Also — amp has two mods that depart from the print.
1) 1uf cathode cap (as opposed to 220uf — recommended by Nik)
2) PPIMV

I feel insane typing this. Either because I should’ve noticed sooner or because my ears have failed me.

But the tone controls on my Bluesbreaker build seem to do almost nothing. Specifically, the bass, middle, and presence controls are so subtle that between 0 and full-on, I’m not sure I can hear any difference at all. And the times when I THINK I do, it’s very subtle. Like, “Okay. Maybe it’s doing something.” This can’t be right, can it?

Where should I start looking? Thanks so much.

Also -- I kept J/K connected as per the original layout. So pin 5 of each power tube connects to a 5.6k resistor, J/K on the main circuit board, and the middle lugs of the 250k dual pot.

That the problem?

I did the mod just like this (220Ks off the board, CDEJK connected as shown to dual 250k pot w/2.2meg resistors):





Bias is up now over 200mv. What am I missing/doing wrong?

Guys. After more than a year, my dad and I FINALLY built his Bluesbreaker. Got it all wired up and double-checked on Saturday. Went through a little testing procedure, which included measuring various voltages before loading up the tubes. 120 mains coming into primary -- good. 3.15 for heaters -- sweet. B+ -- rock and roll. 5v rectifier heaters -- 120 VOLTS!

I'm using a MM transformer (photos of lugs and guide from Mercury attached). It's hooked up, far as I can tell, exactly correctly. It's a multi-mains transformer. To get 120, you just don't connect the other wires and connect only black and COM (common 0 for the multiple mains options). That's what I did. Black to power switch. COM to N leg of mains input. Just like the diagram.

Called MM -- they said it's an impossibility that 120 is coming off the 5V tap; SOMETHING must be wired incorrectly. I don't even know where to look! As I'm typing, I'm not certain that I measured for voltage at 0 and 5 on the transformer. But I definitely did measure between chassis-ground and 5 as well as chassis-ground and pins 2 and 8 of the rectifier tube socket.

Any ideas? It's wreckin' my head!

Thanks! Yeah -- I've come across a thousand links to the Metro forum during my study for this build -- its a drag that it's down!

So! Let me be sure I've got this right! You recommend a 4-wire approach in order to cut down on noise -- something in which I'm abundantly interested! Like this?

4, 1-conductor shielded wires.

Wire 1
Center conductor from pin 1 of the front half of the pot to the circuit board
Shield clipped on the circuit board side, but connected to pin 3 of either half of the dual MV pot.

Wire 2
Center conductor from pin 1 of the rear half of the pot to the circuit board
Shield clipped on the circuit board side, but connected to pin 3 of either half of the dual MV pot.

Wire 3
Center conductor from pin 2 of the front half of the pot to the grids of V5. Shield clipped on the tube socket side, but connected to pin 3 of either half of the dual MV pot.

Wire 4
Center conductor from pin 2 of the rear half of the pot to the grids of V5. Shield clipped on the tube socket side, but connected to pin 3 of either half of the dual MV pot.

That look right?

Apart from tightly twisting the heater wires, any advice for taming the potential noise on this thing? I already intend on wiring the inputs with shielded wire a la the Tube Depot JTM45+ layout. (68k resistors taken off the board and connected directly to the input jacks, shielded wire used to connect inputs to V1).

Thanks again for your help!

---
Cam

So! My dad and I are setting out to build the ultimate Bluesbreaker. We've scrimped and scratched and saved to do it the right way! Nik has been absolutely gracious with his time, advice, and question answering. I realize, though, that time spent answering my questions is time spent NOT doing important things.

My first question regards the PPIMV. I plan on installing one, but am unclear about how to the shielded cabling in order to reduce noise. Here is the diagram I'll be working off of.



Which conductors of how many shielded wires do I connect to where?! Here's what I think I'm s'posed to do:


2, 2-conductor shielded wires.

Wire 1
Center conductors from pin 1 of each half of the pot to the circuit board
Shield clipped on the circuit board side, but connected to either pin 1 of either half of the dual MV pot. Or the back of the pot.

Wire 2
Center conductors from pin 2 of each half of the pot to the grids of the power tubes
Shield clipped on the tube socket side, but connected to pin 1 of either half of the dual MV pot.

This right? Seems right to my mind.

I'm exceedingly interested! However, I reckon that the proposed turnkey option is (WAY FREAKING) out of the bounds of my humble (rhymes with?) budget.

For whatever it's worth -- and I don't suspect it's much, if anything -- I'd be interested in a kit version.

Here's hoping...!...!...

Hi there! I'm new here and thought I'd say hi, thanks, and a quick bit about myself. I don't flatter myself that anybody cares, I just think it's the polite thing to do

So.

Hi!!!

Thanks for the great forum, community, products, and so on! I hope, one day, to be a contributing part of the community.

My name is Cameron. I'm a guitarist (or, at least, a maker of noise by way of guitar). I love tone and love building guitar-y stuff. I've built a hand full of stompboxes and a 5E3 clone from the ground up. I don't much get the chance to play out any more -- the occasional church gig or guest spot is all. But that's on account of my being so busy with work and grad school. If anyone ever has a computer problem, I'm happy to help with it. I'd so much prefer you ask me than you spend money paying somebody who doesn't know what he/she's talking about!

Thanks again for the goodness that happens here!

---
Cam

I know it's my first post -- so I have zero credibility. I KNOW!

But.

The instant this kit is available for me to do so, I will be buying one. I seriously cannot wait.