Hi, I have attached a diagram of DM6 X-Over, as I have a couple of points I would like you guys to help to clarify.
I intend to modify the attenuation range of both the Treble and Midrange of the units, hopefully by just increasing values of resistors on existing level switches.
The high frequency section seems pretty straight forward, as the attenuation comes before the network, which would mean as far as I can see, within reason I can safely increase attenuation value until I get to desired level?
The midrange section seems a bit more tricky as any change of value here would appear to change impedance to network and therefore change x-over frequency. It appears from what I can see that this already occurs with present circuit. Is this standard? are they altering slope so as to have the desired attenuation rate?
I also note the bass speaker being out of phase with respect to plus and minus from amplifier. Is this a common arrangement? wouldn't that mean if you were to use any other speaker to compliment them(if indeed you found it necessary) then the bass would suffer as low frequencies would be reverse phase between the 2 pairs of speakers.
Your comments and advice would be very much appreciated.
I intend to modify the attenuation range of both the Treble and Midrange of the units, hopefully by just increasing values of resistors on existing level switches.
The high frequency section seems pretty straight forward, as the attenuation comes before the network, which would mean as far as I can see, within reason I can safely increase attenuation value until I get to desired level?
The midrange section seems a bit more tricky as any change of value here would appear to change impedance to network and therefore change x-over frequency. It appears from what I can see that this already occurs with present circuit. Is this standard? are they altering slope so as to have the desired attenuation rate?
I also note the bass speaker being out of phase with respect to plus and minus from amplifier. Is this a common arrangement? wouldn't that mean if you were to use any other speaker to compliment them(if indeed you found it necessary) then the bass would suffer as low frequencies would be reverse phase between the 2 pairs of speakers.
Your comments and advice would be very much appreciated.
Attachments
First, are you sure about this? It may be your problems are related to room damping (or lack thereof) instead of the speaker.
What I suggest is you replace a resistor with jumpers, and use that to experiment with, while measuring.
Yes, you could be affecting more than just levels when you change the crossover impedance. Hard to tell if significant without a full speaker analysis.
Reversing polarity for drivers is quite common and important to make sure that speakers mate well at the crossover frequencies. Typically the woofer is left normal with a plus voltage at the plus terminal causing an outward motion, and other drivers are adjusted to match it. So, if you were to use another brand it's unlikely you'd have a noticeable bass problem, but always possible.
Best,
E
What I suggest is you replace a resistor with jumpers, and use that to experiment with, while measuring.
Yes, you could be affecting more than just levels when you change the crossover impedance. Hard to tell if significant without a full speaker analysis.
Reversing polarity for drivers is quite common and important to make sure that speakers mate well at the crossover frequencies. Typically the woofer is left normal with a plus voltage at the plus terminal causing an outward motion, and other drivers are adjusted to match it. So, if you were to use another brand it's unlikely you'd have a noticeable bass problem, but always possible.
Best,
E
This simulation shows the difference between attenuating a midrange unit with a resistor of 9 ohms before and after XO filter. As it appears, the manufacturer obviously wanted to keep the spl around mid/hf XO point(5 kHz)remain intact more or less, while reducing midrange level from one extreme to another. Seas 5" unit filtered as in service manual.
Attachments
Hi, Eric thanks for your reply. Yes, you o pm are on the right track with my room acoustics problem, but tried everything and decided easiest solution is to take a couple of dBs off the Mid and hf units. The Bass polarity thing was as I thought. In the past I have found most manufacturers have the Bass unit in phase with amplifier, so to speak and if anything, the mid and high units possibly out of phase, depending on filter slopes. Did you have a look at the circuit as it stands? what did you think of my observations of positioning of attenuation switches with regard to how they affect x-over loading.
I sent this earlier but it looks like it bounced back, so not sure if you've seen it already.
I sent this earlier but it looks like it bounced back, so not sure if you've seen it already.
Hi again. Went with the attenuation before network, which provided the best integration with the other drive units.
I have now decided to go another step forward, hopefully, and part activate the system. I intend to run the LF of one Amp and the mid/high of another.
I intend to keep the crossover frequencies at 500hz and 5khz using a 24db linkwitz filter.
I will be removing the high pass capacitor c3 from the band pass section of x-over and was wondering whether the midrange unit would still be in phase with the other units or would need reversing?
I have now decided to go another step forward, hopefully, and part activate the system. I intend to run the LF of one Amp and the mid/high of another.
I intend to keep the crossover frequencies at 500hz and 5khz using a 24db linkwitz filter.
I will be removing the high pass capacitor c3 from the band pass section of x-over and was wondering whether the midrange unit would still be in phase with the other units or would need reversing?
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