Focusing on the Seas project. Got them into sanding sealer. The big 3/4 inch round over worked great. I still have a lot of crossover work to do.
I like the visual of the multi-ports on the side, but the measurements I did on diffraction with a moc-up was not much better than a square edge. I have some ideas to take his design to the next visual but with a different driver. I have two other projects that need front ports.
I use WinISD too. I'll pull a Fostex out of the box and do the measurements myself. We should not be getting different answers. I probably typed something incorrectly.
I like the visual of the multi-ports on the side, but the measurements I did on diffraction with a moc-up was not much better than a square edge. I have some ideas to take his design to the next visual but with a different driver. I have two other projects that need front ports.
I use WinISD too. I'll pull a Fostex out of the box and do the measurements myself. We should not be getting different answers. I probably typed something incorrectly.
TVR, did find notes/pics on this box, it was 66hz before I went crazy and cut the sides off. 
I also see 4 strips, which agrees with the previous post.
They didn't have much bass (and why I cut the sides off); I'm pretty sure it sure it should be in the low 60s - also Fostex recommends 57hz.
What did you put the sander sealer on; wood veneer?
I also see 4 strips, which agrees with the previous post.
They didn't have much bass (and why I cut the sides off); I'm pretty sure it sure it should be in the low 60s - also Fostex recommends 57hz.
What did you put the sander sealer on; wood veneer?
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MDF. Just did the first sand and a second coat. I am going to paint these. The last set I used automotive lacquer based primer. Easy to work with, quick drying, but i had a heck of a time getting it sealed so the top coats ( Dupont Centuri) did not go as well as I wish. Considering what a quart of that stuff runs, you don't want any problems. I am going to talk to the paint rep about that some more.
Boxes are drying, so let me look at the Fostex specs again and see why our sims looked different.
Boxes are drying, so let me look at the Fostex specs again and see why our sims looked different.
Actually, new cars have to be water based acrylic. Never dealt with that stuff. As I don't have a powered suit, I have not played with Imaron either, but what a tough finish. The old standard non-activated acrylic is pretty forgiving. If you don't add accelerator, it does take days. I might spring for the extra this time. The brown metallic I used on my last set wound up being about $200 total for the paint. Brown is expensive. This time I think it is going to be green about two steps away from black. It looks like the water born has finally been worked out, so I should talk to the rep about it. The guys over in Beltsvillle are pretty patient with us non-tradesmen hacks.
As I suspected, I had some wrong values for the FF125WK. 9L, 63 Hz looks very good. Now I am going back to what I measured in your boxes and wondering why the response was not quite as solid.
I really don't see an advantage of tuning it lower. Another alignment would be 3L sealed for desktop speakers. (with sub). I bought some Fountek to play with like that too. All of them still need a tweeter!
When you get to using lots of small vents, calculations change as the friction in the ports becomes significant. It is no longer just cross section and length. Dynaco made good use of that years ago. Go for it. Anything to break up the square brown or black box!
As I suspected, I had some wrong values for the FF125WK. 9L, 63 Hz looks very good. Now I am going back to what I measured in your boxes and wondering why the response was not quite as solid.
I really don't see an advantage of tuning it lower. Another alignment would be 3L sealed for desktop speakers. (with sub). I bought some Fountek to play with like that too. All of them still need a tweeter!
When you get to using lots of small vents, calculations change as the friction in the ports becomes significant. It is no longer just cross section and length. Dynaco made good use of that years ago. Go for it. Anything to break up the square brown or black box!
Trick. Come Christmas, check all the paper wrapping paper tubes and see if any two fit snugly inside each other. Really cheap way to make adjustable ports for test. I don't do many ported boxes, but when I do, I put the port on the outside so changing it's length is easy and does not effect the box volume. When done, I build a new box taking the port volume into consideration.
That might be a long wait....haha PE has quite the selection of adjustable ports.
Friction in the ports,,,hummm that what this box needs, I think the vents are too thin now (having flashbacks). I'll be using the clamp-it-together-ploy to tune it, no calculations here!
The large 125wk boxes you have........if you add volume somehow (sand?) won't that drive up tuning frequency? I hope you have been breaking in your full range drivers.
Speaking of full range, my friend ended up with an vintage 80s McIntosh (mid level), I could probably swing a trade; it does work, would it need cap replacement?
Model MA6200
Friction in the ports,,,hummm that what this box needs, I think the vents are too thin now (having flashbacks). I'll be using the clamp-it-together-ploy to tune it, no calculations here!
The large 125wk boxes you have........if you add volume somehow (sand?) won't that drive up tuning frequency? I hope you have been breaking in your full range drivers.
Speaking of full range, my friend ended up with an vintage 80s McIntosh (mid level), I could probably swing a trade; it does work, would it need cap replacement?
