Tube Rectifier Load Question

[bal704]

I'm in the middle of a build, and have the option to have both tube and diode rectifiers. Is it possible to just put a switch that toggles in between the two?

I'm not clear if the tube rectifier needs some sort of load on it at all times.

[Reeltarded]

What kind of circuit?

Generally, it's a waste to do both. The si diodes are cheap and they rarely fail. The tubes are expensive and they fail quite often, lately.

The sound? Most amps you'd never know the difference.

[bal704]

This is a Mesa Lonestar clone. They use about 15 relays in the circuit, however, I'm just trying to clone the pre-amps to make a channel switcher.

I've got the tube rectifier, and I've got diodes, so I COULD do both. I was wondering if implementing it would be as simple as using a SPDT switch on the back panel to switch between them.

[beasleybodyshop]

This is a Mesa Lonestar clone. They use about 15 relays in the circuit, however, I'm just trying to clone the pre-amps to make a channel switcher.

I've got the tube rectifier, and I've got diodes, so I COULD do both. I was wondering if implementing it would be as simple as using a SPDT switch on the back panel to switch between them.

have any photos of your build? Sounds like a hell of a project.

[beasleybodyshop]

This is a Mesa Lonestar clone. They use about 15 relays in the circuit, however, I'm just trying to clone the pre-amps to make a channel switcher.

I've got the tube rectifier, and I've got diodes, so I COULD do both. I was wondering if implementing it would be as simple as using a SPDT switch on the back panel to switch between them.

have any photos of your build? Sounds like a hell of a project.

[morcey2]

I've built several plexi-style amps with a SS/tube rectifier switch in them. If your tube rectifier is a 5AR4, you probably won't hear much of a difference because there isn't much sag in it. I used a 5V4 in a couple of them and there is a definite difference between the SS and tube.

I used a DPDT-center-off switch in most of them with the center being the standby.

Now for the important question. Do you want the tube rectifier to have some sag in the amp? If so, an easier way to do it is to use a switchable sag resistor. The Lonestar uses a 5U4GB, which can handle quite a bit of current but has an internal resistance somewhere between a 5AR4 and 5Y3. If you use a 150-220 ohm 10-watt resistor, you'll be in the right area.

Matt

[bal704]

Where does the sag resistor go?

A little background: I bought a chassis/PCB set for this project. I've built one PCB amp, and halfway through the build I remembered why I hated them so much. The chassis was so nice, I decided to use it for a Lonestar with just the preamps. I don't really need the 747-style controls where everything is a switchable option. So I'm just treating this as one of my other builds. However, I have tube rectifier for it, so I was considering a switch. Normally I just use diodes.

I've built several plexi-style amps with a SS/tube rectifier switch in them. If your tube rectifier is a 5AR4, you probably won't hear much of a difference because there isn't much sag in it. I used a 5V4 in a couple of them and there is a definite difference between the SS and tube.

I used a DPDT-center-off switch in most of them with the center being the standby.

Now for the important question. Do you want the tube rectifier to have some sag in the amp? If so, an easier way to do it is to use a switchable sag resistor. The Lonestar uses a 5U4GB, which can handle quite a bit of current but has an internal resistance somewhere between a 5AR4 and 5Y3. If you use a 150-220 ohm 10-watt resistor, you'll be in the right area.

Matt

[Reeltarded]

Twrrible effing amp. No shit. That switching is the worst hell I have ever been through in my life. The amp was no better than playing pedals through a Peavey 800.

Oh, sorry. I go off.

Carry on.

[roberto]

Is it possible to just put a switch that toggles in between the two?

sure, like the mesa recto:

[roberto]

Double post.

[bal704]

That makes sense. Switch it on the AC side. The Lonestar schematic has it switched on the DC side.

[morcey2]

When you say "just the preamps", is this a preamp-only build?

[bal704]

No, It's a full amp (pre/power). I meant it would be without most of the option switching.

When you say "just the preamps", is this a preamp-only build?

[tictac]

A switch connected to high voltage AC.... something else that can go wrong...

My advice would be to decide which you like better; SS or Tube rectifier and go with it...

If you go tube you can add a SS diode to each B+ winding before the tube rectifier and it will last many decades, plus you get the slow warmup if you use a GZ34/5AR4.....

If you go SS and you want sag you can add resistance after the rectifier which can be switched in or out... more control and reliable than switching between different types of rectifiers....

My 0.02

TT

[pops]

Use the tube and put a diode on each leg of the rectifier so if the tube shorts the diode will take over and unless you can hear it you won't even know the tube has failed. Tube sound with reliability of diodes.