Amp Build: Ceriatone Kraken 50

Marshall Amp Discussion

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lovetone
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Re: Amp Build: Ceriatone Kraken 50

Post by lovetone » Thu Jul 13, 2017 7:43 am

The 1M is to give the grid ground reference either side of the 27K really makes no difference but in this case because of the 0.1uf capacitor it needs to be connected directly to the gird.

Nice build, I think this has been asked what make are the red resistors?

FourT6and2
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Re: Amp Build: Ceriatone Kraken 50

Post by FourT6and2 » Thu Jul 13, 2017 3:18 pm

lovetone wrote:
Thu Jul 13, 2017 7:43 am
The 1M is to give the grid ground reference either side of the 27K really makes no difference but in this case because of the 0.1uf capacitor it needs to be connected directly to the gird.

Nice build, I think this has been asked what make are the red resistors?
Thanks for the info.

The resistors are PRP. I'll be building another one of these as well, with another different voicing. And I'll use Beyschlag MBE 0414 for that.


So if you had a choice for high-gain amp design, would you stick with what Ceriatone has done, or go with something more like this (a friend suggested it a few years ago with regard to the standard 68K input grid stoppers you see in many Marshall style builds (like this one):
"You can also try this as a mod later:

C10 = 22nF/630V
R25 = 1M
C17 = 100pF ceramic (against RF)
R16 = 1K

The result is way less hiss and still a good RF protection.
Also C10 can save your life if you have a faulty ground in the amp (then all B+ goes to the guitar if there isn't a capacitor between you and the amp).

C10 can be also after the 1M (soldering the 1M directly to the jack is common, so just place the 22nF directly to the jack's hot and then run the cable to the grid resistor).

This is the way today's amps are built."

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V2
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Location: Vancouver Canada

Re: Amp Build: Ceriatone Kraken 50

Post by V2 » Thu Jul 13, 2017 4:12 pm

FourT6and2 wrote:
Thu Jul 13, 2017 3:18 pm
So if you had a choice for high-gain amp design, would you stick with what Ceriatone has done, or go with something more like this (a friend suggested it a few years ago with regard to the standard 68K input grid stoppers you see in many Marshall style builds (like this one):
"You can also try this as a mod later:

C10 = 22nF/630V
R25 = 1M
C17 = 100pF ceramic (against RF)
R16 = 1K

The result is way less hiss and still a good RF protection.
Also C10 can save your life if you have a faulty ground in the amp (then all B+ goes to the guitar if there isn't a capacitor between you and the amp).

C10 can be also after the 1M (soldering the 1M directly to the jack is common, so just place the 22nF directly to the jack's hot and then run the cable to the grid resistor).

This is the way today's amps are built."

Image
C17 is added in parallel with the tube's own input capacitance. Parallel capacitances add up, so this is a way to increase the capacitance between grid and cathode/ground. That way, you can reduce the value of the grid stopper and still maintain the cutoff of the low-pass filter formed by the grid stopper and the increased input capacitance. C17 should be mounted close to the tube's grid, preferably on pin 2/7 itself. Reducing R16 from historically common values (68k) to 10k will reduce hiss.

FourT6and2
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Re: Amp Build: Ceriatone Kraken 50

Post by FourT6and2 » Thu Jul 13, 2017 4:32 pm

V2 wrote:
Thu Jul 13, 2017 4:12 pm
FourT6and2 wrote:
Thu Jul 13, 2017 3:18 pm
So if you had a choice for high-gain amp design, would you stick with what Ceriatone has done, or go with something more like this (a friend suggested it a few years ago with regard to the standard 68K input grid stoppers you see in many Marshall style builds (like this one):
"You can also try this as a mod later:

C10 = 22nF/630V
R25 = 1M
C17 = 100pF ceramic (against RF)
R16 = 1K

The result is way less hiss and still a good RF protection.
Also C10 can save your life if you have a faulty ground in the amp (then all B+ goes to the guitar if there isn't a capacitor between you and the amp).

C10 can be also after the 1M (soldering the 1M directly to the jack is common, so just place the 22nF directly to the jack's hot and then run the cable to the grid resistor).

This is the way today's amps are built."

Image
C17 is added in parallel with the tube's own input capacitance. Parallel capacitances add up, so this is a way to increase the capacitance between grid and cathode/ground. That way, you can reduce the value of the grid stopper and still maintain the cutoff of the low-pass filter formed by the grid stopper and the increased input capacitance. C17 should be mounted close to the tube's grid, preferably on pin 2/7 itself. Reducing R16 from historically common values (68k) to 10k will reduce hiss.
Putting C17 on the tube pin itself would change its location in the circuit, no? It should be bypassing R25, between C10 and R16, not from between R16 and the grid to ground?

