There are simple enough resources available to calculate these effects.
I particularly like this LCR calculator from Alan Yates, even if entering data is clumsy due to choice of units:
Alan Yates' Laboratory - VK2ZAY's Engineering Calculators - LCR Resonance
What you do is treat a second order filter as a parallel LCR circuit. You need to measure the DC resistance of the drive unit Re which you use as shunt resistance or perhaps a nominal impedance about 25% higher than Re, then put in the L and C values. It will tell you the LC frequency and Q of the circuit. A Q of 0.5 is a Linkwitz-Riley with a gentle rolloff and kind impedance. A Q of 0.707 is the butterworth with maximally flat response and a more difficult dip in impedance.
Otherwise, you can play with this crossover designer which is well thought out:
2-Way Crossover Designer / Calculator
I make your proposed XO to be second order butterworth LP @1800Hz and 8 ohm. The HP is third order butterworth @ 4000Hz and about 10 ohm. No bad thing, that gap between the two frequencies, it's a common technique with real loudspeaker drivers.
Bit rough and ready, of course. Real loudspeakers are not 8 or 10 ohms. Rules of thumb, LR is less risky to your amp than butterworth, and keeping crossover points apart keeps load impedance higher too. That Zobel on the bass will get quite hot, I reckon, and reduce impedance a bit too. So be careful.
FWIW, I doubt if adding little parallel caps to electrolytics will make much difference. Polypropylenes would be better, but COST!
I particularly like this LCR calculator from Alan Yates, even if entering data is clumsy due to choice of units:
Alan Yates' Laboratory - VK2ZAY's Engineering Calculators - LCR Resonance
What you do is treat a second order filter as a parallel LCR circuit. You need to measure the DC resistance of the drive unit Re which you use as shunt resistance or perhaps a nominal impedance about 25% higher than Re, then put in the L and C values. It will tell you the LC frequency and Q of the circuit. A Q of 0.5 is a Linkwitz-Riley with a gentle rolloff and kind impedance. A Q of 0.707 is the butterworth with maximally flat response and a more difficult dip in impedance.
Otherwise, you can play with this crossover designer which is well thought out:
2-Way Crossover Designer / Calculator
I make your proposed XO to be second order butterworth LP @1800Hz and 8 ohm. The HP is third order butterworth @ 4000Hz and about 10 ohm. No bad thing, that gap between the two frequencies, it's a common technique with real loudspeaker drivers.
Bit rough and ready, of course. Real loudspeakers are not 8 or 10 ohms. Rules of thumb, LR is less risky to your amp than butterworth, and keeping crossover points apart keeps load impedance higher too. That Zobel on the bass will get quite hot, I reckon, and reduce impedance a bit too. So be careful.
FWIW, I doubt if adding little parallel caps to electrolytics will make much difference. Polypropylenes would be better, but COST!
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Ooh, yes, I've just had a good idea.
Add a baffle step circuit to the bass:
Loudspeaker Diffraction Loss and Baffle Step Compensation Circuits
3.7dB on 12" baffle gives 4 ohms and 1.8mH. You'd want at least 2X 10W W/W 8 ohm in parallel here. No idea if your 1.8mH coils are up to it. But that gives you 4dB to play with on padding the horn!
Ah, some interesting ideas. I might try the proposed BSC circuit, to hear what it sounds like.
Somebody earlier mentioned that ferrite-core chokes in the tweeter circuit would cause distortion. Would this be clearly audible with low power input, say a total of 5 watts rms to the crossover inputs?
I'm thinking I need to swap an air core inductor into the HP circuit in that KG5.2-style xover.
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Somebody earlier mentioned that ferrite-core chokes in the tweeter circuit would cause distortion. Would this be clearly audible with low power input, say a total of 5 watts rms to the crossover inputs?
I'm thinking I need to swap an air core inductor into the HP circuit in that KG5.2-style xover.
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It is likely your speaker has already been compensated. Without measurement you can't be certain it hasn't.
FWIW this kind of circuit is somewhat similar to a 'loudness' control, if that helps to understand what it might sound like.
I'm not sure that is so. We're talking about a broad shelved 3-6dB SPL contour. Many speaker FR measurements are taken near-field and don't clearly reveal whether such a broadband EQ has been applied or not. In-room far-field measurements often aren't much clearer at showing whether such a smooth and broadband correction has been applied.
My own experience is that the greater the midrange and treble clarity of the system, the more audibly obvious is the benefit of baffle-gain/loss correction. All of my own speaker systems to which I've applied BSC (stand mounted dynamic mini-monitors, floor-standing dynamic, tall electrostatic/dynamic hybrid) have benefited.
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It sounds like it has been compensated. It has a sort of recessed midrange, with a definite warmth in the mid-bass and as 'sparkley' a high treble response as you would expect from a large-ish horn tweeter.
Whether the shaping was a conscious attempt at BSC, or was just 'voicing,' I can't say.
I suspect that applying BSC to this system might be adding too much of a good thing. I might try it, though, just to hear what it sounds like.
Thanks for the continued flow of ideas, everybody.
Incidentally, the speakers are sounding pretty good, especially considering its cheap drivers and middle-brow crossover components.
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You won't know if you don't try.
The baffle step is not something that necessarily gets separate attention during design which is why I suspected it was OK. It shows up in the measurements and the crossover just flows from the measurements. The lows aren't really missing, just dispersing more widely so you may want to go slowly.
Oh, and I wasn't meaning to make reference to the highs with the loudness control comment.
