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Rs180P/RS28F vs. small DC160 3 way

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  • filmslayer
    replied
    i agree John , good discussion and i learned something .

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  • jhollander
    replied
    Yes I agree with the resistor on either side of the cap is the same watts dissipated. My original note was a warning that pre- x-o vs. post x-o resistors can consume large amounts of power. While it doesn't appear to be the case here it was a fun discussion. I will continue to check watts dissipated to see if I need to bump up the power rating of my resistors.

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  • filmslayer
    replied
    i'm not sure about all this and got to think Ben is right . here are a few different pics . like i have it before X , then after in an L-pad and also the FR and Z when its in the L-pad .

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  • Wolf
    replied
    That's not what I'm referring to, John. I'm saying the wattage dissipation should be exactly the same if you flip the capacitor and pre-series resistor's positions. This means both will be before the shunt coil.

    What I'm getting at, is that the HP limits power going through the series resistor, from whichever position it is in, even when placed before the first series cap, to where the rolloff of the filter will not allow the resistor to have to pass much power. Even out in front, my resistors do not get hotter than when placed after, and this is due to the highpass and how the AC circuit works.

    For example, I have a 9.1 ohm 10W resistor in front of a 3rd order filter, consisting of a 20uF/0.95mH/6.8uF, and it's never gotten warm, even when pushing the LED's to about -15dB on the level indicator.

    Frankly, I really don't think the power meter is a good indication of what really happens with music.

    Later,
    Wolf

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  • jhollander
    replied
    OK the watts dissipated graph is showing S1, you need to show R1.

    Here's are few graphs of Neis x-o. It's interesting how the resistance changed but not as expected. I think this is due to the driver impedance and the x-o...

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  • filmslayer
    replied
    Originally posted by jhollander View Post
    BTW right click on the amp in XSim, tune, and adjust the wattage to something like 30 watts, then look at you components.

    .
    well that do make a difference ! but the two circuits are still the same ... 1st pic is with resistor after the cap ...

    posting now is painfully slow !!!

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  • filmslayer
    replied
    and FWIW John , thank you for starting my day with a chuckle ... i chuckled out loud at " Mr. Slayer " ....

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  • filmslayer
    replied
    John , there wasn't really any change within the circuit with the resistor going before or after the first cap .my question was more of why is the consumption happening so far ahead of where the circuit actually working ?

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  • jhollander
    replied
    Mr Slayer there's not enough information to figure out the change, without seeing which resistor and the circuit change. BTW right click on the amp in XSim, tune, and adjust the wattage to something like 30 watts, then look at you components.

    Ben I'll post a comparison later.

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  • filmslayer
    replied
    y'all got me thinking about this now so lets take a look . this is from after i made the change but the curves are very similar . the biggest peak is around 175hz , i'm crossing the tweet around 3850 ???

    anyone got an explanation for this ?

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  • filmslayer
    replied
    Originally posted by Wolf View Post
    'filmslayer' (I shortened it to fs)
    my friends just call me Slayer ;-)

    and what i saw John was only 1.5 watt dissipation both circuits combined .

    Edit *** just changed them around , and with the resistor after it was just slightly higher than 1 watt in the tweeter circuit ...

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  • Wolf
    replied
    I was referring to what 'filmslayer' (I shortened it to fs) found. In this case, the watts dissipated will not change if it's in series with a capacitor whether before or after it. It won't change as this is an AC circuit.

    Later,
    Wolf

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  • jhollander
    replied
    Ben, Not sure I understand '...as proven by the result fs saw" Watts dissipated is a function of frequency, so while I can't say it's "more" I can say the resistor watts dissipated would be different before and after the cap in the tweeter circuit. Is that the crux of the disagreement?


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  • Wolf
    replied
    John- I don't agree with the wattage sentiment, as proven by the result fs saw. You still have an AC signal, no matter what side the series resistor is on. This means the signal is still being highpassed in both mid and tweeter circuits. In the event the series and shunt resistors are both in front (rarely, and is a no-no) then they see the full bandwidth. In the event the shunt resistor is of small value, solo, and it's across the load and shunting a lot of power, then that could also be of concern.

    Later,
    Wolf

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  • filmslayer
    replied
    never mind John i found it ... its not to bad , 1 watt max in the tweet circuit and about a 1/2 watt in the mid ...

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