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Advices on First Crossover Design (VituixCAD2)
Advices on First Crossover Design (VituixCAD2)
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Old 19th July 2019, 09:16 PM   #381
MrZoltan is offline MrZoltan
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Join Date: Nov 2018
Quote:
Originally Posted by ScottG View Post
-of course don't forget that you are still "gating/windowing".

(..and will need to do a near-field measurement for freq.s lower than 300 Hz.)


Still, what you are typically "shooting" for here is about 500 Hz for most of the baffle effects on dispersion. (..for a typically "narrow" baffle loudspeaker.)


Note: the results of the rear of the open-box will look weird.

Yeah I still have to gate, I have noticed by doing so it smooth the frequency response but I suppose I should not have too much invisible dip & peaks because of that


Yep near-field at -20db, will not forget



I don't understand what you mean by shooting for 500Hz, do you speak about the accuracy of the measurement ?


So at first measuring on just the front baffle without box there is not point passing 90 and even I should get some wave cancellation in some frequencies because it's a narrow baffle and back-wave will cancel front-wave (if I understand right)



I suppose It's only when the cabinet is complete that this can be useful to measure 180


So when you say weird at the rear is it about that Mid High open cabinet or just the front baffle ?
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Old 20th July 2019, 05:23 PM   #382
ScottG is offline ScottG  United States
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500 Hz presents a lower freq. limit where most diffraction effects for typical speakers are relatively uniform. As you go higher in freq. diffraction effects start becoming less uniform.

-of course with your loudspeaker design that's not true because of the open-box design: the dispersion pattern toward the open-rear of the loudspeaker (for mid + tweet) will look quite different: showing a lot of diffraction artifacts that won't look anything like the frequency response of the front/baffle of the loudspeaker. (ie. "weird" looking.)


..and yes, 180 degrees for the loudspeaker box. About 72 degrees for a test baffle.
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Old 20th July 2019, 09:37 PM   #383
MrZoltan is offline MrZoltan
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Quote:
Originally Posted by ScottG View Post
500 Hz presents a lower freq. limit where most diffraction effects for typical speakers are relatively uniform. As you go higher in freq. diffraction effects start becoming less uniform.

-of course with your loudspeaker design that's not true because of the open-box design: the dispersion pattern toward the open-rear of the loudspeaker (for mid + tweet) will look quite different: showing a lot of diffraction artifacts that won't look anything like the frequency response of the front/baffle of the loudspeaker. (ie. "weird" looking.)


..and yes, 180 degrees for the loudspeaker box. About 72 degrees for a test baffle.

Ok clear to me now thanks


I hope that 100uf capacitor is enough to protect that tweeters when I will make measurements, If I measure it at around 75dB taking into account the natural roll-of of the driver it start to go down at 378hz and reach 55Hz at 40dB


I'll have to help my parents to pack & move to a new place, once that is done I'll begin working on the front baffle, I really need to start making some progress
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Old 24th August 2019, 07:58 PM   #384
MrZoltan is offline MrZoltan
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Hi Scott,


It's a long time already, how are you?


I have started the front baffle boards, cutting, and glue them together, I did some routing but it's more difficult than I thought to be precise when cutting, that depth slider isn't holding very well so I have to start again, tweeter cutout is not accurate enough I can't see very well where is my router bit


I'll do a few hours every Saturday it's slow but hopefully I will end up with something that pass my quality expectation.


I find it more difficult to cut squares for the tweeter wave-guides, I'm happy I started with the cheapest MDF I could find!


Have a nice Weekend
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Old 24th August 2019, 08:38 PM   #385
ScottG is offline ScottG  United States
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-good enough.

I just started on my dipole bass baffle today. (..I got side-lined with a *project that got "binned" yesterday.)


*DirecTV (satellite TV provider raised their rates more than double, and I was planning on ditching them this month - scrambling to get an alternative up before then, when they called-up and offered the service at $10 less than I was paying before: so now I've got to return a bunch of stuff I ordered.)
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Old 24th August 2019, 08:44 PM   #386
ScottG is offline ScottG  United States
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Originally Posted by MrZoltan View Post
..depth slider isn't holding very well so I have to start again..
That's a bummer.

Yeah, it's definitely a matter of practice and the "jig's" you use (and often create yourself).

Square cuts? Saw. (..of course if it's an "internal" cut, then it's usually jigsaw with a guide/jig and a fair bit of small-block hand-sanding.)
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Last edited by ScottG; 24th August 2019 at 08:48 PM.
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Old 25th August 2019, 09:16 PM   #387
MrZoltan is offline MrZoltan
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Originally Posted by ScottG View Post
-good enough.

I just started on my dipole bass baffle today. (..I got side-lined with a *project that got "binned" yesterday.)
Great news, do you plan to share some details about that dipole baffle ?



Quote:
Originally Posted by ScottG View Post
*DirecTV (satellite TV provider raised their rates more than double, and I was planning on ditching them this month - scrambling to get an alternative up before then, when they called-up and offered the service at $10 less than I was paying before: so now I've got to return a bunch of stuff I ordered.)
That seem to be a good news in the end, had a look on the DirecTV website out of curiosity and none of the channels are available here, but I rarely watch any I have here anyway I can't bear the amount of advertising and the content is old compared to what I can get on Internet.
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Old 25th August 2019, 09:31 PM   #388
MrZoltan is offline MrZoltan
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Quote:
Originally Posted by ScottG View Post
That's a bummer.

