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Ever tried putting a cap inline with RCA for XOVER

Hi There, I am trying to cross over my speakers on the cheap.

Anyone ever tried putting a cap inline with an RCA input on a amp to act as a passive High Pass Filter? I am trying to cross over my Wilson Cubs at about 70-80HZ.

My amplifier is a Mark Levinson No. 332 for Reference.

My goal is to build an adapter (Female to male RCA) with a capacitor in there to act as a passive crossover. I know this can be achieved on the interior of an amp but this amp is about as much of a cream puff as youll ever find, Im doing nothing to her (She got completely recapped and upgraded with better parts all around in 09 so shes good for a good long while now)

If that doesnt work how about a good DIY design? Should I go active? I am trying to go not too expensive and potentially avoid another box in my system, but I dont want to degrade my signal greatly, however I do believe a little signal loss would be an ok trade off for less woofer excursion

Which is better, Woofers working hard with more signal or.. working less but a tiny bit less signal?

Oh I play my music loud and listen to electronic music, acoustic is not much of an issue, White Zombie made me realize I was within 75% of the excursion limits at mid volume, I want to be able to play these guys loud and cant hit the high 90DB to 100 or so DB like I want, I am probably chickening out at 90 or so if that.

Thanks

Toby
128x128systembuilder
13 responses Add your response
systembuilder's avatar
systembuilder OP
111 posts
 
Jtwrace

You can listen at igh volume for short periods of time and be fine it is long exposure that destroys you.

When I go out to local shows it is so much louder it isnt even funny and I have been to enough to know. As long as you dont over expose yourself youll be fine.

I play my system loud not for very long periods of time. Dont you ever have fun any more, dont you ever have friends over and pound out some tunes?
6550c
393 posts
 
^^ note really. What makes you deaf are the short peaks near 120dB. If you keep the mean at 90 or so and compress the peaks, you shouldn't have any problems with ear ringing even after long term listinging.
jtwrace's avatar
jtwrace
443 posts
 
90dB-100dB will not be an issue because at those levels you'll be deaf pretty quick.
dan_ed
2,451 posts
 
Yep, you can do this, but what will you do about the resulting phase shift?
gbart
290 posts
 
I second the Harrison Labs FMOD passive x-overs from Parts Express. I've used them successfully in the past to bi-amnp my party system.

http://www.parts-express.com/wizards/searchResults.cfm?searchFilter=fmod%20crossover

.
systembuilder's avatar
systembuilder OP
111 posts
 
Thank you again, This is going into my long term notes. I lucked out and forgot I had a Velodyne SMS-1 Lying around so I am using that as a crossover for now.

But I really needed to know how to do this.

Thanks a million yall
almarg's avatar
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almarg
9,670 posts
 
Be mindful of the units when using the equation Jafox supplied. If frequency is in Hertz, and input impedance (R) is in ohms, C will be in farads (and the answer will be a tiny fraction of a farad). Move the decimal point 6 places to the right (i.e., multiply by a million) to get microfarads (uf), or 12 places to the right to get picofarads (pf).

For example, 80Hz and 47,000 ohms works out to 0.000000042 farads = 0.042 uf = 42000 pf.

Regards,
-- Al
jafox
1,456 posts
 
Yes Systembuilder, as 4est stated, it is done frequently. It's a great way to eliminate the need for extra ICs and keep the signal into the main speakers as "pure" as possible rather than running the entire signal through a crossover system first.

All you need to know is the input impedance (resistance) of the amplifier and your desired HP Filter frequency and you can calculate the capacitor value:

C = 1 / (2 * pi * F * R)
jallen
502 posts
 
Parts express has passive xovers on the cheap. Jallen
blkadr
739 posts
 
That's probably what a FMOD is, hlabs.com.
face
516 posts
 
http://www.marchandelec.com/xovers.html

Or google passive line level crossover.
ngjockey
1,042 posts
 
I think you can still get an NHT X2 for $300 new. Relatively transparent.
4est
507 posts
 
Yes, a cap in series will act like a high pass filter. It is done regularly.
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