Of course the woofer filter is nothing like a textbook 2nd order filter. But the tweeter has some similarities to a textbook filter. Do the below results from an online calculator conflict with what you are saying with regards the series high pass capacitor? Or am I reading your comments incorrectly?
2nd Order Butterworth, 1400 Hertz, 4 Ohm Tweeter / 4 Ohm Woofer
Parts List
Capacitors
C1 = 20.09 uF
C2 = 20.09 uF
Inductors
L1 = 0.64 mH
L2 = 0.64 mH
What you write is theoretically correct but I don't think that the coil in series with the woofer for size and number of turns can be 0.6 mh....... What I wrote about a possible RCL filter of the tweeter is wrong because in any case there should be an additional capacitor in series with this, but it could be a serial cross, the frequency should be around 1500 Hz
Regards
Roberto
Regards
Roberto
I agree absolutely about the woofer crossover coil.
Based on some info in this thread: A 7mH coil in series with two 8ohm woofers in parallel (4ohms) would start to roll off the woofers a little under 100hz. But because the “baffle step”(rising response) is so pronounced in an open baffle design, the on-axis response of the woofers ends up being pretty flat to about 1000hz. From that point, a capacitor to ground rolls off the woofer response to meet the tweeter.
I don't know if this could be modeled effectively with existing software----it probably could if you could effectively model the dipole bass cancellation--- or maybe measurement data imported into the modeling software would contain all the necessary information?
When I have done something similar with a dipole/open baffle it has been with a much lower cross-point to the next driver---sometimes a large mid-range, sometimes another, smaller, woofer. Maybe it is just lucky, but I have used very large coils---up to 20mH laminate core on 18” 8ohm woofers ( which would be 10mH on 4ohms), and had good results (driving with solid-state amplification). The added resistance inline may raise the effective woofer Q, and so let the bass “bloom” somewhat. Tube amps have had not enough control over these woofers in my experience, making “flabby” bass.
When working in Open Baffle , it is not always possible to predict whether the frequency response will be one way or another , one thing is a well treated environment and with some absorption behind the dipole and another an untreated environment , I have long since overcome the problem , in that , I model the Crossover + speaker response , first one component and then the other , using a very old , but extremely reliable version of Clio of which I was one of the first users .... this makes it possible to follow a certain design philosophy , trying to avoid large inductors , which inexorably take away efficiency and preferring to work with RCL networks in series also because I use almost only high efficiency components Altec, JBL and Coral , so stuff that even if you put them on the floor just sounds , modern speakers , are much more specific , and therefore more complicated to use and certainly for a discourse related to magnets , baskets , quality of the material of the cone and thickness of the air gaps unmatched today .
if a woofer's bass is poorly controlled you can't change its Qt , but you can tame it by making it drier with a 47 OHM 40/50 Watt resistor in parallel with the speaker coil , it may seem like a no-brainer , but some effect is there , look at the crossover diagram of the Tannoy Westminster Royal .
Regard
Roberto
if a woofer's bass is poorly controlled you can't change its Qt , but you can tame it by making it drier with a 47 OHM 40/50 Watt resistor in parallel with the speaker coil , it may seem like a no-brainer , but some effect is there , look at the crossover diagram of the Tannoy Westminster Royal .
Regard
Roberto
Basta! (which is freeware) can model open baffle speakers, using driver T/S parameters, baffle shape and size, and passive or active crossovers. Have a look at post #126.
Auguri..........If you think you're going to solve everything with freewere software ..I think it's like wanting to learn how to use a wind tunnel with an online course, but in the end if you don't get results , you've only spent Your time ..........
Regard
Roberto
Regard
Roberto
Are you actually familiar with Basta? If you respect what it can and can't do (as with any sofware modeller) it is a very capable sim program. It might be better if you don't criticise something which you seem to know nothing about.
Incidentally, Hornresp and Vituixcad don't charge users either. Does that make them useless?
Incidentally, Hornresp and Vituixcad don't charge users either. Does that make them useless?
None of the following is meant to talk down to anyone, but it may be useful to those getting used to these ideas.
