Shorting rings are pretty common even in TV speakers, which often have some pretty decent engineering to try to limit the substantial space and power limitations. For home hifi I'll never not pay a little extra for some extra shorting paths, as I did for my BMS coaxes and 12" midbass drivers. Both way over-spec for the requirements, but the shorting path is inarguably an advantage, the pertinence at home SPL with over-spec'd drivers certainly is reasonable to debate but not whether it makes for a superior driver. It helps with everything a motor needs to do (besides contributing the flux) from heat management to linearity of inductance and reduction of flux modulation, so in a premium application, or any application where a driver might need to use more of its xmax, they just seem to be a no brainer, no doubt some exceptions apply where the tolerances and design simply don't allow for it.
I can't share much more about it unfortunately, wish I could (believe me really).
All I am willing to say is that this is by far the most limiting number. (well there is another one)
So as I mentioned, I personally wouldn't us it below 100Hz (probably not even under 150-200Hz)
Btw, a shorting-ring or demodulation-ring is not only beneficial for Le(x), but also Le(I), something we unfortunately rarely see data of.
It's not just a no-brainer, but a must at this point.
They can even put them in little 3 inch full-range drivers that will costs you bugger all.
the people who have built 2 ways say they do play ok bass.
anyway, don't shorting rings have to do more with high frequencies ?
As mentioned above, Le(x) and Le(I) or in other words, demodulation distortion.
In simple words, when you play some low frequency stuff together with mid-range frequency stuff, you will get additional distortion.
Plus that other part as well yes.
https://www.gazza-diy-audio.de/speakers/harris-mkii/
I think the similar sized box, tuned a little higher could work with coax version. But I cannot find the crossover recommendation on this one
I think the similar sized box, tuned a little higher could work with coax version. But I cannot find the crossover recommendation on this one
The 5.5 coax will do reasonably clean bass in small format sealed nearfieod environments. Xmax itself is really the major limiting factor compared to delta Le in this driver.
You are correct that adding a copper cap or ring isn't that expensive for a manufacturer these days. Aluminum is even cheaper and some drivers utilize the cast basket edge close to the VC outer diameter as induction control device. Even the lowly peerless TC9 has a copper cap, costing under $20.
The price is under $1 for a 1" VC driver with average winding length. Most of the cost is punching or drawing out the material to fit and to a lesser degree the material itself. Just because a driver doesn't have an induction control device doesn't make it a better driver than those without.
The amplification also plays a role in how well the driver performs. Some amps are worse at driving inductive loads than others, especially those with higher output impedance. Lots of current reserves are beneficial to dealing with large phase swings.
А few dollars per unit in mass production translates into tens of thousands of dollars in the final amount depending on the production scale. There are no objective technical reasons not to use demodulating rings. I reject the hypothesis that Sica does not understand the advantages of using of demodulating rings as surreal. Therefore, the reason for the lack of the demodulating rings most likely lies in the economic plane.
@stv Clearly Sica designed the HF driver in such a way there isn't enough room for effective induction control for the mid driver element. The VC gap is already very tight on this driver and the effective magnetic gap will be larger with a copper cap.
Theres also the extra pole piece height created that takes away from the needed pole standout required to linearize the magnet flux at positive cone excursion. Sometimes you can compensate for this with VC winding offset, but it compounds the effects of any IMD at lower excursion.
Theres a delicate balance between enough VC winding length to produce clean bass and the lower Le a shorter winding allows for, helping midrange sensitivity and distortion performance, but unfortunately hurting low end potential. I'd personally rather have more sensitivity and cleaner mids, then add an LF driver which can handle a higher xover into the 200 hz range as opposed to a sub driver optimized for low end extension.
Most big, lazy subs with long, multi layer VCs do poorly in this lower midrange xover range due to obvious limitations created by the motor design.
There's also the cabinet design itself needing careful design to enable clean midrange performance with proper attention to dampening and midrange spill through the cone or port. This also includes standing waves and enclosure wall resonances. Lower LF xover points in 3 way designs have more potential advantages than disadvantages, provided the midrange / midbass can cope with the extra low mids.
