New project Plexi6L6SE

[Shack]

I wanted to make something with spare parts in a gutted SS Fender amp, and this is what im settling on. I drew up this schematic ( first one ever) Hope I get the size right. Can you guys look it over and give me feedback on it before I start? I intend to use the plexi 6V6 turret board for it.

Not sure which output tranny ill use or what the values for resistors in power supply should be

[Willabe]

You probably will need an extra stage of B+ filtering before the OT B+ node.

SE amps output stage doesn't have the built in noise canceling that a PP amp has.

So you have to add another filter cap then either a choke or a R before the stock B+ 1st filter node. Not a big deal if you plan for it and have the space.

[Shack]

ok, ill do that....anything else I missed? What if I used an EL-34......whats the bias requirements for different tubes here?


I may include the passive effects loop and DC filament for this, since its just a project amp for my education, so any input helps

[tubenit]

A GZ34 will work, but I'd personally use a 5V4 so I could use either 6V6 or 6L6/5881.   JJ 6v6's will take 425v (5V4) easily from my experience.

With respect, Tubenit

[Shack]

Thanx for the ideas...if I use a choke, what determines which one to use for a specific amp, never dealt with them before

[Shack]

Here is my updated schematic.....tell me what ya think

[sluckey]

I would put the choke between the two 33µF caps.

[Shack]

ok, cool Steve.....other than that , is it cool?

[Shack]

Here it is....could I use EL34 here, or stick with 6L6, and is everything else ok to try to build, i.e. DC heaters, and power section values?

[Willabe]

...if I use a choke, what determines which one to use for a specific amp, never dealt with them before.

B+ dcv current.

For a SE amp you can use a Fender choke for Fenders 6L6GB/GC amps. Doug sells 1. I'm using it in my SE amp. 

[Shack]

cool, ill look at it now.....pumped at making schematics, helps me understand this (a little) LOL

[Paul1453]

I built something slightly different, a very clean sounding EF86 - 6L6 circuit.

Looks like you are going for more dirty tones.

I used a simple 12VDC supply with a dropping resistor for the heaters,
and the 12VDC also powers my $8 Chinese DC-DC boost board for B+ of +250VDC at @ 75mA current.

I'm not sure your DC heater voltage will be correct.
Why not just use the 6.3VAC for all the heaters?

Also attached is a Lone Wolf Blues Co SE 6L6 design to compare.   

[Willabe]

Instead off going with DC heaters you could use a elevated heaters/DC stand off voltage with a humdinger pot. I'm putting it in my SE amp and have installed it in all my amps.

New and NOS tubes can leak from their heater to K (cathode) and will be noisy, this can/will stop that.

It would also keep the CF's (cathode follower) K dcv from exceeding the K to heater voltage. New tubes often are not as tough as the old tubes and will die quickly sometimes as a CF.

Here's a link from Merlins web site on heaters that has info on this;

http://www.valvewizard.co.uk/heater.html

And below is my B+DCV schemo that I'm using.     

[Shack]

LOL, I was gonna use the DC heaters, because I bought the bridge and cap in the 90s from the Torres book, and need to use them somewhere, no other reason really......

[Shack]

Thanks for the ideas guys!

[Paul1453]

I did another with a 12AX7 volume pot no tone pot feeding EL34 for a much dirtier gritty tone.

Using the same 12VDC PS design.

I salvaged my 12VDC bricks from the trash at work.
Added a less than $8 delivered boost board.
And used tiny SE OTs from old R-R recorders.

Cheap and simple were my design goals.

I can put one of these designs together for less than $50 in parts.
I have been using the EF86-6L6 on my computer's output for a number of months now.
Often forgetting to turn it off when I go to bed.  8^(
No problems to report yet.  ;^)

[Willabe]

, because I bought the bridge and cap in the 90s from the Torres book,

Your bridge is still fine but an e-cap from the 90's is pretty dried up by now.

I have LOTS of parts I've bought that I never used. 

I would (and so have many) buy parts to have on hand and then change my thinking on what I think was a good idea or not to add/build in an amp.