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Thread: Yup, Another One... Kraken 50 Build: Round II

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    Yup, Another One... Kraken 50 Build: Round II

    Now with more snarl and 400% more aggression!


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    don't forget the joker g1's Avatar
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    Very nice work. What/why is the purple?

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    Certified Dotard

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    Quote Originally Posted by g1 View Post
    Very nice work. What/why is the purple?
    Pretty sure it's shrink wrapped diodes

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    Quote Originally Posted by scottosan View Post
    Pretty sure it's shrink wrapped diodes
    Shrink wrapped Krakens.

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    I thought they were Kraken eggs...

    Justin

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    "... If an older Boogie and classic Marshall had a (clearly illegitimate) child and you baked it in an oven set to clown shit crazy." - Chuck H. -
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    "All I ever managed to do with that amp was... kill small rodents within a 50 yard radius of my practice building." - Tone Meister -

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    don't forget the joker g1's Avatar
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    Something shameful that needs to be hidden? Or is there some functionality that the wrap serves?

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    Certified Dotard

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    Quote Originally Posted by g1 View Post
    Something shameful that needs to be hidden? Or is there some functionality that the wrap serves?
    I dunno. They come heat-shrinked already. I just like purple, so I added it. One contains 12v diodes and the other 20v. Different builders who do this same Jose/Cali circuit use different types of clippers. Some use diodes, some zeners, some use other various things. They all do the same basic function.

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    Last edited by FourT6and2; 07-29-2017 at 03:31 AM.

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    I really love having a power transformer with solder tags. Makes wiring it up much cleaner. Wish more companies would do it this way.




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    Oh, dude (not Dude, with a capital D. I'm talking to you, FourT6and2)... Hey, I just got it! 46 & 2, like our chromosomes

    It only took me 3 months to crack the case and actually read your name correctly. Don't I feel like a Tool!
    (see what I did there, dropping the "Tool" reference in just for good measure)

    Anyway, let me steer this back on the tracks. I noticed you gang up your ground terminals, so I thought maybe these may make you life a little easier. I use them to fasten grounds at the filter nodes and love'em. I've been to give you the heads up about these solder terminals if you're interested:

    Click image for larger version. 

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    Newark has these as an example:
    19.05.745 - ETTINGER - SOLDER EYELET, 3X ANGLED, 0.169" | Newark element14
    I got mine from through ebay, shipped from Israel and remember them being inexpensive.


    But, the holy grail of ground terminals still evades me. For the life of me, I don't know where the hell Morgan Jones got his hands on these
    Click image for larger version. 

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    But, I can't find these anywhere, and I'm pretty good at sourcing components. Much better than I am at reading comprehension when it comes to people's names.

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    If I have a 50% chance of guessing the right answer, I guess wrong 80% of the time.

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    lol dude.

    Stacking them up on a bolt is nice because you can rotate them to whatever position works better for lead dress.

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    Stacking lugs on a bolt is questionable, specialy when we talk about signal returns due to unavoidable mechanical contact residual resistance. I made myself multipole lugs whenever I need it from a piece a plumbing copper pipe. Cut it on lengh, plane straighten, and cut out with a scissor how many pole you want, staining at the end. It takes ten minutes to made a couple if you design a good template.
    There are some "tricks" to make a easy soldering multipole lug. I make the section of the base of each lug as small to limit the thermal transfer from the top of the lug to the rest of the piece.

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    Last edited by catalin gramada; 08-05-2017 at 12:24 PM.

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    Quote Originally Posted by catalin gramada View Post
    Stacking lugs on a bolt is questionable, specialy when we talk about signal returns due to unavoidable mechanical contact residual resistance. I made myself multipole lugs whenever I need it from a piece a plumbing copper pipe. Cut it on lengh, plane straighten, and cut out with a scissor how many pole you want, staining at the end. It takes ten minutes to made a couple if you design a good template.
    There are some "tricks" to make a easy soldering multipole lug. I make the section of the base of each lug as small to limit the thermal transfer from the top of the lug to the rest of the piece.
    Catalin, if you stack them, can you clean off one side of the stack and use a heavy 100W soldering iron and put a bead of solder down to the chassis to get rid of the additional resistance? Ive been scouring the web for photos of vintage chassis like the one Im working on, and I don't know if its factory, or later changes, but many of the chassis with lugs bolted to the chassis have had the lug soldered. Is there any reason for not doing that?

