The program that I tened to use is VituixCAD, which is available at https://kimmosaunisto.net/. It's free to use by hobbyists in non-commercial endeavours. As far as entering the circuit diagrams goes, it's quite straightforward to learn. Once you have the connections of the components and speakers sorted out, it automatically does all the computations and displays plots of the results. Its circuit entry screen is shown below:
Another good program is XSim4, and it has a similar approach. It's available here: https://www.libinst.com/FreeAppDownloads/. Its circuit entry screen looks like the following:
Oh nice. I might download it and play around with it a bit using the crossover so I can compare the results to what you got to be sure I'm doing it right.
Here's the impedance data.
Here's the impedance data.
Thanks for providing the data. It makes the simulation work much more useful. Here is the circuit that I've created. Each driver now has its own ZMA impedance data file attached to it.
The simulated filter functions and the system's impedance curve are shown below. I think that there is now a quite good match between the measured system impedance curve and the simulated one, which is comforting.
The simulated filter transfer functions are shown below. Note that the crossover between the low-pass filter and the band-pass filter in the 2kHz–7kHz is not ideal, as the cross at 4kHz with almost zero attenuation happening. The end acoustic result will of course depend on the acoustic responses of the drivers as well, but the present simulation does provide some useful insights.
The band-pass filter on the midrange/tweeter units seems to be nicely doing the desired job, as is the high-pass filter on the ribbon tweeter. It would seem that the knee of the low-pass filter on the woofer could do with some shifting down in frequency, so that it is −3dB down at around 2.5kHz or thereabouts. Of course, doing that will change all the relative phase shifts through that crossover region, which may require a polarity inversion on the woofer for the best results for the acoustic response function.
If the drivers were all full range, then they would sum together something like the following, assuming that they are all coincident (X=Y=Z=0 for all the drivers), which of course is not the case:
The simulated filter functions and the system's impedance curve are shown below. I think that there is now a quite good match between the measured system impedance curve and the simulated one, which is comforting.
The simulated filter transfer functions are shown below. Note that the crossover between the low-pass filter and the band-pass filter in the 2kHz–7kHz is not ideal, as the cross at 4kHz with almost zero attenuation happening. The end acoustic result will of course depend on the acoustic responses of the drivers as well, but the present simulation does provide some useful insights.
The band-pass filter on the midrange/tweeter units seems to be nicely doing the desired job, as is the high-pass filter on the ribbon tweeter. It would seem that the knee of the low-pass filter on the woofer could do with some shifting down in frequency, so that it is −3dB down at around 2.5kHz or thereabouts. Of course, doing that will change all the relative phase shifts through that crossover region, which may require a polarity inversion on the woofer for the best results for the acoustic response function.
If the drivers were all full range, then they would sum together something like the following, assuming that they are all coincident (X=Y=Z=0 for all the drivers), which of course is not the case:
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One possible issue is I used the impedances DATS showed when I measured the drivers when doing the original 6dB/octave crossover. Not sure why the woofer and Jensen tweeters read slightly different now. I need to see what version of DATS is installed and see if that could be causing a difference in measurement or would using a USB 2.0 port on my Windows 10 PC to power it versus the USB 3.0 port on my Windows 11 PC cause a measurement difference.
Would there be any benefit to removing the resonant peak the woofer has?
That requires a 164.7uF cap, a 75.3mH inductor and a 7.4 ohm resistor.
Would there be any benefit to removing the resonant peak the woofer has?
That requires a 164.7uF cap, a 75.3mH inductor and a 7.4 ohm resistor.
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It can be difficult to track down causes of measurement differences. The room temperature will have an effect, and also whether or not the loudspeaker driver's voice coils had heated up a little under use.
I'm not sure if the different USB ports would lead to different measurements. You could try measuring a known resistor to see what happens.
One benefit of removing the resonance peak in the woofer's impedance is that it would make the impedance more resistive. That usually translates to making the speaker easier to drive and affects the frequency response less when an amplifier with a low damping factor is being used. Low-damping factor amplifiers are usually tube amplifiers, which have a high value of output impedance as a result of using a transformer in the output signal path.
