Hello!
I need a steep HPF for the two 8ohm speakers of my Roland JC120 so that I can keep using them with electric bass (as a mid monitor).
Can somebody guide me to a DIY-compatible circuit design that is somewhat close to the following specs:
I need a steep HPF for the two 8ohm speakers of my Roland JC120 so that I can keep using them with electric bass (as a mid monitor).
Can somebody guide me to a DIY-compatible circuit design that is somewhat close to the following specs:
- Ideally 24dB/oct.
- Adjustable crossover point within 60-80Hz (alternatively: fixed at 80Hz)
- Reliably dissipate the excess energy of the sub frequencies as heat
That won't work in my case because I cannot circumvent the built-in power amps of the JC120.
What's the best filter slope I can achieve at speaker level?
Mind you, it won't be much heat that needs to be dissipated since the cut-off frequency will be pretty low (really just a protection measure for the original guitar speakers).
What's the best filter slope I can achieve at speaker level?
Mind you, it won't be much heat that needs to be dissipated since the cut-off frequency will be pretty low (really just a protection measure for the original guitar speakers).
Realistically 12dB is good enough. Series inductor, and a shunt capacitor.
It won't dissipate much heat, just in the resistance of the inductor.
Here's an example, and you could change the capacitor to change the frequency.
https://www.parts-express.com/80-Hz-Low-Pass-8-Ohm-Crossover-266-442
It won't dissipate much heat, just in the resistance of the inductor.
Here's an example, and you could change the capacitor to change the frequency.
https://www.parts-express.com/80-Hz-Low-Pass-8-Ohm-Crossover-266-442
Need a high pass filter? One could come pretty close to a solution were there a datasheet of some sort for the two 12" units, otherwise we can choose one among many and simulate.
Yes, to clarify that linked LP filter can be used as a HP with a slight rewiring, for a series C, and a shunt L.
Thanks so far.
Two questions:
1) Do I even need a heat-dissipating "power resistor" or will the system as a whole simply not draw the power at sub frequencies in the first place because of the impedance curve (SS amp, no current feedback)?
2) If each speaker gets its own HPF, will the cutoff frequency remain the same if they are connected together in series (as opposed to fully isolated)?
Two questions:
1) Do I even need a heat-dissipating "power resistor" or will the system as a whole simply not draw the power at sub frequencies in the first place because of the impedance curve (SS amp, no current feedback)?
2) If each speaker gets its own HPF, will the cutoff frequency remain the same if they are connected together in series (as opposed to fully isolated)?
Right, no resistor is needed.
If the two woofers are connected in series, only use one HP filter.
The filter curve will be messed up if you connect two of the filters in series.
If the two woofers are connected in series, only use one HP filter.
The filter curve will be messed up if you connect two of the filters in series.
But with both in series and therefore double the resistance, wouldn't the cutoff frequency change?
Just to be clear, the speakers are not woofers. That is the whole reason why I want to protect them through an appropriate HPF.
Just to be clear, the speakers are not woofers. That is the whole reason why I want to protect them through an appropriate HPF.
Yes ok, but I mean going like this: PowerAmp->HPF1->Sp1->HPF2->Sp2 (in series).
Does this result in the same cutoff frequency as a single isolated HPF-speaker pair?
Is there any data of these JC 120 units? We have to find a similar contemporary unit and use its datasheet to feed the simulator. The cabinet volume and type too. When you filter at 80 Hz then there is driver impedance peak nearby to be considered, simple nominal impedance estimate won't help much. Idealy we need T/S parameters and impedance of your drivers, otherwise we can only search for substitute values.
So do it at line level. It's pretty common in the bass world to use a HPF and there are several available on the market as pedals, eg Broughton, and even easier to apply in the multitude of emulator platforms.
I've been playing bass since the 80s and all 5s and 6s these days.
Thanks for the input but it really has to be done at speaker level since the speakers are supposed to be run in parallel to a proper bass cab (and act as a mid monitor).
Anyway, I will just go for the usual 2nd order design.
Two questions:
What kind of parts should I get in terms of power rating and construction (e.g. electrolytic vs. film cap)?
Is it possible to add a variable resistor for volume control or would this throw off the C and L values?
Anyway, I will just go for the usual 2nd order design.
Two questions:
What kind of parts should I get in terms of power rating and construction (e.g. electrolytic vs. film cap)?
Is it possible to add a variable resistor for volume control or would this throw off the C and L values?
Bipolar electrolytics for crossover use typically have Voltage ratings printed on them. It's best to exceed the supply rails of your amplifier, which is similar to saying the maximum peak Voltage the speakers may see.
A volume control is best before the amplifier. Some people use variable resistors when uncertain about crossover values, and in this case a variable L-pad typically holds the crossover point more steady than a single resistor.
A volume control is best before the amplifier. Some people use variable resistors when uncertain about crossover values, and in this case a variable L-pad typically holds the crossover point more steady than a single resistor.