I don't use DSP and I have never knowingly heard it either.
My worry with DSP is that might try to correct room problems which should be tackled physically with absorbers, diffusors and bass traps rather than eq'ing anything.
I fail to see why a. wayne thinks that most active systems would require eq anymore than their passive counterparts.
I had the chance to compare Dynaudio BM5 active and passive (these are small nearfields) and the actives were so much superior to their passive brethren it ain't funny anymore.
Also had the same experience with my Tannoy DCs (midfields I suppose) and from other people who had the chance and finances the same appears to be true for ATCs.
For some things. It is the electrical slope that matters if your interest is in keeping signal off the voice coil to avoid driving cone breakups. It is the electrical slope that (usually) matters if you want to minimize the transition band and avoid driver interactions in the stop band, since it is (again usually) the electric slope chosen which determines transition band size and stop band attenuation.
Why wouldn't it? There are plenty of examples of speakers that "sound natural" with human voice that cross near "the middle" of the voice range.
Why not? If it summs properly in the far field what difference does it make?
Most "passive" crossovers apply equalization (in the crossover) as well . . . it is just commonly ignored, or denied. It is simply more obvious when it is done "active" . . .
Besides power handling, there are two primary issues that should direct you to the most appropriate crossover order: needed phase response and needed response complexity.
If you are trying to achieve crossovers that are in phase through the crossover region (and you should be) then you will need to find the crossover orders that support that. Every order you add will give 90 degrees more phase shift in the stop band and about 45 degrees at the corner frequency. You can invert polarity of a section but you will have to search for the right orders to get good phase overlap over a range of frequencies.
Crossover order also determines the degrees of freedom for response adjustment. Put simply, a first order network just slopes off to its final roll off rate. A second order can bump first, and then roll off. A third order can sag, then bump, then roll off. The number of inflections is determined by the order. If you need response complexity, to fix the driver response or achieve the right corner shape, then higher order will provide it.
Here is a thread covering the redesign of an old AR4x system over at classic speakers that a did a year or so back. It illustrates a search for the right order network both in terms of hitting a phase response target and also in providing adequate response adjustment.
Crossover mods for the AR4x - The Classic Speaker Pages Discussion Forums
Regards,
David S.
If you are trying to achieve crossovers that are in phase through the crossover region (and you should be) then you will need to find the crossover orders that support that. Every order you add will give 90 degrees more phase shift in the stop band and about 45 degrees at the corner frequency. You can invert polarity of a section but you will have to search for the right orders to get good phase overlap over a range of frequencies.
Crossover order also determines the degrees of freedom for response adjustment. Put simply, a first order network just slopes off to its final roll off rate. A second order can bump first, and then roll off. A third order can sag, then bump, then roll off. The number of inflections is determined by the order. If you need response complexity, to fix the driver response or achieve the right corner shape, then higher order will provide it.
Here is a thread covering the redesign of an old AR4x system over at classic speakers that a did a year or so back. It illustrates a search for the right order network both in terms of hitting a phase response target and also in providing adequate response adjustment.
Crossover mods for the AR4x - The Classic Speaker Pages Discussion Forums
Regards,
David S.
Charles
Tell us about the characteristics of the passive Dynaudio BM5, such as driver characteristics and crossover details.
Dewardh
Interesting observations 😉
observation
Different drivers behave differently, a cure for one may not necessarily be a cure for all. To make it easier we may have to define what we want before hand.
A little story (Is all DSP all that bad)
We invite a singer to the town hall and she sings beatifully. We are very pleased with her. So we invite her to the city square, she uses her ears to get feedback and compensate for the different environment. She adjusts her voice and again sings beautifully for us. We are again pleased with her. We pay her a lot of money to express our joy.
Tell us about the characteristics of the passive Dynaudio BM5, such as driver characteristics and crossover details.
Dewardh
Interesting observations 😉
observation
Different drivers behave differently, a cure for one may not necessarily be a cure for all. To make it easier we may have to define what we want before hand.
A little story (Is all DSP all that bad)
We invite a singer to the town hall and she sings beatifully. We are very pleased with her. So we invite her to the city square, she uses her ears to get feedback and compensate for the different environment. She adjusts her voice and again sings beautifully for us. We are again pleased with her. We pay her a lot of money to express our joy.
I forgot to finish story
We then invite her to a windy location, she sings herself hoarse, we dont like it we then chase her away.😀
We then invite her to a windy location, she sings herself hoarse, we dont like it we then chase her away.😀
Sometimes silvered copper wire/traces are used in VHF and UHF power circuits to have the lowest RF superficial impedance as low as can be possible, but at audio frequencies, isn´t too much???😕
@ dewardh
i agree, however, i always design so that the roll off isnt peaked. My philosophy or train of thought being that i dont regard using a peaked corner a good way to fill minor dips, since it would be introducing another resonant element to the system as a whole. In the same way that many dsp users try to correct issues that should be dealt with in design or room treatment. Ive used sallen filters before, butIm sure i recall something about slope rates and q being less flexible, which is a limitation if u want droopy slopes. I may be wrong tho. Dsp, like anything digital, is limited by bandwidth and aa filtering, and doesnt appeal to me at all. Ive heard pro dsp do some awful things to music! I have a behringer studio sound exciter dsp processor, and it CAN sound great, generally when its used the minimum reqd.
i agree, however, i always design so that the roll off isnt peaked. My philosophy or train of thought being that i dont regard using a peaked corner a good way to fill minor dips, since it would be introducing another resonant element to the system as a whole. In the same way that many dsp users try to correct issues that should be dealt with in design or room treatment. Ive used sallen filters before, butIm sure i recall something about slope rates and q being less flexible, which is a limitation if u want droopy slopes. I may be wrong tho. Dsp, like anything digital, is limited by bandwidth and aa filtering, and doesnt appeal to me at all. Ive heard pro dsp do some awful things to music! I have a behringer studio sound exciter dsp processor, and it CAN sound great, generally when its used the minimum reqd.
