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Multi-Way Conventional loudspeakers with crossovers

Passive woofer crossover redux...
Passive woofer crossover redux...
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Old 16th July 2018, 11:15 PM   #1
aceinc is offline aceinc  United States
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Default Passive woofer crossover redux...

I have two monitor type speakers I built. They sound pretty good, but don't go much below 60 hz.

I have a pair of small sealed boxes, which are aesthetically pleasing to my spouse, each with a Dayton 10" Titantic II, 4 ohm I believe. I was using them as part of my sub system, attached to a Crown Amp which in turn was attached to one of the sub outs on my Sound Processor. They really didn't provide much extra oomf in the sub arena as the main sub duty is performed by a Rythmik 15.

Then I built a pair of mains each with dual OB 12's and the 10's became even more superfluous.

So I decided to hook them in parallel to my monitors which are running as surround rears. When I ran a REW plot I got pretty smooth response down to the mid 30's. So for the moment I retired the crown amp and am running things like that.

I was thinking (always a problem according to my spouse) however, should I put a xover in between the two? It would reduce the highs from the woofer, and keep the 5.25" driver in the monitors from trying to produce LF which should theoretically clean things up.

Being lazy & cheap I saw these over at PE;


Parts Express 80 Hz Low Pass 4 Ohm Crossover
Part # 266-440

and


80 Hz High Pass 8 Ohm Crossover
Part # 266-458

which look just the ticket.

They are inexpensive, but that comes at a price of an iron core coil & electrolytic caps.

My questions;

On the coils how can I tell the usable power before saturation?

On the caps;

Should I be concerned on the low pass side that the cap is electrolytic, as it is after all effectively sub frequencies?

Should I be concerned on the high pass side that all of the rest of the frequencies (IMO more important bits) are going through an electrolytic cap?


Anything else I should be concerned about?

Last edited by aceinc; 16th July 2018 at 11:17 PM.
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Old 16th July 2018, 11:32 PM   #2
Galu is offline Galu  Scotland
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Edit: Misread your post - sorry!

Last edited by Galu; 16th July 2018 at 11:41 PM.
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Old 16th July 2018, 11:41 PM   #3
phivates is offline phivates  United States
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Location: Willamette Valley
An 80 Hz passive crossover is not easy to do, at all. Go up an octave at least.
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Old 17th July 2018, 12:12 AM   #4
aceinc is offline aceinc  United States
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Quote:
Originally Posted by phivates View Post
An 80 Hz passive crossover is not easy to do, at all. Go up an octave at least.
I neglected to mention, the woofer cabinets are down facing, and there is ~30" between the woofer and the mid woofer on the monitor.

One area of concern is the woofer generating appreciable HF, and smearing the mid range.
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Old 17th July 2018, 07:40 AM   #5
Sonce is offline Sonce  Macedonia
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Location: Macedonia
Quote:
Originally Posted by aceinc View Post
On the coils how can I tell the usable power before saturation?

Should I be concerned on the low pass side that the cap is electrolytic, as it is after all effectively sub frequencies?

Should I be concerned on the high pass side that all of the rest of the frequencies (IMO more important bits) are going through an electrolytic cap?
Inductor core appears to be large, so no problems with saturation up to 150 W at least (maybe up to 250 W, as advertised).

No.

You can do a much better high-pass filter with simple line-level capacitor at the satellite amplifier input. Check the amp input resistance R and than choose an appropriate capacitor: C=1/(6.28fR)

Last edited by Sonce; 17th July 2018 at 07:48 AM.
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Old 17th July 2018, 11:35 AM   #6
aceinc is offline aceinc  United States
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Quote:
Originally Posted by Sonce View Post
Inductor core appears to be large, so no problems with saturation up to 150 W at least (maybe up to 250 W, as advertised).

No.

You can do a much better high-pass filter with simple line-level capacitor at the satellite amplifier input. Check the amp input resistance R and than choose an appropriate capacitor: C=1/(6.28fR)
Thanks for the reply. My monitors and the woofers are powered by a single amplifier, so puting anything on the input side of the amp would affect the monitor/woofer combination.

My thought for the high pass cap might be to replace it with;

An Audyn 100mfd & an Audyn 68mfd capacitor wired in parallel.

I think I could desolder it and solder in the replacements, or desolder the coil and put everything on a new board.

By using the coil & the new caps, I could maintain the 12 db slope vs a 6 db slope the single cap would provide.
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Old 19th July 2018, 03:16 AM   #7
Sonce is offline Sonce  Macedonia
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Location: Macedonia
Quote:
Originally Posted by aceinc View Post
My monitors and the woofers are powered by a single amplifier
My bad, I didn't pay attention to that.
First, try the original high-pass filter (with the bipolar electrolyte cap) on monitors only, without the subwoofers. Check the sound quality of mid and high frequency spectra with and without high-pass filter. If there is any sound quality difference (besides missing low bass, of course), than try replacing the capacitor with MKT or MKP type.

Last edited by Sonce; 19th July 2018 at 03:19 AM.
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