Model MA6200
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More friction!!...don't want that with this box - now that you have informed me.
Second idea, use two strips and make a simple "<" in the slot, tune with clamps, adjust as needed. That will give me 2 small "horn" shapes on both sides. I guess I could curve them also.
A lot of small commercial speakers flare their ports.
A tweeter with Fostex; well that's a 2-way so I guess we are safe here
(-0;
Second idea, use two strips and make a simple "<" in the slot, tune with clamps, adjust as needed. That will give me 2 small "horn" shapes on both sides. I guess I could curve them also.
A lot of small commercial speakers flare their ports.
A tweeter with Fostex; well that's a 2-way so I guess we are safe here
(-0;
Flaring ports has several advantages. The best description to understand it were some drawings in David Vizzard's book on modifying the BMC-A engine. Basically, without at least a 270 degree flair and initial taper, the effective diameter is actually much smaller, but the mass in the port remains the same. This is a recipe for chuff-chuff noises and also requires differenced port length calculations. When feeding old British sports cars, the correctly designed "velocity stacks" meant as much ad 10% more power. This is fluid dynamics. The math is way the heck beyond me. I use a sim to get close and tune to measure. I would be concerned with the above picture that you will get wind noises by the relative small opening on the box end compared to the mass of air in the port. You have also built 4 Helmholtz resonators ( notch filters) in the cavities top and bottom unless you block the inlet to them. Only your ears will know for sure. You are using unconventional approaches, so we are just guessing until you listen to them. I'll take results over theory any day.
I am just not getting the low end response out of the FF125wk as the model suggests.
Even the 11L boxes, they roll off at 200. The 6800 resonance is really bad. It is interesting to compare ARTA to TrueRTA. As bad as the breakup is, I am wondering if 5K crossover is too high. The harmonic distortion of this guy is pretty high.
To confirm your box building, the big wad of stuffing does help measurably in the 600 t0 800 region.
Even the 11L boxes, they roll off at 200. The 6800 resonance is really bad. It is interesting to compare ARTA to TrueRTA. As bad as the breakup is, I am wondering if 5K crossover is too high. The harmonic distortion of this guy is pretty high.
To confirm your box building, the big wad of stuffing does help measurably in the 600 t0 800 region.
I just finished doing my own TS measurements on the Fostex. Qes came in at .56 and Qms at 7.35. Fs was 72 with VAS at 7.3L. Not as far off as I have seen. Usually it is VAS they lie like a dog about but this is only a couple of percent. The frequency response on the spec sheet, though very small, is closet to what I measure than the model. Of course, it does not show baffle step but the bad breakup at 6800 is there for all to see. I can't see how anyone could consider this driver a full range. A 200 to 2K is more like it. Even that, the harmonic distortion is about 3.5% This means the 11L boxes are tuned at 60 Hz. I think I would try them at 75 Hz. I am going to play with the electronic LR-4 crossover between 3 and 4K to see if it handles the resonance OK. Not as high as I want, but well into the easier range for a dome tweeter. Too low for a ribbon. I can try LR6, but that does force one to stay electronic.
I did not get the concepts across well enough, so let me try again. This is hard to explain without a picture. It has nothing to do with the length of the port being tapered. Remember, air is going both ways in the port. It should be symmetrical.
The sharp edge at each end causes turbulence that effectively narrows the size of the port. The radius reduces this turbulence. Each sharp edge adds about 10% to the "perfect" port length. To make it even more complicated, it varies with velocity. Flaired ports are both shorter and more consistent.
The sharp edge at each end causes turbulence that effectively narrows the size of the port. The radius reduces this turbulence. Each sharp edge adds about 10% to the "perfect" port length. To make it even more complicated, it varies with velocity. Flaired ports are both shorter and more consistent.
It's not that bad..have you ever heard a speaker image better?
2k? That sounds really low
It's a nice little speaker, lacking a little low - lacking a little high (it must be.........)
I did understand what you saying about the flare ports, yes all guess work at this point. Going to spend a little time on them and see if I can enhance the bass (yes yes, considered cheating in the HyFy world).
2k? That sounds really low
It's a nice little speaker, lacking a little low - lacking a little high (it must be.........)
I did understand what you saying about the flare ports, yes all guess work at this point. Going to spend a little time on them and see if I can enhance the bass (yes yes, considered cheating in the HyFy world).
Heard a speaker image better? Yes. But it is not just the speaker that is the magic. It is the room and room treatments. I can bring my little Dayton RS/Vifa's out and you will probably not like them. Crossover is not as good as it can be and the tweeter is,well a $25 tweeter. But, where they are sitting with my panels and room arrangement, the imaging can cause one to do a Tex-Avery. That is the eyeballs pop out and jaw extend to the floor Wil E. Cyotee stuff when sounds come from outside the speaker widths and from behind the wall. The edginess and lack of top octave of the Fostex stops them cold. I think they have great potential. For me, full range is not it.
