@GM I agree, in some way this is actually at the center of my curiosity. The (imho) discrepancy between trying to minimize diffraction at the throat and mouth, but then we blast the midrange, where our hearing is very sensitive, through little holes straight onto the opposite wall of the horn where the wave goes in all directions, notches itself out etc. At least in a synergy type speaker that is.
The gasket is maybe half a millimeter once the drivers are screwed on, so I doubt that increases the front chamber volume that much.
@Patrick Bateman I'm not going to argue about my lack of expertise when it comes to crossovers. So there's always that. But I'm really trying to get at something else here. That's why I started listening to the midrange taps alone. For this I looked at the filter slope of the acoustical high- and low-pass and digitally recreated them approximately on a 'normal' speaker. When comparing these two, the normal speaker with the filters has a pretty similar frequency response and passband, but sounds much cleaner. I would love to be proven wrong here, but can't see how this can be fixed with a crossover. The integration of all the drivers into a truly coherent speaker may be beyond my skills, but I'm really only looking at the mid-range on its own here.
@mefistofelez Yes, these kinds of things do baffle me at times. Not the least because I do work in post production and have learned that my ears can be incredibly sensitive and revealing, but also totally misleading and deceitful, sometimes at the same time.
The gasket is maybe half a millimeter once the drivers are screwed on, so I doubt that increases the front chamber volume that much.
@Patrick Bateman I'm not going to argue about my lack of expertise when it comes to crossovers. So there's always that. But I'm really trying to get at something else here. That's why I started listening to the midrange taps alone. For this I looked at the filter slope of the acoustical high- and low-pass and digitally recreated them approximately on a 'normal' speaker. When comparing these two, the normal speaker with the filters has a pretty similar frequency response and passband, but sounds much cleaner. I would love to be proven wrong here, but can't see how this can be fixed with a crossover. The integration of all the drivers into a truly coherent speaker may be beyond my skills, but I'm really only looking at the mid-range on its own here.
@mefistofelez Yes, these kinds of things do baffle me at times. Not the least because I do work in post production and have learned that my ears can be incredibly sensitive and revealing, but also totally misleading and deceitful, sometimes at the same time.
Not surprised, but like to get known potential issues out of the way first, i.e. acoustical solutions to acoustical problems.
Very true.
Well, a bit of both IM (limited) E from helping others with their builds.
I resemble that remark!
During my active DIY 'career', 1st, 2nd order textbook XOs, zobels, series notch, frequency, shaping filters combined with physical offsets worked plenty well enough for the times.Vathek, I can understand that it is disappointing to make something that you thought would be great only to have it not be what you hoped. I would be very cautious of coming to the conclusion that anything with a tap in it is broken and can't sound good.
If you want to find the problem it is likely going to take some measuring and experimentation. There could be a fault with the drivers, the mounting, something rubbing, something misaligned. The frequency response could be wrong, really it could be any number of things that need to be examined and accounted for if you want to get to the bottom of it.
If you want to find the problem it is likely going to take some measuring and experimentation. There could be a fault with the drivers, the mounting, something rubbing, something misaligned. The frequency response could be wrong, really it could be any number of things that need to be examined and accounted for if you want to get to the bottom of it.
Yes, that's what I'm trying to do here. My conclusion is not that anything with a tap in it is broken, definitely not. I still very much like the concept and am trying to find out why it's not been working for me. And mind you, the issue I'm talking about is not super obvious. People have commented very favourably on these speakers, I've just never been able to get them as clean as I'd like them to be. And I'm pretty confident that the things that have been suggested to possibly be the culprit can be ruled out. But I'm happy to look into all of these as well.
The drivers are fine, I have 10 the HF0410MR that I bought from Italy when they started to disappear from the market and they all measure and sound the same (well four of them I never unpacked as I only needed six of them). The reason I put a bit of foam gasket underneath them is that the built in gasket on these drivers is super stiff cardboardish material and the surface of the waveguide is not perfectly flat because of the printing / filament structure. I can test if leaving that out makes a difference, but I would be very surprised if that improved the situation. Especiall since the frequency response is bang on, flat throughout their passband with a slight bump at around 950Hz and acoustical hi- and low-pass filters that are pretty much 24dB per octave. So the design of the waveguide, the cavities, front chamber etc is excellent (hats off to @bwaslo ).
That's why I came up with that little comparison. So if onyone here has one of these at hand and is willing to compare just the midrange drivers with another speaker next to it with 24dB Filters at 300 and 1300 Hz, I'd be curious what their finding would be.
The drivers are fine, I have 10 the HF0410MR that I bought from Italy when they started to disappear from the market and they all measure and sound the same (well four of them I never unpacked as I only needed six of them). The reason I put a bit of foam gasket underneath them is that the built in gasket on these drivers is super stiff cardboardish material and the surface of the waveguide is not perfectly flat because of the printing / filament structure. I can test if leaving that out makes a difference, but I would be very surprised if that improved the situation. Especiall since the frequency response is bang on, flat throughout their passband with a slight bump at around 950Hz and acoustical hi- and low-pass filters that are pretty much 24dB per octave. So the design of the waveguide, the cavities, front chamber etc is excellent (hats off to @bwaslo ).
That's why I came up with that little comparison. So if onyone here has one of these at hand and is willing to compare just the midrange drivers with another speaker next to it with 24dB Filters at 300 and 1300 Hz, I'd be curious what their finding would be.
Sound waves expand like a soap bubble, so at ~34400 cm/sec it basically 'lights up' the entire horn to a greater or lesser extent depending on the BW response.
OK, but ideally we need a very high Qt driver that the low pass filter can squeeze flat to the desired BW = typically tiny chambers, so at this point need to see the design details since once we move past this (less compression) the more the horn can modulate the vent's harmonics, which could be perceived as a too small BR's vent's harmonics comb filtering with the upper BW; if true, then only lowering the XO's HF corner or modding the mids box design can ameliorate it.
In short, the vents ideally need to be 'blind'/'transparent' to the horn.
Great, perhaps a communication breakdown as your previous post gave me a different impression.
Measuring is going to be the best way to try and narrow down what the issue could be, on and off axis frequency response, impedance, burst decay, near field measurements near and around the ports of the mid, CSD, distortion.
They should help in spotting any mechanical or resonant problems, obvious frequency balance or cross over issues