5E3

[Fictitiousfreedom]

Im making my second amp, My first was a 5F2A. I put a lot of thought into it and have experience with other forms of Audio DIY. My second amp is a 5E3, Im using A hoffman board and adding mods from Robs site. I just wanted to post my Layout to make sure im not about to make any huge errors. If anyone would be willing to just look over it and tell me if its good i would be extremely grateful. Thanks!

mods are
Pre Phase Master volume
Switchable Negative feedback
FX Loop
Cascaded channels
Lead Channel
Phase Inverter Grid Stopper Resistor

[kagliostro]

Dear Friend .....

why don't use a simpler way to show your idea, a schematic will be way more readable than a layout when you want to show a circuit, expecially if there are involved mods

Ciao

Franco

[Fictitiousfreedom]

Dear Friend .....

why don't use a simpler way to show your idea, a schematic will be way more readable than a layout when you want to show a circuit, expecially if there are involved mods

Ciao

Franco

Well i could try, i already put a ton of work into the layout and would rather not have to do it all over again. All of the diagrams and layouts on the Hoffman site use this format so i assumed that was the proper way to communicate ideas.

[sluckey]

Well i could try, i already put a ton of work into the layout and would rather not have to do it all over again. All of the diagrams and layouts on the Hoffman site use this format so i assumed that was the proper way to communicate ideas.

A layout is handy to see how the components will be arranged physically but is not very useful to communicate circuit operation or accuracy. A schematic is needed for that. No one is suggesting you should start over. But you want to know if your modified layout is good. There's no way to tell if it's correct without comparing to the schematic.

Hoffman's 5E3 document file includes a schematic as well as a layout. You have modified his layout. Now modify his schematic and we'll tell you if they match.

[Fictitiousfreedom]

Alright, I will get to work. Thanks guys, i dont mean to sound annoyed or unappreciative. It is just a lot of work. Ill See what i can come up with, thanks!

[EL34]

My advice is to build the amp just like the original layout and then once it is working, do mods


If you have problems, how do you know what caused it?

[tubeswell]

… It is just a lot of work… !

It sure is, but it’s part of the amp building journey. May I suggest you get some free schematic drawing software which can speed things up? This one is a free cross-platform tool. http://jschem.bplaced.net/
 

[Fictitiousfreedom]

That is a good idea to do the original build first and then add mods. My only question would be, what do you do when adding holes in the chassis? Would you add the holes for the extra pots and jacks from the start and then you wouldn't have to Drill new holes once its assembled? I guess i just answered my own question. I will still work on a schematic but i will take your wise advice. My first build went so flawlessly that i may have over estimated my abilities.

I use a Mac, i have Kicad downloaded and have used it before but never really mastered it. I will check out the other one that was linked. Thanks for the advice guys. I usually don't ask questions but i really have been trying to learn as much as possible and do everything as well as possible. I have a load of half usable pedals and didn't want to repeat the mistakes i made early on with those.

Thanks for everyones time!

[thetragichero]

i use kicad on Linux and it's a nice little piece of software. used it to lay out a pcb for an active in guitar tone control... just haven't mastered cutting pcbs with a cnc just yet (thing was doing divebombs into the board)

that being said, i use a notebook and a pen when I'm sketching out ideas. just getting em out is easier for me

which brings up another suggestion: get a notebook and devote it to amp stuff. voltage readings, what works and doesn't work, etc. VERY handy reference

[pdf64]

It looks like the NFB switch is by the input sockets?
If so that may be dodgy, input stuff and output stuff not mixing happily.

[Fictitiousfreedom]

i use kicad on Linux and it's a nice little piece of software. used it to lay out a pcb for an active in guitar tone control... just haven't mastered cutting pcbs with a cnc just yet (thing was doing divebombs into the board)

that being said, i use a notebook and a pen when I'm sketching out ideas. just getting em out is easier for me

which brings up another suggestion: get a notebook and devote it to amp stuff. voltage readings, what works and doesn't work, etc. VERY handy reference

I do have one already, its pretty empty as of right now because My 5F2A has given me no problems, other than a slight buzz out of the power transformer. I think its caused by the transformers being too close together. I used Kicad to make a large Control surface, it helped immensely. I would love to be able to create my own PCBs, that would be really cool. Too many skills to learn, im afraid i have maybe become a jack of all trades. I assume a lot of you are in the same boat lol

It looks like the NFB switch is by the input sockets?
If so that may be dodgy, input stuff and output stuff not mixing happily.

Thanks! thats extremely helpful!

[thetragichero]

Too many skills to learn, im afraid i have maybe become a jack of all trades. I assume a lot of you are in the same boat lol

if you have the space/ability to get the tooling, making the cabinets you put amps in can be rewarding (although frustrating in the beginning until you have a process down. i suggest sticking to sandeply or pine before springing for the expensive baltic birch (if you ever do, i'm fine with anything above construction-grade ply that can have huge voids and cause weird buzzes. plus it doesn't tool very easily for our needs. works great for subfloors or sheathing though)). while finer joinery is nice, i find butt joints with wood glue and hardwood dowels are strong as hell especially after adding tolex
if you have some GOOD step bits/metal drill bits and chassis punches (don't cheap out with harbor freight as they cause more headaches. something quality like greenlee are worth the price) you can buy blank chassis and not be tied to the most common builds (maybe not yet but with some reading of merlin, etc you'll start to view schematics as circuit blocks and maybe come up with some fun designs)
faceplates are probably my most hated part of builds because they're needed but get in the way of me building! my dad's friend has a cricut that can cut out a vinyl 'stencil' that can be put on sheet aluminum that we've had some success etching through electrolysis and then filling with paint. trophy shops can be useful as well. i had one by my old house that could print on thin aluminum using dye sublimation. cheaper than sending away to get faceplates made and it supports a local business (and they usually sponsor little league teams which is cool). reverse printing on the back of plexiglass is also an option
so yeah kinda have to be a jackass of all trades unless you want to buy premade and stick to somebody else's ideas. i've never been good at that

