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Question 5Is the idea behind a tractrix horn to amplify the signal without coloration of the sound?By coloration do you mean say the duck voice? If so its caused by the plastic horn material, you would use a real wood horn.
Hi, my name is James and I am new to this forum so please excuse me if I do something I’m not supposed to.
In a crossover, I am aware that all components add specific delay amounts to the audio signal, with some components having little to no delay and with others having a big delay to the audio signal. My questions are as follows.Question 1Are there specific crossover components that I can use to solely adjust the time delay of each driver in a multi-way speaker? Components that won’t effect anything except time delay? The issue im trying to resolve is PHASE ALIGNMENT of the drivers. My concern is that once my speaker drivers are locked in place on the baffle, once I build my crossover, some of the drivers will be out of phase with the others to a certain degree. My first instinct was to create individual moveable cabinets for each driver so that even after I design my crossover I can physically time align my speakers. I’m told that the issue with this is the possibility of reflections and diffraction due to the uneven baffle surface which will cause coloration to the audio signal. With this in mind, my next instinct is to have one baffle for all the drivers, and mount each driver a certain depth into the baffle.
Question 2 (also a continuation of question 1)The issue I’m worried about in doing this is, for the mid and high frequency drivers, how will I mount the drivers deeper into the baffle in a way that I won’t cause coloration to the drivers due to the throat I will be making that the driver will be sitting behind.. My first instinct to solve this issue is to round the corners of the cutouts I make to mount the drivers deeper into the baffle. My concern in doing this is that I will create a boost/Horn effect to the driver at a specific frequency and up due to an effect similar to baffle step loss.
Question 3Is there a way I can mount my drivers deeper into my baffle without coloration to the sound? Is it a matter of me being unable to mount the driver past a certain depth into the baffle so that I can avoid having a throat deep enough to effect the frequency range of a specific driver? If this is the case then it’d be nearly impossible to have no coloration to the tweeter as this is the driver I will have to mount the deepest if I want to time align each driver at the horizontal axis.
Question 4With all this in mind, is there a shape that I can make the cutouts so that the cutouts won’t add coloration to the signal?
Question 5Is the idea behind a tractrix horn to amplify the signal without coloration of the sound?
Because physical appearance is such a big part of selling speakers, and a plain, vertical baffle without angles and horns is the preferred fashion, designers must be able to time-align the drivers using the electrical crossover only, which drivers mounted flush on a vertical baffle. They do this by using asymetrical crossover filters. Most common example of this is a 2nd order filter on the woofer and a third order filter on the tweeter. Using an extra electrical pole (aka order) on the tweeter delays the launch of the tweeter wave by 90 degrees, because each pole adds 90 degrees of delay. 90 degrees of a 360 degree wave is 1/4 wavelength. A wavelength calculator converts your crossover design frequency to wavelength, then you divide that by 4 to determine the distance of delay per pole at the xo freq. At typical tweeter crossover frequency of 2400 Hz with 2nd order filter on woofer, and 3rd order filter on the tweeter (asymmetrical filters) makes the tweeter act as if it was recessed relative to the woofer by 1.4". The problem with asymmetric crossover filters is their rolloff slopes are not the same steepness, and steepness relates directly to phase rotation. So the filters do not remain in phase with each other throughout the entire crossover band, they're exactly in phase only at the nominal xo freq. But this is one of many design compromises made in speaker design and its very common. Symmetric filters is preferred because they will remain in phase throughout the crossover band. In the real world, bandaids are often required to reach the design goals and it's rare that a perfectly harmless speaker design is bestowed upon the world. One useful bandaid is the use of notch filters in a xo design to give small tweaks to the slope and phase to fine tune the time and phase alignment through the entire xo band. Filter order is primary effect, while notch ("EQ") filters have secondary effect for fine tuning FR and phase.
Thank rhichidoo! You’ve covered every base of my questions regarding to this specific aspect of crossover design, but this still leads me to more questions. My first question is unrelated to this topic but has to do with how this forum works. If I reply to your message as I am doing right now, how easy is it for you to notice I replied? Do you get a notification when I reply or do you have to manually check this thread to see whether of not I replied?
Second Question is, let’s say you have a 5th order XO (I assume this is how you achieve 360° phase shift).
Does this really delay the driver in time, or does it just change the phase of the driver back to normal?
For instance if a have a 2-way design with my tweeter on a 5th order and my woofer on a 1st order, does this mean that if I play a frequency sweep through the speaker, that they will be playing the sweep at different times regardless of listening position?
Is adding poles to the crossover really the same as physically moving the drivers backwards when looking specifically at time arrivals of the drivers?
Also would you say that physically moving the drivers while keeping a symmetrical XO would be a superior solution vs having them rest ok the same vertical axis and adjust their phase relationship through the use if an asymmetric XO?
Also as a main question I want answered, Can you adjust the actual physical time delay of the drivers, using the crossover?
Can I actually delay the whole signal with the crossover and not just the phase shift?
Does this really delay the driver in time, or does it just change the phase of the driver back to normal? If you mean say delay the signal a few seconds or even more you will need a place to store the signal as an HD and a another amp to release the signal to the driver when desired, what seems a advanced military weapon.
It's all manual, but the "Notify" button at the bottom of every page in a thread subscribes you to that thread to receive an email when a new post is made since the last time you read it. The button toggles to Yes, it delays the driver in time. Phase can only be delayed, never advanced. If you need something advanced you do that by delaying everything...
When designing a crossover, each pole adds 90° of phase rotation. Does this mean exactly 90° at only the crossover frequency?
If this is true, then a 2nd order high-pass crossover at 2700hz would be equivalent to a 2.5” distance change away from you?
You said the the roll off slope directly relates to phase shift rotation. Does this mean that in a high pass filter, the phase continuously changes rotation while moving down in frequency?
Does the phase rotation remain the same above the high pass xo frequency?
Also if the phase rotation is continuously changing above or below the crossover point, doesn’t this mean that in a two way speaker, the tweeter will be out of phase at certain frequencies with the woofer below the crossover frequency and vise versa for the woofer?
No. It's rotated exactly 90 only in the pass band, or the frequency range outside of the filters influence. In the filters influence, the phase rotates greater than 90 with increasing filter effect. The more attenuation, the more phase rotation.
Good question, you're getting it! Actually, symmetrical order filters rotate phase at same rate and same direction so they do stay in phase through the crossover band, like magic!
how can I get the whole speaker to be 8 ohm without sacrificing sensitivity? I know you can use resistors to up the impedance, but won’t this have an effect on efficiency? Also, more speakers in parallel=more efficiency, and more speakers in series = less efficiency, right?
Any xover part will decrease driver efficiency and loss low level music signal as heat, tô avoid it you would use a FR driver direct from the amp.
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