I have searched this and got a lot of conflicting results. I'm basically curious what your opinions are, and also if anyone here has actually measured the effects of these different inductors on a woofer. In the past, I've always used air core on a midrange and a tweeter, and usually a steal laminate on a woofer (crossed under 500 Hz). But when we had the recent steel laminate shortages, I decided to give C-core toroidal inductors a try... Jantzen 4.7 14 AWG C-Coil Toroidal Inductor
The first build I used this on was a 3 way that used a 10" SB29NRX75-6 woofer, crossed at around 350 Hz (IIRC it was actually a 5.6, not a 4.7). I had originally mocked the crossover up using a steel laminate (same value) from my "crossover voicing stock of crossover parts". But at that time, once I voiced that crossover and it came time to solder everything up, I couldn't find a steel laminate coil (I don't like to use my stock of parts that I use to voice)... so I decided to try that Jantzen toriodal inductor. I was actually pretty shocked, it was an expensive dice roll because I've read the toriodals increase distortion a LOT, but on that woofer the bass seemed tighter, more controlled and simply sounded better than it did using the steel laminate.
Then I did another build, this time it was a TMWW using a pair of 8 ohm Scanspeak Revelator 18W woofers, crossed around 300 Hz. I mocked the xover up again using steel laminate, then purchased a toroidal to replace the steal laminate again. This time the swap didn't change much at all, the toroidals sounded pretty much exactly like the steal laminate on the woofers.
So, based on my experience, it seems like a toroidal is better on a large woofer with a large motor, but on smaller woofers it doesn't really matter. It would be interesting to try an air core on that Scan 18w build, but I'm not willing to spend on a 14awg, 5.6mH air core to try that experiment.
Also, for what it's worth, the actual response of the woofers didn't change much at all in either of those inductor comparisons. But, measuring FR below 400Hz has always been tough to do anyhow so I don't put a whole lot of stock in what my mic tells me down that low. But, as far as SPL and what I could see of the actual bass response, not much changed at all in either of those situations.
So... curious if anyone has actually measured the effects of different coils, and can either substantiate my experience, or tell me I'm delusional
😊
The first build I used this on was a 3 way that used a 10" SB29NRX75-6 woofer, crossed at around 350 Hz (IIRC it was actually a 5.6, not a 4.7). I had originally mocked the crossover up using a steel laminate (same value) from my "crossover voicing stock of crossover parts". But at that time, once I voiced that crossover and it came time to solder everything up, I couldn't find a steel laminate coil (I don't like to use my stock of parts that I use to voice)... so I decided to try that Jantzen toriodal inductor. I was actually pretty shocked, it was an expensive dice roll because I've read the toriodals increase distortion a LOT, but on that woofer the bass seemed tighter, more controlled and simply sounded better than it did using the steel laminate.
Then I did another build, this time it was a TMWW using a pair of 8 ohm Scanspeak Revelator 18W woofers, crossed around 300 Hz. I mocked the xover up again using steel laminate, then purchased a toroidal to replace the steal laminate again. This time the swap didn't change much at all, the toroidals sounded pretty much exactly like the steal laminate on the woofers.
So, based on my experience, it seems like a toroidal is better on a large woofer with a large motor, but on smaller woofers it doesn't really matter. It would be interesting to try an air core on that Scan 18w build, but I'm not willing to spend on a 14awg, 5.6mH air core to try that experiment.
Also, for what it's worth, the actual response of the woofers didn't change much at all in either of those inductor comparisons. But, measuring FR below 400Hz has always been tough to do anyhow so I don't put a whole lot of stock in what my mic tells me down that low. But, as far as SPL and what I could see of the actual bass response, not much changed at all in either of those situations.
So... curious if anyone has actually measured the effects of different coils, and can either substantiate my experience, or tell me I'm delusional
😊
I have measured once an Intertechnik ferrite inductor for saturation current.
https://www.diyaudio.com/community/threads/saturated-low-pass-inductor.313449/#post-5212914
Saturation causes inductance to drop, so you have x/o point shifting.
https://www.diyaudio.com/community/threads/saturated-low-pass-inductor.313449/#post-5212914
Saturation causes inductance to drop, so you have x/o point shifting.
The Jantzen says its a "toroidal iron core"... do you think this helps alleviate the saturation vs using ferrite core? Or would the Jantzen behave similarly to the ferrite inductor you tested?
@wolf_teeth , in another thread I found, you wrote, "I do have plans to try the C-coils in comparison at some point, just for the heck of it....