The baffle step is not something that necessarily gets separate attention during design which is why I suspected it was OK. It shows up in the measurements and the crossover just flows from the measurements. The lows aren't really missing, just dispersing more widely so you may want to go slowly.
Oh, and I wasn't meaning to make reference to the highs with the loudness control comment.
Most likely the woofer falls quiet very fast at around 1.6 kHz, though that in it self is probably a nasty peak which needs a Zobel network to flatten out, then a drop to silence, and then there is some nasty loud residue around 5 kHz which no one wants to listen to. To put a crossover point at 4 kHz, yeah?! Failure to launch. Put it at 2 kHz. 1 mH and 6.8 uF on both the woofer and tweeter should go a long way.
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Hello Strawberry,
I know this is an old thread but have seen that you have great knowledge and was hoping you'd look at my design. I've done the simulations and have listened through countless configurations though digital cross-over but would like to dial them in with a second order. I think I need a Zobel on my 10" woofer.
I'm not sure how to exchange emails but maybe you do.
I'f you'd take a look at my two driver's parameters I'd be grateful.
I know this is an old thread but have seen that you have great knowledge and was hoping you'd look at my design. I've done the simulations and have listened through countless configurations though digital cross-over but would like to dial them in with a second order. I think I need a Zobel on my 10" woofer.
I'm not sure how to exchange emails but maybe you do.
I'f you'd take a look at my two driver's parameters I'd be grateful.
I don't have time to read through this entire thread. My apologies.
With my Accuton Diamond tweeters, I too had a harshness I couldn't get rid of.
You don't need to be a believer that different wires make a difference. But, try removing any multi-strand wire from your system.
For the tweeter, 24awg or smaller is fine. If you have an old pair of interconnects lying around, open them up.
Replace your speaker wire (assuming it's multi-strand) with any solid core wire you have around. Remember we are just trying to isolate the 'harshness' at this point.
With my Accuton Diamond tweeters, I too had a harshness I couldn't get rid of.
You don't need to be a believer that different wires make a difference. But, try removing any multi-strand wire from your system.
For the tweeter, 24awg or smaller is fine. If you have an old pair of interconnects lying around, open them up.
Replace your speaker wire (assuming it's multi-strand) with any solid core wire you have around. Remember we are just trying to isolate the 'harshness' at this point.
I have mixed and matched several different wire configurations and have it boiled down to be the woofer's break-up or rising impedance at around 2300hz.
I was experimenting again today after reading the threads from this forum. I started dropping the woofer's cross-over point from 2300 by about 50hz at a time and found a nice place for it at 1840hz (mind you at 48sb per octave). I brought the tweeter's cross point down (to 2040hz 24db per octave) with it and it seems to work. I've been here before and climbed back up again, I don't know why other than it's not as full sounding with the CD playing lower. I was thinking maybe a passive Zobel on it's own and clime up a little again with the active cross-over points. I've heard many people say Zobels do nothing for an active situation but I can't see why not. Even though the EL34s don't have to push through a passive cross system they still have the task of driving a rising impedance load.
My question is,,,,,, could a zobel network help to soften the upper end of this 10" mid-woofer when using a digital cross-over bi-amped to a CD.
Thanks for your reply by the way,
I was experimenting again today after reading the threads from this forum. I started dropping the woofer's cross-over point from 2300 by about 50hz at a time and found a nice place for it at 1840hz (mind you at 48sb per octave). I brought the tweeter's cross point down (to 2040hz 24db per octave) with it and it seems to work. I've been here before and climbed back up again, I don't know why other than it's not as full sounding with the CD playing lower. I was thinking maybe a passive Zobel on it's own and clime up a little again with the active cross-over points. I've heard many people say Zobels do nothing for an active situation but I can't see why not. Even though the EL34s don't have to push through a passive cross system they still have the task of driving a rising impedance load.
My question is,,,,,, could a zobel network help to soften the upper end of this 10" mid-woofer when using a digital cross-over bi-amped to a CD.
Thanks for your reply by the way,
I have had sibilance a few times and can usually be traced to cone breakup. Measure the frequency response and look at the impulse response. If you see a ringing that decays, that is the sibilance. Count periods of the ringing - e.g., 10peaks in 1 ms, that is 10khz breakup mode. Either notch it out, use a XO that avoids it, or EQ it out until it is barely visible in the impulse response. Now listen to the speakers again and see if gone. If using class D amps, sometimes harshness can be reduced using snubber circuits before the main filter coil. On the TPA3116D2 for example, a 330pF cap and 10R to ground connected before the main inductor really helps to reduce harshness.
The trouble is I don't have testing equipment yet.
I have graphs from the manufacturer but think there must be a smoothing gone on. The woofer drops off nicely starting at 2300hz. without any upward spiking higher up.
I'm thinking there must be breakup higher up or the phase rise of this woofer is just too quick,,, 18ohms at 2000hz. I'm not worried about the CD, I think it's fine, maybe a bit of dampening on the outside of the cast aluminum Celestion H1 70/50 horn needed is all.
I'm still wondering if a zobel will help when using an active digital cross-over.
Thanks,
I have graphs from the manufacturer but think there must be a smoothing gone on. The woofer drops off nicely starting at 2300hz. without any upward spiking higher up.
I'm thinking there must be breakup higher up or the phase rise of this woofer is just too quick,,, 18ohms at 2000hz. I'm not worried about the CD, I think it's fine, maybe a bit of dampening on the outside of the cast aluminum Celestion H1 70/50 horn needed is all.
I'm still wondering if a zobel will help when using an active digital cross-over.
Thanks,
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