[BUILD] CAPI 553F~500 Series~LC Equalizer~Official Support Thread

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jsteiger

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Since the kits are finally ready to ship, it's time for the support thread!  :)

**This is a pretty easy build. A touch harder than a VP25, VP26 or VP312 but easier than a VP28 or Love Child. I recommend reading completely thru the Assembly Aid before starting on anything. There are some points made in the doc that can save you much time and prevent crucial errors during the build.

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September 21st, 2015 Update:
All support docs for this project can be found on the recently added
Support Docs page at www.capi-gear.com
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Some details can be found here http://capi-gear.com/catalog/product_info.php?cPath=22_117_119_170&products_id=417

temp-553F.jpg


Cheers, Jeff
 
Marc Duchesne said:
Received mine also yesterday... Will start built this week-end. Very nice packaging and parts from Jeff as usual. He is consistent. :)
Thanks Marc. Can you please make sure you have the 3 and 5 pin right angle headers for the 2 filter boards. They should be in with the main PCB components. I missed them on the first shipment of kits but I think yours had them.
 
Thanks Marc. Can you please make sure you have the 3 and 5 pin right angle headers for the 2 filter boards. They should be in with the main PCB components. I missed them on the first shipment of kits but I think yours had them.

Yes Jeff, 1 X 3 pins right angle and 1 X 5 pins right angle header...

Thanks !
 
Jeff - great design and kit! I've used the API 553 in the past and adding the HPF is most useful in combination with the low EQ inductor (one cutting the other boosting). All I remembered from the original and then some!

Took me around 5hrs to complete - iPad with the assembly aid helped out greatly...

 

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Recently finished a pair of these -- it was a fun build and not very difficult. Hardest part is the fiddly little screws and nuts...

A couple notes for anyone building one:

-I found that the resistors/caps/transistors on the discrete followers need to be installed flush to the board, and trimmed very closely as there's not much clearance between the two boards once installed.

-I almost forgot to solder the bourns pots once everything was fitted together and tested. (The instructions don't explicitly state to solder them, and I guess I was following along a little TOO closely).

These EQs sound great -- the three available bands are surprisingly versatile, and on most sources, can be pushed to extremes without sounding bad. LC53a's will be ordered soon for comparison.

Btw, I built these with gar2520's, but I'm going to order some gar1731's for comparison..... will report back.
 
OK, that was a relaxing and enjoyable build. I'm not used to building things that are so well-documented. Thanks Jeff!

My pre-flight measurements came out OK, except one: On the A1 DOA, probes between "O" and "C" doesn't register anything on my DMM. Does this indicate a problem? There is no continuity between the two, but also no measurable resistance.  The A-2 DOA registers properly at 56.8Ω between O and C.

Actually, would 150MΩ be a problem? The DMM stays blank until I click up to the 200M range, and which point it reads 1.5.

What do you think?
 
jsteiger said:
You should be good to go.

OK then! From postal box to boxed module in two leisurely weeknights. A nice change of pace from builds that have stretched on for months. I see more CAPI modules in my future...

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Here is a quick example of the 553F on acoustic guitar. Loving it so far. How musical this Eq is is very surprising. I will need another one for stereo operation. Great work Jeff !!!

https://www.dropbox.com/sh/1kzq1qioe1xsr7m/or4_0cs7a-
 
Calibration Q:

A 1k sine wave doesn't vary in volume at any point in the full 25T of the trimpot. Does that indicate a problem?
 
jsteiger said:
Are you using one of my Extension Test Jigs or a special XLR cable?

It's plugged straight into the rack.
EQ not engaged / bypassed.
Sine wave into the XLR jack unbalanced.
Output tapping off the clips identified in the help doc.

Is there something special about the test jig I need to emulate somehow? I saw it has a CMRR setting that needs to be "out."

 
Thank you!  Cable built. Unit calibrated.

I cranked the sine wave through nearfields. It was nice to hear that tone disappear to complete silence as I turned the trimmer.  Thanks again for a great project.
 
I made a crude recall sheet using one of the photos from the website... I'm sure someone could do better with 5 minutes and photoshop, but this will get the job done for me.

 

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