@ Circlotron from down under 
If you can speak German here is a good link, if not, at least try to interprete the diagrams:http://www.visaton.de/de/forum/pc_doppelschwingspulen.html
Cheers,
Fosti
If you can speak German here is a good link, if not, at least try to interprete the diagrams:http://www.visaton.de/de/forum/pc_doppelschwingspulen.html
Cheers,
Fosti
Hi,
I would expect a 4layer coil to be wound as a 2layer for one VC and the other 2layer laying on top for the second.
Some wind the VC on both sides of the coil former. This again will probably not be bi-fillar wound.
It would be possible to wind the layers alternately, but that would be a manufacturing nightmare.
If the VC is 2layer then how do they get the far end wires back to the start? Same applies to a single layer single VC.
I would expect a 4layer coil to be wound as a 2layer for one VC and the other 2layer laying on top for the second.
Some wind the VC on both sides of the coil former. This again will probably not be bi-fillar wound.
It would be possible to wind the layers alternately, but that would be a manufacturing nightmare.
If the VC is 2layer then how do they get the far end wires back to the start? Same applies to a single layer single VC.
Re: Re: dual voice coils & impedance
Hi Svante,
Le does... or I am missing something here, (do you mean another spec.?)
Visaton GF 200 2 X 4 OHM
http://www.visaton.de/en/high_end/tiefton/gf200_2x4.html
Possible connections:
(1) one voice coil not connected
(2) both voice coils in series
(3) both voice coils in parallel
D.C. resistance Re:
(1) 3,0 Ohm
(2) 5,8 Ohm
(3) 1,5 Ohm
Inductance of the voice coil Le:
(1) 0,7 mH
(2) 1,3 mH
(3) 0,3 mH
Svante said:
Hi Svante,
Le does... or I am missing something here, (do you mean another spec.?)
Visaton GF 200 2 X 4 OHM
http://www.visaton.de/en/high_end/tiefton/gf200_2x4.html
Possible connections:
(1) one voice coil not connected
(2) both voice coils in series
(3) both voice coils in parallel
D.C. resistance Re:
(1) 3,0 Ohm
(2) 5,8 Ohm
(3) 1,5 Ohm
Inductance of the voice coil Le:
(1) 0,7 mH
(2) 1,3 mH
(3) 0,3 mH
Re: Re: Re: dual voice coils & impedance
Well, I don't know how they get those numbers, but if one makes an impedance matching in Basta to the impedance curves on that web page, I end up with these numbers:
Single: Le=0.2 mH, Le loss=0.69
Series: Le=0.9 mH, Le loss=0.69
Parallel: Le=0.26 mH, Le loss=0.69
Now, the inductance numbers cannot be directly compared to those of the data sheet, since Basta! uses a slightly different model with loss, but it is clearly visible that Le does not scale as Re. The series connection results in a ~4 times as large Le, as expected.
BTW, it is rather strange that Vas should vary with the connection of the voice coil, as it is stated in the data sheet.
Inductor said:
Well, I don't know how they get those numbers, but if one makes an impedance matching in Basta to the impedance curves on that web page, I end up with these numbers:
Single: Le=0.2 mH, Le loss=0.69
Series: Le=0.9 mH, Le loss=0.69
Parallel: Le=0.26 mH, Le loss=0.69
Now, the inductance numbers cannot be directly compared to those of the data sheet, since Basta! uses a slightly different model with loss, but it is clearly visible that Le does not scale as Re. The series connection results in a ~4 times as large Le, as expected.
BTW, it is rather strange that Vas should vary with the connection of the voice coil, as it is stated in the data sheet.
Hi Svante,
I butted out there waiting for other comment.
My measurements with DVC drivers show impedance approx 4X when in series compared to parallel (as expected from L=n^2) and virtually identical whether voice coils used single or parallel.
This ties in with your comment.
(Did someone at Visation write that part of the spec after a night on the beer ?)
