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Multi-Way Conventional loudspeakers with crossovers

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Old 6th April 2014, 02:21 PM   #21
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ok thanks, and wonder if that tweeter gone dry inside ?
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Old 6th April 2014, 02:53 PM   #22
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The MC4 bass unit isn't Rogers, it's an Audax MTX20X25TDSN; the tweeter is by TDL.
The tweeter X/O is third order electrical, 2R7 on the input, then 3mfd, 0.22mH, 6mfd. Bass is a weird kind of 2nd order - it has 9.87mH in parallel with a 1.2mH inductor which has 30R resistance - cap is 9mfd.

Strange you say they are bright - I found them a bit dull with some hardness around 4k and a suck-out 2-3k.
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Old 6th April 2014, 03:49 PM   #23
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Thanks Zuhl, I just picked up these speakers off of ebay. I had a pair back in 1987 but sold them sadly. Now I am starting over again !

I think something is wrong with these for them to be bright as you say they are normally have a bassy balance.

If I renew the caps am I correct with:

2x 3.00uF 250 V and 2x 6.00uF 250 V for each xover. (I noticed up by the tweeter output ? on the xover the 3.00uF and the 6.00uF caps seemed to be connected together)

Last edited by Barbieboy; 6th April 2014 at 04:01 PM.
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Old 6th April 2014, 05:07 PM   #24
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The bass had 6mfd and 3mfd in parallel to make 9mfd - and I forgot earlier, a 0R47 resistor in series - I'm doing this from memory and haven't seen the x/o for about 10 years...

The bass x/o was connected with red and black wires, the tweeter x/o with thin yellow and blue wires.
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Old 6th April 2014, 05:15 PM   #25
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I will open up the cabinets again and take some better photos, but this will have to wait until tuesday
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Old 8th April 2014, 04:59 PM   #26
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Default MC4s too bright

Ok guys, as promised photos of my MC4 (V1) crossover. Hope someone can make some sense of whats under all that glue
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Old 8th April 2014, 06:10 PM   #27
system7 is offline system7  United Kingdom
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Quote:
Originally Posted by Barbieboy View Post
Ok guys, as promised photos of my MC4 (V1) crossover. Hope someone can make some sense of whats under all that glue
What I'm coming up with is below. I'll ignore a 9.87mH coil. That makes no sense, it's too big a value. Maybe they've deliberately obscured the value.

It doesn't look like anything I've ever seen though. That 1.2mH coil with 30R resistance that Zuhl mentioned might be tailoring the bass crossover slope and phase a bit.

But it's really odd, IMO. Is that what it looks like to you BarbieBoy? See, I'd just expect a simple ca. 1.5mH coil here.

FWIW, the tweeter crossover looks totally standard, even down to being wired in negative polarity here.

BTW, I think I've drawn the RC (0.47R +9uF) shunt the wrong way round from your crossover.
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File Type: png Weirdness MC4 XO.PNG (7.7 KB, 26 views)
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Well, there it is! Best regards from Steve in Portsmouth, UK.

Last edited by system7; 8th April 2014 at 06:14 PM.
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Old 8th April 2014, 06:31 PM   #28
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Ok got the glue off the coil
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Old 8th April 2014, 06:40 PM   #29
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You can't see it on those images, but I have what's left of the crossovers I had here. The inductor says 9.87 on it - I have no way of measuring inductors, but it's a similar size to some 10mH I have in a sub x/o.

The 0.47R does go to the negative.

Interesting you have a single board. Mine had two boards: bass was glued in the bottom of the cabinet and the tweeter in the top rear of the cabinet.
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Old 8th April 2014, 06:51 PM   #30
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Click the image to open in full size.

Best I can do for an image.
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