High voltage pedal like Victory Kraken

[caspercody]

Does anyone have a schematic for a SMPS topower (3) tubes? Or know of a good one to buy say from Ebay?

[GibsonGM]

Dude, if this is your first high voltage preamp, I strongly suggest you follow along what others have done    I know, I know, it's only TWO tubes.  That's FOUR triodes...some of the world's best nasty rock was done with less...  ha ha.    This isn't a 'little distortion pedal', it's a full preamp. You CAN get it in a floor box, or a 'rack unit' if you prefer so you have room to build.

This is the entire build, and there is a thread ALL about this build (search "GTFO" on here)    Making the power supply isn't hard. I did it in perfboard (no pcb).

[caspercody]

I do plan on starting with the GTFO, but I wanted to get parts list set up in Mouser, Tayda, and Antique Electronics. If the parts are not much more, I will order, since I am paying all this shipping. Otherwise I have the parts set up in my lists for future.

[GibsonGM]

I bet that SMPS shown above will power 2 more triodes OK.   They don't draw a lot of current, at all.  Just that you'd be winging it if not experienced.

As you go along, you'll want to have a set of 1/2W resistors (ebay, get a whole 'kit' with all the standard values).

Bunch of oh, 600V caps  in coupling cap values (.01u, .022u, .033u, .047 come to mind)

Look at some schematics of what you are interested in....they will use lower uF electro caps in various voltage ratings, like 22u/450V. 

A set of poly caps, 100V is fine, can be good for cathode bypass (low voltages there). 

The fast diodes used in the SMPS are good to have 10 or 20 of (UF4007), as are some of those inductors (more on that in the GTFO thread, can be hard to locate).  The 5k pot is a trimmer.

Sockets sockets sockets...

[GibsonGM]

I went back to that marshall mid control, and for the LIFE of me can't figure out why it sounded good when I messed with it a few months ago, but now it sounds like crap, LOL.  I don't recommend it, so I'm going to remove the image.    I think the tone control from a Drivemaster might be good for the GTFO instead.

[Sooner Boomer]

Just as an item of note... In a post up there ^ is mention of overloading the front end of an amp.  Is there not a standard value for amp/pre inputs?  I seem to remember the old 0 dB = 0.707 VAC into a 600 Ohm load or something like that...

[vigilante397]

I use exclusively tube overdrives (Matchless Hotbox and GTO) on my board and I have never had an issue with overloading my amp's front end.

Also with the SMPS question I use the same SMPS in the GTFO project and have run 3 tubes no problem.

[GibsonGM]

Just as an item of note... In a post up there ^ is mention of overloading the front end of an amp.  Is there not a standard value for amp/pre inputs?  I seem to remember the old 0 dB = 0.707 VAC into a 600 Ohm load or something like that...

There probably IS a standard value for design, and you're probably not far off, but a lot of people like to beat the crap out of the input to get a hotter tone    If it's a tube amp, the only real limitation (within limits of normalcy) would be the voltage rating of whatever you're running thru prior to hitting the grid.  If the input is protected from DC with a cap, you could exceed its working voltage and pop it.    With a semiconductor amp, well....whatever the device is rated for.

Think of 18V effects....surely SOME are putting out near that?  I haven't heard of any issues.  To be safe, I check WHAT is coming out of any high voltage builds.   I will edit this in a while for the GTFO, I measured it once but forget the max output.

EDIT: OK, I went back and checked mine.  For .7VAC input at 1KHz, I'm getting 1.5VAC out.   That's only x2 gain....it's been quite a while since I built it, and I bet I put a voltage divider in there to make it safe to 'line in'.     This has me curious, if I get a minute I'll open it up and check!  So many project, I often have to look to make sure...build notes would be good....

[Ripthorn]

I put a tone stack bypass switch on my GTFO and THAT will overload an amp input, because there is a lot of volume loss going through the tone stack. Great pedal.

Keep in mind that if you choose to go with a linear regulator (LM7806 or LM7812) for your heater voltages, you will need to use a heatsink or bolt it to your enclosure, as pulling 300 mA and dropping a few volts will require plenty of heat dissipation capacity.