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You are completely right Osvaldo; I was not being serious. Sorry for my contorted sense of humor. I just thought one more non sequitur wouldn't do any harm.
vac
Yes, there are. It's very easy. Le/Cz=Re squared.
What this tells you about a woofer is that low inductance makes a woofer MUCH easier to filter. 😀
Let's look at a classic KEF B200 plastic woofer. Le=0.45mH. Re=7 ohms. Therefore the Zobel capacitance is 450/49=9.18uF. This means you can use a bafflestep coil around 0.45mH and capacitor around 10uFor 20uF to get a easy crossover at 2.5kHz and a flat impedance which is nice for valve and transistor amps and low Q's which reduce time delay. This is what you want for bookshelf types.
A 2mH woofer is a much tougher beast to tame. You need a big bafflestep coil above 2mH, with all the bass boost and reduced efficiency that that implies. You end up with a freestanding reflex design with rotten impedance and some horrible peekiness around crossover, which is what most commercial speakers are these days. I actually get quite frustrated by high inductance woofers. Horrible things to work with. Never mind all this (ringing) metal driver baloney. 😡
Now the tweeter crossover can be second or third order and they can both work well, but strangely it's often the woofer that decides what works best. Let's put it this way. A low inductance woofer with a smooth frequency response is just plain nicer to work with. If you go high inductance because you want thumping tight bass, you'll end up with a speaker that is VERY compromised in other areas.
The most musical speakers, IMO, go low inductance with drivers that have natural gentle rolloff slopes. It's also nice if the tweeter is more efficient than the woofer, because you have more leeway and flexibility in your crossover design. The benefit is simpler filters that sound better, have natural damping built-in, and present a nicer load to the amplifier. 🙂
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I've never had those particular problems. A high inductance woofer should have a naturally lower midrange level and probably need less input capacitance. Remember, voice coil inductance is no different than externally added inductance, it reduces HF current through the woofer and rolls off response in the same way. If you could build two woofer samples, the same in all other ways, but with different inductances, then adding inductance to the one would make it look like the other.
If high external inductance leads to high network Q (that problem I've run into) then a damper resistance in the C shunt to ground deals neatly with that.
As to "high inductance because you want thumping tight bass", eh??
David S.
If high external inductance leads to high network Q (that problem I've run into) then a damper resistance in the C shunt to ground deals neatly with that.
As to "high inductance because you want thumping tight bass", eh??
David S.
Yes, quite right. After the acoustic slope, keeping out-of-band signal away from the drivers is of next importance. For reasons of power handling, distortion, etc. Definitely not to be neglected.
I just said acoustic shapes are "really" important because many who are new to crossover don't think about them at all - they tend to think in terms of electrical slopes, only. Not surprising, as that's what gets talked about most.
Don´t worry, the misunderstanding is mine. My natural language is spanish, and my english isn´t too good. I´m sorry. Apologize the error.
I did not say they needed "more" , I said they needed and because they do I find that active/passive to be the best combination over straight active . Maybe you have never heard a good passive monitor ...
Just saying ....
Wait , you are comparing adjustments made in a Passive xover to active EQing , let me have a seat ..
🙂
+10
Oddly enough they wouldn't let me take them apart.
But in fact there were 3 versions, all using the same drivers and cabinet: The DynaudioAcoustics BM5, DynaudioAcoustics BM5p and a domestic Dynaudio badged one.
Back then (pre-TC Group buy-out) Dynaudios studio fare was badged 'DynaudioAcoustics' and either tweaked from their domestic line or designed ground up by Andy Munro.
Share that experience.
The Tannoy K3838's I have employ one of the most elaborate analogue xover's I have ever seen, including time alignment in the Urei sense of the word, that is using an all pass to get zero phase shift over the xover region.
Yet, a home brew active with good but not premium grade opamps, and no all pass, sounds absolutely better.
vac
I totally disagree. There in NOTHING magic, just several reasonable approaches. One of my favorites is a wide range mid so that the bulk of our most sensitive hearing range, 2K to 4K does not have a crossover in it. This goes back to a woofer going to 800 or so, 800 to 5K mid and a tweeter above that. Unfortunately, most drivers are designed for a two way mini-monitor so it forces a crossover somewhere in the 1700 to 2500 range. I want to play with some "full range" drivers more. I will when I think I have run out of ideas with more conventional 2-ways.
How steep the slope depends completely on the drivers. Metal drivers, all other things equal, may require a steeper slope due to breakup issues. Things are never equal. Higher power may require steeper slopes.
I suggest some here are looking for easy answers to very complex system problems. The crossover design should have nothing to do with the amount of feedback the amp has. All that "control" is bull stuffing. Any DF over about 20 is irrelevant when you understand the complete system. Different amps may behave differently with different crossovers and drivers. It depends on the stability of the amp and other topology choices. I learned a huge amount, almost enough to be a stark rookie, from forum members about amp design and how different compensation methods change the masking effects of other problems. Putting an ugly load on an amp with no output inductor is looking for trouble.
I have built and heard others pure electronic multi-amp systems that were far better than most pure passive systems. Mr. Linkwitz would seem to suggest active filtering has more advantages than passive. There are only a few here who can argue with him. As I understand it, Dick Small may. I usually build hybrids as the electronic crossover can't notch ultrasonic harmonics that may excite a less than desirable tweeter as well as a passive network can. Unfortunately the kind of filtering I want to do with DSP relies on A2D and D2A of lower quality than I can get with analog. Catch-22.
+1 to that! Exactly what i wouldve liked to have said in my post, but said far more eloquently than i
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