Theres also the extra pole piece height created that takes away from the needed pole standout required to linearize the magnet flux at positive cone excursion. Sometimes you can compensate for this with VC winding offset, but it compounds the effects of any IMD at lower excursion.
Theres a delicate balance between enough VC winding length to produce clean bass and the lower Le a shorter winding allows for, helping midrange sensitivity and distortion performance, but unfortunately hurting low end potential. I'd personally rather have more sensitivity and cleaner mids, then add an LF driver which can handle a higher xover into the 200 hz range as opposed to a sub driver optimized for low end extension.
Most big, lazy subs with long, multi layer VCs do poorly in this lower midrange xover range due to obvious limitations created by the motor design.
There's also the cabinet design itself needing careful design to enable clean midrange performance with proper attention to dampening and midrange spill through the cone or port. This also includes standing waves and enclosure wall resonances. Lower LF xover points in 3 way designs have more potential advantages than disadvantages, provided the midrange / midbass can cope with the extra low mids.
Is this your hypothesis, or can you show photos of the disassembled speakers?
Its a bit of both, but having dealt with the Sica 5.5 in small nearfield designs, it was evident by removing the HF element how little room there was for the tweeter itself.
They attempted to sink the HF VC plane as close to the mid VC as possible and reducing the gap between both driver elements to better control the dreaded notch in FR most coax drivers have.
Sica has some of the closest tolerances I've seen in this regard. It makes the Seas coaxes look cheap in comparison. I dont currently have drivers here to show you. I'll get pictures next time I get another set of drivers on hand to build with.
They attempted to sink the HF VC plane as close to the mid VC as possible and reducing the gap between both driver elements to better control the dreaded notch in FR most coax drivers have.
Sica has some of the closest tolerances I've seen in this regard. It makes the Seas coaxes look cheap in comparison. I dont currently have drivers here to show you. I'll get pictures next time I get another set of drivers on hand to build with.
Its actually not that difficult to measure delta Le effects via static measurments. By applying various increasing levels of both negative and positive DC offset voltages to the driver while having the swept test signal ride on top of it, Le can be measured at these varying levels of cone offset. This is how many test setups do it.
The swept impedance is derived by filtering the DC with a very low frequency HP filter. The DC offset is added to the test signal in the digital domain and the applied offset voltage is then subtracted from the series reference resistor. The trick is avoiding VC heating during measurements at higher offsets with smaller VC diameters. Thermal compression sets in fast with small drivers.
The swept impedance is derived by filtering the DC with a very low frequency HP filter. The DC offset is added to the test signal in the digital domain and the applied offset voltage is then subtracted from the series reference resistor. The trick is avoiding VC heating during measurements at higher offsets with smaller VC diameters. Thermal compression sets in fast with small drivers.
Can someone please confirm that any of these coax tweeters (KEF/SICA) has ferrofluid in the air gap? (or not , which I would prefer) I've seen Z curves of the Sica coax having a quite flat Z peak and a much higher peak , but do not remember if it was the same driver size or both sizes 5inch/6.5inch ... removing ferrofluid is very difficult because typical these neo tweeter parts are glued together and opening would destroy the assembly most likely ...
Ferrofluid can ruin the performance of a tweeter if not designed very well .
I tend to avoid it if possible ...
Damn' , no YT video link this time for my dear hobby friends here
Sh?t you must be really hungry now
Life without music is not possible!
It's a must have ingreedient!
Ferrofluid can ruin the performance of a tweeter if not designed very well .
I tend to avoid it if possible ...
Damn' , no YT video link this time for my dear hobby friends here
Sh?t you must be really hungry now
Life without music is not possible!
It's a must have ingreedient!
Thank you, this is not a fundamental issue for me. Even if you have these photos, we still can’t do anything with the driver design. Therefore, for my sake, it is not worth disassembling the driver, it is a waste of your time.
@Marveloudio i can't say if it does have a FF damped tweeter or not. If it did, they made an effort to optimize it for FF. The top end is very good on these Sica coaxes. Maybe not as good as a SS revalator or 9700 soft dome, but it gets the job done nicely. Its a reasonably inert sounding tweeter and (most importantly).integratez well with the mid.