On the other hand I was checking out the current market and listened to some of the current $3 to $6K speakers out there. In the room where they had them, all of the imaging was point-source from the box or a narrow line between them. No depth, no height.
I was thinking last night about modifications to the driver. One could dope it with a very rigid material, raise the breakup frequency, only slightly increases mass, lowering Fs and increasing VAS. Or, dope them with a very low modulus to try and control the breakup, probably increasing the mass even more and moving their roll off even lower. I may play with this on some much cheaper parts first. Fostex is not a fool, so making it worse is probably much easier than making it better.
Why a low crossover? To get far enough away from the breakup modes. The steeper the crossover, the higher. I don't do 4th order passive. Just too complicated and expensive. So I would prefer to be two octaves away. Hooking up my DCX today to see what dialing in some BSC, 6th LR crossover and the XT25's will sound like. These 11L boxes may be a candidate for a small side firing woofer. 50 to 200. They behave so large as the tuning does very little. Almost IB. I added my blocks to bring them down to 7.5L and played with smaller ports. Nothing helped much.
More java and time to get busy. All out of primer for the SEAS boxes.
On the other hand I was checking out the current market and listened to some of the current $3 to $6K speakers out there. In the room where they had them, all of the imaging was point-source from the box or a narrow line between them. No depth, no height.
I was thinking last night about modifications to the driver. One could dope it with a very rigid material, raise the breakup frequency, only slightly increases mass, lowering Fs and increasing VAS. Or, dope them with a very low modulus to try and control the breakup, probably increasing the mass even more and moving their roll off even lower. I may play with this on some much cheaper parts first. Fostex is not a fool, so making it worse is probably much easier than making it better.
Why a low crossover? To get far enough away from the breakup modes. The steeper the crossover, the higher. I don't do 4th order passive. Just too complicated and expensive. So I would prefer to be two octaves away. Hooking up my DCX today to see what dialing in some BSC, 6th LR crossover and the XT25's will sound like. These 11L boxes may be a candidate for a small side firing woofer. 50 to 200. They behave so large as the tuning does very little. Almost IB. I added my blocks to bring them down to 7.5L and played with smaller ports. Nothing helped much.
More java and time to get busy. All out of primer for the SEAS boxes.
I worked on this a bit today, I cut some wider boards and cut them horn shape. They lowered the tuning quite a bit; so just kept trimming them as needed to bring it back up.
With the lower tuning (low 50s) the bass rolled off more smoothly, so as I trimmed the boards I stopped at 60hz.
This is where I starter to hear the "loud" uneven sound I heard yesterday around 55hz.
The roll off is somewhat even now (tuned at 60hz).
(Fostex does recommend 57hz in a 9 liter box)
With the lower tuning (low 50s) the bass rolled off more smoothly, so as I trimmed the boards I stopped at 60hz.
This is where I starter to hear the "loud" uneven sound I heard yesterday around 55hz.
The roll off is somewhat even now (tuned at 60hz).
(Fostex does recommend 57hz in a 9 liter box)
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Did a bunch of impedance sweeps and then crunched the numbers. ( I need to build a spreadsheet for this before I wear out my D'Appolito book)
The 11L box is in fact tuned at 67Hz. By blocking some of the port, I could reduce the tuning to 44Hz. Reducing the box to 7.5L I could tune between 64 and 532 Hz. Of course, lowering the tuning is the opposite direction we need as we are looking for a broad hump before rolloff 100 to 200Hz If I were to pick an alignment from comparing the models with the measurements, I would go 7.5L at 75Hz.
I still don't know where you are going with that horn shaped port. Other than looks, what is it you are trying to achieve?
The 11L box is in fact tuned at 67Hz. By blocking some of the port, I could reduce the tuning to 44Hz. Reducing the box to 7.5L I could tune between 64 and 532 Hz. Of course, lowering the tuning is the opposite direction we need as we are looking for a broad hump before rolloff 100 to 200Hz If I were to pick an alignment from comparing the models with the measurements, I would go 7.5L at 75Hz.
I still don't know where you are going with that horn shaped port. Other than looks, what is it you are trying to achieve?
In a few words... trying to warm the speakers up a bit, a little more umpf in the low end.
I made 4 pairs of boxes, I think this pair might be heading in the right direction.
Will be gluing sides and trimming later today.
One thing nice about this, I can add damping material in the top and bottom of box, no worries about it getting into the slot.
*The square boxes you have...could cut an angle on back(s) making them smaller.
I made 4 pairs of boxes, I think this pair might be heading in the right direction.
Will be gluing sides and trimming later today.
One thing nice about this, I can add damping material in the top and bottom of box, no worries about it getting into the slot.
*The square boxes you have...could cut an angle on back(s) making them smaller.
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