Amp Build: Ceriatone Kraken 50

[CrazyNutz]

FWIW, my 50w has ~430vdc B+ and uses 1M from the screen node and 100k to ground. My mini-Major taps from the ~490vdc PI node (cuz there is no screen node) and uses 1M with 82k to ground. Both are between 35-40v.

Yeah, that sounds about right. But it depends on the cathode voltages on V1 and V2 as well. You need to elevate the heaters such that their negative swing is above the highest cathode voltage in the preamp. Without knowing that it's a bit futile. It's typically around 35-40v. But I'd like to be sure. If you're off by 1-3v too low, then you haven't actually elevated the heaters all the way.

Would either of you guys have a layout or schematic for the elevated heaters setup? Or point me to one, I had one years ago but it's long gone. THX! Interested to hear what you think of those PRP resistors, I see you went with your fave's the Mallory 150's, might as well start with something you know you like...

If you have a classic marshall style SLP circuit this is my favorite way to elevate heaters.


This takes advatage of the screen filter node, using the bleeder resisters as a first stage voltage divider, then one more voltage divider (470k/82k) and a smoothing cap. The "0V Heaters" is where you tie it to your heaters center tap, or a faux center tap if you PT does not have a real center tap. (of course make sure you lift the ground on your center tap). This gets you about a ~60vdc elevation depending on your B+ voltage. you can up the value of the 82k resister to adjust if your too low.

 

[Deanmachine]

Amazing work here !

 

[fusedbrain]

FWIW, my 50w has ~430vdc B+ and uses 1M from the screen node and 100k to ground. My mini-Major taps from the ~490vdc PI node (cuz there is no screen node) and uses 1M with 82k to ground. Both are between 35-40v.

Yeah, that sounds about right. But it depends on the cathode voltages on V1 and V2 as well. You need to elevate the heaters such that their negative swing is above the highest cathode voltage in the preamp. Without knowing that it's a bit futile. It's typically around 35-40v. But I'd like to be sure. If you're off by 1-3v too low, then you haven't actually elevated the heaters all the way.

Would either of you guys have a layout or schematic for the elevated heaters setup? Or point me to one, I had one years ago but it's long gone. THX! Interested to hear what you think of those PRP resistors, I see you went with your fave's the Mallory 150's, might as well start with something you know you like...

If you have a classic marshall style SLP circuit this is my favorite way to elevate heaters.


This takes advatage of the screen filter node, using the bleeder resisters as a first stage voltage divider, then one more voltage divider (470k/82k) and a smoothing cap. The "0V Heaters" is where you tie it to your heaters center tap, or a faux center tap if you PT does not have a real center tap. (of course make sure you lift the ground on your center tap). This gets you about a ~60vdc elevation depending on your B+ voltage. you can up the value of the 82k resister to adjust if your too low.

This is awesome

Thanks for posting the schematic!!

 

[SpiderWars]

That's a great way to do it Crazynutz. FWIW, in the Friedman JCM800 I had both screen cap cans were 100uFx100uF but he only used one section of each can for the screens. The can that has it's ground lug actually connected to ground is now a 'free' node, you just need to add the voltage divider. No extra caps required.

 

[FourT6and2]

I must be crazy.

I've been trying to source some Beyschlag MBE0414 resistors. Nobody in the US has them and nobody outside the US will ship them here for some reason. The EU version of Mouser (Distrelec) has them. But they hate Americans apparently lol. I spent the last few days trying to source some with no luck. Called Vishay (they bought Beyschlag), called Mouser, Digi-Key, AVNET, Arrow, and a bunch of others. The only way to order these things is to buy in bulk at like 2,000 pieces each. No way. That's serious monies.

Finally found some wholesale distributor in Japan of all places. Had to buy in bulk. But at much much much lower quantities. Enough to build a few amps with some left over. So... looks like I'm the new US "distributor" of these things if anybody wants some lol

 

[rstites]

I've been trying to source some Beyschlag MBE0414 resistors.

What's special about these resistors? Just consistency appearance-wise?

Nice looking work. Your soldering looks professional. Hell, it's prettier than mine and I'm an electronics professor.

 

[SavageRiffer]

Dude I'm excited to hear that damned thing. It looks awesome. I don't fully understand the mods you made to the original circuit design, but I can't wait to hear some audio. Makes me want a Ceriatone real bad.

 

[FourT6and2]

I've been trying to source some Beyschlag MBE0414 resistors.

What's special about these resistors? Just consistency appearance-wise?

