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Xmax, does it kill?

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luthier View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote luthier Quote  Post ReplyReply Direct Link To This Post Posted: 25 January 2019 at 10:50pm
Saying this the 1550 has a higher MMS, larger voice coil, 2.5mm more xmax, low power compression and proven horn loading history. 

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Post Options Post Options   Thanks (0) Thanks(0)   Quote ceharden Quote  Post ReplyReply Direct Link To This Post Posted: 26 January 2019 at 1:40am
PD1550 would also make for a very heavy mid-top!

In terms of the cone, it's hard to tell from the specs, you can judge it better by looking and comparing them.

I've got some RCF MB15H401's here which I'm wondering if I could get away with horn loading.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote luthier Quote  Post ReplyReply Direct Link To This Post Posted: 26 January 2019 at 1:50am
Originally posted by ceharden ceharden wrote:

PD1550 would also make for a very heavy mid-top!

In terms of the cone, it's hard to tell from the specs, you can judge it better by looking and comparing them.

I've got some RCF MB15H401's here which I'm wondering if I could get away with horn loading.

I agree and so do the sims, the response looks bad at the top end and very logarithmic overall. Looks like it would make very good thump at 80hz but not much use for anything else in this horn. Similar to the pd1850 and v18 in the Es18bph. 


I think the 12 version of that rcf is used in the Peter Morris mid top with good results, certainly looks good to me. I'll sim it tomorrow.


Edited by luthier - 26 January 2019 at 1:50am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Crashpc Quote  Post ReplyReply Direct Link To This Post Posted: 28 January 2019 at 6:51pm
Not that I would be sure about horn loading with 15ND76, but when I had these out, I could almost see through the surround, and the cone wasn´t like night and day sturdier by feel. I would not torture this one with high pressures. Also, if I remember well ,the cone was significantly more curvilinear than some other products. That is no good at the edge of the cone for high pressure.
Anyway, hope you find some more valid info...
Nikon and Canon people should not be married to each other. Why did you let this happen?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote luthier Quote  Post ReplyReply Direct Link To This Post Posted: 31 January 2019 at 5:23pm
Originally posted by Crashpc Crashpc wrote:

Not that I would be sure about horn loading with 15ND76, but when I had these out, I could almost see through the surround, and the cone wasn´t like night and day sturdier by feel. I would not torture this one with high pressures. Also, if I remember well ,the cone was significantly more curvilinear than some other products. That is no good at the edge of the cone for high pressure.
Anyway, hope you find some more valid info...

Thank you for the advice, I think it will just have to come down to a bit of testing on my part.

From what I gather, hornloading drivers can be risky business,  a strong motor and a stiff cone like on the pd1550 will take a good amount of abuse, but will be too heavy to reach higher frquencies and seem to have a very logarthmic response. Lighter cones like my ndl76 will play higher but ultimatley don't like small throats and high compression ratios and have a tendancy to rip cones if overdriven and/or unloaded. 

Hopefully I can work out a good driver through a bit of hornresp sims, guesstimating and real world testing.










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Post Options Post Options   Thanks (0) Thanks(0)   Quote Crashpc Quote  Post ReplyReply Direct Link To This Post Posted: 31 January 2019 at 9:22pm
It´s funny that pd.1550 doesn´t have that much more Mms, yet it is perceived as significantly sturdier.

Obviously, your plan is technically demanding, which is good, but it gets you cornered with issues like these. I wonder if interesting 12" couldn´t do betwen 100-500Hz... Just and idea. I also push things far, so I have sympathy for this. As usual, you´ll have to pay your experience with your wallet for broken cones. That´s what we all do unless some angel comes and helps us from our misery and clueless lifes. :-D
Nikon and Canon people should not be married to each other. Why did you let this happen?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ceharden Quote  Post ReplyReply Direct Link To This Post Posted: 31 January 2019 at 10:48pm
The difference is most likely that the 1550 has a straight cone which is much stiffer than the curved or exponential cones which most bass-mid drivers have.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote luthier Quote  Post ReplyReply Direct Link To This Post Posted: 31 January 2019 at 10:53pm
A straight cone I imagine would be loaded more evenly under high pressure but surely a cone with a curve in it causes it to be under a certain amount of extra tension, causing increased rigidity?

The force would be then be transferred to the surround, VC and spider which can guesstimate with the EBP.

Surely this is the kind of experiment that pro audio companies do with FEA analysis.

Edited by luthier - 31 January 2019 at 10:55pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote fatfreddiescat Quote  Post ReplyReply Direct Link To This Post Posted: 31 January 2019 at 11:05pm
Originally posted by ceharden ceharden wrote:

The difference is most likely that the 1550 has a straight cone which is much stiffer than the curved or exponential cones which most bass-mid drivers have.

Looks like the 1550 is a curved cone, not as curved as some though, All the drivers used in the FK1’s I think are curved.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote citizensc Quote  Post ReplyReply Direct Link To This Post Posted: 01 February 2019 at 12:03am
Originally posted by luthier luthier wrote:

I'm trying to decide if EBP of a driver be a more accurate way to estimate a drivers suitability in a horn loaded design?

I've been calculating the EBP of the 15" drivers I have been modeling and have come up with this.

B&C NDL88 - EBP 125
Oberton 15B450 EBP 153.3
PD 1550 - EBP 153.9
B&C 15ndl76 - EBP 154
PD.153er - EBP  181

Would this make the PD.153er first choice for my ported BPH?

Sorry to wake up a post from last page but I have experience using PD.153ERin xtros (horn loading them). 

They hate it and will die. They will sound good for about 5 shows, then fall apart. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ceharden Quote  Post ReplyReply Direct Link To This Post Posted: 01 February 2019 at 12:45am
The cones drivers designed for 2-way mid tops etc are designed to flex such that at higher frequencies only the centre of the cone is moving and the outer section effectively stays still.  This gives a better midrange performance but has an impact on cone strength.

As above, if you put too high an air load on any driver, asymmetric as you get on many bass horns is even worse, what you end up building is a confetti cannon!


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Post Options Post Options   Thanks (0) Thanks(0)   Quote luthier Quote  Post ReplyReply Direct Link To This Post Posted: 01 February 2019 at 12:50am
Originally posted by citizensc citizensc wrote:

Originally posted by luthier luthier wrote:

I'm trying to decide if EBP of a driver be a more accurate way to estimate a drivers suitability in a horn loaded design?

I've been calculating the EBP of the 15" drivers I have been modeling and have come up with this.

B&C NDL88 - EBP 125
Oberton 15B450 EBP 153.3
PD 1550 - EBP 153.9
B&C 15ndl76 - EBP 154
PD.153er - EBP  181

Would this make the PD.153er first choice for my ported BPH?

Sorry to wake up a post from last page but I have experience using PD.153ERin xtros (horn loading them). 

They hate it and will die. They will sound good for about 5 shows, then fall apart. 

Well that is very useful to know.
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