Bad solder joint somewhere is my guess.
[BUILD] CAPI LC53A~500 Series~Love Child EQ Kit~Official Support Thread
- Thread starter jsteiger
- Start date
Help Support GroupDIY Audio Forum:
tripple-checked everything now, every resistor, diode, capacitor, the transformer, DVFs, DOAs, every solder joint...even put more solder on the DOA sockets...measured possible connections of solder joints, re-calibrated CMRR...can't find nothing.
any more ideas?
any more ideas?
If the level keeps changing, there must be some intermittent problem somewhere on the build.
Yes indeed. A short piece of resistor lead will work a treat.PeteJE said:
Silly newbie question.... I got to the first unity gain test before final assembly. When first put up, the output was loaded down and the unit was humming. I swapped out the A2 (output?) gar 1731 op amp to a different one (ML2520) and all was fine - simple, bad op amp (both kit built).
Now, just for grins, I put back that first op amp again (gar 1731) and the original issue cleared up and unity gain good with no hum.
Why would this happen - it seemed seated fully first time - maybe components touching, seating exercised?? not sure. Hoping not another coincidental issues or really just some A2 op amp issue on that first try?
Now, just for grins, I put back that first op amp again (gar 1731) and the original issue cleared up and unity gain good with no hum.
Why would this happen - it seemed seated fully first time - maybe components touching, seating exercised?? not sure. Hoping not another coincidental issues or really just some A2 op amp issue on that first try?
Are they fully seated? http://classicapi.com/catalog/DOA_Install.php
Thanks for the link, Jeff. That is all I can imagine, maybe not fully seated at first, then swapping back and forth fixed this issue and brought it to working condition.jsteiger said:
I guess I ask because, if not fully seated A2 are possible symptoms a loaded down or reduced output and hum (not clean, more like harmonics - a humming buzz)?
It works! Sounds incredible, so smooth, musical, no odd nodes or resonances, just perfect! Thanks Jeff for your help along the way and Chunger for making this possible for me to do (I call it adult legos - because your guide is so good). I currently have gar2520 in A1 and gar1731 in A2 - I would be curious to know any differences to be expected with both 2520 or both 1731 or any other op amp preferences/experiences.
I have one BIG problem.... I need a second one ASAP, and the store is out for now,
- I'll keep checking stock. (also kind of excited for the FC526 too).
I have one BIG problem.... I need a second one ASAP, and the store is out for now,
- I'll keep checking stock. (also kind of excited for the FC526 too).
kante1603
Well-known member
Congrats,you can sell your 480 or 300 to gain a lot of money for several lovechildren (that's a LARC on the right side in the pic,no?) ;D .......but only if you have a spare one,hahaha!PeteJE said:I have one BIG problem.... I need a second one ASAP, and the store is out for now,
Did you experience that the LC53 adds fantastic "sound" even when in bypass
?I have them inserted just for that in a lot of scenarios (on a stereobus to get rid of "digital sound" we have to deal with nowadays)!
Have fun,
Udo.
(Edited typo)
kante1603 said:Congrats,you can sell your 480 or 300 to gain a lot of money for several lovechildren (that's a LARC on the right side in the pic,no?) ;D .......but only if you have a spare one,hahaha!PeteJE said:I have one BIG problem.... I need a second one ASAP, and the store is out for now,
Did you experience that the LC53 adds fantastic "sound" even when in bypass
I have them inserted just for that in a lot of scenarios (on a stereobus to grid rid of "digital sound" we have to deal with nowadays)!
Have fun,
Udo.
Ha! It is a 480L. On that note, although I like them very much, the JLMs may get "traded in" for the FC526......... we'll see.
kante1603
Well-known member
Don't do that!PeteJE said:
Use them in a chain,I do it all the time to get the mostt "bombastic" Rock-Vocals ever:1176(F76 in my case) to catch just the transients,then into optocomp (LA500s in my case too) to make it "powerfull".Maybe do the slow-attack-mod.
Very curious for Jeff's take on the FC576 btw.!
Best,
Udo.
just wanted to add that the issue with different I/O levels is solved. the problem was a solder joint of a resistor leg, which looked perfectly soldered from the backside of the pcb but apperently wasn't. so no chance to see it, it was solved more or less incidentally. nonetheless, thx for the support!
Hi all, new to this forum - thanks for having me.
Big fan of Jeff's kits and have built several pre-amps now building this EQ.
The CMRR calibration has me stumped.
I got the test jig to make this easier, but to be fair I'm pretty clueless (I play bass)...
I'm out putting a 100hz sine wave from my DAW to my 500 rack.
have the card plugged in, to the rack and the main pcb, put a DMM on as chungers build suggested but got nothing from C to the negative of the large blue cap? I get something from V+?
Can I measure what ever it is i'm supposed to be measuring back at my DAW?
Totally no idea, and the CMRR doc and chungers build don't use the jig, so not even sure how this works?
help!
Big fan of Jeff's kits and have built several pre-amps now building this EQ.
The CMRR calibration has me stumped.
I got the test jig to make this easier, but to be fair I'm pretty clueless (I play bass)...
I'm out putting a 100hz sine wave from my DAW to my 500 rack.
have the card plugged in, to the rack and the main pcb, put a DMM on as chungers build suggested but got nothing from C to the negative of the large blue cap? I get something from V+?
Can I measure what ever it is i'm supposed to be measuring back at my DAW?
Totally no idea, and the CMRR doc and chungers build don't use the jig, so not even sure how this works?
help!
You must engage the pushbutton switch on the Extension Jig's PCB to do the CMRR adjustment. You are trying to measure the output of the first amp stage. If you are using a DMM you must set the meter to ACV. Do you have an opamp in position A1?
I would imagine that its a DMM thing. It may be better for you to try an monitor this level thru your DAW. You will need to rig up and unbalanced cable with the signal coming from the same cap location that you had the red probe hooked to.
jaminem said:
Not sure if helpful but I can share how I did mine. I used a protools channel on input, sent the unbalanced signal back to this input with some alligator clips using a TT to XLR (XLR back into protools from my snake, and using a tt to xlr because the tt is easy to clip onto with the clips from the unit). I have a plug in that reads pretty sensitive and instantaneous dbu (avid pro limiter) and this made it easy to see and verify the low point of the trim pot. I did use 400hz as in the instructions, not sure if 1k would be better (since I wasn't really dealing with a DMM), but my unit ended up quiet and clean. This was using Jeff's extension jig for connection to the rack and input to the unit (with the button in and led lit on the extension jig).
