model # on the Tek DSO tho. Buddy of mine had the same little Oscope on the upper shelf.
Started out knee high to a billy goat and those landing gears are on my shelf too
You got landing gears on your workbench too? You have to tell me more. I got a garage full of RC planes.
Floor coupling adds ~6dB effectively eliminating the baffle step loss. In a 2way bookshelf the step forces you to reduce the mid/tweeter level by upwards of 6dB or more to compensate for the loss at the low end to sound flat. Like wise a 2.5way adds the second woofer to double the power driven in the low midrange and down. While this only adds an additional 3dB boost having full compensation is not recommended as it will become boomy and unnatural sounding. Only stuff like dubstep would be where we would even want more than full compensation
So your port right now is 2" diameter by 5" long, in approx. 1.3 ft³? That should work fine.. There will be a rising response without a proper crossover design, but you should have already heard that in your rough test box.
If the 17 liter box was sealed, you should have way more bass now. If the 17 liter was ported at a high frequency, though, you might have had a bass peak in that one. I am thinking that may have been the case? It would explain what you described when knocking the port tube off the current one, as that should also give you a peak in the 60Hz neighborhood (with a major loss of extension).
Make sure you're getting a good seal around the front baffle (including, especially, the bottom edge that would leak into the bottom chamber), put the tube back on, and evaluate with test signals below ~300Hz only, and/or get some significant inductance on that woofer.
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Thats a big space for some small speakers! It's not the carpet.
I'll save you here. Make another board, lets call it a shelf, but is solid. Subdivide the box by roughly half. I think a few posts back wires got crossed and we built a box for two drivers, not one. Dont dispair, it needed the height anyway. Think of it as a built in stand
Castle Creations speed controls/Axi and Mega motors (in and outrunners), have had my hand in building planes since I was a wee lad. Built or had a hand in building about everything
Love flying 3D best. Nothing better than a Spiraling Parachute maneuver and bury it in the pavement nose first and laugh about it. Next morning are back out with same plane pulling the same stunts
I'll save you here. Make another board, lets call it a shelf, but is solid. Subdivide the box by roughly half. I think a few posts back wires got crossed and we built a box for two drivers, not one. Dont dispair, it needed the height anyway. Think of it as a built in stand
Castle Creations speed controls/Axi and Mega motors (in and outrunners), have had my hand in building planes since I was a wee lad. Built or had a hand in building about everything
Love flying 3D best. Nothing better than a Spiraling Parachute maneuver and bury it in the pavement nose first and laugh about it. Next morning are back out with same plane pulling the same stunts
Tony, also make sure something else is not turned off (e.g. bass knob) or wires connected wrong, xo setting, etc.
Checked the 1.2cf box with a 2" x 5.75" long port, looks okay, that should be working.
Yes if you take the port off there will a lot of bass at a higher feq - balancing out the box, drivers, tweeters is a major goal.
Checked the 1.2cf box with a 2" x 5.75" long port, looks okay, that should be working.
Yes if you take the port off there will a lot of bass at a higher feq - balancing out the box, drivers, tweeters is a major goal.
The interior dimensions are 10"W X 10 1/4" D X 22" H. Before I took the speaker upstairs I did infact connect it to a signal generator. My signal generator has a 600 ohm output (think 600 ohm resistor in series from the output stage to the output jack) and therefore can only deliver a few hundred millivolts to an 8 ohm load. At 25 Hz I observed a huge rise in cone travel and a corresponding rise in impedance (the wave form on a scope rose). Sweeping further I saw another rise at 70 hz.
Tony
The smaller box was ported. I think the port was around 4" long which is probably wrong but it was just a makeshift setup but it is certainly giving me something to compare to. I'll try doubling up the inductance but there is no denying the rise in bass when I lay the speaker on its side. My wife hears the huge difference. Maybe we are just old bast**ds and cant hear too well. Is there some kind of simple online hearing test for these purposes?
Tony
Tony,
This is what I do with every BR speaker
You'll need a load resistor (can just make one).
