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Re: 7Pi Build 2014 [message #80464 is a reply to message #80463]

Fri, 12 September 2014 15:02

rkeman
Messages: 78
Registered: March 2010
Location: Florida

Viscount

Check everything! Crossovers, wiring, insulation, drivers, driver gaskets, back panel bracing, amplifier... If both speakers have the problem it is probably a crossover or construction issue because simultaneously defective drivers or channels of amplification are very unlikely. The build is fairly complicated and it is very easy to miss something. When assembling a 3PI, the insulation in one speaker came loose and fell against the back of the woofer cone and it sounded very bad indeed!

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Re: 7Pi Build 2014 [message #80465 is a reply to message #80463]

Fri, 12 September 2014 15:10

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

Viscount

On a scale from 1 - 10 I would rate the voice quality a 5.
Everything is hooked up with Neutrik so I can test things one driver at a time.
I triple checked all polarities and wiring before assembly...
2226h black to 3+, Mid red to 2+ and de250 black to 1+

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Re: 7Pi Build 2014 [message #80469 is a reply to message #80113]

Fri, 12 September 2014 17:11

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

Viscount

Not the problem, but one resister was rattling around in the XO box. Nothing close to touching it. A mystery. I soldered it back on and they still sound bad.

Picture of XO and wiring. Wires with black shrink wrap are negative all the way back to the drivers.

Attachment: 7pi XO.jpg
(Size: 1.98MB, Downloaded 9763 times)

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Re: 7Pi Build 2014 [message #80472 is a reply to message #80113]

Sat, 13 September 2014 12:52

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

Viscount

And something sounds out of phase. Kind of like some of the old school sound enhancement programs like "Stadium". Not as bad but noticeable. At first, I used a popsicle stick between the mid cone and the MDF and that's about how much clearance I had. Now, three popsicle sticks.

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Re: 7Pi Build 2014 [message #80473 is a reply to message #80113]

Sat, 13 September 2014 19:34

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

Chancellor

It appears you have resistors R1b and R1d touching the trace from L1. I think they should not touch this trace and only touch at the pad below. Double check all traces against the schematic

Matt

Attachment: pi7 xover markup.jpg
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Re: 7Pi Build 2014 [message #80474 is a reply to message #80473]

Sun, 14 September 2014 04:03

tubemax
Messages: 37
Registered: February 2012
Location: Netherlands

Baron

It looks like 15Ohm damping resistor is also not connected to the ground?

Max

Attachment: 7pi+XO II.jpg
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Re: 7Pi Build 2014 [message #80475 is a reply to message #80473]

Sun, 14 September 2014 04:42

tubemax
Messages: 37
Registered: February 2012
Location: Netherlands

Baron

Hmmm, there is also a missing coil on your crossover which you connected only with jumper wire?
Please have a look at the picture of finished crossover form Wayne, there is a extra coil being soldered for mid horn ( I think 1mH )!

Max

Attachment: Pi7_Crossover.jpg
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Re: 7Pi Build 2014 [message #80476 is a reply to message #80475]

Sun, 14 September 2014 05:27

tubemax
Messages: 37
Registered: February 2012
Location: Netherlands

Baron

Just one more thing... there is also a missing resistor in the voltage divider part of mid horn ( resistor between coil and small blue capacitor ), supposed to be two 16 Ohm resistors in parallel ( for desired 8 Ohm resistance ) connected with another four of 16 Ohm resistors in parallel ( for desired 4 Ohm series resistance ) to form correct low-end response of the horn ( 4 Ohm series resistor followed by 8 Ohm shunt ).
If you have only one 16 Ohm resistor then is your midrange response probably double louder in the lower-end of spectrum...
Also you used 15 ohm instead of 16 ohm resistors, this could change somewhat impedance of crossover, not the attenuation, Wayne can give as input on that.

Max

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Re: 7Pi Build 2014 [message #80477 is a reply to message #80476]

Sun, 14 September 2014 10:38

Wayne Parham
Messages: 18789
Registered: January 2001

Illuminati (33rd Degree)

I can see that resistor R5a is missing, so I'd suggest putting that back. And I agree with Matt, I would check to make sure the leads from R1b and R1d are not bent, touching the trace from L1.

But to tell the truth, crossover problems usually present as missing or over-represented portions of the frequency spectrum. Examples would be too much bass or bass that's too thin, missing treble or too much. Vocals can sound too throaty or hollow. When there's something wrong with the crossover, it usually sounds like the response curve is off, because it usually is.

When people complain of distortion in a new speaker, it's most often caused by something rubbing or buzzing. So look for things that may be rubbing against the cone. Make sure the gasket isn't in contact with the cone or surround, and make sure it's sealed. No gaps. Check the wiring too, making sure the wire isn't resting on the cone, which will make a buzzing sound. And finally, make sure the back panel is secure and doesn't vibrate. See the post about Midhorn bracing. You'll probably want to do the "rubber ball brace" for the back panel.

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Re: 7Pi Build 2014 [message #80478 is a reply to message #80113]

Sun, 14 September 2014 11:15

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

Viscount

First thing, it seems that 2226h are wired "black to + forces positive displacement". Good to know.
I will fix that in the XO box as well as the other suggestions.
The resistor came off by itself inside the XO box. It's a mystery because nothing could have knocked it off.
How much clearance is optimal between the mid cone and the panel it's mounted to?
Mid horn bracing is not an issue.. The back panel seal is not perfect now but I will fix that once I determine the proper clearance for the mid driver.

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