Vibrolux 5f11 build from integrated amp

[tonebrulee]

Hey folks - novice here with my first build. I had done some reading on converting old integrated tube amps into guitar amps when the tube complement and transformers made sense for a conversion. Found this 1959 Craftsman "Conterto" CA-11 amp on eBay a while back for $70 and grabbed it for the tube complement which I thought might match some of the old Fender circuits. Did some research and was originally going to build a Tweed Deluxe 5e3, but then figured the tube complement exactly matched a Vibrolux 5F11, so I'm going with that.

Original front panel


Front panel parts installed:


Original shot from rear


Guts of integrated amp before stripping out


Project with new sockets installed and filiment runs in place


Shot from side showing power and output transformers

[tonebrulee]

Also, part of the challenge here is there's no room for a proper layout on a card or turret board, so I have to re-interpret the layout diagram and "fly" the components old school! I did wire up the power supply on a couple of terminal strips though. I'm trying to route all the connections properly to reduce hum and will be using a multi-star grounding scheme. A friend suggested covering the component leads with housing stripped from other wire which seems like a cool idea, so I've been doing that.

If anybody sees any problems or has any suggestions I'd be happy to hear from ya. Thanks.




Layout diagram showing completed wiring in orange:

[tonebrulee]

I've been studying up on grounding (i.e. "the other half of the circuit") and have come up with the star grounding scheme shown below. There are 18 ground points in the schematic and the different colors each represent a local star node. There are 5 nodes (blue, orange, brown, purple, yellow) and each will have a wire run to the star. Plus 4 individual ground points (9, 14, 16, 17 in green) which will each be connected directly to the star.



Any feedback (no pun intended!) very much appreciated.

[tubeswell]

Further to my comments on the telecaster forum, read Merlin's article on grounding here:

Click here to view the article (360kb PDF)

[loudthud]

Merlin's article will take a while to digest. The first thing you will need is an updated schematic. Old Fender schematics do not meet current safety standards. First of all, eliminate the "Death Cap" at point 9. Add a three wire line cord or IEC socket for power cord connection. One side of the heater winding is grounded, that system is (almost) never used these days. You will want to use a heater winding with a center tap, or create a "virtual center tap" with a pair of 100 ohm 1/2W resistors. Lastly, show the ground connections of the input, speaker and footswitch jacks. These will need to be isolated from that chassis, either with stepped washers or plastic jacks.

[tonebrulee]

Merlin's article will take a while to digest. The first thing you will need is an updated schematic. Old Fender schematics do not meet current safety standards. First of all, eliminate the "Death Cap" at point 9. Add a three wire line cord or IEC socket for power cord connection. One side of the heater winding is grounded, that system is (almost) never used these days. You will want to use a heater winding with a center tap, or create a "virtual center tap" with a pair of 100 ohm 1/2W resistors. Lastly, show the ground connections of the input, speaker and footswitch jacks. These will need to be isolated from that chassis, either with stepped washers or plastic jacks.

Yup, Merlin is one of the first things I read... been digesting it for months. Been using the old schematic for illustration only - have been planning all the updated mods you recommended. Thanks.

[Wittgenstein]

Any new updates? Looking good so far.

[tonebrulee]

Any new updates? Looking good so far.

Hey, thanks. Guess I'm a low-down, no-good two-timing scoundrel b/c I have the same post going over at TDPRI (link below) where I've had some luck gathering info in response to my grounding post above. 'Bout ready to move ahead with building though and will be posting build updates to the thread here too.

Vibrolux 5f11 build from integrated amp - TDPRI