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Old 5th March 2018, 11:30 PM   #241
aczern is offline aczern
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A voltage on a capacitor is also important because in the resonant circuit it can be larger than an output voltage of an amplifier.
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Old 6th March 2018, 04:30 AM   #242
kimmosto is offline kimmosto  Finland
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^Theoretically yes, but has someone succeeded to damage e.g. 100 VDC (rough foil) electrolytic or 160 VAC PE with 500 W to 8 ohms (63 VAC) amp when drivers were connected and crossover has some sense otherwise?
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Old 6th March 2018, 09:14 AM   #243
DBMandrake is online now DBMandrake  Scotland
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Quote:
Originally Posted by kimmosto View Post
Level tuning possibilities with fully passive crossover are very limited - within less than 1 dB.
Struggling to understand what you are trying to say here ? Limited in what way ?
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Last edited by DBMandrake; 6th March 2018 at 09:18 AM.
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Old 6th March 2018, 09:55 AM   #244
kimmosto is offline kimmosto  Finland
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Originally Posted by DBMandrake View Post
Limited in what way ?
After you have adjusted tonal balance close to perfect with passive crossover, you probably don't want to change level of tweeter (with L-pad) more than about 0.5 dB up or down. There is no absolute limit of course, but sound won't be so perfect anymore.
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Old 6th March 2018, 10:47 AM   #245
DBMandrake is online now DBMandrake  Scotland
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Quote:
Originally Posted by kimmosto View Post
After you have adjusted tonal balance close to perfect with passive crossover, you probably don't want to change level of tweeter (with L-pad) more than about 0.5 dB up or down. There is no absolute limit of course, but sound won't be so perfect anymore.
I agree, although I don't see the connection to the original post by gfiandy. I assume he already has the tweeters padded to the correct level for frequency response but now wants to easily calculate the power dissipation of the tweeter taking into account that attenuation.

Not that he is adding attenuation to the tweeters without consideration for frequency response.

I have a similar situation on my speakers where the tweeters have about 5dB of attenuation in the final design - which means the dissipation of the tweeters is also quite low for a given input power. But that was of course done to match sensitivity with the baffle step corrected midbass driver.

0.5dB is actually a large error for the attenuator of a tweeter since it is affecting several octaves, (large area under the curve) so it will definitely sound wrong with the tweeter 0.5dB too high or too low.

Relative attenuation levels of different drivers in a multiway system I find critical to a fraction of a dB (say 0.2dB) because each driver is covering several octaves, whereas a response error over a fraction of an octave 1dB or more may not be audible at all.
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Old 6th March 2018, 11:25 AM   #246
kimmosto is offline kimmosto  Finland
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Quote:
Originally Posted by DBMandrake View Post
I agree, although I don't see the connection to the original post by gfiandy. I assume he already has the tweeters padded to the correct level for frequency response but now wants to easily calculate the power dissipation of the tweeter taking into account that attenuation.
I just asked some questions from gfiandy, and that was additional comment because I didn't see reason to calculate tweeter's power dissipation if one cannot do much about it with L-pad in pure passive system.
Anyway, I will consider adding driver power, amplifier output power and some indication about maximum SPL produced with given voltage/power.
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Old 6th March 2018, 05:04 PM   #247
gfiandy is offline gfiandy  United Kingdom
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Hi, my reason was pretty much what Simon is saying.

It is quite common in small speakers for the tweeter level to be reduced by arround 3dB even up to 10dB. If the tweeter is say a 20w part and the woofer a 100W part. It would be good to know that with the crossover attenuation the tweeter is OK to rate the system at 100W.

Often this is done with a L pad but sometimes a simple series resistor with a capacitor or RC in parrallel with the tweeter can work better as it gives you another degree of freedom in adjusting the response.

Thanks,
Andrew
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Old 7th March 2018, 05:52 PM   #248
kimmosto is offline kimmosto  Finland
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Output and drivers added to power dissipation graph. Checkboxes to reduce amount of visible curves.

An externally hosted image should be here but it is no longer accessible. Please upload images instead of linking to them to prevent this.


Few other small changes too. See changelog. Export file format for IFFT is added for configuration tool of FourAudio. It's quite generic, but probably not very valuable.
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Old 7th March 2018, 07:15 PM   #249
gfiandy is offline gfiandy  United Kingdom
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Excellent, thank you for this. I just had a quick look at it and it looks like it will be a really helpful extra piece of information on system performance.

Its amazing how fast you can pull these changes together.

Thank you.
Andrew
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Old 8th March 2018, 07:13 AM   #250
kimmosto is offline kimmosto  Finland
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You're welcome. I also found output and driver power curves interesting. They are not mandatory, but give additional information how much and where power is lost. That information may reduce bad decisions when optimizing frequency response or noise floor too aggressively or foolishly.
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