Its a Monacor HT-30 / 8ohm / 100wattDifficult to say without some information on the tweeter.
@DoubleMIDI will be more knowledgeable then me for this.
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Double Bass Installing new tweeter in Markbass combo
- Thread starter PaulKing
- Start date
- Impédance (Z): 8 Ω
- Gamme de fréquence: fx-20 kHz
- Fréquence de résonance (fs): 2 kHz
- Rec. crossov. frequ. (fmax.) (12 dB / oct.): 5 kHz
- Puissance (RMS): 50 W
- Puissance de sortie maximale de la musique (MAX): 100 W
Good.
The impedance of a 4.7uF capacitor at 5KHz is 6.8 ohms.
I don't know the exact rule to calculate the capacitor.
Does it need to have the same impedance as the driver (8 ohms) for the crossing frequency?
In that case that would mean a 4.0uF capacitor. (3.9uF is a standard value)
Maybe I don't know the rule, sorry.
The formula to get the impedance of a capacitor at a given frequency is:
1/(2*pi*f*C )
The impedance of a 4.7uF capacitor at 5KHz is 6.8 ohms.
I don't know the exact rule to calculate the capacitor.
Does it need to have the same impedance as the driver (8 ohms) for the crossing frequency?
In that case that would mean a 4.0uF capacitor. (3.9uF is a standard value)
Maybe I don't know the rule, sorry.
The formula to get the impedance of a capacitor at a given frequency is:
1/(2*pi*f*C )
I’m not familiar with the design of frequency filters for multi-driver cabs.
If I ever need it, I have to look at the formulas and compare it to real designs.
So no value I can tell you.
i think @fdeck is more familiar with this kind of stuff.
The one capacitor to take off the low frequencies from the tweeter is a simple design that might work since the woofer couldn’t reproduce it, but in fact both, woofer and tweeter are acting together. So the impedances are acting in parallel.
In general this is not good, but since the amplitude of the high frequencies of musical signals is much lower than the lower ones that reach the woofer only it might not harm the amp.
Piezo tweeters can easily be connected in parallel since the impedance is much higher than the woofers and doesn’t load the amp much more. The physical characteristics allow both, woofer and tweeter, to act in their range only.
If I ever need it, I have to look at the formulas and compare it to real designs.
So no value I can tell you.
i think @fdeck is more familiar with this kind of stuff.
The one capacitor to take off the low frequencies from the tweeter is a simple design that might work since the woofer couldn’t reproduce it, but in fact both, woofer and tweeter are acting together. So the impedances are acting in parallel.
In general this is not good, but since the amplitude of the high frequencies of musical signals is much lower than the lower ones that reach the woofer only it might not harm the amp.
Piezo tweeters can easily be connected in parallel since the impedance is much higher than the woofers and doesn’t load the amp much more. The physical characteristics allow both, woofer and tweeter, to act in their range only.
I did the job. I put a 8ohm/10watt resistor in serie with a 4,7uF/250V capacitor to the tweeter. And all works fine! Now I am sure that I don’t blow up the tweeter. The 12” cab sounds really musical to my ears. Big difference with the LeSon piezo. And… all hissing noise is gone
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My Genz Benz Focus 112 has a tweeter attenuator/disabling switch and I like the sound with the attenuated tweeter best. Seems you have done something similar with your resistor.
10 watts is a little bit below maximum load. 50 watts/8 ohms speaker and 8 ohms resistor in series means 16 ohms for the tweeter with capacitor and resistor. 25 watts with the same input due to the higher impedance equally distributed to resistor and tweeter, so 12.5 watts each. But that should not be a problem as there is no constant high load on the higher frequencies.
You can think of putting a resistor bypass switch and a disconnecting switch in to have the same options as me.
10 watts is a little bit below maximum load. 50 watts/8 ohms speaker and 8 ohms resistor in series means 16 ohms for the tweeter with capacitor and resistor. 25 watts with the same input due to the higher impedance equally distributed to resistor and tweeter, so 12.5 watts each. But that should not be a problem as there is no constant high load on the higher frequencies.
You can think of putting a resistor bypass switch and a disconnecting switch in to have the same options as me.