Since I started dabbling in open baffle, it has been evident that the big sensitivity-reducer in the bass range and lower mid-range was the limited isolation between the front/back of the cone(s). Increasing the distance between the front/back has seemed like the main way to maintain bass response. But in any OB/dipole design that I want to live with, I am left with a steeply rising response to filter towards flat somehow.
This thread is chiefly about replicating the Caladan speakers, which apparently use a largish air core coil in series with the woofers---which in parallel present a nominal 4ohm load. It is suggested in this thread that the woofer coil is 7mH. If the load was 8ohm nominal, then that coil would need to be 14mH for the same effect. So these are big coils.
It has been suggested to me by a couple of friends ,who are not new to this game, that if one wants to open up the bass response, by limiting the damping ability of an amplifier over the the driver motor, adding some resistance into the speaker wire, which a coil does, can allow the driver to resonate more easily. Naturally one does not want too much of this, but in some circumstances (like very low QTS drivers in an open baffle---not the case with the Caladans) when the alternative is weak bass, a choice can be made to add some resistance.
The two Beyma 12BR70 8ohm woofers discussed here, in parallel, should present a 4ohm, 97db sensitivity. Even knocking down their mid-range sensitivity by 9dB, should give a system sensitivity of around 88dB. In an average living room with 60-100 watts to play with, this should go louder than most people want to listen to most of the time.
When I heard the Caladans at the Seattle show, it did look as though they had a significant amount of amplification behind them. I am still not sure whether there was any line-level EQ being applied. The bass sounded very good.
Linkwitz (and others), using proprietary analog circuits at line level, and so many others now using DSP at line level, are able to couple their amps directly to the drivers. This allows ideal pairings of amps and various drivers. This is more complicated to hook up and can be expensive. If one wants to squeeze more out of the system, then DSP and Bi-amping may be more appropriate. Either way, the X-max displacement capability of the woofers will likely be the limiting factor. The X-damage spec is pretty large on these drivers, from what I remember.
Since I started dabbling in open baffle, it has been evident that the big sensitivity-reducer in the bass range and lower mid-range was the limited isolation between the front/back of the cone(s). Increasing the distance between the front/back has seemed like the main way to maintain bass response. But in any OB/dipole design that I want to live with, I am left with a steeply rising response to filter towards flat somehow.
This thread is chiefly about replicating the Caladan speakers, which apparently use a largish air core coil in series with the woofers---which in parallel present a nominal 4ohm load. It is suggested in this thread that the woofer coil is 7mH. If the load was 8ohm nominal, then that coil would need to be 14mH for the same effect. So these are big coils.
It has been suggested to me by a couple of friends ,who are not new to this game, that if one wants to open up the bass response, by limiting the damping ability of an amplifier over the the driver motor, adding some resistance into the speaker wire, which a coil does, can allow the driver to resonate more easily. Naturally one does not want too much of this, but in some circumstances (like very low QTS drivers in an open baffle---not the case with the Caladans) when the alternative is weak bass, a choice can be made to add some resistance.
The two Beyma 12BR70 8ohm woofers discussed here, in parallel, should present a 4ohm, 97db sensitivity. Even knocking down their mid-range sensitivity by 9dB, should give a system sensitivity of around 88dB. In an average living room with 60-100 watts to play with, this should go louder than most people want to listen to most of the time.
When I heard the Caladans at the Seattle show, it did look as though they had a significant amount of amplification behind them. I am still not sure whether there was any line-level EQ being applied. The bass sounded very good.
Linkwitz (and others), using proprietary analog circuits at line level, and so many others now using DSP at line level, are able to couple their amps directly to the drivers. This allows ideal pairings of amps and various drivers. This is more complicated to hook up and can be expensive. If one wants to squeeze more out of the system, then DSP and Bi-amping may be more appropriate. Either way, the X-max displacement capability of the woofers will likely be the limiting factor. The X-damage spec is pretty large on these drivers, from what I remember.
Would you be able to give an example of this type of network to deal with open baffle bass response? I have heard of using these as notch filters and something somewhat similar as band pass filters, but I don't know about how to use them to EQ the bass in an open baffle. Are these with the RLC in parallel, then in series with the driver? Or maybe the RLC in series, parallel to the voice coil?? Or some other arrangement?