The resistor will exaggerate the box tuning (should be near the 39hz). Just sweep the generator and jot down the two peaks and the valley frequencies; jot down the peak voltages also.
Also a good time to check out the bass response, check for knocks, air leaks, etc.
This is what I do with every BR speaker
You'll need a load resistor (can just make one).
The resistor will exaggerate the box tuning (should be near the 39hz). Just sweep the generator and jot down the two peaks and the valley frequencies; jot down the peak voltages also.
Also a good time to check out the bass response, check for knocks, air leaks, etc.
Attachments
Thats a big space for some small speakers! It's not the carpet.
I'll save you here. Make another board, lets call it a shelf, but is solid. Subdivide the box by roughly half. I think a few posts back wires got crossed and we built a box for two drivers, not one. Dont dispair, it needed the height anyway. Think of it as a built in stand
Castle Creations speed controls/Axi and Mega motors (in and outrunners), have had my hand in building planes since I was a wee lad. Built or had a hand in building about everything
Love flying 3D best. Nothing better than a Spiraling Parachute maneuver and bury it in the pavement nose first and laugh about it. Next morning are back out with same plane pulling the same stunts
I'm so confused about the speaker stuff. I probably should have posted my room dimensions first but really my house is not very big so I never thought it was significant.
Lets go off topic a bit. I've been flying for 40 years. Back in the day, if your plane went nose up you were in trouble and usually crashed. I don't know how you 3D guys do it. Theses days after 2 or 3 attempts I can get a plane into a hover. I can hold the hover for 5 seconds or so 10 the max. I have no problem with the roll correction but if the vertical attitude gets too far off I get totally confused with the plane pointing up especially when it needs rudder input and have to throttle up and abort.
Tony
Tony,
I just ran this driver through BassBox 6 Pro which has both the published specs for this driver (295-335) and a set of measured specs. Standard Bass reflex alignment with a 2" diameter port, normal dampening, golden rule enclosure.
The published specs give me a box size of 0.7'³, with an F3 of 36.5Hz.
The measured driver give me a box size of 0.78'³, with an F3 of 35.Hz.
In both cases driver would be over driven below cutoff with more than 25 watts so a high pass would be a safe bet.
If you want I can email you the full results.
I just ran this driver through BassBox 6 Pro which has both the published specs for this driver (295-335) and a set of measured specs. Standard Bass reflex alignment with a 2" diameter port, normal dampening, golden rule enclosure.
The published specs give me a box size of 0.7'³, with an F3 of 36.5Hz.
The measured driver give me a box size of 0.78'³, with an F3 of 35.Hz.
In both cases driver would be over driven below cutoff with more than 25 watts so a high pass would be a safe bet.
If you want I can email you the full results.
Easy peasy with a 2:1 thrust to weight ratio. When I started flying them the first thing I learned was do not build it like the instructions say. What they have you build will break something even with a perfect landing. Beef that puppy up with more carbon, like on the leading edge of wings, bit of tape and various foam safe adhesives. Normal built (no battery) weight should be ~10.5oz, whereas the properly built would weigh in at around say 12.5oz. Considering this additional weight gain one simply cannot ignore the the power plant. So look at what they recommend which normally results in a thrust to weight ratio of 1:1.1 - 1.2 ie just enough to hover and pull out. Now double the power result in a motor that weighs in at a whole whopping 1/2oz more, BUT! now you have a hungrier motor and bigger batteries are required. Typically my all up weight would be in the 15oz range, perfect 2:1 with flight times exceeding 10 minutes, depending on how much HOSSing it around ya did
Neighbors would gather around, made a few sick watching me fly in what I call RC control line. Where you fly in a perfect circle 3' off the ground no more than 15 feet away. Gotta have a good sense of balance with all the spinning around for 5+ minutes. Could pull out of a straight down dive less than 7' off the ground and hold it immediately in a hover at 3'. Lot of fun
Practiced everything on Reflex XTR (couple thousand of hours), bit cheaper than buying bearings from Boca or finding that you'll have to wait a few days for more glue < instead of a new plane!