VAS is related to Cms, which varies with voice coil connection, so I did not think those figures challengeable.
Not a bad X-max for this driver.
Cheers .......... Graham.
I butted out there waiting for other comment.
My measurements with DVC drivers show impedance approx 4X when in series compared to parallel (as expected from L=n^2) and virtually identical whether voice coils used single or parallel.
This ties in with your comment.
(Did someone at Visation write that part of the spec after a night on the beer ?)
VAS is related to Cms, which varies with voice coil connection, so I did not think those figures challengeable.
Not a bad X-max for this driver.
Cheers .......... Graham.
Graham Maynard said:
Yes, inductance should be the same for single coil and parallel be and 4 times that value for series connection. At least theoretically in an ideal world.
But that Cms varies with the way the coils are connected? How would that be possible?
The Xmax of the driver is, as far as I can see +/- 7 mm, which is good but not extreme.
Graham Maynard said:
Ah, yes, that is what I think too, that it really is a measurement error. The real Cms (and Vas) value does not change by connecting the DVCs differently.
I suppose they have connected the driver to some measurement rig that spits out numbers, rather than measuring the Cms directly by means of force and displacement.
Graham Maynard said:
Silly me, it was an 8"... I was under the impression that it was larger, yet I actually entered the Sd yesterday in Basta!. Ah, well... No, I don't know of such a driver from the top of my head.
Anyway, the senitivity of this particular driver does not reach 92 dB either. In series connection, which is the one most similar to 8 ohm impedance, the sensitivity is <91 dB @2.83 V, 1 m half space.
BTW it is rather educating to look at the impedance curves of this driver.
Parallel, 2 ohm:
Single coil, 4 ohm:
Series, 8 ohm:
Comparing the 2 and 4 ohm version, it is clear that there only is a small offset in the impedance curve, ie the only difference is Re. Le is about the same, and so is the resonance peak. The 8 ohm, series curve is very different, though. The voice coil inductance is clearly larger (which can be seen towards higher frequencies the impedance at 20 kHz is ~4 times that of the other two curves), and so is the resonance peak.
Parallel, 2 ohm:
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Single coil, 4 ohm:
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Series, 8 ohm:
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Comparing the 2 and 4 ohm version, it is clear that there only is a small offset in the impedance curve, ie the only difference is Re. Le is about the same, and so is the resonance peak. The 8 ohm, series curve is very different, though. The voice coil inductance is clearly larger (which can be seen towards higher frequencies the impedance at 20 kHz is ~4 times that of the other two curves), and so is the resonance peak.
H Svante,
I hope you did not think I was trying to catch you out, I am genuinely looking for a reasonably priced 8" mib-bass having decent sensitivity and x-max.
The 4 ohm single coil connection might be better with a series R+C connected across the second voice coil winding, this to both level impedance and to damp above say 2kHz.
But this driver is not that cheap either.
Cheers ........... Graham.
I hope you did not think I was trying to catch you out, I am genuinely looking for a reasonably priced 8" mib-bass having decent sensitivity and x-max.
The 4 ohm single coil connection might be better with a series R+C connected across the second voice coil winding, this to both level impedance and to damp above say 2kHz.
But this driver is not that cheap either.
Cheers ........... Graham.
Graham Maynard said:
Ok.
I wouldn't have minded anyway Graham Maynard said:
Yes, DVC drivers can be used for many educating experiments, but I think that most of them prove to be just that and have very small real benefits. The main use for them is IMO when a single driver is needed for a stereo configuration, ie to connect one coil to each channel.
Driving only one coil is a waste of resources, since half of the coil just fills up the gap of precious magnetic field doing little but acting as dead weight.
Graham Maynard said:
SM108 - Beyma 8" low frequency (Fs=69Hz) loudspeaker 150W
http://www.bmm-electronics.com/Producten_c.asp?Productgroep_B_ID=656&Productgroep_A_ID=70
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