Everyone in this hobby or job, wastes time as they want in life and all simulators for me are a huge waste of time, unless you are a company where an engineer works on the simulator and another works on the actual data collection, then they get together and decide if there is correlation or not .... furthermore we are losing sight of an important thing, listening, since our ear is infinitely superior to any detection or simulation system and at that point experience intervenes, in the field ....... think how masterpieces like the concentric Tannoy or Altec or the BBC 3/5 could have been designed which were designed perhaps only with a sweep generator ......... which you probably have never even heard of ......
Regards
Roberto
Would you be able to give an example of this type of network to deal with open baffle bass response? I have heard of using these as notch filters and something somewhat similar as band pass filters, but I don't know about how to use them to EQ the bass in an open baffle. Are these with the RLC in parallel, then in series with the driver? Or maybe the RLC in series, parallel to the voice coil?? Or some other arranement?
On the low frequencies, it makes no sense to use anything, otherwise you risk assuming that it makes sense to correct a response on the bass, as certain equalizers did that did more harm than improvement, especially because in the Open Baffle it depends from the speaker Qt and as always on the environment in which it is inserted, it may make sense to use it at the crossover point, in this way you obtain a targeted and important attenuation, you can start looking for documentation on the crossover of the BBC 3/5, even if there the RLC network mainly compensates for an increase in efficiency caused by the sizing of the cabinet, but it reaches up to the crossover point of the Woofer, what can RLC networks do, have a cross point with a significant slope, without having to use large inductors that have a constant decay and not having to use filters with an order greater than 2nd that may not be entirely suitable in the listening phase .... it goes without saying, that you have to get an audio detection system, learn to have certain data and experiment, otherwise you work blindly and you have no idea of what you are doing in general, specifically even at the phase at the cross point between the two speakers, however, to work at these levels you also need specific studies and to have worked in companies in the sector, as I did .....
Regards
Roberto
On the low frequencies, it makes no sense to use anything, otherwise you risk assuming that it makes sense to correct a response on the bass, as certain equalizers did that did more harm than improvement, especially because in the Open Baffle it depends from the speaker Qt and as always on the environment in which it is inserted, it may make sense to use it at the crossover point, in this way you obtain a targeted and important attenuation, you can start looking for documentation on the crossover of the BBC 3/5, even if there the RLC network mainly compensates for an increase in efficiency caused by the sizing of the cabinet, but it reaches up to the crossover point of the Woofer, what can RLC networks do, have a cross point with a significant slope, without having to use large inductors that have a constant decay and not having to use filters with an order greater than 2nd that may not be entirely suitable in the listening phase .... it goes without saying, that you have to get an audio detection system, learn to have certain data and experiment, otherwise you work blindly and you have no idea of what you are doing in general, specifically even at the phase at the cross point between the two speakers, however, to work at these levels you also need specific studies and to have worked in companies in the sector, as I did .....
Regards
Roberto
The bass drivers that I have used on open baffle have exhibited a rising response, greatly emphasizing the mid-range when played without some type of filter. I acknowledge this is partly due to not wanting super-wide baffles. I really like to even out the response and have a sufficient bass response. My present opinion/state of knowledge is that most woofers behave like this. Higher Qt woofers are typically less lean in the bass than lower Qt woofers, but weaker motors have their drawbacks too.
I am interested in knowing more about RLC networks. It was suggested in some readings that an RLC network could be useful to reduce a sub 1000hz resonance in a dome mid-range (many seem to have a hump in this area) that I was using in a 3way. I am not even sure what to call the arrangement I ended up using, or exactly why it worked. I think it involved a 30mfd cap to ground, in addition to the other band-pass components. I think the driver was 8ohm. The dome still had a one octave dip centered on 1500hz, which got fixed with a 7inch diameter wave-guide, probably messing with overall dispersion balance. The speakers do sound nice.
I am interested in knowing more about RLC networks. It was suggested in some readings that an RLC network could be useful to reduce a sub 1000hz resonance in a dome mid-range (many seem to have a hump in this area) that I was using in a 3way. I am not even sure what to call the arrangement I ended up using, or exactly why it worked. I think it involved a 30mfd cap to ground, in addition to the other band-pass components. I think the driver was 8ohm. The dome still had a one octave dip centered on 1500hz, which got fixed with a 7inch diameter wave-guide, probably messing with overall dispersion balance. The speakers do sound nice.
