Ribbons and active XO - problems?

AJ · 26th July 2004, 08:58 AM

I've been thinking of buying a pair of Fountek JP2 ribbon tweeters and I read the following at a site that sells them:

Electronic crossovers show a dead short to the amp, you must use a passive component too!

I understand the need to be careful with ribbons, but I had never heard of problems with active XO's (I'll be using one). Can anyone explain the meaning of this warning? What kind of passive components are they referring to? Maybe a high-pass 'safety cap" or some such?

Thanks,
Allan

paulb · 26th July 2004, 01:00 PM

The statement makes little sense: if it's a 'dead short' how could it produce any acoustic energy?
It must mean to put a cap in series. A good idea regardless.

BobEllis · 26th July 2004, 01:13 PM

I think what they meant to say is if you use an active XO, the driver presents a very low impedance load at low frequencies. a large value high quality cap will block LF, take care of dc offset and turn on/off thumps. Try 20 -30 uf to start.

AJ · 26th July 2004, 04:21 PM

Thanks guys. That's kind of what I thought they were getting at but the "dead short" thing was confusing.

Allan

26th July 2004, 08:58 AM	#1
AJ diyAudio Member Join Date: Aug 2003 Location: Oregon	Ribbons and active XO - problems? I've been thinking of buying a pair of Fountek JP2 ribbon tweeters and I read the following at a site that sells them: Electronic crossovers show a dead short to the amp, you must use a passive component too! I understand the need to be careful with ribbons, but I had never heard of problems with active XO's (I'll be using one). Can anyone explain the meaning of this warning? What kind of passive components are they referring to? Maybe a high-pass 'safety cap" or some such? Thanks, Allan

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26th July 2004, 01:00 PM	#2
paulb diyAudio Member Join Date: Jun 2001 Location: Calgary	The statement makes little sense: if it's a 'dead short' how could it produce any acoustic energy? It must mean to put a cap in series. A good idea regardless.

26th July 2004, 01:13 PM	#3
BobEllis diyAudio Member Join Date: Sep 2003 Location: Upstate NY	I think what they meant to say is if you use an active XO, the driver presents a very low impedance load at low frequencies. a large value high quality cap will block LF, take care of dc offset and turn on/off thumps. Try 20 -30 uf to start.

26th July 2004, 04:21 PM	#4
AJ diyAudio Member Join Date: Aug 2003 Location: Oregon	Thanks guys. That's kind of what I thought they were getting at but the "dead short" thing was confusing. Allan

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