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odc04r View Drop Down
Old Croc
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Joined: 12 July 2006
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Points: 5482 		Post Options Post Options   Thanks (1) Thanks(1)   Quote odc04r Quote  Post ReplyReply Direct Link To This Post Posted: 10 April 2019 at 7:51am
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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Points: 465 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Crashpc Quote  Post ReplyReply Direct Link To This Post Posted: 10 April 2019 at 8:43am

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
Nikon and Canon people should not be married to each other. Why did you let this happen?
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odc04r View Drop Down
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Points: 5482 		Post Options Post Options   Thanks (0) Thanks(0)   Quote odc04r Quote  Post ReplyReply Direct Link To This Post Posted: 10 April 2019 at 11:02am
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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Points: 1092 		Post Options Post Options   Thanks (0) Thanks(0)   Quote smitske96 Quote  Post ReplyReply Direct Link To This Post Posted: 11 April 2019 at 8:04pm
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 View Drop Down
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Points: 465 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Crashpc Quote  Post ReplyReply Direct Link To This Post Posted: 11 April 2019 at 8:20pm
The project looks interesting. Let us now about the results!😍
Nikon and Canon people should not be married to each other. Why did you let this happen?
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Points: 26 		Post Options Post Options   Thanks (0) Thanks(0)   Quote IvCu Quote  Post ReplyReply Direct Link To This Post Posted: 12 April 2019 at 1:44am
Originally posted by smitske96 smitske96 wrote:

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.


If you are looking at X4 that is on markplaats now - it seems as a pretty nice deal! Smile
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Points: 1092 		Post Options Post Options   Thanks (0) Thanks(0)   Quote smitske96 Quote  Post ReplyReply Direct Link To This Post Posted: 12 April 2019 at 8:17am
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 LOL
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IvCu View Drop Down
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Points: 26 		Post Options Post Options   Thanks (0) Thanks(0)   Quote IvCu Quote  Post ReplyReply Direct Link To This Post Posted: 12 April 2019 at 11:50am
haha apparently too good deal to be true, busted!! 
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smitske96 View Drop Down
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Points: 1092 		Post Options Post Options   Thanks (0) Thanks(0)   Quote smitske96 Quote  Post ReplyReply Direct Link To This Post Posted: 12 April 2019 at 1:49pm
The only time I had such a good deal whas on my old PL380 , 450 euros Smile
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smitske96 View Drop Down
Young Croc
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Points: 1092 		Post Options Post Options   Thanks (0) Thanks(0)   Quote smitske96 Quote  Post ReplyReply Direct Link To This Post Posted: 19 May 2019 at 2:38pm
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 Unhappy
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Points: 1092 		Post Options Post Options   Thanks (0) Thanks(0)   Quote smitske96 Quote  Post ReplyReply Direct Link To This Post Posted: 27 May 2019 at 6:20pm
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 View Drop Down
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Points: 179 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Maze Quote  Post ReplyReply Direct Link To This Post Posted: 03 June 2019 at 1:02am
Originally posted by smitske96 smitske96 wrote:

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.


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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