Hi there,
I am trying to make 2 way stereo speakers with an active crossover. For this purpose I have an active crossover with four outputs (2 for left and 2 for right channel) and a four channel amplifier naturally.
Problem is, my woofers are 8 ohms and the tweeters are 4 ohms. So I felt a bit strange to connect these directly to the amplifier's output.
My crossover frequency is 1136 which is unrelated with the subject I believe. Many people told me that there is no need to make a modification on the active crossover and I should match the drivers with the amp where I need your help...
I will be glad if you could suggest me a way to make this right
PS: I am using 47uF caps to protect tweeters. With 47uF and 4 Ohm tweeters, high pass filter freq is 846Hz , right below my crossover freq. which is 1136 Hz.
Thanks already...
I am trying to make 2 way stereo speakers with an active crossover. For this purpose I have an active crossover with four outputs (2 for left and 2 for right channel) and a four channel amplifier naturally.
Problem is, my woofers are 8 ohms and the tweeters are 4 ohms. So I felt a bit strange to connect these directly to the amplifier's output.
My crossover frequency is 1136 which is unrelated with the subject I believe. Many people told me that there is no need to make a modification on the active crossover and I should match the drivers with the amp where I need your help...
I will be glad if you could suggest me a way to make this right
PS: I am using 47uF caps to protect tweeters. With 47uF and 4 Ohm tweeters, high pass filter freq is 846Hz , right below my crossover freq. which is 1136 Hz.
Thanks already...
Hi,
1. Each filter causes a phase shift. I try to have corner frequency of "protection filters" at least 3-4 octaves away from the frequency range in use - makes isi difficult in your case to avoid electrolic caps, though.
2. Even a Mundorf PP gold/silver added some signature. It was removed for better sq.
hth
Ulli
As long as amp can drive the load, just the speaker efficiency may be an issue which can be easily solved if amplification can be adjusted for each amp.
Two remarks:
1. Each filter causes a phase shift. I try to have corner frequency of "protection filters" at least 3-4 octaves away from the frequency range in use - makes isi difficult in your case to avoid electrolic caps, though.
2. Even a Mundorf PP gold/silver added some signature. It was removed for better sq.
hth
Ulli
Hi modmix,
The amp can handle 8 ohms but I dont think I can adjust the the amplification for each channel. I have also realised that the amp I used, has beed reviewed here on the forum so maybe I should ask on that subject how to adjust channels individually... Here is the amp : link to the amp
I have also used Jantzen Audio metalized polypropylene foil. (47uF 400Vdc Jantzen Cross Cap Capacitor)
I somehow feel like I have to use attenuator for the tweeters but this does not feel right
Hey, I have decided to go with 1136 Hz since I overlapped the graphs of drivers on photoshop. Seems 1136 is perfect I just need to attenuate the tweeter and solve the 4 ohm issue.
I think log 2 potentiometers on the tweeters will solve all the problem...
I just need to attenuate the tweeter and solve the 4 ohm issue. I think log 2 potentiometers on the tweeters will solve all the problem...
An externally hosted image should be here but it was not working when we last tested it.
I can solve your 4 ohm issue. Ignore it, and its solved.
To put it another way, your tweeter is rated to put out 95 db with 2.83 volts.
Your amplifier will put out the appropriate current at any frequency to maintain that voltage, up to 16A <eek!> Since your tweeter is never exactly 4 ohms anyway, the amp doesn't care.
If you look, the woofer isn't exactly 8 ohms either. Amp still doesn't care.
The graphs you display are the output volume and impedance at a fived voltage.
I do recommend you attenuate the tweeter in the electronics, not with a resistor on the tweeter.
The crossover frequency and slopes are always a compromise.
Cross to low, and speaker will not play very loudly before the tweeter runs out of excursion.
Cross to high, and the woofer will start to beam, and may exhibit breakup that will affect the sound.
What crossover slope are you using? Its another compromise between phase shift and group delay vs excursion and out of band issues.
I hope this helps.
Doug
To put it another way, your tweeter is rated to put out 95 db with 2.83 volts.
Your amplifier will put out the appropriate current at any frequency to maintain that voltage, up to 16A <eek!> Since your tweeter is never exactly 4 ohms anyway, the amp doesn't care.
If you look, the woofer isn't exactly 8 ohms either. Amp still doesn't care.
The graphs you display are the output volume and impedance at a fived voltage.
I do recommend you attenuate the tweeter in the electronics, not with a resistor on the tweeter.
The crossover frequency and slopes are always a compromise.
Cross to low, and speaker will not play very loudly before the tweeter runs out of excursion.
Cross to high, and the woofer will start to beam, and may exhibit breakup that will affect the sound.
What crossover slope are you using? Its another compromise between phase shift and group delay vs excursion and out of band issues.
I hope this helps.
Doug
Doug, thank you this definitely helps... I like the method of your problem solving
I am using 12dB/octave slope and this is my first time with active crossovers...
I agree about not using resistors on the tweeter. Using resistors is like backwards... I think I will use pots between the crossover output and amplifier input just for the tweeters. So that I can adjust whenever I need to.
I am still using 47uF caps to protect the tweeters...
Thanks again...
Yes, it is too low. Troels Gravesen recommends 1400 Hz.
You don't need resistor, only capacitor for the tweeter.
Thank you Sonce, I think I will stick with 1136 for now. :roll eyes: I want to try and see for myself...
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.