Cooked SEX Cap

buddythunder · 2323

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Offline buddythunder

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on: September 09, 2023, 01:34:51 PM
I got all excited after successfully building the Pass ACA amp kit and thought I'd have a go at a Tube amp next, so ponied-up and bought the S.E.X. kit.

I got through the entire build and failed my voltage checks on the B-socket side. I found a bad solder, but in the course of correcting it did a bad thing - cooked the 1.5uF 630V cap with my soldering iron. Ignoring sanity, I powered-up but was rewarded with a plaintive crackle, so immediately powered-down. No visible smoke and I couldn't smell anything, so not sure what crackled but I can guess. Notable that nothing crackled when powered up before the damage. I'm looking for validation really - given the damage you can see in the pic and the evidence of my ears, I think immediate replacement of the cap is required. Anyone care to disagree?

Oh, there was also an excessive 19.8V DC at terminal 3 on the A-side, having wired for my 240V AC. It was outside of the range, but figured it was close enough, given the wide 15% tolerance on other voltages. Yell if I'm wrong!

First time builder and poster. Great community tho, thanks for taking a look.



Offline Mucker

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Reply #1 on: September 09, 2023, 02:06:33 PM
Yep .... I did that before. It's toast.

Good opportunity to upgrade the caps. I attached a pic of what I did. Caps from PartsExpress.

small caps ........... Jantzen Superior Z-cap 1200 VDC 0.1uF
big caps .............. Jantzen Superior Z-cap 800 VDC 2.2 uF

had to finesse them in place the best I could ..... and they work well ....
« Last Edit: September 11, 2023, 05:26:10 AM by Mucker »



Offline buddythunder

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Reply #2 on: September 09, 2023, 02:40:30 PM
Yep .... I did that before. It's toast.

Good opportunity to upgrade the caps. I attached a pic of what I did. Caps from PartsExpress.

small caps ........... Jantzen Superior Z-cap 1200 VDC 0.1uF
big caps .............. Jantzen Superior Z-cap 800 VDC 2.2 uF

had to finesse them in place the best I could ..... and they work well ....

Thanks so much, good to have the confirmation. I've ordered exactly those parts, thanks for the quick, no fuss reply. Nice looking attenuator too, what's that wee fella? I have the CS4 kit to install too, it really does look like a tight squeeze with that and the big caps! Cannot wait.



Offline Mucker

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Reply #3 on: September 09, 2023, 02:56:49 PM
Glad I could help. Just take your time with these bigger caps getting them positioned and fastened mechanically before the final solder.

The pot is an Audio Note 100K Stereo Volume Potentiometer Log (audio) Taper Solder Lug

bought from here:

https://partsconnexion.com/products/audio-note-100k-stereo-volume-potentiometer-log-audio-taper-solder-lug?_pos=1&_sid=34146efd2&_ss=r

I really like these pots (especially the nice solder lugs), they are very smooth .... nice feel.

You may have to play with the mounting as it is not a drop in. I had to cut off about 3/16 inch of the shaft for it so the volume knob was acceptably flush with the top plate.

« Last Edit: September 09, 2023, 03:10:56 PM by Mucker »



Offline buddythunder

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Reply #4 on: September 09, 2023, 03:10:54 PM
Glad I could help. Just take your time with these bigger caps getting them positioned and fastened mechanically before the final solder.

I certainly will! Cheers for the other info too. I LOVE the chicken head volume knob and the scale around the base, cool build.



Offline Mucker

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Reply #5 on: September 09, 2023, 03:14:18 PM
Thanks! I believe the S3X to be one of the best headphone amps (tube or other) ever designed IMHO. Great with planars and dynamics .... so dam good!

I may straighten out that small cap one of these days by getting the C4S out of the way temporarily. It was there prior to the installation of that cap. But I also may not, it isn't hurting anything how it is, just looks funky.

Edit: My OCD got the best of me .... sigh ...
« Last Edit: September 11, 2023, 05:28:21 AM by Mucker »



Offline buddythunder

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Reply #6 on: September 19, 2023, 01:21:08 PM
Heh, I feel your pain - I've got to fit the CS4 upgrade in here too somehow... Hmmmm, a problem for another day.

Anyway, got the new caps installed and the beast lives! The birth was scary, but the resistances and voltages checked out fine, and it's currently driving my desktop Omegas and sounding lovely in semi-stock form. Thanks so much for your help!



Offline Mucker

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Reply #7 on: September 19, 2023, 07:05:53 PM
Nice Buddy! Looks really great, nice clean build. And great idea with the vertical mount of the small caps! Why didn't I think of that??? The C4S should go in there nicely with that arrangement. Enjoy!!!
« Last Edit: September 19, 2023, 07:18:34 PM by Mucker »



Offline Neuronal

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Reply #8 on: September 20, 2023, 04:40:02 AM
not to totally hijack this thread, but what desktop Omegas do you have, buddythunder? I'm just about to place an order so I'm curious. How do you like them?

Bob D
Rega P2, Cosecant DAC, Reduction, EFP III, Paramount V1.0 + soft start, Omega CAMs + DeepHemp 8s


Offline buddythunder

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Reply #9 on: September 20, 2023, 11:24:32 AM
No bother at all Neuro, I got an so-far unlisted design called the Baby Alnico Monitor wrapped in hickory. It's a slimmer, front-ported version of the Compact Alnico Monitor, which was about perfect for my desktop needs. It took plenty of breaking in and really came alive when I added a 6.5" sub, but those notes aside, I couldn't be happier. They're really sensitive, so a great match with flea-watt amps, and they sound wonderful. Lovely midrange-forward sound with a little top-end fizz, and the soundstaging is incredible as they're full-range single, point-source drivers. They look lovely too, these are the exact pair: https://www.facebook.com/photo?fbid=726196092351203&set=pcb.726196172351195

I Highly reccommend emailing Louis with your needs, as he directed me to these in response to my enquiry, and it's hard to imagine a better fit for me in his regular catalogue. He's also lovely and an absolute pleasure to deal with.