Of course, EQ-ing out the resonance peak does increase the current requirements, as a high-impedance region has been transformed into a much lower impedance region.
However, the inductor needed to equalize the woofer's impedance curve is huge: 75.3mH. Adding the impedance EQ will likely simply serve to reduce the bass output a little bit when a low-damping factor amplifier is used.
I've added the impedance EQ components to the woofer's filter circuit, and the simulated impedance is shown below.
I'm not sure if the different USB ports would lead to different measurements. You could try measuring a known resistor to see what happens.
One benefit of removing the resonance peak in the woofer's impedance is that it would make the impedance more resistive. That usually translates to making the speaker easier to drive and affects the frequency response less when an amplifier with a low damping factor is being used. Low-damping factor amplifiers are usually tube amplifiers, which have a high value of output impedance as a result of using a transformer in the output signal path.
Of course, EQ-ing out the resonance peak does increase the current requirements, as a high-impedance region has been transformed into a much lower impedance region.
However, the inductor needed to equalize the woofer's impedance curve is huge: 75.3mH. Adding the impedance EQ will likely simply serve to reduce the bass output a little bit when a low-damping factor amplifier is used.
I've added the impedance EQ components to the woofer's filter circuit, and the simulated impedance is shown below.
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Said inductor would be $59.95
https://www.newark.com/triad-magnetics/c47u/inductor-75mh-1a-50-20/dp/03F734
The film caps would be about as expensive.
Also I don't know how an iron core inductor would affect the sound.
Honestly the speaker sounds real good as is so that may be money I don't need to spend. Also far as I know I've never had any speakers with a notch filter and most of the speakers I've had sounded real good.
https://www.newark.com/triad-magnetics/c47u/inductor-75mh-1a-50-20/dp/03F734
The film caps would be about as expensive.
Also I don't know how an iron core inductor would affect the sound.
Honestly the speaker sounds real good as is so that may be money I don't need to spend. Also far as I know I've never had any speakers with a notch filter and most of the speakers I've had sounded real good.
Keep in mind that the "notch filter" that you refer to is just an impedance equalizer. Its effect on the acoustic output of the woofer will often be quite small.
Oh ok so its use would only be in certain cases where the impedance must be more constant.
The speaker sounds real good like it is now so I don't think I'll do anything further to it.
It's ok for the wood bottom to be sitting directly on the carpet and that won't negatively affect the sound, right?
The speaker sounds real good like it is now so I don't think I'll do anything further to it.
It's ok for the wood bottom to be sitting directly on the carpet and that won't negatively affect the sound, right?
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Keeping the wooden base on carpet shouldn't be a problem, as it will help isolate any flexural vibrations of the wooden panel from being transmitted into the floor. Considering that we have a lot of rearward sound radiation from the open-backed loudspeakers bouncing off nearby surfaces, as long as you don't excite any buzzing sounds you're probably doing as well as can be expected.
If you'd like to do some experimentation, you could consider hanging some sound absorptive fabric directly behind the midrange/tweeter units. That would help to attenuate the rearward sound radiation from those three drivers. This may may improve the clarity of what you are hearing, as the delayed smearing sound effects (added reverberation?) would be reduced in intensity. Of course, you may like those effects in your listening environment, but I tend to lean towards a more directly generated sound field.
If you'd like to do some experimentation, you could consider hanging some sound absorptive fabric directly behind the midrange/tweeter units. That would help to attenuate the rearward sound radiation from those three drivers. This may may improve the clarity of what you are hearing, as the delayed smearing sound effects (added reverberation?) would be reduced in intensity. Of course, you may like those effects in your listening environment, but I tend to lean towards a more directly generated sound field.
I think it is worth pointing out that at the very start of the schematic diagram, the 2.83V source signal is quoted as having an impedance of 1m ohm >
this doesn't actually equal the impedance of the tube-output transformer, so the simulations are not strictly accurate > by how much I'm not sure.
True microphone/analyzer measurements are more accurate given the non-linear impedance of the output transformer. Good ears are also invaluable.
Here's the simulation of the filter functions with Rg=1mΩ.
