Although the voltage is halved, the frequency remains the same. Are you saying the slew rate is responsible for an inductor's increasing resistance, rather than frequency? Crossover points don't move up and down with changes in amplitude so this can't be right
You have to consider baffle step (unless you are building infinite baffles). Then you will see that it's the woofer that defines the system efficiency. And most midranges will fit perfectly, you may even have to dampen them with resistors.
Practically speaking you will not get 90 dB efficiency in the bass region and the rest of the speaker system will have to adapt to this efficiency, probably 84-86 dB.
Rs125 will be perfectly fine, maybe even the 8 ohm version.
Edit: also consider doubling of impedance with speakers in series and the effect on their output!
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Vd1 = Vtotal(Zd1/(Zd1+Zd2))
So, where the impedance (Z) of driver1 equals that of driver2...
Vd1 = Vtotalx(1/2)
While the impedances vary with frequency, their relationship does not hence there is no 'f' in the above.
So, where the impedance (Z) of driver1 equals that of driver2...
Vd1 = Vtotalx(1/2)
While the impedances vary with frequency, their relationship does not hence there is no 'f' in the above.
See AllenB's response. It only holds true if the drivers are identical. If one had slightly higher inductance than the other (e.g. due to manufacturing tolerance), then at higher frequencies that driver would see slightly more than half the total drive voltage. It's possible that the higher inductance would also result in a slightly falling frequency response for that driver, and the higher drive voltage would tend to negate this. So series connection would tend to "even out" the response of two similar drivers.
Let's stick to two of the same driver with a factory similar impedance and do it in layman's terms for ease of processing. 1st order figures.
A 4Ω woofer xo at 635Hz requires a 1.0 mH choke
A 8Ω woofer xo at 635Hz requires a 2.0 mH choke.
When you double the impedance you require twice the inductance to roll off at the same point. Consider the voice coils as the inductors they are and it's simple. Without other factors, there is no HF attenuation when running drivers in series.
A 4Ω woofer xo at 635Hz requires a 1.0 mH choke
A 8Ω woofer xo at 635Hz requires a 2.0 mH choke.
When you double the impedance you require twice the inductance to roll off at the same point. Consider the voice coils as the inductors they are and it's simple. Without other factors, there is no HF attenuation when running drivers in series.
OK, and maybe I do now if we're just having a 'failure to communicate' 😉 in that if I follow this reasoning, then you're referring to a matching HF slope order roll off [which it sims] whereas I'm referring to the higher inductance causing the HF to roll off at a lower frequency [which it sims] if comparing a single driver Vs a single composite driver = four summed specs since HR won't let me do directivity calcs otherwise.
We're are getting closer Greg. 🙂
There is no difference in either the slope nor the frequency at which roll off begins. The doubling of the inductance, that tells the back of your mind that it will cut it off sooner, is overridden by the doubling of the impedance which prevents that. I believe that will apply no matter the number of drivers in series.
This is the part I am not sure what you are saying. I was using an example only of one driver vs two of the same driver in series.
There is no difference in either the slope nor the frequency at which roll off begins. The doubling of the inductance, that tells the back of your mind that it will cut it off sooner, is overridden by the doubling of the impedance which prevents that. I believe that will apply no matter the number of drivers in series.
This is the part I am not sure what you are saying. I was using an example only of one driver vs two of the same driver in series.
Hmm, OK, what I didn't post is that for the composite [4x Vas, Sd, Re, Le and let HR calc the rest] I changed [Eg] to 1 W @ 32 ohms = 5.66 V [HR calc] in HR's IB [no box/horn inputs].
My tweeter suggestion would be the Seas DXT - works like a charm here with a Dayton RS125(alu version) and two 8" woofers - crossed at 5Hz and 2kHz.
But... I run it active though, so I worry not about sensitivity (much) and other specs of the driver. Build a good box with the right front baffle and measure the response and add EQ to each driver until the sum of all drivers behave nicely both on and off-axis - done.
Even a USB microphone (with calibration file) and free software - you go very far. My guess is that it would be even easier than fiddling with simulations and passive components - in the long run - it still requires a learning curve... but I do not regret that I jumped straight to active and never looked at passives.
Inspiration can be found here:
3 ways d'appolito floor standing speaker | Fully active with DSP
Of course... if you choose to use a woofer with a sensitivity of 85 dB with a tweeter that has one around 95dB.... the woofer will lack the higher potential SPL that the tweeter has.... but it can still be done.
Some say that you have to build 20 speakers to get good results.... well.... maybe and maybe not. There are so many tools out there to help create something great... and even after years of construction and listening.... you will still learn something new.
I have heard tons of super high quality drivers and speakers in all kinds of constructions - almost no price limit here. But my "cheap" drivers in simple boxes combined with a well designed active system.... plays very close to anything I have heard. It's mostly a matter of how you do it - less with what the drivers cost and how they look.
And if you chose to go for active.... consider the Dayton alu.... to me... they have more detail than paper cones. I know that some say that paper is a little more forgiving.... but mostly that is an EQ thing.... which is very easy to work with in a DSP. Though.... if active or passive... do promise me to read up on measuring the result... it can really help you understand whats going on between theory and praxis.
A good place to start is here:
Loudspeaker measurements
Have great fun... it's an awesome hobby 🙂
But... I run it active though, so I worry not about sensitivity (much) and other specs of the driver. Build a good box with the right front baffle and measure the response and add EQ to each driver until the sum of all drivers behave nicely both on and off-axis - done.
Even a USB microphone (with calibration file) and free software - you go very far. My guess is that it would be even easier than fiddling with simulations and passive components - in the long run - it still requires a learning curve... but I do not regret that I jumped straight to active and never looked at passives.
Inspiration can be found here:
3 ways d'appolito floor standing speaker | Fully active with DSP
Of course... if you choose to use a woofer with a sensitivity of 85 dB with a tweeter that has one around 95dB.... the woofer will lack the higher potential SPL that the tweeter has.... but it can still be done.
Some say that you have to build 20 speakers to get good results.... well.... maybe and maybe not. There are so many tools out there to help create something great... and even after years of construction and listening.... you will still learn something new.
I have heard tons of super high quality drivers and speakers in all kinds of constructions - almost no price limit here. But my "cheap" drivers in simple boxes combined with a well designed active system.... plays very close to anything I have heard. It's mostly a matter of how you do it - less with what the drivers cost and how they look.
And if you chose to go for active.... consider the Dayton alu.... to me... they have more detail than paper cones. I know that some say that paper is a little more forgiving.... but mostly that is an EQ thing.... which is very easy to work with in a DSP. Though.... if active or passive... do promise me to read up on measuring the result... it can really help you understand whats going on between theory and praxis.
A good place to start is here:
Loudspeaker measurements
Have great fun... it's an awesome hobby 🙂
Simulation and the work surrounding it is just as necessary whether you do active filters or passive. Unless you do this you cannot make fair subjective comparisons.