#2 build - 5E3 with some mods

[Meteorman]

6 months after my modest success with a Champ build, http://el34world.com/Forum/index.php?topic=19968.0
I'm ready to take on number 2.
Small step up to a 5E3.
Concentrating on a cleaner build on this one, and trying a new assembly sequence: wiring sockets and pots and jacks first, and doing the board last.
I did it the other way around with the Champ and yeah you know...  kinda crowded and fiddly hookin up the sockets once in the chassis.
Made a wooden jig for spacing control, and hoping the whole assembly transfers to the chassis reasonably well - haven't tried it yet.
Mods are a master volume, a 3-way switchable negative feedback, and a FX loop coming out the back.





/mike

[PRR]

> Made a wooden jig

I like that very much.

[eleventeen]

Excellent technique and off to a fine start. Really like that approach. Like the green chassis too.


Might get a bit hairy moving all the parts of a Deluxe Reverb (6 little tubes, 3 big ones) 9 pots...flopping around as you make the transfer...but you've certainly come up with a fine methodology. Bravo!

[Meteorman]

Well, i can't claim this idea.
I saw a picture of a guy using a wood template on a google search - he had done a superfine job of lead dress with it.
It is nice having all the parts held firmly when it comes to soldering.

[shooter]

i can't claim this idea.

maybe not the idea, but, the application, you can, and should.

[kagliostro]

I find this method very intriguing

large work space, easily control of the junctions ...........

COOL !!!

 

Franco

[Meteorman]

This was the inspiration.

 https://www.flickr.com/photos/49986928@N02/sets/72157623912240883

Now that's a clean build - shrink tube over every socket tab !!

[eleventeen]

Now that is OCD! Thing of beauty, though. It makes 10 times the difference on a tweed vs a blackface amp with tight tweed chassis, that's for sure.

[NO_H2O]

Very nice work on both I say.

[Meteorman]

Board mostly populated.
Remaining coupling caps and board wires will get put in after whole rig gets transferred into chassis.
No idea how thats gonna go, but I'll report cheers or tears here.
See if I can get all 10 of my thumbs to work together & do it without breaking something.

[Meteorman]

The assmbly transferred into the chassis pretty smoothly.
The final wiring on the back wall, given the mod components I stuffed back there, was dicey tho, - crowded and fiddly once in the chassis.
It'd be nice to have preamp sockets that mount from the inside, so one could do all that on the template.
Heater twists will be flyers.
Any visible issues?
Thanks,
/mike

[Meteorman]

I'm in the process of wiring up the PT.
I have the ClassicTone 40-18016; schematic pictured below.
I interpret that to say I have no center tap off my filament secondaries, and thus I should install an artificial center tap
to quiet heater hum.
I can do this with a pair of 100ohm resistors on one of the power tube sockets, connecting 2 & 8, and 7 & 8.

Am i thinking correctly?
Theres no other inherent center tap in the Hoffman design that I'm not seeing?
Thanks much for any advice.
/mike

[sluckey]

I can do this with a pair of 100ohm resistors on one of the power tube sockets, connecting 2 & 8, and 7 & 8.

That will work just fine. Hoffman put the resistors on the indicator lamp assembly and connected them to ground.

[Meteorman]

Thank you Steve.
The a.c.t. at the lamp would be easier to do for sure.
I can just run the joined leads of the 100Rs to a transformer mounting lug as ground?

[Meteorman]

That will work just fine. Hoffman put the resistors on the indicator lamp assembly and connected them to ground.

They sure do. 
Can't believe I've been staring at that schematic for a month and didn't connect the dots.
Actually... I can believe it.  But I ain't proud of it!!

Thanks again Steve.
/mike

[Meteorman]

Everything in now except the power cord.
Standby switch is a little baffling.
It only goes in one way, since the chassis hole and switch's threaded neck are keyed.
So now the switch is "on" when the bat is towards "Standby" on the chassis - this seems backwards to me, but whatta I know.
Please yell at me if you see any issues.
Thanks,
/mike

[Meteorman]

So in the last few weeks i powered it up through phases, light bulb limiter, etc and it sounds pretty good to me.
a very slight hum that doesn't change with volume knobs - normal tube hum i think.

one thing of concern:
behavior of the standby switch: the hum is MUCH louder when standby switch is in "Off" (i.e. standby) position.
unacceptably loud.
Plus, when switched into standby mode when amp is already powered up (e.g. playing along nicely, want to stop for a bit, switch amp into "standby" mode), a loud electronic buzz - almost like one of those small gas-powered RC airplane engines, comes on immediately, and then winds down to the steady loud buzz in about 3-4 seconds.
This doesn't seem normal....
The wire to my standby switch comes from pin 8 of rectifier and wraps around my PT, lieing next to the AC mains, then to standby switch, and then on to B+1 filter cap.
Is this lead dress around the PT and AC wires likely my problem ?

I mapped my DC voltages:

the plate voltages on V1 and V2 seem a little low.
i'm using .022uf coupling caps instead of the vintage .1uf.
any thoughts ? are the plates voltages out of line ?
thanks for all the support here!
/mike