Nice looking work. Your soldering looks professional. Hell, it's prettier than mine and I'm an electronics professor.

Well they look pretty as fuck.

In all seriousness, they're supposed to be good, sound-wise, in a guitar amp. None of this audiophile crap. They're metal film, but according to some peeps in the know, most MF resistors are suffer from parasitic inductance, leading to their brighter, "sterile" sound in some cases, compared to carbon film. The Beyschlags have low(er) series inductivity. So the theory is they are more "musical" but also very quite in terms of thermal noise (which is more important in a high-gain circuit). More common MF resistors, like the RN65D, are very quite. But they are also kinda crappy sounding IMHO. They're also only rated for 300v or so. I like the Vishay CCF60 because they are small, affordable, easily obtained, and rated for 1W/500v. I use those in the power and bias sections. I've never used these red PRPs before. So I'm giving them a try. But the Beyschlags come highly recommended and I really want to try them. Because hey... why not.

Will any of this make a real difference? I don't know. I'm hoping to find out.

I've been told they might pair well with the caps I'm using (MPW), which are brighter and more aggressive. The Beyschlags, while being low-noise because they're MF, might also help take a little bit of the top-end harhness away from the metalized polypropylene caps. So... low noise + high voltage handling + 1% tolerance + subdued top-end to balance out with the brighter caps. Maybe. We'll see when I build a second amp.

 

[FourT6and2]

Dude I'm excited to hear that damned thing. It looks awesome. I don't fully understand the mods you made to the original circuit design, but I can't wait to hear some audio. Makes me want a Ceriatone real bad.

Yeah the mods I'm implementing aren't novel. I'm just re-voicing the circuit to my personal preferences with the help and guidance of many others smarter than I. Hopefully it sounds good!

 

[FourT6and2]

A small sample of those Beyschlag resistors came in today. They are some fairly high-quality parts. A bit smaller than the PRPs, almost the same size as the CCF60s. So they will fit in tighter spots on the board. Consistency is good. They feel pretty hefty as well. Like they're weighty lol. I'm going to use these in a second build once I get this one voiced how I like it.

 

[scottosan]

I got started on my board tonight. Not quite as tidy as yours, but you have inspired me to take my time with this one. It's a BE based build with a SS clean channel and all of the goodies. Still waiting on iron.

 

[FourT6and2]

Sexy. Looking forward to seeing how it turns out. What are those box caps, Wima something or other?

You make the turret board?

 

[scottosan]

Sexy. Looking forward to seeing how it turns out. What are those box caps, Wima something or other?

You make the turret board?

Yes to both

 

[IndyWS6]

I don't know much about electronics, so some of the discussion is above my head, but threads like these make me want to build an amp. I'm reasonably smart and can follow directions, so a kit with detailed instructions and forum support would be a requirement. I'd love to do a SLO clone, but there's no way I could live up to FourT6and2's work, which would make my OCD flare

 

[SpiderWars]

That looks impressive scottosan. Is it two DPDT 5v relays for switching? I see two sockets.

 

[CrazyNutz]

I got started on my board tonight. Not quite as tidy as yours, but you have inspired me to take my time with this one. It's a BE based build with a SS clean channel and all of the goodies. Still waiting on iron.

Do you like the WIMA's, have you tried them before?

Man I've tried to like them but they sound so dull and hollow to me. I've tried both polypropylene, and polyester versions.

 

[scottosan]

That looks impressive scottosan. Is it two DPDT 5v relays for switching? I see two sockets.

thanks, yes they are for channel switching

 

[scottosan]

I got started on my board tonight. Not quite as tidy as yours, but you have inspired me to take my time with this one. It's a BE based build with a SS clean channel and all of the goodies. Still waiting on iron.

Do you like the WIMA's, have you tried them before?

Man I've tried to like them but they sound so dull and hollow to me. I've tried both polypropylene, and polyester versions.

I have and do like them . I find them more neutral. I have tried sozos, and while alot of people like them because they are clear, I feel they lack body

 

[FourT6and2]

Which Wimas are they?

 

[paulyc]

I don't know much about electronics, so some of the discussion is above my head, but threads like these make me want to build an amp. I'm reasonably smart and can follow directions, so a kit with detailed instructions and forum support would be a requirement. I'd love to do a SLO clone, but there's no way I could live up to FourT6and2's work, which would make my OCD flare

Ceriatone makes kits...or just by a Chupacabra or Yeti and tweak it, that's what I might do...reasonably inexpensive and pretty damn fine amps.