[kagliostro]

The program suggested by our friend Tubeswell produces files with .sch extension and Is very often used here on the forum

I'm near sure that if you do a search in the forum and forum archives you can find a .sch file with the 5E3 circuit, if you have It under hands It will be an easy and quick job to add your mods to the original schematic , if you are able to manager a cad program like Kikad, It will be very easy to learn to use Jschem, It Is a very easy to learn program, simple and of satisfactory results, aestetically can be more agreable with other software, but who care ?

Franco

[Fictitiousfreedom]

Too many skills to learn, im afraid i have maybe become a jack of all trades. I assume a lot of you are in the same boat lol

if you have the space/ability to get the tooling, making the cabinets you put amps in can be rewarding (although frustrating in the beginning until you have a process down. i suggest sticking to sandeply or pine before springing for the expensive baltic birch (if you ever do, i'm fine with anything above construction-grade ply that can have huge voids and cause weird buzzes. plus it doesn't tool very easily for our needs. works great for subfloors or sheathing though)). while finer joinery is nice, i find butt joints with wood glue and hardwood dowels are strong as hell especially after adding tolex
if you have some GOOD step bits/metal drill bits and chassis punches (don't cheap out with harbor freight as they cause more headaches. something quality like greenlee are worth the price) you can buy blank chassis and not be tied to the most common builds (maybe not yet but with some reading of merlin, etc you'll start to view schematics as circuit blocks and maybe come up with some fun designs)
faceplates are probably my most hated part of builds because they're needed but get in the way of me building! my dad's friend has a cricut that can cut out a vinyl 'stencil' that can be put on sheet aluminum that we've had some success etching through electrolysis and then filling with paint. trophy shops can be useful as well. i had one by my old house that could print on thin aluminum using dye sublimation. cheaper than sending away to get faceplates made and it supports a local business (and they usually sponsor little league teams which is cool). reverse printing on the back of plexiglass is also an option
so yeah kinda have to be a jackass of all trades unless you want to buy premade and stick to somebody else's ideas. i've never been good at that

I actually already do quite a bit of woodworking. Here is a picture of my 5F2A, it wasnt finished yet in that but close. I also Hate faceplates, they are always my weak point. Ive made a bunch of solid wood speaker cabinets as well. It all started during COVID, i had decided 6 months before lock down i would finally spend real time learning the craft. I gave myself a year to design and make a studio Desk, I got it done in 6 months because i was always home. I have a website with music, woodworking, DIY electronics, and animations ive done if you want to check it out. I spent a lot of time on it even though no one sees it lol


www.FictitiousFuzz.com

[kagliostro]

I've find what I was talking about, the 5E3 .sch file

Download the file and the jschem program to open it

to learn to use jschem will be a very quick thing


http://jschem.bplaced.net

Ciao

Franco

[pdf64]

Rob’s optimised layout incorporates some mods that have a genuine technical benefit, eg elevated heater circuit, single connection between the amp’s 0V common and the chassis, failsafe backup silicon diodes for the valve rectifier.


Rather than the Fender ‘up and over’ style of balanced heater wiring, I think that tweed type chassis may benefit from the Marshall style of ‘tuck into the chassis corner’.
Thereby keeping the heater wiring away from the circuit board and other wiring etc.
If so, my ‘modified Merlin’ method may be helpful, ie rotating the noval sockets 180°.

Anything to make that cramped chassis easier to work in!

[Fictitiousfreedom]

Rob’s optimised layout incorporates some mods that have a genuine technical benefit, eg elevated heater circuit, single connection between the amp’s 0V common and the chassis, failsafe backup silicon diodes for the valve rectifier.


Rather than the Fender ‘up and over’ style of balanced heater wiring, I think that tweed type chassis may benefit from the Marshall style of ‘tuck into the chassis corner’.
Thereby keeping the heater wiring away from the circuit board and other wiring etc.
If so, my ‘modified Merlin’ method may be helpful, ie rotating the noval sockets 180°.

Anything to make that cramped chassis easier to work in!

Thanks! When laying everything out on the chassis I had already turned The rectifier and power Tubes 180 degrees. I had no idea that there was a common way to do it or which brands do what. Im using a pretty small chassis and it will be mounted in a head so i needed all the room i could get. I still haven't drilled or cut anything other than the PT but I'll probably keep that orientation for the rectifier and PT.

[Fictitiousfreedom]

Ok, I have finished the schematic and updated the layout. Let me know what you think. Id be shocked if there are not a few errors. Thanks!

[pdf64]

The schematic shows the lead input permanently shorted.
The fx loop has no feed to the send.
The degree of nfb is too high, half the speaker signal is being fed to the cathode.
It may be better for the HT winding CT to be connected to the reservoir cap negative terminal.

[Williamblake]

Does your hum balance short the heater supply voltage? Maybe not, but i just looked at your layout. Also i do believe there is a big takeaway for oneself when drawing a schematic.