@ZANROY19
You seem to have your own approach to speaker design. Fine, I have no problem with that. I have a different approach - there's no need for you to be rude to me because of that. And please don't make assumptions about what I know or don't know.
You're new on this forum, so let me offer some friendly advice. First, if you want to quote part of a post, highlight it. Then a little box saying 'quote' will appear. Click it, and, it will automatically be shown correctly in your post. Second, I advise you to write in sentences - it's much easier for others to understand.
As for your suggestion that people should avoid large inductors because they "take away efficiency", I really don't see your point. Reducing the midband SPL is exactly what needs to be done with OB woofers. A large inductor does it nicely. What's the problem?
Your example of an alternative approach, the LS3/5a, is irrelevant, because it's a small sealed box, not an open baffle. (Also, it does use a series inductor on the B110, as well as a parallel trap.) And it's not exactly a high efficiency speaker.
@howardg In my experience, the best way to start to learn about RLC networks, or any other circuit element, is to get a software modelling program and play around with it. It's quicker and cheaper to learn from your mistakes in software, than in solder, wrong-sized components and unsuitable drivers.
You seem to have your own approach to speaker design. Fine, I have no problem with that. I have a different approach - there's no need for you to be rude to me because of that. And please don't make assumptions about what I know or don't know.
You're new on this forum, so let me offer some friendly advice. First, if you want to quote part of a post, highlight it. Then a little box saying 'quote' will appear. Click it, and, it will automatically be shown correctly in your post. Second, I advise you to write in sentences - it's much easier for others to understand.
As for your suggestion that people should avoid large inductors because they "take away efficiency", I really don't see your point. Reducing the midband SPL is exactly what needs to be done with OB woofers. A large inductor does it nicely. What's the problem?
Your example of an alternative approach, the LS3/5a, is irrelevant, because it's a small sealed box, not an open baffle. (Also, it does use a series inductor on the B110, as well as a parallel trap.) And it's not exactly a high efficiency speaker.
@howardg In my experience, the best way to start to learn about RLC networks, or any other circuit element, is to get a software modelling program and play around with it. It's quicker and cheaper to learn from your mistakes in software, than in solder, wrong-sized components and unsuitable drivers.
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Good points. I totally agree about the suitable drivers. You may be referring to my comments about the troublesome mid-domes. I was (gasp) re-imagining the AR3a in some donated, unmodified original boxes. I had some domes that fit nicely: Dayton DC50FA 2” fabric dome. (Parts express no longer sells these, maybe others do?). Other drivers: original AR woofers and HiVi QR1 tweets. The dome mids are very detailed sounding; they are built like (big) tweeters. My innovations with these: wave-guide grill frames (the cabinets have recessed baffles) and bespoke crossovers.
I think that I would benefit from keeping a modeling program open when I am designing/ tweaking a crossover. I would probably still play with the parts, because I now have a good stash, and because I relate to physical parts better---just a temperament thing. I think I end up remembering/learning best in hands-on mode.
No, I wasn't thinking of those comments. I was actually thinking of some of my own bad decisions in the past. 😀
The sims I posted earlier in the thread were done in Basta which I find really good for playing with initial ideas, finding out what has potential and what doesn't. (I've also recently started playing with Hornresp, for modelling TLs.) That's just the planning stage, though. The actual crossover design is best done based on actual measurements of drivers in box (or baffle), and that needs something like Vituixcad. Once you have a prototype, including crossover, that's when the ears become the most important thing, and some trial and error at that stage is bound be needed.
My friend who is ahead of MY curve with modeling programs, assisted me using hornresp to model a mass loaded TL. I built it and it worked well to produce extended low bass in a tapered tower shaped enclosure that was not large for the size of driver used (14” woofer in 2 cubic ft). The same woofer will work in a squat rectangular ported cabinet of that volume, but will roll-off sooner.
Hi Babus, I wonder if you would be kind enough to share the circuit diagram you used to achieve the favourable audible results you got? Like many on here, I'm going to attempt to clone the Caladan as my first DIY project to use with my 300b Audion amp, as an alternative to my ageing Living Voice Avatars