High voltage pedal like Victory Kraken

[caspercody]

Hello

I have a pedal version of the Victory Kraken and love it. Is it possible to make pedal versions of say a 5150 pre amp using tubes and a high voltage charge pump?

So if I were to take the pre amp schematic of the 5150, and power it up with the charge pump will it work?

I know I will also need 12 v for the tubes and need to use high voltage rated resistors and capacitors. Which devices in the circuit would need to be rated at high voltage? I hat resistors are rated for 300 plus volts?

Thanks
Rob

[GibsonGM]

Hi Rob,  the short answer is "yes", if you build a preamp into a pedal and power it with the same voltages the original used, you'll have that preamp.   Generally, that will be used to 'replace' the preamp already in your amp - you can run it 'preamp in' if you want.     

That doesn't give enough high-powered goodness for me, though, and I generally run into my amp's existing preamp, to goose it.    In that case, you have to be sure of what your output is!   You shouldn't feed your amp's input more than what it can safely take, typically a couple of volts, say <18V p-p, I'd assume.  And it may not be JUST like the 5150, because your preamp will color the sound.      Best way is, of course, to BUILD the whole amp, incl. the cabinet, LOL! 

If you're going to the trouble to make a 5150 preamp, I'd consider just getting a transformer set up for it, which will include secondaries for B+ and the heaters....I don't know the kind of charge pump used in the Kraken so I can't tell you more.    But I'm old school, the charge pump may well work.

Check out Merlin's site, lots of preamp info, might be useful!  His preamp book is great:  http://www.valvewizard.co.uk/

250V is a common 1/4W resistor rating.   Typically, 1/2W units are used at the plates...1/4W is fine for cathodes.  1/2W in coupling networks where you're going to have HT.    Some ppl just use 1/2W thruout...power supply may (will) have different needs.     I plan on HT voltage possibly being present anywhere but cathode, really, and use caps rated for it and at least 1/2W resistors.    I mean - if a coupling cap fails...out comes the smoke if the parts downstream are too wimpy!  Don't cost any more, really, either. 

[caspercody]

Thanks for your reply.

I have one other question, about the heater. I have a 12vdc voltage regulator I was planning on using to power the heaters, but a lot of things I see talk about 6.3v. Some say 12 VFE in series or 6.3v in parallel. Can I hook up my 12vdc filtered voltage regulator to pins 4 and 5 and it will work?

[vigilante397]

I have one other question, about the heater. I have a 12vdc voltage regulator I was planning on using to power the heaters, but a lot of things I see talk about 6.3v. Some say 12 VFE in series or 6.3v in parallel. Can I hook up my 12vdc filtered voltage regulator to pins 4 and 5 and it will work?

Yup, that's exactly how it works.

As someone that has built way too many tube preamp pedals, my favorite way to do it is with 6N21B submini tubes instead of 12AX7. Gives the same sound in a smaller package

[caspercody]

Thank you for your reply!!

I actually have (2) 12AX7 tubes from my Marshall lying around, and that is why I thought of trying this preamp to pedal idea.

Where do you buy your high voltage capacitors from? I am thinking of using DIY layout software and designing using a turret board for the components.

Any help and or ideas is appreciated. Thinking of doing a 5150 preamp first to see if this will work.

Thanks
Rob

[temol]

Hi Rob.

In my opinion 5150 is quite challenging as for the first tube pedal.  And it requires 3 tubes .
I'd try with well documented build, Something like GTO (or GTFO). It runs from 12V and uses smps to boost the voltage to 300V.

T.

[vigilante397]

Where do you buy your high voltage capacitors from? I am thinking of using DIY layout software and designing using a turret board for the components.

Well I'm different because I use SMD, so I go to Mouser for my high voltage caps. But for through-hole stuff I generally go to Antique Electronic Supply (www.tubesandmore.com).

In my opinion 5150 is quite challenging as for the first tube pedal.  And it requires 3 tubes .
I'd try with well documented build, Something like GTO (or GTFO). It runs from 12V and uses smps to boost the voltage to 300V.

I agree, if you've never done anything like this before jumping straight into a scratch build of a 5150 would be very challenging. The GTO is a great-sounding pedal and not absurdly complicated to build.

[caspercody]

Thanks, I will look into the GTO

[GibsonGM]

...and here's one source for your parts!  https://www.tubesandmore.com/

I've built the GTFO, and it sounds VERY good.  Built the 'nixie supply' type SMPS to run it.  I use it often for recording, direct to a USB-equipped effects pedal (I don't use the effect, too cheap to buy an interface) right into my computer.   Nails GNR sounds as well as more classic rock if you want (I added a pre-gain control).     You can build it on a standard turret board (I did).

Let me know if you need some info on the thing. 

PS - about the 12.6V vs 6.3V...if you look on the 12AX7 data sheet, you'll find that at 6.3V, the heater draws 300mA, and 150mA when run at 12.6V.    .3 Amperes is a LOT of current to have to source from a power supply, so most will run them at 12V.   

