New single BR |
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odc04r
Old Croc Joined: 12 July 2006 Location: Sarfampton Status: Offline Points: 5482 |
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Was thinking a bit more on this, if you consider the modelled Cms as lossless (no capacitor in the real world is, but modelling...) then a stiffer suspension means for a given force a driver will displace less from its rest position than another with a higher compliance. But it doesn't tell you anything about how the motion of the driver will dampen once the force holding it in position is removed and it moves back towards its rest position. This is where Qms comes into play, in conjunction with Rms which represents the mechanical losses of the driver. Just thinking from common sense I would wager Rms has a lot to do with driver mass, Sd, and air resistance in general.
Generally it doesn't matter a lot because Qms is seen in parallel with Qes such that Qes dominates, and Qes is often much lower. |
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Crashpc
Registered User Joined: 26 February 2008 Location: Czech Republic Status: Offline Points: 465 |
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I would be very afraid of such simplistic view, and very
careful with conclusions based on these. For example B&C
drivers are known for that the suspension is the main mechanical limit of the
cone excursion. Therefore at some point, mostly Cms eats up the whole force developed by the
voice coil (which is not that high, with 50% or more coil out of the magnetic
field). The Qms and Qes
relations only work with small signals, and relations can get absolutely
different in not that high excursion. Also carefully
about ignoring certain elements in the math, as their chronology is important
for the outcome. Rms is not just static parallel element to the Cms and for all
frequencies. You cannot deduce one from each other and count with it like that
to reach the right outcome. But I´m happy to
see that communities are diving into this science deep stuff.. J |
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Nikon and Canon people should not be married to each other. Why did you let this happen?
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odc04r
Old Croc Joined: 12 July 2006 Location: Sarfampton Status: Offline Points: 5482 |
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Yes I should make it clear that I refer only to small signal models, anything large signal is a different model of behaviour entirely. You always have to beware of modelling limitations to use one properly. Sure you can also have series resistances with Cms etc too, you can put a resistor pretty much anywhere in an acoustic model to represent air leaks or enclosure wadding etc if you have a good reason to. Another problem with regression of real data to TS models is that some elements (especially resistances) will compensate for the behaviour of one another. It is easy to overfit such a model with terms that can end up describing noise in the data - which is another world of science in it's own right.
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smitske96
Young Croc Joined: 16 February 2016 Location: The Netherlands Status: Offline Points: 1092 |
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The Br cab design is almost finished but, I'm also going to build two TH-18's.
They will look like the original TH-118 with only two handles and the two wheels, that way it's easy enough to roll them around for one person. So two BR cabs loaded with 18SW100-4, two TH-18 with 18SW115-4. Reason for going for 4 ohm drivers would be that I've got some more amplifier choice, atm I'm looking at two K3 or one X4. Also grills: They have two sparing for cardioid arrangment, not going to use them, but install the speakons just for the looks.
Edited by smitske96 - 11 April 2019 at 8:09pm |
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Crashpc
Registered User Joined: 26 February 2008 Location: Czech Republic Status: Offline Points: 465 |
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The project looks interesting. Let us now about the results!😍
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Nikon and Canon people should not be married to each other. Why did you let this happen?
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IvCu
Registered User Joined: 16 August 2014 Location: Netherlands Status: Offline Points: 26 |
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If you are looking at X4 that is on markplaats now - it seems as a pretty nice deal! |
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smitske96
Young Croc Joined: 16 February 2016 Location: The Netherlands Status: Offline Points: 1092 |
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I saw that one, but those fotos are from another ebay lot (which alrrady ended for a more normal price). So I don't trust it
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IvCu
Registered User Joined: 16 August 2014 Location: Netherlands Status: Offline Points: 26 |
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haha apparently too good deal to be true, busted!!
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smitske96
Young Croc Joined: 16 February 2016 Location: The Netherlands Status: Offline Points: 1092 |
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The only time I had such a good deal whas on my old PL380 , 450 euros
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smitske96
Young Croc Joined: 16 February 2016 Location: The Netherlands Status: Offline Points: 1092 |
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Update: I've now got two Powersoft 3004PFC4 amps available. They would be ideal with 1X TH-18 and 1X top per side, running the TH-18 on two bridged channels. Other option would be to still go for 4X BR cabs, but the amp module would only give 1500 Watt per sub, which gives me no headroom
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smitske96
Young Croc Joined: 16 February 2016 Location: The Netherlands Status: Offline Points: 1092 |
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Instead if another TH-18, I gave it a try to build a paraflex design.
Test cab (not finished): Probably a bit light on bracing, but I'll see how it performs. Also the diagonal pieces will be added in the mouth. Powersoft module: If they pass the test, I'll build two out of ply, and add wheels and some small handles. |
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Maze
Registered User Joined: 13 April 2014 Location: China Status: Offline Points: 179 |
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How did it go with this one? (the paraflex) I'm might look to built these over the summer. I haven't heard them though, so I'd like to hear what you think of them.
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