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V2
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Re: Amp Build: Ceriatone Kraken 50

Post by V2 » Thu Jul 13, 2017 5:15 pm

In both positions, C17 ties grid to ground. As drawn in the circuit above, you'd think its purpose was to bypass the grid leak resistor, but that is not the case. Its purpose is to add to the input capacitance of the tube. And the best place to do that is right at the tube. R16 should come before C17, although ideally both are tied to pin 2/7.

FourT6and2
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Re: Amp Build: Ceriatone Kraken 50

Post by FourT6and2 » Thu Jul 13, 2017 6:55 pm

V2 wrote:
Thu Jul 13, 2017 5:15 pm
In both positions, C17 ties grid to ground. As drawn in the circuit above, you'd think its purpose was to bypass the grid leak resistor, but that is not the case. Its purpose is to add to the input capacitance of the tube. And the best place to do that is right at the tube. R16 should come before C17, although ideally both are tied to pin 2/7.
Thank you

Cameron
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Re: Amp Build: Ceriatone Kraken 50

Post by Cameron » Fri Jul 14, 2017 2:32 am

FourT6and2 wrote:
Thu Jul 13, 2017 7:20 am
I've asked on some other forums. But maybe y'all might be able to help?

This is how Ceriatone wires the input. Seems a bit strange to me. Can anybody shed some light on what's going on here, compared to say... having the 1M-to-ground Grid Leak BEFORE the 27K Grid Stopper, instead of AFTER? I've read this causes some small signal attenuation. Maybe not enough to really matter. But still, seems like a weird design choice...

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It's that way to stop the scratchie pot on the guitar...or when you go too low of a voltage on that first preamp tube ...it will build up a small voltage on the grid ..this is because of the 330k or higher plate resistor... also the guys that use VVR circuits have to do this also for the input and the input to the second gain stage after the gain pot. You also need a ground reference after a cap ....so you need the 1m on the grid of the tube....if you put it before it will do nothing.....without the cap ...you can do it both ways...it just depends on which way it sounds better to you .....but if it's after ....it will make the grid stopper resistor less affective in its RF noise reduction....so ....some people put a small 47pf cap over the 1m at the grid to get some of the noise reduction back....this has to do with the capacitance that the grid stopper adds in conjunction with the tube ....you can read Merlin's web site for more about all that...some great explanation on it about what and why.

For me ...I hate the way crapatone does that ...I don't like the way it sounds or makes the amp feel. So I use higher voltage transformer so there is no need for that nonsense. But if you go for a lower voltage transformer ...then you have to do it. This circuit sounds better with higher voltages anyway. But these are things you need to try ..to be able to see what works for you....and to learn about this stuff.....so try both ways and see what you like....

FourT6and2
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Re: Amp Build: Ceriatone Kraken 50

Post by FourT6and2 » Fri Jul 14, 2017 3:18 am

Cameron wrote:
Fri Jul 14, 2017 2:32 am
FourT6and2 wrote:
Thu Jul 13, 2017 7:20 am
I've asked on some other forums. But maybe y'all might be able to help?

This is how Ceriatone wires the input. Seems a bit strange to me. Can anybody shed some light on what's going on here, compared to say... having the 1M-to-ground Grid Leak BEFORE the 27K Grid Stopper, instead of AFTER? I've read this causes some small signal attenuation. Maybe not enough to really matter. But still, seems like a weird design choice...

Image

Image
It's that way to stop the scratchie pot on the guitar...or when you go too low of a voltage on that first preamp tube ...it will build up a small voltage on the grid ..this is because of the 330k or higher plate resistor... also the guys that use VVR circuits have to do this also for the input and the input to the second gain stage after the gain pot. You also need a ground reference after a cap ....so you need the 1m on the grid of the tube....if you put it before it will do nothing.....without the cap ...you can do it both ways...it just depends on which way it sounds better to you .....but if it's after ....it will make the grid stopper resistor less affective in its RF noise reduction....so ....some people put a small 47pf cap over the 1m at the grid to get some of the noise reduction back....this has to do with the capacitance that the grid stopper adds in conjunction with the tube ....you can read Merlin's web site for more about all that...some great explanation on it about what and why.