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    Nice work. I would recommend moving the center tap of your 2x 350V secondary over to the HT PCB. Specifically the negative terminal of the first filter cap, right after the rectifiers. There are exactly zero good reasons to have the ripple current from the HT supply flow through the chassis. Make the HT supply PCB be completely 'floating', then route ground and HT to the rest of the amp.

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    Quote Originally Posted by mikepukmel View Post
    Catalin, if you stack them, can you clean off one side of the stack and use a heavy 100W soldering iron and put a bead of solder down to the chassis to get rid of the additional resistance? Ive been scouring the web for photos of vintage chassis like the one Im working on, and I don't know if its factory, or later changes, but many of the chassis with lugs bolted to the chassis have had the lug soldered. Is there any reason for not doing that?
    Welding bolts/lugs on steel chassis is perfect. When don.t - I think plated crimp washers is acceptable compromise from a standard perspective

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    To be more specific: You should have all three wires from the 2x 350V secondary be routed together to the HT PCB. Make a three wire twisted bundle, like the heater wiring. This will vastly reduce the magnetic noise flux from the secondary HT transformer wiring.

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    As an aside, FourT6and2, did your Cereatone kit come with all of the discrete parts, or did you source them yourself?

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    Quote Originally Posted by Thoriated Tungsten View Post
    Nice work. I would recommend moving the center tap of your 2x 350V secondary over to the HT PCB. Specifically the negative terminal of the first filter cap, right after the rectifiers. There are exactly zero good reasons to have the ripple current from the HT supply flow through the chassis. Make the HT supply PCB be completely 'floating', then route ground and HT to the rest of the amp.
    Hi T.T., question for you, if you don't mind. If the CT's are routed to the neg terminal on the first filter cap, there is still a wire running from that point to chassis ground, on many amps. What would you do with that ground wire? (Sorry, very new to all this here)

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    Somebody write a long post, I can't remember where. I don't know if they are a guru or not. They said, for the Fender style chassis anyway (and I know this is not that style), there were two main ground points. One near the power transformer, that had the HV stuff grounded directly to the chassis. Another on that brass plate that the pots and input jacks mount to, that the low signal wiring (input jacks, preamp tubes) get grounded to. They said that the eddy currents were separated enough, first since there are two different pieces of metal (the steel chassis, and the brass plate), and 2 they were grouped together in separate areas of the amp, that the amp would still be OK for hum and noise due to ground loops. Admittedly, I don't have the physics chops at hand to be able to understand this argument fully. Was it a baloney argument?

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    Quote Originally Posted by Thoriated Tungsten View Post
    Nice work. I would recommend moving the center tap of your 2x 350V secondary over to the HT PCB. Specifically the negative terminal of the first filter cap, right after the rectifiers. There are exactly zero good reasons to have the ripple current from the HT supply flow through the chassis. Make the HT supply PCB be completely 'floating', then route ground and HT to the rest of the amp.
    HT PCB? The PCB in this amp is not HT. IT's DC rectification for V1/V2 filaments. Maybe I'm misunderstanding...

    You're saying to route PT secondary CT like this?


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    Quote Originally Posted by mikepukmel View Post
    As an aside, FourT6and2, did your Cereatone kit come with all of the discrete parts, or did you source them yourself?
    I ordered the chassis, turret board, and a few of the miscellaneous parts like jacks and tube sockets and switches. Everything else, I sourced. You can buy a full kit from Ceriatone. But I'm not building the stock Chupa/Yeti. These are slightly different.

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    Run CT wire dirctly to minus pole of first filter cap. then also another short wire from those terminal to the chassis. Those link to the ground is just to provide a ground reference . Do not run high ripple current through it. The power supply return current should run just from first cap to CT but not through chassis. If you use the chassis as signal return you will not modulate the signal with high noisy ripple, meant 100/120 cps hum

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    Last edited by catalin gramada; 08-05-2017 at 03:29 PM.

