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Old 7th December 2004, 02:20 PM   #171
tiroth is offline tiroth  United States
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Well, it sounds as though someone may already have done the work of determining the proper Fc, Q, and order for your particular design. If this is the case, and if you trust that person's judgement, then there may not be a lot to gain from expermiementation, although I would encourage it. (as moamps said, this is DIY)

The more typical case, replacing a passive xover with an active one a priori, you cannot assume simply because you know the passive points and topology that you know the proper active parameters. Even proper simulation of the crossover/loudspeaker system does not always reveal the proper design choices.
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Old 7th December 2004, 10:56 PM   #172
cowanrg is offline cowanrg  United States
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tiroth,

that helps out a bit. im just not too knowledgable with xovers at all.

so, is there something i can read that further explains how an active xover operates differently than a passive xover, or is that just something that needs to be experienced?
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Old 7th December 2004, 11:25 PM   #173
tiroth is offline tiroth  United States
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For a good example, check out this thread. You can see that the active filter is not quite making it because of the impact of the driver inductance etc.

I made a mistake here, I should have tried higher Q values for a better fit.

Proac Response 2.5 active xo

This was the process I went through to create an active filter from a known passive filter. But, it sounds like this work may have been done for you already?
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Old 8th December 2004, 12:09 AM   #174
cowanrg is offline cowanrg  United States
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well, it just states in the manual that if using an external (doesnt specify whether active or passive), to use a 1khz xover point...

audio research actually did make an outboard active xover that was designed for my speakers, but i think its variable, so it works with different xover points...

now another question... with xovers (regarding active and passive), does the driver type make a difference? for instance, my speakers dont use conventional cone drivers, but are planers. does this change the characteristics at all of the xovers?
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Old 11th December 2004, 03:21 AM   #175
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It should differ because of the effect of the drivers on the passive crossovers. Active crossovers have a power amplifier in between them and the speakers, so the reverse emf and impedences, etc. are not affecting the active xover. The passive is more a part of a complex circuit including the drivers. Just saying it is different, not suggesting how or what to modify to match them. Being able to tweek easily is a good thing. -Marsupialx
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Old 11th December 2004, 05:17 AM   #176
cowanrg is offline cowanrg  United States
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hum, i understand that well enough...

well, i just dont like playing with my speakers. actually, just last night i blew a tweeter on one of my speakers, NOT very happy about that... guess i have to send it to be repaired.
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Old 11th December 2004, 12:05 PM   #177
tiroth is offline tiroth  United States
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Did you have a series capacitor between the tweeter and the amp? Highly recommended!
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Old 11th December 2004, 06:08 PM   #178
cowanrg is offline cowanrg  United States
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no

my old models had a fuse in line, so they didnt blow, but i forgot my new ones didnt... i was GOING to install a fuse, but didnt.

oh well, they are relatively cheap to replace, and they didnt sound matched either. so, its an excuse to get them replaced anyways. sigh.
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Old 21st December 2004, 07:02 PM   #179
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OK...

From the dumbest MOX constructor in North America...

I'm ready to fire this up but I don't want to really "fire" it up!

I built the discreet op-amp boards and would like to know which way they plug in? Q1 Does the component side face the power input side of the board or the proto side of the board?

I will be using a 15VDC supply from a wall wart. I recall being told that it has to be AC but that doesn't make sense to me.

Q2 Should be a 110VAC/15VDC transformer, right?


At least smart enough to ask before applying power...
Thanks!
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Old 21st December 2004, 10:44 PM   #180
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nudge
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