hello,
i have finished my active 3 way crossover and these days i will finish the 6ch power amplifier to trim amp my speakers.
Will i need to use a capacitor in series with the tweeter for some kind of protection? the tweeter is the seas excel t29cf002 and my active crossover frequency is at 3khz 24db/oct.
and if i need a cap what cap do you suggest to use? i mean how many uf/volt and what type of quality?
i have finished my active 3 way crossover and these days i will finish the 6ch power amplifier to trim amp my speakers.
Will i need to use a capacitor in series with the tweeter for some kind of protection? the tweeter is the seas excel t29cf002 and my active crossover frequency is at 3khz 24db/oct.
and if i need a cap what cap do you suggest to use? i mean how many uf/volt and what type of quality?
Not if you are convinced there is no DC on the line, and as long as you are sure the DSP settings are right. So, under normal circumstances, you don't need one.
If you are uncertain about it, the problem is that you will need a very large capacitor. Otherwise, there will be phase shift were you don't want it.
If you are uncertain about it, the problem is that you will need a very large capacitor. Otherwise, there will be phase shift were you don't want it.
Kind of capacitor: film type, polyester or polipropylene
Voltage : 250 V and above
Capacity: about an octave well under the cut-out frequency...that would mean about 20 uF...but you can go better with a 47 uF or even 100 uF ( 180 uF is ok but also expensive )
Voltage : 250 V and above
Capacity: about an octave well under the cut-out frequency...that would mean about 20 uF...but you can go better with a 47 uF or even 100 uF ( 180 uF is ok but also expensive )
Also keep in mind that in addition to what vacuphile said, a cap won't protect against power-on/off surges and thumps, over-voltage and/or high frequency oscillatory amplifier failures. Having said that, I've never had any problems using well designed, well built, stable amps. So it boils down to how confident you are in the amplifiers you use. Another option would be to use a speaker protection circuit.
Mike
Mike
HELLO,
as for the power on surges and thumps i have a dc protection and delay board. i am afraid about the few millivolts dc on the output (maybe this is not a problem). i would like to have a capacitor because these tweeter are expensive. my analog active crossover is working fine so this shouldn't be a problem. i already have those capacitors from the passive cross (47f+3.3uF in parallel/400v) :
KPQS/47/400 - AUDYN-CAP KP-QS foil capacitor 47uF 400V 42 x 66mm - Audio.nl
i think they should be ok isn't they?
i also have a 125uf (five different values in parallel of the same line cap total 125uf) of this kind of caps:
https://www.intertechnik.com/Shop/C...ors/Audyn-Cap-Q4/_Q41000400_1768,en,279,46797
so what type you think is better 50uf/400v or 100 or 125 uf/400v of the second line capacitor?
the first line is little better quality capacitor. Now i have it in series with midrange and the second one capacitor is in parallel with the woofer right now.
as for the power on surges and thumps i have a dc protection and delay board. i am afraid about the few millivolts dc on the output (maybe this is not a problem). i would like to have a capacitor because these tweeter are expensive. my analog active crossover is working fine so this shouldn't be a problem. i already have those capacitors from the passive cross (47f+3.3uF in parallel/400v) :
KPQS/47/400 - AUDYN-CAP KP-QS foil capacitor 47uF 400V 42 x 66mm - Audio.nl
i think they should be ok isn't they?
i also have a 125uf (five different values in parallel of the same line cap total 125uf) of this kind of caps:
https://www.intertechnik.com/Shop/C...ors/Audyn-Cap-Q4/_Q41000400_1768,en,279,46797
so what type you think is better 50uf/400v or 100 or 125 uf/400v of the second line capacitor?
the first line is little better quality capacitor. Now i have it in series with midrange and the second one capacitor is in parallel with the woofer right now.
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For a 6 ohm tweeter @ 3kHz you need at least 20uF, preferably more to avoid adversely affecting the phase response through the crossover region.
Mike
Mike
thank you all for your answers,
so i will be use the AUDYN KPQS 47uf/400v capacitor in series with the tweeters.
thank you
so i will be use the AUDYN KPQS 47uf/400v capacitor in series with the tweeters.
thank you
Almost all directly coupled power amps have a couple of mV DC on their outputs. This is nothing to worry about. Just make the calculation how much Watts these mVolts develop over the impedance of the tweeter. You are litteraly talking about micro-Watts.
Therefore what I suggest is to play for some time through a cap to make sure there are no problems, and then take it out.
Btw, FYI, I have never used a cap myself in front of drivers in an active multiway setup. After all, one of the advantages of an active setup is that you can do away with caps and coils in front of your drivers.
Therefore what I suggest is to play for some time through a cap to make sure there are no problems, and then take it out.