For me ...I hate the way crapatone does that ...I don't like the way it sounds or makes the amp feel. So I use higher voltage transformer so there is no need for that nonsense. But if you go for a lower voltage transformer ...then you have to do it. This circuit sounds better with higher voltages anyway. But these are things you need to try ..to be able to see what works for you....and to learn about this stuff.....so try both ways and see what you like....
Thanks for the help! I was really trying to understand the motivation behind Ceriatone's choice of doing it this way. I mean, it can't be just a random thing. Some people were saying oh it doesn't matter either way. But I figured there was intent there. And now I know. Thank you, again.

Yeah, I'm using a higher-voltage power transformer for this build. The stock Chupacabra I have (50 watt) has 325-0-325 secondaries and I measure about 337v in reality. B+ is 448v. The transformer I'm using is 350-0-350 and B+ will probably be closer to 475v-480v. Stock amp's V1a plate reads 97v with the 470K plate resistor. In my build, I'm lowering it to 390K. But I'll try a few lower values as well (330K, etc.). I'm also going to play with raising the 820R cathode bypass resistors to 2K7 on the first two stages. Is there a certain voltage I Might want to aim for on V1a plate? I do like the sound of my Chupacabra as is. I'm just building my own to play around with the circuit a bit. Maybe a bit tighter, a little fuller, a little darker, more modern sounding rather than brown. But I really like the aggressive snarl it has.

FourT6and2
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Re: Amp Build: Ceriatone Kraken 50

Post by FourT6and2 » Sat Jul 15, 2017 1:58 am

It's time for everybody's favorite part of building an amp—heaters!

JK, it's the worst.

Decided to run DC on V1 and V2; regular AC on V3-V6.

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V2
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Re: Amp Build: Ceriatone Kraken 50

Post by V2 » Sat Jul 15, 2017 3:28 am

Cameron wrote:
Fri Jul 14, 2017 2:32 am

It's that way to stop the scratchie pot on the guitar...or when you go too low of a voltage on that first preamp tube ...it will build up a small voltage on the grid ..this is because of the 330k or higher plate resistor... also the guys that use VVR circuits have to do this also for the input and the input to the second gain stage after the gain pot. You also need a ground reference after a cap ....so you need the 1m on the grid of the tube....if you put it before it will do nothing.....without the cap ...you can do it both ways...it just depends on which way it sounds better to you .....but if it's after ....it will make the grid stopper resistor less affective in its RF noise reduction....so ....some people put a small 47pf cap over the 1m at the grid to get some of the noise reduction back....this has to do with the capacitance that the grid stopper adds in conjunction with the tube ....you can read Merlin's web site for more about all that...some great explanation on it about what and why.

For me ...I hate the way crapatone does that ...I don't like the way it sounds or makes the amp feel. So I use higher voltage transformer so there is no need for that nonsense. But if you go for a lower voltage transformer ...then you have to do it. This circuit sounds better with higher voltages anyway. But these are things you need to try ..to be able to see what works for you....and to learn about this stuff.....so try both ways and see what you like....
Hi Mark - Can you elaborate on how this arrangement helps when voltage is low on the first preamp tube?

-- John

FourT6and2
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Re: Amp Build: Ceriatone Kraken 50

Post by FourT6and2 » Sun Jul 16, 2017 11:56 pm

More progress today. Finished up the power section and did the power tube sockets, bias test points, impedance switch, and a few other things here and there.

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FourT6and2
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Re: Amp Build: Ceriatone Kraken 50

Post by FourT6and2 » Tue Jul 18, 2017 1:19 am

A bit more today. Having routed a bunch of stuff now, I'm making some notes about how to do it better the next time around. And by better, I mean more OCD lol.

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FourT6and2
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Re: Amp Build: Ceriatone Kraken 50

Post by FourT6and2 » Wed Jul 19, 2017 2:49 am

Preamp tubes all done. In the home stretch now.

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joeboo88
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Re: Amp Build: Ceriatone Kraken 50

Post by joeboo88 » Wed Jul 19, 2017 3:56 am

FourT6and2:
Wow that's nice..... you missed a solder joint where the little tan colored mica cap is from your last picture. keep going!

FourT6and2
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Re: Amp Build: Ceriatone Kraken 50

Post by FourT6and2 » Wed Jul 19, 2017 4:17 am

joeboo88 wrote:
Wed Jul 19, 2017 3:56 am
FourT6and2:
Wow that's nice..... you missed a solder joint where the little tan colored mica cap is from your last picture. keep going!
I missed it on purpose ;) A wire needs to go there later.

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