In 1998 I built a 2-way speaker from a kit I bought. The tweeter is a ScanSpeak D2905/970000,and the midwoofer is an AudioTecnology 5H 52 17 06 SD. Back then it was something of the top and it is still very nice drivers.
The XO was designed by someone who knowing what he was doing, I believe, and it generally has good components in it. The coils are the flat CFC air coils, and the 2 capacitors direcktly in the tweeter line are Mundorf Supreme. The capacitor in parallel with the bass is however, only a M-cap also from Mundorf. The resistors are a bit of a mystery. These are 3 very different resistor types. There is a 47 ohm which bypasses the large coil for the bass so it sits in a direct line. It's a metal one with a heatsink 25W. It is unfortunately gorn off the one XO so it has been replaced by an M-Resist from Mundorf 20W. Then there is a 2.2 ohm which bypass a capacitor to the tweeter and it is a very strange resistance. It's such a small plastic RCH resistor. Finally, it is an old-fashioned sandcast resistor parallel to the bass.
What I intend to upgrade the XO a bit is to replace the last 2 resistors with M-Resist. Sandcast is in any case a somewhat inferior resistance than M-resist the price is in any case below 10%. But that RCH resistance is in Denmark quite expensive, but it is a good resistance. I think there must be a reason why the designer chose it. In addition, I will
Bypass the 2 supreme capacitors that are in direct line with the tweeter, with a 0.01 µF silver-gold-oil from Mundorf. The reason for that it is Mundorf I mention, is that they are the ones I have good access to. I'm just trying to see if I can figure out how to put one image of the XO.
The XO was designed by someone who knowing what he was doing, I believe, and it generally has good components in it. The coils are the flat CFC air coils, and the 2 capacitors direcktly in the tweeter line are Mundorf Supreme. The capacitor in parallel with the bass is however, only a M-cap also from Mundorf. The resistors are a bit of a mystery. These are 3 very different resistor types. There is a 47 ohm which bypasses the large coil for the bass so it sits in a direct line. It's a metal one with a heatsink 25W. It is unfortunately gorn off the one XO so it has been replaced by an M-Resist from Mundorf 20W. Then there is a 2.2 ohm which bypass a capacitor to the tweeter and it is a very strange resistance. It's such a small plastic RCH resistor. Finally, it is an old-fashioned sandcast resistor parallel to the bass.
What I intend to upgrade the XO a bit is to replace the last 2 resistors with M-Resist. Sandcast is in any case a somewhat inferior resistance than M-resist the price is in any case below 10%. But that RCH resistance is in Denmark quite expensive, but it is a good resistance. I think there must be a reason why the designer chose it. In addition, I will
Bypass the 2 supreme capacitors that are in direct line with the tweeter, with a 0.01 µF silver-gold-oil from Mundorf. The reason for that it is Mundorf I mention, is that they are the ones I have good access to. I'm just trying to see if I can figure out how to put one image of the XO.
The diagram can be seen here. Can anyone tell me what kind of filter it is. I've always thought it was 2 LR filters, but I'm a bit doubtful as there are 2 capacitors in series with the tweeter. But then the parallel coil should probably be between the 2 capacitors if it was 3rd order. So I think the first capacitor with the bypass resistor is a notch of some kind. The base can also be 1. order and the parallel can be af LCR filter. But I am green to XO.
Attachments
Imagine it without the capacitor. It is 2nd order with a resistor. The capacitor then lifts the top end.
Wirewound (sandcast) resistors are a good choice in a crossover.
Thanks AllanB
It's starting to make sense to me🙂. So the first part in the tweeter XO means that the high frequencies can pass the capacitor (highPass) and then the "rest" is dampened by the resistance, as the tweeter is a little more sensitive than the midwoofer. If you calculate on a 1st order XO, the 1.5 µF will also provide a highpass filter around 15KHz if you calculate that the tweeter is 4.6 ohms as it is on the datasheet. And right at the very top from around 15 KHz there is actually a small dip according to the frequency curve from the datasheet, then it make sense. What I wrote about sandcast resistor is perhaps because I have just seen almost all the GR Reserce upgrades this weekend and Danny says that sandcast is NoGo, so I'm probably a bit colored by that. Do you know about the small plastic resistor I'm talking about. I will try to take a picture of it.
It's starting to make sense to me🙂. So the first part in the tweeter XO means that the high frequencies can pass the capacitor (highPass) and then the "rest" is dampened by the resistance, as the tweeter is a little more sensitive than the midwoofer. If you calculate on a 1st order XO, the 1.5 µF will also provide a highpass filter around 15KHz if you calculate that the tweeter is 4.6 ohms as it is on the datasheet. And right at the very top from around 15 KHz there is actually a small dip according to the frequency curve from the datasheet, then it make sense. What I wrote about sandcast resistor is perhaps because I have just seen almost all the GR Reserce upgrades this weekend and Danny says that sandcast is NoGo, so I'm probably a bit colored by that. Do you know about the small plastic resistor I'm talking about. I will try to take a picture of it.