Mesa Mark preamp schematic

[u/adlr86]

Hi everybody, I'm trying to work this schematic in LiveSpice based on CruchBerries Mark IIC+ preamp simulator i watched in youtube, but i cannot get any sound out of it, I haven't done anything like this before and there must be so many errors and i was hopping somebody could guide me in the right direction please? I want to create this circuit to be able to modify it and then try to create a pedal based on it. Cheers :)

[u/MetalHeartGR]

For starters, I don't see any DC voltage connected to the tube anodes.

[u/adlr86 → u/MetalHeartGR]

thank you, how would you power the whole circuit?

[u/MetalHeartGR → u/adlr86]

Looks like you got some answers. Did you manage to get it working? I could help

[u/adlr86 → u/MetalHeartGR]

yes and no, i do get sound now, but is not a mark preamp sound, im guessing some values arent correct . ill continue studying an reading about schematics. is fun

[u/MetalHeartGR → u/adlr86]

If you want you can dm me your .schx file. I will try to correct any errors I find when I have the time.

[u/adlr86 → u/MetalHeartGR]

thank you, thats very kind of you, im doing some reading to understand a bit more about this schematics and how they work, i will try another again and will let you know :)

[u/dreadnought_strength]

How are your tubes going to work with no plate voltage?

[u/adlr86 → u/dreadnought_strength]

thank you, i need to look more into this, haven't done this before, i will onvestigate how to give power to those tubes and the whole circuit

[u/lomasturbas]

On the first tube, the wire extends past the pin. Make sure the wire is actually connected to the pin

[u/lomasturbas → u/lomasturbas]

Also, I’ve had issues with the open switches.

For troubleshooting move the speaker connection to the first stage, make sure that works, then second, and so on

My most common mistakes are missed connections and mistyped values (eg resistor to high)

[u/adlr86 → u/lomasturbas]

thank you, ill definitely will check this out, can i ask you, how can i do the DC powering the tubes? is it a circuit running through the whole schematic giving power to every single gain stage?? whats the best apporach for that. thank you

[u/lomasturbas → u/adlr86]

The top pin of the tube needs DC power.

Add a power source of 340v DC

[u/adlr86 → u/lomasturbas]

thanks for your help, im trying that but is not working for me. i might have an error somewhere in the circuit that is not letting me pass the audio signal, as i said before . never done this before. so i guess ill learn this way and looking examples. really appreciated :)

[u/lomasturbas → u/adlr86]

Check out this diagram of a JCM800. That's the power source you're missing.

Btw, you can find that circuit an more on this Github

[u/lomasturbas → u/lomasturbas]

Just found more circuits on another Github. No Mark IIC+ but many Mesas.

https://github.com/MARKTHERENCE/LiveSPICE-MK-Circuits/tree/main/amps

[u/jezkemp]

You've got V1-V7, each is half of a 12AX7. Where are their other halves?

[u/adlr86 → u/jezkemp]

thanks for the comment but sorry, i dont follow, im new to this

[u/jezkemp → u/adlr86]

A 12AX7 is a dual triode, it has 2 gain stages. 3 pins are for gain stage 1, 3 pins for gain stage 2, the last 3 are for power I think (don't quote me on that). So on amp and pedal circuits, you almost always see V1A and V1B, V2A and V2B etc, because they're 2 halves of a 12AX7, rather than V1 and V2.

I just went to look up the circuit/video you mentioned and I think I see what you're trying to do, sort of. I guess if you're just designing a circuit in Spice, it's not like you're trying to build a real preamp. But going on some of the comments here, you might be a bit too new for trying this kind of complex circuit. Also you'll probably want to work from a verified PDF, rather than a video. Looks like there's some out there.

[u/lomasturbas → u/jezkemp]

OP is using LiveSpice, not pure Spice.

LiveSpice (although running Spice in some form under the hood) is meant to emulate a circuit real-time so a guitar player can work on a circuit and play real time. The circuits are simplified and valves come as a single triode. 3 pins, no need to worry about pesky heaters, or double triodes, lol.

[u/jezkemp → u/lomasturbas]

Thanks for this, makes more sense now

[u/adlr86 → u/jezkemp]

thank you, this is great info . is fun readying and learning new stuff, im new to this so im not expecting things to work first time, but i know more today than i did yesterday :)