I have used them before." (from this thread The best inductors?)
Did you ever do this comparison? Curious what you think about the Jantzen toroidals. I still remember the coil comparison you did at Meniscus, very informative and fun. My opinion so far about the Jantzen toroidals is that they aren't worth the extra expense over steal-laminate for smaller woofers, but will work just as well as steal laminate if I can't find one.
I have used them before." (from this thread The best inductors?)
Did you ever do this comparison? Curious what you think about the Jantzen toroidals. I still remember the coil comparison you did at Meniscus, very informative and fun. My opinion so far about the Jantzen toroidals is that they aren't worth the extra expense over steal-laminate for smaller woofers, but will work just as well as steal laminate if I can't find one.
The data from Jantzen about their toroidal inductors looks very lightweight: ideally, you would want to see more detailed data, especially regarding the inductance vs. frequency behavior, THD level under some well-defined conditions, inductance vs. frequency.
The fact that they mention that inductance measurement needs to be performed under special conditions is also worrying: an inductor is an inductor, and under small-signal conditions (99% of the inductancemeters), the value should be nominal: it only deviates under extreme conditions.
Also note that close-circuit, laminated steel inductors are the worst possible choice regarding linearity, thus THD
The fact that they mention that inductance measurement needs to be performed under special conditions is also worrying: an inductor is an inductor, and under small-signal conditions (99% of the inductancemeters), the value should be nominal: it only deviates under extreme conditions.
Also note that close-circuit, laminated steel inductors are the worst possible choice regarding linearity, thus THD
I meant inductance vs. current. Frequency is covered later in the phrase.
Both are the dominant criteria for this type of application, and inductor manufacturers ( even for non-audio applications) readily publish them
This, positively, that's why I would never use a steel laminate, or a toroidal on anything but a woofer that was crossed fairly low. That said, just like everything else in speaker design, I guess it just boils down to what matters more in that specific application. I don't think I can hear the higher distortion that I get from steel laminate or toroidal on a woofer. And actually, even though the distortion is technically higher, steel laminate inductors (usually) sound better to me on a woofer in a 3 way than an air core inductor.
Was mainly curious if anyone else has done experimenting and actually measured one of the Jantzen toroidals more deeply than me. For now my take-away is... Good ole steel laminate is still the best, most cost effective option for a woofer, but a toroidal inductors will work if steel laminate can't be found, they're just generally 4x more expensive for the same value. The only place I question this is on a bigger woofer where higher power is factor- is a toroidal a better option there than a steel laminate?? Guess I need to play some more.
I notice that there are few turns, suggesting the core is heavily relied upon to perform.
Tighter sounding bass as a result of a lower Q, doesn't suggest that the signal is more accurate or has suffered less damage. Resistance in a bass circuit is fine, it's the system Q that has an effect on response which can make the difference.
The other side of the coin is the lower resistance it offers... and the slightly lower system Q that can go with that.
Tighter sounding bass as a result of a lower Q, doesn't suggest that the signal is more accurate or has suffered less damage. Resistance in a bass circuit is fine, it's the system Q that has an effect on response which can make the difference.
The problem with an iron powder core for a crossover inductor is that the inductance will shift with excitation level, because the iron powder permeability also shifts with excitation level. A better choice might be something like a 60 mu Sendust core, which in addition to higher saturation flux density than powdered iron, will also have s smaller shift in permeability with excitation level compared to a comparable powdered iron mix.
Yes, that could be why the toroidal swap was noticable to me (in a good way) on the bigger driver and not so much on the smaller drivers.
Just so the lines don't get blurred, I would never use a steel laminate or a toroidal inductor in a 2-way. So none of the steel laminate vs toroid would apply on a 2 way. As a matter of fact, IME, sometimes a smaller, 18 gauge inductor on a 6.5" woofer works better for adding baffle step than using a larger inductor. It can tame a mildly shrieky upper mid and (oddly) doesn't seem to sacrifice much lower punch
But generally on the woofer circuit in a 3 way, crossed under 400 or 500Hz, I usually go for lowest DCR and that usually works... until I swapped the steel laminate with the Jantzen toroid on the 18W woofers. The toroid is quite a bit lower DCR than the steel laminate, and it didn't change much at all on those woofers. But, the same swap on the SB 10" woofer did seem to add a tad more slam in the bass. Just curious if anyone could quantify my subjective opinion of that.
