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Just another K-12 Build
http://diyaudioprojects.com/Forum/viewtopic.php?f=9&t=3226
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Author:  the4ork [ 21 May 2011, 00:38 ]
Post subject:  Just another K-12 Build

So, indeed... I am new to THIS forum, so I'm treading light water in my world at an attempt at a thread that will try to be interesting and incorporate a small bit of my OTHER hobby.

Most certainly a s-5 electronics K-12G tube amp kit build, somewhere over the rainbow, in California (dreadful to say the least). I probably won't be able to touch this for a few more days (?) as I'm still in the process of buying supplies and deciding on what wood I want to use for a frame, and to not style my hair to 250v DC (at a funeral, who care's what your hair looks like!). Along with this, I had a different project in my vehicle that took some priority (speaker related, amongst other things) and I ended up getting a bit carried away, haha.
Attachment:
Tube1.JPG

In any case... S-5 delivered, and delivered quickly! Double boxed?!?.... indeed. Can't wait to start building this thing :smoking:
-AJ

p.S. Not digging the potentiometer... any recommendations for a better (100kohm) ohne? *bada pish*

Author:  JimOfOakCreek [ 21 May 2011, 11:38 ]
Post subject:  Re: Just another K-12 Build

I built the K12G with numerous mods including, an ALPS Blue Velvet volume pot upgrade. It's a worthwhile mod with better balance and quieter operation. I also recommend removing the DC blocking caps, upgrading the coupling caps, installing snubber caps and UF diodes. All of those mods are documented on this Web site with even more links to other sites.

I also found some EIC / Mullard 10GV8 tubes.

Bottom line is I love my K12G.

Image

Author:  the4ork [ 22 May 2011, 01:20 ]
Post subject:  Re: Just another K-12 Build

Thanks for the heads-up. Did some looking around and it seems as if the the ALPS pot isn't too expensive of an upgrade- looking at that or some kind of stepped pot. But for now, I'm focusing on getting the darn thing together, haha. I'm not making any modifications until I get to listen to the sock product, so I can enjoy/gauge the upgrades to follow. One thing that I like about the kit so far- easy to assemble. Way easy... I've made an analogue sound generator before... with a billion parts. Let's just say... never again. Digging the simplicity- the instructions are quite useful, but common sense can seriously guide anyone towards the finish line.

Note that I'm talking about this as if no one has never heard of it before... this is just so that other "knobs" to tube amps can have a beginners perspective :)

I actually had to spend 2 hours cleaning out the garage JUST to be able to have a working area again because things were just all over the place/dusty/dirty/etc. At least I have my little station setup again (finally). Took some more pictures at the same time...

Here's a fun question- am I the only one who uses liquid flux in addition to rosin core?Whenever I don't use it, It just bothers me.... and I'm painfully anal when it comes to a clean/perfect board (or at least I pretend to be 8-) ).
Attachment:
Tube 2.JPG

Attachment:
Tube 3.JPG

Cheers

-AJ :smoking:

Author:  Gio [ 22 May 2011, 10:13 ]
Post subject:  Re: Just another K-12 Build

Looking good AJ.

Before you mount the caps, give some thought to the enclosure you plan to use. If you want the tubes to poke out of an enclosure you will want to mount the caps from the underside. If you do this, be sure to observe the polarity of the caps.

What are you using to clean the PCB?

Cheers

Author:  Les [ 23 May 2011, 09:09 ]
Post subject:  Re: Just another K-12 Build

VERY nice solder work AJ! :thumbsup:
the4ork wrote:
am I the only one who uses liquid flux in addition to rosin core?

Nope. A lot of people do that, I would imagine. I do it when I have some larger pads & leads and when I'm tinning wire leads. I don't do it so much on the small pads. It just seems to make the solder flow more quickly on the larger pads and I like to keep the exposure time to a minimum, so if the solder flows faster - all the better.

Gio, 99% pure IPA and an old tooth brush goes along way to a good clean PCB.

Author:  Gio [ 23 May 2011, 10:03 ]
Post subject:  Re: Just another K-12 Build

Les wrote:
99% pure IPA and an old tooth brush goes along way to a good clean PCB.

That is what I use, but the finish turns out to be dull rather than glossy like in AJ's photo.
Cheers

Author:  Suncalc [ 23 May 2011, 10:44 ]
Post subject:  Re: Just another K-12 Build

IPA?

India Pale Ale????? Do you really use beer to clean your circuit boards?

Author:  Les [ 23 May 2011, 12:31 ]
Post subject:  Re: Just another K-12 Build

Suncalc wrote:
IPA?

India Pale Ale????? Do you really use beer to clean your circuit boards?

:D IsoPropyl Alcohol. The same stuff found in rubbing alcohol, but with out the extra water and other stuff.
Gio wrote:
That is what I use, but the finish turns out to be dull rather than glossy like in AJ's photo.

Are you talking about the solder or the board? The board probably has a hard lacquer finish which is shiny by nature. The good ol' fashion lead/tin solder should have a shiny appearance or you have a cold joint, silver solder joints always have a dull lustre - unless you want to take the time to polish them ;-).

Some people I know use acetone to clean the excess rosin, but acetone can damage the lacquer finish. IPA won't damage a good lacquer job. If you can't get 99%, 90% will work, just slower to evaporate. I would not use anything less than say 80% as then you're getting a considerable amount of water introduced at that point, which doesn't evaporate as readily and doesn't dissolve the rosin as effectively.

Author:  the4ork [ 23 May 2011, 18:57 ]
Post subject:  Re: Just another K-12 Build

Suncalc wrote:
IPA?

India Pale Ale????? Do you really use beer to clean your circuit boards?

I was thinking the same thing, hahaha :o
I use IPA... but the consumable kind, hehe.

@Gio: I use a rather unorthodox method of cleaning my boards up, and actually a bit of a secret, but it works well so might as well stick to it and this is an open forum, so where advice is received, some must be given. I use a specific brand of brake parts cleaner to blast the board, then wipe with paper towels. removes any residue and leaves the board squeaky clean. I've done the IPS (90%) technique, and I swear, the leftover flux just does not want to alleviate itself from the board/everything just turns into smudges and wipes.
Along with this, exactly the reason why I'm doing everything else FIRST and leaving the caps last since I'm still contemplating which way I'll be mounting the board up. Chances are, it will be upside down (99% sure actually), and i'll be remote-mounting the in/out/pot on the chassis itself instead of on the board.

I spent a mere $15 today at HSC and walked way with a dozen caps and 6 inductors... still need to finish building filters for my bookshelf speakers and fix a power supply for my friends wine cooler :(

Any recommendations on what wire to use? I was guessing some 22 gauge stranded wire with a ground wire, wrapped? (RBG - Power, Negative, Chassis Ground).

-AJ

Author:  Gio [ 25 May 2011, 12:13 ]
Post subject:  Re: Just another K-12 Build

Hi AJ, I assume you mean wire for power cord and that will be fine as the current draw from the K-12G is rather small. 18 ga is good too.

FWIW - here is an American Wire Gauge (AWG) Size Table
Cheers

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