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    Quote Originally Posted by catalin gramada View Post
    Run CT wire dirctly to minus pole of first filter cap. then also another short wire from those terminal to the chassis. Those link to the ground is just to provide a ground reference . Do not run high ripple current through it. The power supply return current should run just from first cap to CT but not through chassis
    Sorry, I'm confused.

    "Run CT directly to negative terminal on first cap": OK

    "Then another short wire from those terminals (PLURAL?) to the chassis": What terminals? There's only one... We are talking about the negative terminal on the first cap. What other terminals are you talking about?

    "Do not run high ripple current through it." What? Through what?

    "Power supply return current should run just from first cap to CT but not through chassis": But you just said, "then another wire from those terminals to the chassis."

    Like this???? This looks problematic to me. How is the filter cap supposed to bleed to ground when you turn the amp off?


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    Quote Originally Posted by FourT6and2 View Post
    I ordered the chassis, turret board, and a few of the miscellaneous parts like jacks and tube sockets and switches. Everything else, I sourced. You can buy a full kit from Ceriatone. But I'm not building the stock Chupa/Yeti. These are slightly different.
    Thanks!

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    Quote Originally Posted by FourT6and2 View Post
    HT PCB? The PCB in this amp is not HT. IT's DC rectification for V1/V2 filaments. Maybe I'm misunderstanding...

    You're saying to route PT secondary CT like this?

    Yeah, I think this is what Catalin meant. CT wires to cap neg, then short wire cap neg to chassis.
    Catalin: the 0 (HV CT) would also go to the - cap as well, right?

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    Quote Originally Posted by mikepukmel View Post
    Yeah, I think this is what Catalin meant. CT wires to cap neg, then short wire cap neg to chassis.
    Catalin: the 0 (HV CT) would also go to the - cap as well, right?
    Why is this any better than CT directly to ground though? It looks like you get the same result either way. The CT is still going to ground. The cap negative terminal is still going to ground. I'm a bit confused. Aiken has this to say on his website:

    "If you look at the schematic for an amplifier, you will see the capacitors are arranged in a line or series configuration, or sometimes in a parallel or "branch" configuration. Usually the series connection is used, because it provides better filtering as you go down the line. The ground connections of these caps are the star points in multiple-star systems. The first cap ground is the first star point (or the only star in a single-star ground system). It should be physically located closest to the power transformer center-tap. The power transformer center-tap wire should be soldered directly to the ground lug of this cap, and a very short, heavy wire should run from there to the chassis ground connection (if there is one). Do not connect the power transformer center-tap to the chassis and the first cap ground to the chassis at a different spot; this will cause heavy ground current flow in the chassis."

    So Aiken says it should be like this:


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    Quote Originally Posted by FourT6and2 View Post
    HT PCB? The PCB in this amp is not HT. IT's DC rectification for V1/V2 filaments. Maybe I'm misunderstanding...

    You're saying to route PT secondary CT like this?

    Yes, exactly like that. Have the two 350V phases follow the first red line from the transformer to near the first filter cap (the one to the right in your photo) for as long as possible. Hopefully the 'right side' cap is also the one you intend to use as the first filter cap after the rectifier.

    Yes, I was confused by your low voltage PCB, as I thought the pair of twisted purple wires going to it were connected to the 350V phases. I have now spotted the HT diodes on the turret board.

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    Click image for larger version. 

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    Do you feel a difference ?

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    Quote Originally Posted by FourT6and2 View Post
    Why is this any better than CT directly to ground though? It looks like you get the same result either way. The CT is still going to ground. The cap negative terminal is still going to ground. I'm a bit confused. Aiken has this to say on his website:

    "If you look at the schematic for an amplifier, you will see the capacitors are arranged in a line or series configuration, or sometimes in a parallel or "branch" configuration. Usually the series connection is used, because it provides better filtering as you go down the line. The ground connections of these caps are the star points in multiple-star systems. The first cap ground is the first star point (or the only star in a single-star ground system). It should be physically located closest to the power transformer center-tap. The power transformer center-tap wire should be soldered directly to the ground lug of this cap, and a very short, heavy wire should run from there to the chassis ground connection (if there is one). Do not connect the power transformer center-tap to the chassis and the first cap ground to the chassis at a different spot; this will cause heavy ground current flow in the chassis."

