I think that we all think of different things when we think "cutoff". The point is to be clear what we mean by that. 1/2 power is a norm, but that's not consistent with it's usage in "horn" theory (and some physics) where it means complete shutoff of output. Very different things.
The 1/2 power of the above would be at 660+- Hz. Since there is output, then this can be the only applicable definition of cutoff in this case.
The 1/2 power of the above would be at 660+- Hz. Since there is output, then this can be the only applicable definition of cutoff in this case.
Last edited:
Well at least we agree. I know am concerned about a horn builders definition when thousands of dollars are at hand...
Sometimes by putting up a number, implying cutoff without saying the words, "cutoff" lets one get away with murder...then again, without being totally specific about what one means by it, it, can essentially mean anything.
Sometimes by putting up a number, implying cutoff without saying the words, "cutoff" lets one get away with murder...then again, without being totally specific about what one means by it, it, can essentially mean anything.
Attachments
Last edited:
"Full loading to 400hz", it says......IN my mind there is no full loading past the point where acoustic impedance peaks...it falls off above or below this point depending on Q of the peak but below, it seems to fall off most, in my research.....Potentially the drivers F is a factor but looking at the graph above I would think that this horn cutoff is where I highlighted....why am I wrong? I guess I should look at this as old data maybe not governed in the light of the ideas we have now? I just know there is a group delay bump in there but maybe its just a small one...
Attachments
Cutoff in a conical is even more of a hopeless description than when applied to OS. Here is a pretty big 50x50 modelled after the SH50.
This is the radiation impedance the scale only goes down to 1K because it is already at virtually nothing by then. Apart from concentrating the radiation into a smaller space there is not much help from a flat sided horn. Real = Imaginary at about 3.4K. A secondary flare hardly changes the Rad Imp at all, it does a lot for directivity though.
Overkill and more is more are always popular in DIY. If one is good 20 must be amazing.
You have to be careful in oversizing or overrating things for the sake of it without understanding why it might be a good idea or a bad one. It is easy to make a virtually perfect amplifier at very low power outputs, it becomes increasingly hard to do so as you raise the power output needed. If you achieve it, it comes at the cost of expense, size, heat, noise or something else.
When you build a PA system and listen to it at 5m plus the chance of hearing hiss from an amplifier is very low. When you put a sensitive compression driver in a horn a listen to in an active system at 1m you will most likely be looking for ways to reduce the hiss.
Making a horn bigger than it needs to be for the use case might end up in the same category.
Attachments
A number of pages ago i said i'd look for impedance traces of the me464. Found i didn't have any so just now made some .
Here's the lower section of the dcx464 CD, first with no horn and then on the me464 horn.
Here's the same thing with the bms4594HE.
CD lower section no horn, then on the me464.
Here's two more horns with the bms just for comparisons....sorry don't have the horns for the dcx too.
bms 4594he lower section on XT1464 (in a box with very small baffle)
And last, bms on current syn9 75x60 conical horn.
It's similarity to the CD without a horn illustrates fluids last post i think
Here's the lower section of the dcx464 CD, first with no horn and then on the me464 horn.
Here's the same thing with the bms4594HE.
CD lower section no horn, then on the me464.
Here's two more horns with the bms just for comparisons....sorry don't have the horns for the dcx too.
bms 4594he lower section on XT1464 (in a box with very small baffle)
And last, bms on current syn9 75x60 conical horn.
It's similarity to the CD without a horn illustrates fluids last post i think
I knew Mark was a real one! =) thank you so much for coming through with measurements!
First controversial statement...
That is NOT a 150hz horn....is NOT good at 300hz...
That horn is tuned to 400hz...and group delay should confirm....max resistance/reactance is at ~400hz....measure GD on horn with no filter for nail in coffin.
Boom
First controversial statement...
That is NOT a 150hz horn....is NOT good at 300hz...
That horn is tuned to 400hz...and group delay should confirm....max resistance/reactance is at ~400hz....measure GD on horn with no filter for nail in coffin.
Boom
Last edited:
lol on this page maybe
B&C says it loads to 300 Hz and I see nothing in there to doubt them. The raw impedance of the dcx has a lower peak of 400Hz in free air that moves to 300 and is damped quite a lot on the ME464.
Maybe you should should learn how to read and interpret the graphs you are asking for.
You'll have to explain what you think you see here that has any relevance to mark's measurements.
At the tuning note, at the fundamental, at the root mode, at max resonance etc etc etc
Group Delay peaks...Pressure Peaks.... I've said this stuff before, I wonder if its been passed off as "my crazy theories"....maybe pay attention to horn resp more? I described group delay (in a horn) as a function of pressure on the diaphragm, causing the diaphragm to lag behind. Another one of my crazy theories? Maybe....
I also said that excess decay can be found here...
Non of these things are good for Sound Quality I said.
Attachments
Last edited:
At the tuning note, at the fundamental, at the root mode, at max resonance etc etc etc
Group Delay peaks...Pressure Peaks.... I've said this stuff before, I wonder if its been passed off as "my crazy theories"....maybe pay attention to horn resp more? I described group delay (in a horn) as a function of pressure on the diaphragm, causing the diaphragm to lag behind. Another one of my crazy theories? Maybe....
OK so you can't explain it because you don't understand it. These horns you show with the horrible impedance and group delay are examples of how not to build a horn. Your current attitude is at an all time low. This feels like arguing which I have no interest in.