But generally on the woofer circuit in a 3 way, crossed under 400 or 500Hz, I usually go for lowest DCR and that usually works... until I swapped the steel laminate with the Jantzen toroid on the 18W woofers. The toroid is quite a bit lower DCR than the steel laminate, and it didn't change much at all on those woofers. But, the same swap on the SB 10" woofer did seem to add a tad more slam in the bass. Just curious if anyone could quantify my subjective opinion of that.
I think I tried to quantify that in the last paragraph of post #9. If you put the higher resistance coil back in and you adjusted the damping material to increase the box losses then you'd have the same result.
In some respects this is sensible. On the other hand where any reduction of inductance takes place the woofer may start producing higher frequencies. Not the same thing, sure, but just exploring the situation.
Not necessarily a different subject, it's still inductor related but in a different application... I completely agree and actually used to always use at least a 16awg air core inductor on a woofer in a 2 way. But I did a build using a 7" Wavecor woofer under a Satori tweeter. When I voiced the crossover, IIRC I used a 18awg, 1.2mH coil in the mockup xover. But after I voiced it, when I ordered the parts for the final xover I ordered a 16awg, 1.2 coil. I figured the only place that might impact it was in the bass, and having a smidge more bass on a 2 way is never a problem so I didn't even bother to measure it.
Well that mild inductor change made no noticeable difference on the bass, but it did bump the upper midrange by about 1 to 1.5 db, IIRC the bump was around 1,500 Hz. Wasn't enough for me to take the speakers apart and change out the coils, but I do think it actually sounded better with the 18 gauge than they do with the 16 gauge coils.
I guess long story short, I'll never assume again and I'll make sure I measure every change I ever make, before hauling out the soldering station lol.
With non air core inductors there is a potential of non linear distortion that leads to strange “memory” effects. I have had pretty good luck with laminate iron core on woofers but on an EI core inductive (choke) load for a SE Class A amp, I had some distortion that depended on the depth of the bass that preceded it. So if there was a deep bass note, the successive music would sometimes clip early - flat top hard clip because the stored energy was depleted by the previous music. Hence, there was a memory of what played earlier. I have not experienced this on a woofer crossover but imagine the effect could be similar. It shows up on pulse transients and not on sine wave sweeps.
I appreciate reading about all of this. I do not have good knowledge of the subject except what was taught in electronics class at a high school level many years ago. Having said that I do remember about core saturation and that, as stated here, generally iron core inductors being used for the bass crossover. So now, for a moment, I would like to know what might be gained in using a foil type conductor as opposed to round wire. I am thinking that there is little difference between them, but when I installed a ready built cross over in set of speakers for one of my customers (a two-way design) only foil type inductors were used. What I do know is the big difference in price between the two inductor designs.
This is where things get dicy, or maybe argumentative. In my opinion (and this is not me saying someone that disagrees is wrong), I have not found the benefits to using foil inductors over an air core on a midrange or a tweeter. In my opinion, the extra expense of a foil inductor did not seem to have enough benefit to justify that additional expense. But take that with a grain of salt, because admittedly I have not done a lot of experimenting, only tried a foil once or twice on a tweeter and I've never tried one on a midrange.
I generally use 20 gauge air core on tweeters in my xovers. Midrange will usually be an air core and the gauge will vary but usually its a 18awg on a mid.
Another inductor option that hasn't been talked about yet is Litz. I've tried using a Litz in lieu of an air core before, but my experience the few different times I've tried it, the Litz actually changes the response too much compared to the air core. For example, a driver using a 0.47mH air core will actually measure slightly different than the same driver using a 0.47 Litz inductor. Because of that, I quit trying to use Litz, and that's because I don't know why they change the response so much when the value of the inductor seems to be the same. Maybe someone more sciency than me can answer that 😁
Edit: It just occurred to me that a Litz might make a driver measure different because it has a higher DCR than the inductors I used in the comparisons I tried, much like when I swapped the 18 gauge for a 16 gauge in the 2 way I talked about earlier. Now I need to measure the inductors I have and see if that's what happens.
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This is exactly what I was looking for, thanks for sharing your experience. This makes sense, but I'm really curious why the steel laminate seems to sound better on a woofer (to me) when what you had is definitely a well known phenomenon.
Something that occurred to me this morning while thinking about your response some more... Technically what you stated would give that Jantzen C-core an edge over a regular steel laminate inductor. I read that a major benefit to using a toroidal is that it almost eliminates crosstalk. Would you agree with that??