Btw, FYI, I have never used a cap myself in front of drivers in an active multiway setup. After all, one of the advantages of an active setup is that you can do away with caps and coils in front of your drivers.
... at a much higher price (*).
There's always a better component at a higher price, you have to settle down to what is acceptable for you.
Still I think that implementing a proper delay start and DC protection board renders useless the use of a cap for tweeter protection.
Ralf
(*) From an European distributor for a 22uF cap: ESA 21 Euro, PX 15 Euro, KPQS 9 Euro. If you move to a 33uF cap the difference is even greater.
There's always a better component at a higher price, you have to settle down to what is acceptable for you.
Still I think that implementing a proper delay start and DC protection board renders useless the use of a cap for tweeter protection.
Ralf
(*) From an European distributor for a 22uF cap: ESA 21 Euro, PX 15 Euro, KPQS 9 Euro. If you move to a 33uF cap the difference is even greater.
Allen, indeed you can, but it is not so easy to do it right. You will have to take care to get the Q of the total filter right. An LR4 filter consists of two cascaded 2nd order filters with a Q of .7 so the total Q of the filter is .5 (multiply the Q's). A first order filter (cap in front of tweeter) has a Q of .7 (there is dispute as to whether you can speak of Q with 1st order filters, let's not go there). This means that the active filter will have to be changed so that the Q of the now 3rd order filter becomes .7. You cannot just leave the first stage as it is.
It is much easier to combine an electronic 2nd order filter with a physical 2nd order filter. So, if you want to go that route, I would advise to leave 2 orders out of the active xover, and have a second order LC filter with a Q of .7 on the tweeter.
However, why would you do so, the purpose is to get rid of the analog filter? (It is useful though on the low end by using the acoustic slope of driver in a closed enclosure, which is 2nd order with a Q of .7).
It is much easier to combine an electronic 2nd order filter with a physical 2nd order filter. So, if you want to go that route, I would advise to leave 2 orders out of the active xover, and have a second order LC filter with a Q of .7 on the tweeter.
However, why would you do so, the purpose is to get rid of the analog filter? (It is useful though on the low end by using the acoustic slope of driver in a closed enclosure, which is 2nd order with a Q of .7).
output offset once settled to your SET value is usually not a problem, if your set value is appropriate to the very fine wire used in the voice coil.
Power ON and Power OFF are a much bigger problem. Drift of output offset during warm up is also a problem that should be considered.
The capacitor coupled tweeter is good for continuous DC offset, but it does not protect against a step change in voltage. The capacitor has to charge or discharge to the new voltage and that charging current passes through the tweeter.
So far I have only built one active speaker setup. It uses lm3886 as the amplifiers.
The 3886 has three levels of protection for output loads.
It does not turn ON until V- exceeds ~-9Vdc
The mute circuit mutes output (including output offset) for a short delay duration.
The output offset stabilises to a lowish value quickly.
I find that the cap coupled tweeter switches on apparently silently to music just a fraction after power ON.
The Mid has a delayed relay isolation.
just wanna share with you the crossover circuit and its response. This circuit was designed with the leap software. The response curves are real and not circuit simulation. this crossover will be used for the seas excel w26fx001 - w15ch001- T29cf002 units. As for the tweeter capacitor i will use the audyn 47uf (i have it already so i don't have to buy new) and later i will probably take it out of the circuit. later i will post some photos of the completed crossover unit. all the opamp are opa2134.
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In the case where one order was subtracted from the active crossover (BTW I am fond of the passive line/amp level crossover which uses capacitors that would have been there anyway.. in combination with speaker level adjustments so one order is usually a stand-alone filter), ensuring a clean first order from a capacitor in series with the tweeter may require a band-stop filter at the tweeter resonance.
Where two orders are being reassigned the filter may have enough control to do away with this.
Have you considered your listening axis and used a measurement axis that reflects this?
hi,
when i say that the measurements are real i mean that those curves have beed measured by sending a sweep to the crossover and measuring the crossover output not the speaker output if i understand your question right.
Of course if you mean if i used speakers measurement on axis as a data for the crossover calculation then yes, i have.
when i say that the measurements are real i mean that those curves have beed measured by sending a sweep to the crossover and measuring the crossover output not the speaker output if i understand your question right.
Of course if you mean if i used speakers measurement on axis as a data for the crossover calculation then yes, i have.
Ok. When you're ready to measure the speakers again a suggestion would be to compare your on axis measurement to say, 30 degrees off axis to see how different they are. This off axis measurement might be more indicative of the overall response as this axis is sometimes closer to this, although further measurements should remove doubt. This is mostly aimed at matching what you hear directly to the tone contributed by room reflections and may indicate a desire to listen to them at some other axis.
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