    So Aiken says it should be like this:

    Wish I knew!!

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    Quote Originally Posted by Thoriated Tungsten View Post
    Yes, exactly like that. Have the two 350V phases follow the first red line from the transformer to near the first filter cap (the one to the right in your photo) for as long as possible. Hopefully the 'right side' cap is also the one you intend to use as the first filter cap after the rectifier.

    Yes, I was confused by your low voltage PCB, as I thought the pair of twisted purple wires going to it were connected to the 350V phases. I have now spotted the HT diodes on the turret board.
    So which of these two is better?




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    Quote Originally Posted by mikepukmel View Post
    Somebody write a long post, I can't remember where. I don't know if they are a guru or not. They said, for the Fender style chassis anyway (and I know this is not that style), there were two main ground points. One near the power transformer, that had the HV stuff grounded directly to the chassis. Another on that brass plate that the pots and input jacks mount to, that the low signal wiring (input jacks, preamp tubes) get grounded to. They said that the eddy currents were separated enough, first since there are two different pieces of metal (the steel chassis, and the brass plate), and 2 they were grouped together in separate areas of the amp, that the amp would still be OK for hum and noise due to ground loops. Admittedly, I don't have the physics chops at hand to be able to understand this argument fully. Was it a baloney argument?
    No, more than one ground point can certainly work with careful testing and layout. I would speculate that Fender had the resources to get it done properly, with as low a parts count as possible.

    The reason for having more than one ground point could be due to wanting the input connectors grounded directly. In the fifties it was quite common in the US that small towns had their own AM radio station transmitting in the range of 500-1700 kHz, as FM stations were not nearly as widely used as they were in Europe at the time. If a strong, local AM radio station were present in the neighborhood, then it could easily be picked up by the external wiring to the guitar etc. Having the input connectors grounded directly to the chassis would be quite beneficial to help reduce interference problems, despite the potential for problems with ground loops. If the inputs were floating, you'd have to connect the cable shields to chassis ground at the input via a bunch of low-ish value capacitors. The caps should have a low impedance for RF yet a high impedance for audio and mains hum. This would be more expensive and less reliable due to the higher component count. So using the resources to get the grounding right would be beneficial with no downsides.

    I would further speculate that the potential for AM radio interference was also the reason why Fender et al. used those very high value grid stopper resistors, noisy as they are, though that is probably a subject for a different thread. (This has probably been discussed at length before here on M-E-F.)

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    Quote Originally Posted by FourT6and2 View Post
    So which of these two is better?
    Top.

    Not-very-ninja-edit: Strictly speaking the answer would depend on how you connect the rest of the amp to the pair of filter caps.

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    Last edited by Thoriated Tungsten; 08-05-2017 at 04:23 PM.

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    Quote Originally Posted by Thoriated Tungsten View Post
    Top.

    Not-very-ninja-edit: Strictly speaking the answer would depend on how you connect the rest of the amp to the pair of filter caps.
    I'm basically following the Ceriatone layout, which for the most part stays true to how Marshall did it in a 2204: http://www.ceriatone.com/ceriatone/w...-June-2015.jpg

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    Last edited by FourT6and2; 08-05-2017 at 04:45 PM.

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    I would definitely lift the grey '0' wire on the 2x 350V secondary from the star ground and have it follow A1 & A2 over to the bottom of the 220k bleeder resistor on the top filter cap. There is zero benefit to having the HT center tap going to the star ground. Right now the full ripple current from the transformer is flowing through a wire carrying signal current (the green wire from the bottom cap to the star ground).

    Note that the low voltage supply for the DC heaters does things correctly by isolating the ripple currents from the chassis ground.

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