Tube pedals are a lot of fun, but they are just enough different that you want to make sure you heed the voice of experience from a lot of the guys in here.

[GibsonGM]

I used a (I think, and will check when I open it up) 10 ohm, 10W resistor to drop 18V to 12V for the heaters....I just hot-glued it to the chassis and it doesn't get very warm, being a big @ss cement job.   Good advice - a regulator will NEED to be heat-sinked for heaters, which is why I opted out of that route.   Good info in this thread!

Now I'm sure I did a divider before my volume pot, and that may be why my marshall mid-scoop job sounds like poo now.

[caspercody]

So I connected my 12vdv wall plug into the Nixie I have (I posted a link to it earlier on this thread) and with no load I get 400 plus volts out of it. But when I connect a 10 ohm 5 watt resistor I get like 18 volts. Does that sound right? I also have a 250 ohm 15 watt resistor and the voltage was at 54 volts. Does that sound right?

[temol]

Where did you connect those resistors? To the HV side? You need to split the voltage before nixie.

T.

[GibsonGM]

What are you trying to do?   Power the heaters, or just see what the nixie can supply?      A triode will have a plate resistor of like 100k.  Try that in there, to ground.   The R values you listed are low, and are drawing current and thus dragging the supply down.   

Be careful - that voltage could really mess you up!!  If you are not sure what you're doing, I would say stop and learn about electrical safety, please!

Yes, for the heaters, you would tap off the DC input directly to heaters (or a dropping resistor >> heaters, if the supply is bigger).   The nixie supply is ONLY for the plates of the tubes.

[caspercody]

I connected the power supply to the Nixie terminals on the low voltage side and connected another set of wires from the terminals and went to my 12v regulator which will power my tube heaters. I read about 11v after the regulator. I connected to wires on the HV side of the Nixie and with no load read upwards of over 400v. And using the trim pot I am able to adjust the output voltage.
I have two big resistors I connected to the HV wires to put a load on the Nixie and measured the voltage with a load. This is when I got the way low voltage readings.
The power supply I am using is rated at 1.5 amps.

[caspercody]

Here is a picture of my Nixie connections, and the two resistors I used for a load

[temol]

Voltage reulator usually has 2-2.5V voltage dropout. So you need fo feed it with 14-15V minimum to have 12V output.

T.

[GibsonGM]

What Temol said.   And what I said earlier...the load you put on that nixie supply is going to be very small, so check it out using 100K resistor, something in that range.  A 'regular' 1/4 or 1/2W resistor is ok to CHECK IT OUT but don't leave it on there.    100k at 400V = 4mA, tiny load, but the voltage is high and can ruin the resistor (or light it up).   And it's 1.6W, so don't expect the resistor to last    

If you regulated to 12V, you will not need the big resistors for heaters!    And hooking that to 400V will ask the supply to deliver 40A. That is why is sags down so low      It can probably output 10mA or something like that.

[caspercody]

Thanks. I am just using those two resistors to check the voltage I am not planning on using for any pedal builds. I need to order those parts. I only have resistors and caps for my low voltage builds.

Temol

Do you happen to have part numbers for that PCB for the GTFO, and or who I can email to get that list and ordering info?

All I can find are big caps that probably are to big for that PCB

[PRR]

> the nixie board I bought and I am limited to .5 amps.

No. 6mA on the 250V side. They figure this will suck 0.5A on the 5V-15V side.

Check: 250V 6mA is 1.5 Watts out. 5V and 0.5A is 2.5 Watts input. I would hope the input current falls-off with 12V supply. 60% efficiency is not great but not absurd at this low power (and price).

Never believe the specs for-sure. But it can easily supply two triodes, and four if the plate resistors are higher than 150k.

[caspercody]

Looking at the GTFO and 5150 schematics, they are very similar. I attached a copy of the 5150 schematic where I highlighted the components that are in the GTFO, and wrote in red the changed values to make it a GTFO. Just a FYI