On my GTFO, I use a walwart that outputs 18V, and can deliver 1A.     4 triode stages will draw squat, just a few mA, less than 10mA on average.   The heaters, 300mA  (2 tubes, heaters running on 12V).     So there is plenty of room to spare!   I tapped the 18V before the SMPS unit, and run it thru a dropping resistor (think it was 10 ohms, 10W but you may have to play around to get the right R for your power supply - the 10W is the important part!) and right to the heaters. 

[caspercody]

Of all the preamps you built which one do you think gives you the highest gain,distortion?

[vigilante397]

Of all the preamps you built which one do you think gives you the highest gain,distortion?

Well I have a three-tube Dual Rectifier preamp pedal, so obviously that one

For two-tube preamps though it would be the GTO, and that's actually the pedal I keep on my board for higher gain stuff.

[temol]

You have to remember that hi-gain is not very  forgiving when it comes to layout. Do not try to make gain monster as your first tube build because you may end up with nothing but squeals as soon as you crank up the gain pot. GTO has plenty of gain and you can always boost it with a TS.

T.

[diydave]

You have to remember that hi-gain is not very  forgiving when it comes to layout. Do not try to make gain monster as your first tube build because you may end up with nothing but squeals as soon as you crank up the gain pot. GTO has plenty of gain and you can always boost it with a TS.

T.

With 3 tube-pedals under my belt, all with SMPS power supply's, I agree with Temol: beter make a pedal with 2 tubes (= 4 stages) than trying to make a shredder with 3 tubes (= 6 stages) as you first build. You can always boost the input with a TS, SHO, or whatever if you want more gain out of the beast. But then again, I'm a 2204 lover (Marshall jcm 800 pre-amp).
3 tubes in a Hammond like enclosure... besides the questions about how to snug it all in the enclosure, I forsee all kinds of anoying sound-issues.
If you are going for 3 tubes, keep in mind that the heaters will pull nearly 0.5 amps running them on 12.6 V DC.... which warm things up a great deal. So you need enough ventilation + a way to keep the voltage-regulator happy (heatsink). You'll be using a wallsocket which can handle the voltage (+15V minimum) and the current.

[GibsonGM]

I agree with everyone above.  It is hard to really describe "high gain" as a musical term...the (GTO) GTFO is extremely high gain (if you turn up the gain pot, LOL!)...add another two stages, you get even MORE squashing and 'gain'.   You can 'bump' it with a TS or mosfet boost or anything else, if you think you need 'more'...     

If you were to put a marshall-esque mid scoop on the GTFO, it will sound like GNR, Ratt...JCM800 and that - it's all in the EQ.  But the additional 2 stages of something more modern add a well, modern kind of compression to the tone. They are not trying to get all the distortion in such a short space, ha ha.    To me, 4 stages are more gritty than if you use more (depending on design). 

I absolutely recommend the GTFO as it is well-documented here, and many ppl have actually built it and can help.  Layout isn't as critical tho you want to use a turret board.  I built mine into a Jameco enclosure (like a head) rather than a 'pedal', but some have done a pedal, and THOSE layouts exist already for you to make a PCB.   Most don't have the tone controls...if you follow the thing with an EQ pedal, you might be (happily) surprised at the tones you can come up with! 

[temol]

I've built GTFO with a single tone knob and another one with TMB tonestack. I vote for single knob version. I've also added a switchable 10u bypass cap (FAT mode) to the last cathode and some other mods (mainly changed capacitor values here and there). But it's good to start with stock values.
If you want to go fancy then you can use 12V relay switching instead of regular 3pdt switch.
Drop me a pm with your email. I have some GTFO layouts.

T.

[GibsonGM]

I've been messing around with the EQ, and now have a marshall "contour" control at the end of the thing.   Holy cr@p, totally nails that 80s sound (among other things). 

Now I want to build a 2nd one, ha ha...switchable between them.... :evilgrin: 

[caspercody]

Thanks everyone. I will start with the GTFO. Plus with the info everyone has been giving me, I looked at the nixie board I bought and I am limited to .5 amps. Here is link to what I bought:

https://www.ebay.com/itm/Magic-Eye-Neon-Nixie-VFD-Geiger-Tube-HV-DC-Power-Supply-Adjustable-95-340V/202391124136?_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20160908105057%26meid%3De6fdb8904e3a40bfa0144673f4d95de3%26pid%3D100675%26rk%3D1%26rkt%3D15%26sd%3D202391124136%26itm%3D202391124136%26pmt%3D0%26noa%3D1%26pg%3D2481888&_trksid=p2481888.c100675.m4236&_trkparms=pageci%3Aa8ba4f72-e131-11e9-b9e3-74dbd1804cef%7Cparentrq%3A7316405b16d0a6e4737d057cff7b3dcc%7Ciid%3A1

[caspercody]

Anyway to get a schematic of that marshall "contour" control?

[GibsonGM]

This is the gist of it.  It works (and sounds good), but needs to be buffered - it sucks a lot of signal.   It is used in a few pedals with an opamp before and after; I haven't found time to reproduce that in a way that works well with the output of the GTFO.   But you can try it out and see if you like the sound!   I've literally tacked it on to the last stage of the GTFO.

Nah, there are better tone controls out there!

[temol]

Rob, there is no need to buy a separate SMPS. From what I remember almost every GTFO layout has onboard SMPS. You need a dozen or so somponents for this.. and works like a charm.

T.