Hey guys. Can someone chime in and tell me the value of this ceramic capacitor(yellow) in my crossover. I am having problems transferring the pic to this post. Anyway the cap reads 4 . 0 J 100v CMC Thanks
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It's probably not a ceramic cap...most likely it's a varistor or thermistor to protect the tweeter and/or the mid driver, if there is one.
Mike
Mike
Doesn't the CMC stand for ceramic. My speaker is a Monitor Audio 452MD and the crossover contains one resistor and one cap. It is a two driver speaker.
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Pure guess
4.0 = 4uF (typical crossover component value)
J=5% tolerance
100V = DC voltage
CMC may be the manufacturer. Can you try to post your pic. that will help.
4.0 = 4uF (typical crossover component value)
J=5% tolerance
100V = DC voltage
CMC may be the manufacturer. Can you try to post your pic. that will help.
Yes, 4uF would be the best guess with so little information to go on.
I can find reference to an R452/MD which has a12dB/octave crossover network.
Is this the same as yours?
Monitor Audio R452/MD Speaker System Review price specs - Hi-Fi Classic
However, if it is, I would expect there to be more than a single resistor and capacitor.
I can find reference to an R452/MD which has a12dB/octave crossover network.
Is this the same as yours?
Monitor Audio R452/MD Speaker System Review price specs - Hi-Fi Classic
However, if it is, I would expect there to be more than a single resistor and capacitor.
If you can't post a photo (Go Advanced under the Quick Reply box then click on the paperclip symbol at the top of the new window) then please state shape and dimensions of the component. It may be a 4uF NP capacitor, but won't be a ceramic.
It is possible that the mid/bass driver is run 'full range' without a crossover and the tweeter has a high pass filter and attenuator consisting of a series capacitor and resistor.
Assuming Z = 8 ohm, a 4uF capacitor would roll off the tweeter below 5,000Hz, but with a shallow electrical slope of 6dB/octave.
It is possible that the mid/bass driver is run 'full range' without a crossover and the tweeter has a high pass filter and attenuator consisting of a series capacitor and resistor.
Assuming Z = 8 ohm, a 4uF capacitor would roll off the tweeter below 5,000Hz, but with a shallow electrical slope of 6dB/octave.
Here is a pic. Can anyone comment on the resistor also. Is it wirewound? Yes Galu that is my exact speaker. About 30 years old. I plan to replace the resistor and capacitor since they are so old.
Attachments
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Yes, 4uF film capacitor and wirewound resistor.
Bottom right is an air cored inductor which will be in parallel with tweeter.
Bottom left is an iron cored inductorwhich will be in series with the bass/mid.
Bottom right is an air cored inductor which will be in parallel with tweeter.
Bottom left is an iron cored inductorwhich will be in series with the bass/mid.
P.S. Film capacitors and wirewound resistors do not age (nor do inductors) so there is no need to change them.
P.P.S. You could replace the 4uF with an audio quality polypropylene type to see if it improves the treble sound any. Wouldn't bother with the resistor, but it won't do any harm if you replace with a 2.2 ohm wirewound with a higher wattage rating.
Low pass filter is 6dB/octave and high pass filter is 12dB/octave.
HF crossover frequency is likely to be in the area of 3,500Hz.
Low pass filter is 6dB/octave and high pass filter is 12dB/octave.
HF crossover frequency is likely to be in the area of 3,500Hz.
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I don't know what is intended there but it would probably be more trouble than it was worth to remove the existing resistors without causing damage. By the look of the glue, it hasn't become hot in its 30+ years but a 5W 2R2 resistor isn't going to get hot there, short of severe oscillation or overdrive from the amplifier .
A second consideration is the inductance of the WW resistors. These can have quite different manufacturing techniques according to range of value and end use. Mixing the types, as with other components, may well make enough difference to be noticeable in the critical crossover region.
There is no reason to change the components, apart from the warm glow you will experience when you tell your friends that you have 'upgraded' the speakers.
After taking in the info you guys have presented I have decided not to change any component in the crossovers. The poly films and wirewounds do not really age and deteriorate. Reading other forums on old crossovers it seems that as time goes by the listener/owner does not realize the deterioration of the sound caused by cap leakage, cap resistance, resistor value increase etc.. and when someone decides to change crossovers with new parts there is an obvious improvement in the sound causing regret that it was not done sooner. Even though the sound from my Monitor Audios to me still sound good I was worried this was happening to me but after all this info I can see that it is not. Thanks again.
Wirewound resistors do not age. Well-built film caps do not develop leakage. Old bipolar electrolytics may need changing, but you will probably only see them in really old or really cheap speakers. Much of what you will read on forums about 'upgrading' old components is bunkum.
Changing crossover components will change the sound, simply due to component tolerances, and any change will be interpreted as an improvement - especially if serious money has been spent.
Changing crossover components will change the sound, simply due to component tolerances, and any change will be interpreted as an improvement - especially if serious money has been spent.
As it was said - they usually not age (in such devices). But if you want to change something - you can think about change type of this capasitot to polypropylene one (on thew photo - it is "usual" film type = lavsan = polyester = polyethylene-tereftalat (PET) ets.). You can change it to polypropylen type - it can change sound a little (may not).
And thouse wired resistors could be bad ones (could not) - they can do same small amount of distortion if they made from bad (magnetic) type of alloy. But it is minor reason of distortion.
But the thing that definitely could be aged - it is loudspeaker.
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You chose not to quote the essential part of my sentence which commenced with 'Wouldn't bother with the resistor, but . . .'
I was merely giving Harmon an excuse to change the resistor if he felt compelled to do so. There is absolutely no point in changing like for like and I'm glad that Harmon has understood this.
Happy listening Harmon! 🙂
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