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Re: 7Pi Build 2014 [message #80640 is a reply to message #80639]

Mon, 06 October 2014 14:30

Wayne Parham
Messages: 18802
Registered: January 2001

Illuminati (33rd Degree)

I think I see the problem. If this is it, I owe you a big old bottle of your favorite adult beverage.

Look at the crossover photo you sent earlier. See the area I've circled in red:

If those resistors are touching the land in the circled area, then the tweeter circuit is shorted and it has no output. Pull the resistors up away from there - so they touch only the line going to the (+) lug - and see if you don't have nice tweeter output.

If that's it, I apologize not only for sending the boards out that way but also for not looking closer at the photo you posted. I have someone building boards for me, and they may not have tested their work as thouroughly as we should have.

And let me know what you drink.

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Re: 7Pi Build 2014 [message #80641 is a reply to message #80640]

Mon, 06 October 2014 14:46

my0x
Messages: 23
Registered: October 2012
Location: Philadelphia, PA

Chancellor

Yeah, that's what I saw touching per my previous post. Whatever it is, I hope you get it right and you'll know what all the fuss is about!

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Re: 7Pi Build 2014 [message #80642 is a reply to message #80641]

Mon, 06 October 2014 14:47

Wayne Parham
Messages: 18802
Registered: January 2001

Illuminati (33rd Degree)

I just re-read this thread and saw your post on September 13th where you suggested checking exactly that. Good catch!

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Re: 7Pi Build 2014 [message #80643 is a reply to message #80113]

Mon, 06 October 2014 14:54

compaddict
Messages: 86
Registered: April 2014
Location: Auburn, CA USA

Viscount

Yea, I fixed that a long time ago. The other XO was just fine.

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Re: 7Pi Build 2014 [message #80644 is a reply to message #80643]

Mon, 06 October 2014 15:00

Wayne Parham
Messages: 18802
Registered: January 2001

Illuminati (33rd Degree)

I think we've narrowed our focus to the tweeter circuit. If you'd like, send the crossovers back to me, and possibly the compression drivers too.

From the measurements, it is evident that the compression driver is not providing any output.

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Re: 7Pi Build 2014 [message #80645 is a reply to message #80113]

Mon, 06 October 2014 15:13

compaddict
Messages: 86
Registered: April 2014
Location: Auburn, CA USA

Viscount

Not much you can do that I can't do here.
In the file I posted I have separate readings from each driver all taken 1M from Mid axis. Just for information.
I'll tear into the XO today check the specs on everything.
Wayne, if you want you can send me a set of known good XOs.

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Re: 7Pi Build 2014 [message #80646 is a reply to message #80645]

Mon, 06 October 2014 15:24

Wayne Parham
Messages: 18802
Registered: January 2001

Illuminati (33rd Degree)

Well, that's probably true. It's a simple circuit and you can easily troubleshoot it there. I just didn't want to see you get stuck, so the deal always stands.

One thing you might do is to put a single series capacitor inline with the compression driver instead of using the crossover. Run the woofer and midrange directly off the amp, and the tweeter having just a series cap, value in the 5-10uF range.

What you would see when measuring that is the midhorn would be about 6dB hotter than the bass and the tweeter would be another 3dB hotter than that. So this would let you see the tweeter output, and would help isolate that huge rolloff.

If you see this - and I expect you would - then you could trace the signal through the tweeter circuit. It's pretty simple, with the signal going first through the 6.8uF capacitor and then shunted by the 1.0mH coil, passing then through the 20uF capacitor and onto the R1/R2 padding network. My guess is either somewhere the signal is shorted, possibly by one of the leads under a coil where it is siliconed to the board, or one of the series components is misconnected. It pretty much has to be one of those things, because there just isn't that much in the signal path.

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Re: 7Pi Build 2014 [message #80647 is a reply to message #80646]

Mon, 06 October 2014 15:38

compaddict
Messages: 86
Registered: April 2014
Location: Auburn, CA USA

Viscount

Have an extra set of known good XO you can spare?

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Re: 7Pi Build 2014 [message #80648 is a reply to message #80647]

Mon, 06 October 2014 16:17

Wayne Parham
Messages: 18802
Registered: January 2001

Illuminati (33rd Degree)

We build crossovers to order. With all the options available for each model, it just makes more sense for us to assemble the crossovers at the time of order. So we maintain a large stock of unstuffed crossover boards and all the components for each model and option. But we do not stock completed crossovers.

If all else fails, I'll build up a board and send it to you for a baseline.

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