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Re: My 4 Pi Build [message #97074 is a reply to message #97073] Mon, 16 October 2023 14:04 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
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Registered: January 2001
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Unity_Coupled wrote on Mon, 16 October 2023 13:15
Potentially there's another issue, this one not so easy (or cheap) to resolve. I suspected from the get-go that at least one of my drivers was reconed, due to the over-application of glue around the dust cap on one of the cones, and the absence of a part number stamped on the backsides.
...
Compared to the JBL data, the impedance is not as smooth above 500hz, but it doesn't seem particularly bad either. As you've said in another post, the impedance notch at around 1k is a good indicator that the cone is aftermarket.
...
I'm going to wait until I can conduct final FR measurements and listening tests before making any decisions. I paid about $300 for both drivers, and if they're good enough I'm inclined to keep using them.

I would do the same thing. Measure the response to know for sure.

Even if it's not, a recone isn't too expensive and will make the driver 100% good as new. That's one of the really great things about the 2226H driver.
Re: My 4 Pi Build [message #97179 is a reply to message #97053] Fri, 10 November 2023 13:51 Go to previous messageGo to next message
frederf69 is currently offline  frederf69
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Thank you for this; these little details can be so important. I have not built/ put together a speaker before, but I'm seriously thinking about the 4Pi with the JBL2226H MW & B&C DE250 CD. Just one question please - how is the compression driver attached to the waveguide? H290C
Re: My 4 Pi Build [message #97180 is a reply to message #97179] Fri, 10 November 2023 14:21 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18945
Registered: January 2001
Illuminati (33rd Degree)

The compression driver mounts onto the horn with a couple of 1/4-20 bolts that are spaced 3" apart. Each mounting bolt is 1-1/2" from the center. Some call this the "standard two-hole mounting pattern."

In the case of the B&C DE-250, you could use 1/4-20 bolts but they include a couple of studs and nuts with that compression driver so I personally always use 'em.
Re: My 4 Pi Build [message #97183 is a reply to message #97180] Fri, 10 November 2023 16:38 Go to previous messageGo to next message
frederf69 is currently offline  frederf69
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Thank you, much appreciated Cool
Re: My 4 Pi Build [message #98737 is a reply to message #96988] Sat, 28 June 2025 19:34 Go to previous messageGo to next message
Unity_Coupled is currently offline  Unity_Coupled
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Registered: September 2023
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Happy Tau Day!

After taking a break from this project for nearly two years (life, eh?) I decided it's time to get back into it.

The next order of business is to build up the boxes.  The design I settled on reflects that of the original, but with a front lip to accommodate a removable grill cloth, and some additional bracing.  Since I would be using my CNC I implemented several slots and reliefs to aide in panel alignment during glue-up.

/forum/index.php?t=getfile&id=3508&private=0

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Re: My 4 Pi Build [message #98738 is a reply to message #98737] Sat, 28 June 2025 19:44 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
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Registered: January 2001
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Sweet!

That looks incredible!
Re: My 4 Pi Build [message #98748 is a reply to message #96988] Thu, 03 July 2025 16:54 Go to previous messageGo to next message
Unity_Coupled is currently offline  Unity_Coupled
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Enclosures getting glued up...

I realized too late that the CNC table wasn't as flat as I thought it was, which caused the depths of the dados to vary by up to +/- 0.1".  It took a fair bit of touchup on the router table to get everything to fit correctly.

/forum/index.php?t=getfile&id=3516&private=0

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Oh yeah, I was a dingbat and installed the back panel inside-out on one cabinet and didn't notice until today.  D'oh!  I'll have to route the recess for the terminal plate by hand...

/forum/index.php?t=getfile&id=3513&private=0
Re: My 4 Pi Build [message #98749 is a reply to message #98748] Thu, 03 July 2025 17:11 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18945
Registered: January 2001
Illuminati (33rd Degree)

Unity_Coupled wrote on Thu, 03 July 2025 16:54
I realized too late that the CNC table wasn't as flat as I thought it was, which caused the depths of the dados to vary by up to +/- 0.1".  It took a fair bit of touchup on the router table to get everything to fit correctly.

That's a pretty big variance, nearly 1/8".  But you sure can't tell - your speakers look great!
Re: My 4 Pi Build [message #98751 is a reply to message #98749] Thu, 03 July 2025 23:57 Go to previous messageGo to next message
Unity_Coupled is currently offline  Unity_Coupled
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Wayne Parham wrote on Thu, 03 July 2025 17:11

Unity_Coupled wrote on Thu, 03 July 2025 16:54
I realized too late that the CNC table wasn't as flat as I thought it was, which caused the depths of the dados to vary by up to +/- 0.1".  It took a fair bit of touchup on the router table to get everything to fit correctly.

That's a pretty big variance, nearly 1/8".  But you sure can't tell - your speakers look great!

Thanks, Wayne-  Roughly half of the panels required rework as stated, and if you examine the enclosures closely it's evident that things are still slightly askew...but it's nothing that can't be mitigated with a dose of flush trimming and some sanding.  At least the joints mate properly and the boxes are air-tight where they need to be.  Overall I'm very pleased with how everything is taking shape.

Funny thing... I was contemplating running a surfacing pass on the mill before starting but ultimately chose to just "send it".  My impatience got the better of me!  I suspect it will strike again as I'm anxious to load in the drivers and crossovers for a listen.

I think the next step is to prime and paint the baffles satin black before applying the veneer to the rest of the cabinets, but I'm not quite sure how to go about it.  Maybe black lacquer with a paint sprayer?  I'll have to consult by brother who has more experience with this kind of stuff.
Re: My 4 Pi Build [message #98753 is a reply to message #96988] Fri, 04 July 2025 13:33 Go to previous messageGo to previous message
Unity_Coupled is currently offline  Unity_Coupled
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Wayne,
Do you recommend using standoffs when mounting the Zobel resistor to the enclosure?
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