And now we increase Rg to 4Ω, which is a damping factor of 2 re 8Ω. The differences are noticeable, but not huge in their effect. It all boils down to knowing what that output impedance is.
And now we increase Rg to 4Ω, which is a damping factor of 2 re 8Ω. The differences are noticeable, but not huge in their effect. It all boils down to knowing what that output impedance is.
So the damping factor is a reason why some multi-way speakers sound better on some amps than they do on others as it has an effect on the crossover performance.
The more I listen to the speaker the better I like it. I do tend to stream KNKX Jazz 24 a lot on this system as it's very relaxing music smd good way for me to wind down before bed. I do need to figure out a way to disable the space heater function of the Magnavox AMP-142 though as it gets my bedroom quite warm.
I seem to be really enjoying building open baffles.
Listening to another potential open baffle project as I type this. Will likely be my last build for awhile as it will use up my last two woofers that are good enough to use for HI-FI. As I keep building these the quality will get better and I might even learn something I can use to revisit my other designs to make them better. Using VituixCAD will allow me to run sims on a crossover design to optimise it before I order the first part. I do need to figure some sort of glue I can use that will hold the parts to the crossover board securely, but still allow me to remove parts as necessary.
I find that even some lower cost drivers that one thinks are junk due to the junk cabinet they are in and the junk audio amplifier powering them seem to sound real good on an open baffle far as bass response is concerned.
The more I listen to the speaker the better I like it. I do tend to stream KNKX Jazz 24 a lot on this system as it's very relaxing music smd good way for me to wind down before bed. I do need to figure out a way to disable the space heater function of the Magnavox AMP-142 though as it gets my bedroom quite warm.
I seem to be really enjoying building open baffles.
Listening to another potential open baffle project as I type this. Will likely be my last build for awhile as it will use up my last two woofers that are good enough to use for HI-FI. As I keep building these the quality will get better and I might even learn something I can use to revisit my other designs to make them better. Using VituixCAD will allow me to run sims on a crossover design to optimise it before I order the first part. I do need to figure some sort of glue I can use that will hold the parts to the crossover board securely, but still allow me to remove parts as necessary.
I find that even some lower cost drivers that one thinks are junk due to the junk cabinet they are in and the junk audio amplifier powering them seem to sound real good on an open baffle far as bass response is concerned.
Yes, amplifiers with low damping factors will cause audible frequency response changes in the acoustic output of multi-way loudspeaker systems. Below is a graph that compares the simulated frequency responses of vented box loudspeaker when it is connected to amplifiers with damping factors ranging from 1 to 16. It's not a pretty sight.
Below are the results for loudspeaker simulation with amplifiers whose damping factors are 100 and 800. The value of 100 is easily attainable by many solid state amplifiers. It's clear that the loudspeaker's frequency response is affected much more subtly.
Below are the results for loudspeaker simulation with amplifiers whose damping factors are 100 and 800. The value of 100 is easily attainable by many solid state amplifiers. It's clear that the loudspeaker's frequency response is affected much more subtly.
That explains why some speakers sound good on certain amps and bad on others.
If more people understood that, there would be less money spent to get a good quality system.
I've always felt a speaker made before solid state should be run on tubes as that was the only available amplification at the time the speaker was designed and what you posted seems to somewhat validate that.
If more people understood that, there would be less money spent to get a good quality system.
I've always felt a speaker made before solid state should be run on tubes as that was the only available amplification at the time the speaker was designed and what you posted seems to somewhat validate that.
BRILLIANT !
You're a very 'smart cookie' with an excellently presented post.
You have very clearly described a technical explanation of a situation that usually falls into the realm of 'subjective & preference'. [ ethereal ]
I actually hope this post gets re-posted into 2 or 3 other threads 🙂
PS.
My little addition to the post is >
Poor quality speaker cable effects the sound more with amplifiers of high damping factor than it does with amplifiers of low damping factor.
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Yep a good speaker cable should not add much if any inductance, capacitance and extra resistance.
I've often felt it is best to locate an amplifier as close as reasonably possible to the speaker sdo that the speaker wire is kept as short as reasonably possible.