Did some slope soaring 2m stuff, some of our local club heads out to Oregon /Washington Mt Hood area slooping it up every summer. Flying site here is a sod farm, big open spaces where we still manage to put planes in trees or even attacked by bald eagles! That's actually rather scary and happens at least once a year. I do wildlife rescue and know how the feds handle such potential situations, it's an OMG crash the plane to protect the bird.
What do you have hangin from the ceiling?
What they have you build will break something even with a perfect landing. Beef that puppy up with more carbon, like on the leading edge of wings, bit of tape and various foam safe adhesives. Normal built (no battery) weight should be ~10.5oz, whereas the properly built would weigh in at around say 12.5oz. Considering this additional weight gain one simply cannot ignore the the power plant. So look at what they recommend which normally results in a thrust to weight ratio of 1:1.1 - 1.2 ie just enough to hover and pull out. Now double the power result in a motor that weighs in at a whole whopping 1/2oz more, BUT! now you have a hungrier motor and bigger batteries are required. Typically my all up weight would be in the 15oz range, perfect 2:1 with flight times exceeding 10 minutes, depending on how much HOSSing it around ya did Neighbors would gather around, made a few sick watching me fly in what I call RC control line. Where you fly in a perfect circle 3' off the ground no more than 15 feet away. Gotta have a good sense of balance with all the spinning around for 5+ minutes. Could pull out of a straight down dive less than 7' off the ground and hold it immediately in a hover at 3'. Lot of fun
Practiced everything on Reflex XTR (couple thousand of hours), bit cheaper than buying bearings from Boca or finding that you'll have to wait a few days for more glue < instead of a new plane!
Did some slope soaring 2m stuff, some of our local club heads out to Oregon /Washington Mt Hood area slooping it up every summer. Flying site here is a sod farm, big open spaces where we still manage to put planes in trees or even attacked by bald eagles! That's actually rather scary and happens at least once a year. I do wildlife rescue and know how the feds handle such potential situations, it's an OMG crash the plane to protect the bird.
What do you have hangin from the ceiling?
Doug,
Two wired in parallel in a 1.3'³ box gives me an F3 of 37.25Hz, port 2.273" dia x 6.182" long. Looks very good!
Tony,
I'd still say shelve it but with this additional info applied and later if you want to add another for more bass, pull that shelf out and change the port. Same box and all is good
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Tony, I don't think you need to panic. Correct me if I am wrong.
You have about 35L with a 5.75" x 2" port and no xo to compensate for baffle step loss. The bass stinks.
Layed on the floor, baffle step loss in nullified and the bass is back. Is it enough or is it just ok?
Take the port out and now you essentially have a .75" x 2.25" tiny port and you hear more bass but it's not very satisfying.
Seems to me that you just discovered that you can very much hear the effects of the baffle step loss and different box tunings.
The 1st graph below compares each of these responses. Blue shows no baffle step compensation so the bass is going to be 6dB lower than the mids and thus unsatisfying. Black is similar to the boost from the floor working in conjunction with a much different baffle step loss point because the baffle width has also just changed from 11.5" to 34" by laying the speaker on its side. Better. And the violet shows a large 70 Hz peak from the wea little port the plywood provides that gives the impression of more bass but isn't really doing a very good job of it either.
So the take away is that once you add in a baffle step compensation circuit the sound is going to be more like the ported version on its side on the floor. And again, if your hearing is actually a little weak in the bass frequencies, then choosing an alignment that gives you about another 3dB boost may be the way to go.
I've been suggesting 28L tuned to 40Hz for a single woofer. The second graph shows just about the same response - 35L tuned to 37Hz and this is with the walls covered with foam. Port is 2" x 2.9". Try your currently ported version on its side on the floor and then maybe compare it with this shorter port. See which one you like better. These will be similar to what you'll hear with the speaker standing up and with the xo circuit attached.
