No, no problems using screws or nails. Technically, the glue is doing most of the work...to a certain extent, the nails or screws are just holding the joint together while the glue cures.
Enjoy the benefits of a premium membership!
Upgrade Account
-
TalkBass has been independent since 1998. Add your voice.
Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
Join free Log in
Want zero display ads or expanded classifieds tools? Compare plans.
DIY - 212 cabinet - help with ports calculation
- Thread starter KoziejMaclowski
- Start date
-
- Tags
- diy cabinet
Are you in the Czech Republic? Or my second guess, Poland? Based on nothing more than your name, of course. My apologies for being a dumb American about it...just interested.
I guess I wasn't keeping up... I didn't know you had decided to go with a HF unit. Do you have a specific driver in mind?
First thing: I'm not an expert on passive crossover design...I've been an active crossover guy my whole career. I'm only just learning how much I don't know about it. So take this for what it's worth.
Philosophically, there's a lot to be said for just using a high-pass filter on the HF unit and letting the cone drivers roll off naturally. And using a 2-pole filter for that.
OK, I guess that's it. I'm personally not in favor of 2-way boxes with compression drivers for bass speaker systems, but there is a large contingent of folks here who really like them. IF I was going to go for a 2-way system, I'd use a cone-type mid-range driver like a 150mm and go for a much lower crossover point. I'd still just use a 2-pole high-pass filter.
But I'm happy enough with a single driver system for bass...I don't need the additional high end for my own taste and style. No disrespect is intended for the full-range guys, but it's just not my thing. I've been learning about passive crossovers in hopes of upgrading my beloved JBL monitors. And maybe building something nice to listen to music on in the living room...I've got loads of good components, but I'm thinking bi-amping is a little too complicated for my home stereo.
Philosophically, there's a lot to be said for just using a high-pass filter on the HF unit and letting the cone drivers roll off naturally. And using a 2-pole filter for that.
OK, I guess that's it. I'm personally not in favor of 2-way boxes with compression drivers for bass speaker systems, but there is a large contingent of folks here who really like them. IF I was going to go for a 2-way system, I'd use a cone-type mid-range driver like a 150mm and go for a much lower crossover point. I'd still just use a 2-pole high-pass filter.
But I'm happy enough with a single driver system for bass...I don't need the additional high end for my own taste and style. No disrespect is intended for the full-range guys, but it's just not my thing. I've been learning about passive crossovers in hopes of upgrading my beloved JBL monitors. And maybe building something nice to listen to music on in the living room...I've got loads of good components, but I'm thinking bi-amping is a little too complicated for my home stereo.
any ideas for mid range driver? I was thinking about that, but I think adding mid range speaker will complicate cabinet design (need for separate chamber??) thanks for tip I will make some prototype first crossover without low pass filter, only hp for tweeter and see how it works
I don't have any recommendations for mid-range drivers. I'm experimenting with some old drivers because that's what I already have. There are a lot more good drivers in that category than there used to be...I'm sure someone will contribute their better info about them soon enough.
But yes, adding a mid-range speaker would complicate your design considerably. I suggest designing for the 2-way speaker, but just building the 212 box first with plans to add the HF unit later if you decide you want that. As usual, it's just my 2-cents worth.
But yes, adding a mid-range speaker would complicate your design considerably. I suggest designing for the 2-way speaker, but just building the 212 box first with plans to add the HF unit later if you decide you want that. As usual, it's just my 2-cents worth.
I mounted 12pr300 drivers to my old cabinet and made some temporary ports. Yesterday my friend that is much better bass player than me, listened to it. Told me that it's much better than old ones drivers, progress is huge. But told also that I still need a tweeter. So I thinking about that.
I allready bought black mdf 1000x700 for front panel, waiting for delivery.
Problem is with other panels. I was about baltic britch. But hard to get here in Kraków good one BB or BB/CP. I heard that poplar wood is also recomended? Is that right?
I allready bought black mdf 1000x700 for front panel, waiting for delivery.
Problem is with other panels. I was about baltic britch. But hard to get here in Kraków good one BB or BB/CP. I heard that poplar wood is also recomended? Is that right?
You'll figure just the same "science" for passive filters as is common known for active filters.
1st order or second order or anything else that shows even higher order numbers for the slope
Type of filter alignment such as Butterworth or Bessel or Chebyshev or Linkwitz-Riley etc.
The type of filter alignment tells something about step response and group delay and damping (filter Q).
- Feb 12, 2006
- 61,010
- 5
- 220,847
- Disclosures
- Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
Of course the challenge with passive filters is that while the source impedance is low and fairly linear, the load impedance is not. This affects very much how the filters operate in the real world, and also limits the possible alignments that are possible due to the lack of feedback necessary for higher Q filters.
This is an area where experience helps, not just experience with filters but experience with a wide variety of drivers and the loads the present to the filters. In some cases there is a lot of latitude with the results and in other cases no matter how hard you try you "can't get there from here". Having this experience goes a long way towards effective results, and without wasting a LOT of time and money using trial and error methods.