Yeah, it's definitely a matter of practice and the "jig's" you use (and often create yourself).

Square cuts? Saw. (..of course if it's an "internal" cut, then it's usually jigsaw with a guide/jig and a fair bit of small-block hand-sanding.)

Yes my Jig's game is really nowhere, I have the one that is delivered with the router but it's quiet limited what I can do with it.


I have seen a few video about making a circle cutting Jig for small and big radius but I have yet to find which I will make, I wish I could buy one that fit my router so I don't have to spend extra time on that.



The square is to flush the Radian Waveguide, so I have to use a router, I either have to buy the Triton guide bushes kit but I find it very expensive for what it is, or buy myself a straight bit with a bearing on top so I can cut myself a guide with a jigsaw to limit my cut



I ended up going out of lines, can't see very well where the bit is in relation to the markings through that plexi and I have to be more gentle when plunging so I don't force that depth limiter beyond what I set.
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Old 25th August 2019, 10:19 PM   #389
ScottG is offline ScottG  United States
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Great news, do you plan to share some details about that dipole baffle ?




That seem to be a good news in the end, had a look on the DirecTV website out of curiosity and none of the channels are available here, but I rarely watch any I have here anyway I can't bear the amount of advertising and the content is old compared to what I can get on Internet.

The baffle I just routed is barely large enough to mount the two 15" drivers (..still have to drill the bolt-mounts). Once I've figured-out orientation in-room it will get attached in a much larger "baffle" path-length (for phase cancellation/dipole) under the rear seats for the HT. Basically a tiny baffle mounted on a much larger "baffle" that utilizes the room floor and the raised seating area floor.


Advertising sucks. ..but it's what pays for all those new-content shows. Plus, I pretty much record everything and then FF through the commercials. It's super annoying with Movies that have been chopped-up, BUT with DirecTV they usually have a weekend every quarter with free access to premium channels like HBO, and at that time you just record every movie you are interested in. It works out for my family in particular because of the integrated guide (both local channels and "cable" channels on the same guide). The solution I was looking at to replace it was "over-the-air" for local broadcast channels (plus an automatic commercial skip solution from MythTV) and then adding-on SlingTV Blue w/DVR for that. While there is an ability to integrate them both on the same guide, you can't really do that AND have a complete commercial skip result for local channels. Except for hardware costs it would have been cheaper still, but several android TV boxes plus a PC server to record local shows would have added at least $600 done the way I wanted. DirecTV (for at least a year then) will be about $47 a month with taxes (where before it was close to $60). This last month after the price hike it was near $130 a month (but I got a $70 rebate for the last month as well). So at least I have it cheap"ish" for a year. Tried to get a lower rate on my internet (which is about $60 a month), but no luck there - no real alternatives in my area (..sort of "p!$$!ng in a pond").
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Last edited by ScottG; 25th August 2019 at 10:27 PM.
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Old 25th August 2019, 10:47 PM   #390
ScottG is offline ScottG  United States
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Quote:
Originally Posted by MrZoltan View Post
I have seen a few video about making a circle cutting Jig for small and big radius but I have yet to find which I will make, I wish I could buy one that fit my router so I don't have to spend extra time on that.
I just did this for my 15" driver holes.

Here you are making a new "base-plate" for your router (you do NOT use the base plate on your router, but you do use the screws that the plate is using for attachment to your router).

Had some floor ceder plank scrap wood (the type used in closets to keep bugs out) that was reasonably thin (slightly thicker than my router's base plate) and just wide enough for 2 of the 3 mounting screws that the router base-plate uses. Note: you need two mounting points as a minimum, but preferably as many as your router has. In this case though my scrap wood wasn't wide enough to accommodate all 3 mount-points.

Marked-out center on the board and then drilled a hole large enough for a phillips head screw driver to slide into it firmly. Made an identical hole for the ceder plank on one end. Made sure the screw driver would fit/couple the two boards together but still allow for rotation.

Measured from the center of that baffle hole out to half of the driver's diameter and then subtracted the amount for the mounting "lip" of the driver and made several lines showing where the router hole would be with the ceder plank covering that hole area. Then put the ceder plank onto the board with the screw driver in the center hole, and then marked the location for the router bit hole on the ceder plank. Drilled the (slightly larger than) bit-sized hole through the plank and board.

Then I pulled the plank off (pulled out the screw driver) and then mounted the plank on the router's bit. Moved it back and forth until I found where two of the base-plate holes would fit on the plank, drilled them and then used a counter-sink drill bit to allow the base-plate screws to mount flush (slightly inset actually) to the board. Attached the ceder plank to those base-plate screw holes with the base-plate's screws (..basically replacing the base-plate).

Finally: put the router bit through the router "outside" hole on the board to be cut and moved the plank to where the other holed lined-up with the center hole and pushed the screw driver through it.

Then I powered up the router and cut the circle.

..and did the other hole (though much easier, just taking off the ceder plank from the router and using it as a guide for the two other holes for the other 15" diameter hole).

..though in my case the two 15" holes I cut weren't quite lined-up, so one of the drivers is going to be slightly off-set from the other.
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Last edited by ScottG; 25th August 2019 at 10:57 PM.
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