You have about 35L with a 5.75" x 2" port and no xo to compensate for baffle step loss. The bass stinks.
Layed on the floor, baffle step loss in nullified and the bass is back. Is it enough or is it just ok?
Take the port out and now you essentially have a .75" x 2.25" tiny port and you hear more bass but it's not very satisfying.
Seems to me that you just discovered that you can very much hear the effects of the baffle step loss and different box tunings.
The 1st graph below compares each of these responses. Blue shows no baffle step compensation so the bass is going to be 6dB lower than the mids and thus unsatisfying. Black is similar to the boost from the floor working in conjunction with a much different baffle step loss point because the baffle width has also just changed from 11.5" to 34" by laying the speaker on its side. Better. And the violet shows a large 70 Hz peak from the wea little port the plywood provides that gives the impression of more bass but isn't really doing a very good job of it either.
So the take away is that once you add in a baffle step compensation circuit the sound is going to be more like the ported version on its side on the floor. And again, if your hearing is actually a little weak in the bass frequencies, then choosing an alignment that gives you about another 3dB boost may be the way to go.
I've been suggesting 28L tuned to 40Hz for a single woofer. The second graph shows just about the same response - 35L tuned to 37Hz and this is with the walls covered with foam. Port is 2" x 2.9". Try your currently ported version on its side on the floor and then maybe compare it with this shorter port. See which one you like better. These will be similar to what you'll hear with the speaker standing up and with the xo circuit attached.
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Hi,
Bass tunings and power handling is covered here :
Zaph|Audio - Bargain Aluminum MTM
Also note one driver would need double the series
inductance (and half the capacitance) in the x/o.
https://sites.google.com/site/undefinition/hitmakers
Is a nearfield (less BSC), still uses 2mH series +cap.
rgds, sreten.
Bass tunings and power handling is covered here :
Zaph|Audio - Bargain Aluminum MTM
Also note one driver would need double the series
inductance (and half the capacitance) in the x/o.
https://sites.google.com/site/undefinition/hitmakers
Is a nearfield (less BSC), still uses 2mH series +cap.
rgds, sreten.
Thanks sreten. I hadn't gone searching for the DA175 in other projects.
Tony, let's also take a look at the alignment that seemed to work better for you - your 1st attempt in a smaller box. What was the internal volume, the baffle dimensions, the port dimensions and the set-up situation (eg sitting on top of your test bench)? That will give us more info to work with.
Tony, let's also take a look at the alignment that seemed to work better for you - your 1st attempt in a smaller box. What was the internal volume, the baffle dimensions, the port dimensions and the set-up situation (eg sitting on top of your test bench)? That will give us more info to work with.
Also ment to ask what the internal dimensions were. The height/ driver/port position may have an effect akin to a improperly designed MLTL. The shelf would help here if it is. Will model that too if you need.
Besides, for your first outting, you're doing fine.- No screwdriver through the surround/cone like most of us have at one time or other, nice looking boxes and a simple tweak to fix
Besides, for your first outting, you're doing fine.- No screwdriver through the surround/cone like most of us have at one time or other, nice looking boxes and a simple tweak to fix
I'm not panicking. This is fun, but just when I think I'm learning , something happens to contradict what I learned. Yes you are correct its 35L with a 5.75" x 2" port and no xo to compensate for baffle step loss but no tweeter hooked up either.
When I had it standing up and the 5" port still in there, when I covered the port with a block of wood, I heard no discernible difference in bass. Now with he 5" port removed, when I cover the port opening I hear a big drop in bass. So it seems to me the 5" port was doing nothing.
I have an Overnight Sensation MTM here that I built for fun. I had posted in another thread here that I thought it was muddy sounding and lacking in the midrange. That was with it sitting on the floor. I never tried it raised off the floor. I don't know if it will prove anything but I'm going to try it right now. If that sounds like it has no bass then my situation is probably hopeless. I'll post what I find soon.
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