This is an area where experience helps, not just experience with filters but experience with a wide variety of drivers and the loads the present to the filters. In some cases there is a lot of latitude with the results and in other cases no matter how hard you try you "can't get there from here". Having this experience goes a long way towards effective results, and without wasting a LOT of time and money using trial and error methods.
I said I wasn't an expert...I didn't say I doesn't know nothin'. For the longest time, I knew about as much about passive crossovers as a race-car engine builder knows about hydraulic lifters...I knew enough to know that it wasn't high-performance enough for my purposes. And then when 4th-order, state-variable active filters became cheap and common in the early 80's, I stopped caring too much about anything else...that did the job plenty well enough, at least until the digital era came along and blew the roof off more exotic filter design. To this day, I don't understand why the audiophile world messes around with passive crossovers when the whole function is so much more easily accomplished in the active domain.
Anyway, I recommended a 2nd-order filter because of the traditional wisdom of a 12dB filter being 180-degrees out-of-phase at crossover; that being dealt with by a simple polarity reversal. That, and the advantages that come with the steeper slope than his proposed first-order design. IME
As far as the 'science' is concerned, I don't recall seeing too many inductors being used in active filter design...at least not since the 70's. But as I've gotten interested in designing some passive crossovers for home stereo purposes, I'm learning that there's a lot more variables involved that my previous understanding was allowing for. Once again, I'm learning the key to learning is understanding what I don't know.
Especially with the opportunity to sell power amplifiers individually tuned for each frequency domain, and of course so many more $500 connection cables...
[later]
I have a sudden vision of different spec connection cables for each frequency domain. I mean, obviously tweeter speaker leads must need to be quite different to sub bass speaker leads because of physics...
Last edited:
Active filters "emulate" inductive property via the feedback loop. That's the reason why there is no need for inductors with active filters AND also provides the possibility to "emulate" even very large inductors.
The math of filters in general does NOT take into account the way how the filter is realized in practice. For (general) filter math it makes no difference if the filter was designed as passive filter or active filter.
In first place filter math deals only with filter Polynomes rather than any magnitude for "C" or "L" or "R" or the presence of "active elements" within the schematic.
btw, even with active filters its not so bad to know one or two things about (general) filter math. It helps a lot to "trade off" essential filter properties (for example step response) vers application respectively desired audio properties.
Last edited:
12dB/octave filters (2nd order filters) are rarely (if ever) critical with step response and group delay issues while the 180 degree phase shift at f3 is actually the worst case scenario at f3 you can get.
A 4th order filter would shift the signal by 360 degree which in total would equal the exatly the same as 0 degree of shift.
High order filters such as 4th order filters can be critical in regards of damping and group delay. That's the main reason why Tschebyshev alignmet isn't popular for audio designs and we see more of Butterworth and Linkwitz-Riley stuff or something in between.
Last edited:
I really do suspect that dollars does figure into it. After you've spent $10-20K on a power amp, it might be hard to justify spending another bunch of bucks on another one. Spending mega-bucks on the most pristine signal path, but then pushing the final signal through a passive crossover, no matter how exquisitely designed, just doesn't add up for me. It's kind of like putting Firestones on your Ferrari. On the other hand, for my ordinary plebian listening environment at home, passive crossovers are good enough...at least as far as the trade-off of the additional complexity goes. Plus the old Spouse Approval Factor starts to figure in.
Now I guess I'll pull on the old flame suit for when the Firestone tire aficionados start in on me.
I'm not sure what you're saying here. Are you suggesting the OP should be designing and building a 4th-order passive filter for his project?
Nope, nothing at all.
But I wouldn't suggest a 2nd order due to only 180 degree of shift vers more of shift which comes (naturally) along with higher order filters than 2nd order.
Phase shift is kinda most overthinked issue with filters and I think very often poorly understood even by engineers.
My theory was along the lines of this was for something that was going to be built, not a mathematical exercise. Or am I overestimating the difficulty of realizing a 4th-order filter in the passive domain?
Also, and again, I don't really know that much about it, as must be painfully obvious: If a 4th-order filter is employed and the output is delayed 360 degrees, the result is now delayed by one full cycle, rather than a portion of one, right? Is that an improvement over the 180-degree inversion? And as far as the phase relationship at F3, isn't that addressed by keeping the crossover point well above that point? Sorry if these are dumb questions...I'm still trying to figure this stuff out.
Also, and again, I don't really know that much about it, as must be painfully obvious: If a 4th-order filter is employed and the output is delayed 360 degrees, the result is now delayed by one full cycle, rather than a portion of one, right? Is that an improvement over the 180-degree inversion? And as far as the phase relationship at F3, isn't that addressed by keeping the crossover point well above that point? Sorry if these are dumb questions...I'm still trying to figure this stuff out.
