Master Volume - 5e3 or No?

I built a Mission 5E3 kit about ten years ago. The original circuit. Still my only amp.

Every now and then I think about modifying it. Changing to fixed bias and adding a choke would make it a lot more like a brown Deluxe. Or doing Rob's switchable NFB mod. Or a master volume. But, I always decide to keep it just as it is. It still makes me grin every time.

 

Nope, no MV.

 

No mv

 

Little to no benefit... Experts say .... If you are skeptical, roll your own ... Dice ...

 

I built the Mission kit over ten yrs ago...perfect as-is.

 

Tried it. Took it out. Used Robrob's 1/4 power mod, dropped to 1/10th power with bigger resistors. Worked great.

 

Put one in (Pre PI). Although I generally don't like Master Volumes (going as far as removing one from my JTM45), in this application, on this amp, it works beautifully. I love it, I set my volumes where I want them, then adjust the Master to the room. It allows me to get right to that point where I can go from clean to some hair just with my picking hand and maybe the volume control on my guitar.

 

... same here, but am seriously considering the switchable NFB.

 

Ever mod something you really like, trying to make it even better? Then absolutely not liking the results and changing it back, and not ending up back where you started? It's the same on paper, but it isn't the same? That's why I'm not modding my 5e3. Too much risk.

 

All good info here, and I would like to agree in spirit with the folks who say "leave the little guy alone."

But as Rob's superb and ever-growing mods page demonstrates, the 5e3, famous in its own right, can also host dozens of mods. The most famous 5e3 in the world, Neil's, is part of a long chain of effects, robot arms, other amps, cabs, and speakers, that in effect mod it a ton.

Lots of TDPRI-ers have reported lots of success with 5e3 mods. Yes, some of them are in the group that doesn't like the native 5e3. But many more (and Rob himself) especially favor defeatable mods that allow you to return to stock sound but also give the little guy new skills and sounds.

I take Rob seriously when he says his three favorite mods are 3-way NFB, lead channel, and MV. Being Rob, he shows us a lot of MV options, but the tidy pre-PI version mentioned by @Paul G. above is especially appealing -- it's easy, easily defeated, and adds not only MV control but the ability to tune down or tune out ratty PI blocking distortion. What's not to like?

 

+1 on the NFB, it just adds some "flavor" options to the amp and lets you get back to the original with a flip of a switch.

as far as a Master Volume, I just use my guitars volume pot.

 

Excellent point; our wise friend @Wally always points out both guitar volume and picking force / attack are key with a 5e3.

You remind me of one other thing that gets overlooked. The stock 5e3 in some ways has an MV -- the active channel volume (and to some extent the tone) act like 'gain' or drive knobs once they're turned up past the 2-to-4 region. And the non-active volume acts like a 'politeness' knob.

 

The wattage is so low on a 5E3 that a simple, small attenuator is a pretty affordable solution.

 

An attenuator or a flux density adjustable speaker would be my choice. I want the output of a 5E3 working.

 

Both you and @Wally hit the nail squarely on its head, especially about the "picking force!"

And yessirree-boobarrooney, an attenuator allows running the amp at its own internal "sweet spot" while having the ability to adjust the actual "sound pressure level" to an appropriate point!

I have installed a completely passive effects loop/preamp out-power amp out and can see how a Master may be beneficial, either before or after said loop! I'll try it both ways.

I Need Tweed Indeed!
Gene

 

My "Evolution Three" modified tweed Deluxe has absolutely zero "stupid pet trick" mods. No master volume. No negative feedback. It has cathode bias. In other words surprisingly stock.

I went through a ridiculous amount of Forbon before I finalized the layout. I must have built four dozen tag boards and used four. I may go one more evolution and change a few things on the power supply side of the board.

My advice for anyone considering modifications is to build another amp. If you need to tinker with that one build yet another one. And so on.

 

Yep. As above, I agree with the spirit of “if it ain’t broken.” Also that if modded, the mods should be easily defeated.

But not all mods are like that. I used my first 5e3 as a test bed for a more subtle set of mods than we’re discussing here; small differences in coupling and bypass capacitance, CC vs. MF on the V1 plates, a PI grid stopper, a slightly bigger reservoir cap, that kind of thing. Then I built those I liked into v.2, an amp I love just a bit more.

The 5e3 is like a '57 Chevy. Some people accessorize: Fender skirts, full chrome, spare wheel carrier, whatever. Others drop in a racing engine, everything Edelbrock, Dana 60, etc. And some set out to win the concours, all stock, numbers matching, period-perfect restoration.

Rob points out the difference: We can work out our mod urges or lack thereof on new builds, and leave the rarer vintage amps stock — though with new belts, hoses, tires, and brake pads, please.



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I don't know what liberties Bruce Collins took with Leo's original 5e3 circuit and layout, but I think it's minimal. My Mission kit has the brass plate behind the front panel for grounding, and that seems to be the first thing to go in most current versions I've seen. Almost noiseless to my ears. No 60 hz. hum and just the slightest whisper of white noise with the volume maxed. The only issue I have is the volume control. Too soft up to about 2-2.5, then full volume at 3.5. Very sudden reaction to very small control adjustment. I usually just run it around 5-7 and control volume from the guitar.

 

You’re right, changing the brass plate doesn’t actually change the circuit — most folks who lose the plate do it because it’s a pain to solder to. Also prone to brass-induced steel corrosion over time.

And you’re also right about the volume — that’s a pretty good description of the stock amp's volume slope. Bruce's 5e3 always did have a good rep IIRC.



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