Hello
Thanks that helps. I don't use sealed boxes for bass so I have never used LT. It's also normally a plus EQ inverse to roll off so I was a bit confused as to why you would roll off usable output with a Low pass filter and then make it back up with gain. Just seems counter productive. I use reflex boxes for low frequency and use a bump filter @ Fb to bring up the last octave or so very much like BX-63A for the JBL subs. It's high pass, bump, low pass. Does the same thing without gain manipulation.
Rob
Attachments
They are not opposed. You are not simply turning the system up by moving closer, you’re changing the direct to reverberant ratio. You may also move inside the critical distance window, for the majority of frequencies of interest, if you were outside of it before.
If the receiver location is fixed, increasing the speaker output does not change the direct to reverberant ratio at that position, for steady-state signals.
Changing directivity is a different matter, even if the direct SPL at the receiver is kept the same. However, without an understanding of what surfaces are ‘lit up’ by any speaker, their absorption and scattering coefficients, angle, and distance, then you can’t talk in absolutes. A narrow, long room will need a larger source to control directivity to keep sound off the walls, but then you may struggle to fit them at the optimum locations, for example.
That’s the definition of diminishing returns, and often why the room is considered to be at least as important as the system choice.
Also, I’m referring to SPL because you’re talking about your subs in the most recent posts - which are far too small to have any sort of useful directivity, even if your room was acoustically large enough for it to matter.
If the receiver location is fixed, increasing the speaker output does not change the direct to reverberant ratio at that position, for steady-state signals.
Changing directivity is a different matter, even if the direct SPL at the receiver is kept the same. However, without an understanding of what surfaces are ‘lit up’ by any speaker, their absorption and scattering coefficients, angle, and distance, then you can’t talk in absolutes. A narrow, long room will need a larger source to control directivity to keep sound off the walls, but then you may struggle to fit them at the optimum locations, for example.
That’s the definition of diminishing returns, and often why the room is considered to be at least as important as the system choice.
Also, I’m referring to SPL because you’re talking about your subs in the most recent posts - which are far too small to have any sort of useful directivity, even if your room was acoustically large enough for it to matter.
This is the same approach we have towards the decay character of a loudspeaker. Nothing special about it.
This reply would of gone differently if I had of caught the SPl aspect. Though I am not sure I agree with your reasons, no one here is looking to increase spl, in terms of a gain knob, to defeat the room. Thats how, what you are saying, comes across to me. Even though I am not looking to make this argument I wonder have you ever even looked at the measurements? Experimenting with my sub, I definitely can see a difference in the measurements depending on low volume of high volume....turning up the volume increase direct energy whether it was your intent or not....Thats not foolish thats physics.
The area I am trying to explore has to do with creating a system that creates the most Direct energy (reasonably I should argue)
As I listed the aspects
Radiation Size
Directivity
Close proximity
Increase those elements, Direct energy increases, and you never have to touch the gain knob....you might have to lower it actually.
My system design reflects those goals. Horns and waveguides are the devices for said goals regarding a tweeter. Thats exactly what I have have or intend to have....Whats the confusion?
I disagree, and maybe my misinterpretation of measurements is the cause>? So why when I turn up the volume and do a measurement at a louder volume, SQ goes up?
OK yeah I get you there, I am speaking from a more basic view of the design. I could maybe one day try cardioid.
Lets see you do the same with not as much GD manipulation as using gain...Read that as Filter induced GDHello
Thanks that helps. I don't use sealed boxes for bass so I have never used LT. It's also normally a plus EQ inverse to roll off so I was a bit confused as to why you would roll off usable output with a Low pass filter and then make it back up with gain. Just seems counter productive. I use reflex boxes for low frequency and use a bump filter @ Fb to bring up the last octave or so very much like BX-63A for the JBL subs. It's high pass, bump, low pass. Does the same thing without gain manipulation.
Rob
Last edited:
I am not concerned about the group delay added by the bump filter below 30Hz. I don't see that as an issue. If I was adding group delay above 500 Hz or in excess of the BL curve I would be concerned. How audible will the group delay added be under actual use in a real room with standard program material?? I am not worried.
Your gain structure should be predicable and quite manageable not trying to reinvent the wheel. If making GD a paramount concern in your design have at it. I think there are much bigger fish to fry.
We seem to think differently which is fine and make opposite choices which can lead to good discussions. Since this is an active system you can dial it in using both methods. Try both see what you like.
Rob
If you guys didn't know, you can hit shift+ windows key+ s and it will let you select, copy, and paste, wysiwyg style. One day free loudspeaker design software will be that simple lol, moving the mathematicians out of the way via software.
So this is my VituixCad, If I start designing a waveguide. Would I want it to be as wide as the width of the enclosure....or would I just match the size of the woofer and have it on a baffle as wide as the enclosure. I could ask in Mabats thread but I don't want muddy up his thread with "hey can you please tell me what waveguide to build", as he normally has some really good discussion going geared towards the leading of waveguides. Maybe I am being too polite. At one point in time a person actually had an Axi2050 they were trying to design a waveguide towards....I wonder what came of it....
This will be one of several efforts into fostering a conversation on the topic.
What Waveguide does the forum think is the proper selection for my application. This is me letting go of any ideas of a certain XO point.
A 15" on top of a PPSL-dual 18's is a version of the best one could do in the amount of space it takes up... below a horn/waveguide/synergy. At least I got that part right.
Last edited:
I appreciate your ability to agree to disagree, while not trying to devalue or condescend on my choice.
I do obviously like to try and compete. I am just not a sore loser lol
With that being said...
I wonder which method, would lead to the best measurements, since we say that matters most.
I'm going to say using gain as a group delay free, eq filter, in this instance, wins out, with the loop hole being THD not being exposed due to 2 high pass filters.
Well it for sure increases the SPL. The distance from room boundaries and room sizes set's the reverberant field. I think that's correct. So the question is does an increase in SPL change the ratio of reverberant to direct at the listening position?? I think this would be independent of SPL leaving all other aspects the same.
Rob
This made me laugh, how the crowd seems to feel about caring about group delay, I approach constant power response lol....not literally, but sorta...we just exposed that constant can be different things.
Different strokes for different folks...or maybe I'll eventually be persuaded by personal experience? I think even more so in your favor is the idea that GD can be fixed later....Since neither route affords me any benefits I could go either way.
it increases Sound Quality, The Phase, GD, Burst Decay, all improved, in my recent experience...
I don’t need to be ‘open-minded’ about Euler’s number, because a mathematical constant isn’t what you meant, and doesn't really describe the shape of a curve plot either.You should be open minded....and I should be more confident
I would look to as big a waveguide as you can live with. Then pick a coverage angle, I'd go round - it's the easiest and works the best from what I have seen. With throat size and angle (readily known) you have all you need to build a magnificent source for 60-70% of the sound that you hear. From the waveguide design found at Mabats thread "something"360 (don't remember), or simply put as OS with a gradual flare to the baffle. Measure or sim this. Now match that with the next driver down, your mids, with both filter summation and polar angle - this will occur at only one frequency (most likely) and that becomes dictated as the crossover point - it's not chosen at will. Fill in the bottom in the last step - done in-situ. That's my recipe. Worked every time.
IMO you are working backwards, as many do, focusing on the very low. Not very important at this stage of the game.
PM me if you really can't find a design over at ATH. I'd stay away from their current discussions, as good as they are, but they are very (b)leading edge stuff. Just ask for a design around the specs that want - coverage angle, throat size and baffle size. That fixes the design. Everything else is just fluff.
Last edited: