Fender Blues Deluxe Reissue to 5F6A

[emerson909]

I'm looking at converting a Fender Blues Deluxe reissue to a Bassman,

There's nothing wrong with the amp but I got it for a good price want to rewire it as a fun project.

This will be my first attempt at something like this so looking to keep the mods fairly simple by replicating the rectifier and bias circuits although addition of a master volume is essential!

I was looking at mounting the tube sockets on a board similar to the Hoffman Blues Junior conversion design so I can prewire before installing in the amp.

I've attached a circuit diagram and layout, would appreciate it anybody who has done this before might let me know if I've made any mistakes or if there's anything that could be improved.

Cheers!

[sluckey]

Your layout takes forever to load! Guessing you used DIYLC and converted to pdf?

[emerson909]

No it was done it Visio then converted to pdf, not sure why it takes so long to load as its not as high quality as your diagrams! Hopefully its legible once opened

[sluckey]

I can see it, just wasn't sure when it would ever stop loading. Yellow wires on a white background are very hard to see.

All my files are simply printed to Adobe Acrobat v9 and I use a reasonable page size. The page size of your pdf file is 48.6" x 22.88". So your file has a whole lotta white around your actual layout work. Looks like the attached. I suggest you take a look at your Visio page settings and print settings.

[emerson909]

Should look better now

[emerson909]

Well I’ve just finished the build, went as well as could be expected, a few measurement errors from trying to get the boards done without taking the amp apart which in hindsight didn’t really save any time, should have just bit the bullet and taken it to bits straight away. Was also following the order of the tone pots from the Hoffman layout, Bass, Mid, Treb whereas the faceplate is Mid, Bass, Treb  , will sort that one day! The valve board was a waste of time, I would just mount the sockets to the chassis if I was doing it again. Going to point to point check it tomorrow and then hopefully power up on Sunday, fingers crossed! I've attached some pics, let me know if you spot any mistakes!

[emerson909]

another pic

[emerson909]

another pic

[sluckey]

Looks neat and tidy except for those crimp connectors over by the PT.

[emerson909]

Thanks, yeah the crimp connectors aren't ideal. I'd originally planned to put terminals on the board but would have taken up to much space, would you just splice and solder?

I could probably get a tag strip in vertically between the board and transformer to do the links

[emerson909]

I'm going to try and dress the PT leads a bit better but feels more like art than engineering!

[sluckey]

Wait until you fire it up before changing the crimp connectors.

[tubeswell]

You could try a screw terminal connector block mounted neatly to the chassis on one side of the PT

[emerson909]

Thanks for the feedback guys, I massively appreciate you looking at the photos. Just want to check are you saying the crimps are bad just because they’re a bit ugly or they’re badly done and unsafe?

[sluckey]

They are a bit ugly when compared to the rest of your work. No technical issues.

[emerson909]

Not sure I've made it any better 

Ah well, it will be out of sight!

[emerson909]

All installed and powered up, no issues during the start up although I'm glad it's over, gets quite tense measuring those HT DC voltages! :)

I've attached the voltages we recorded, I'll be honest I'm not sure how I can say if they are right or wrong given the changes I've made, they seem a bit low compared to the blues deluxe schematic. V1 is  12AY7, V2 and V3 are 12AX7 and V4 and V5 are 6L6GC.

Very pleased anyway and it sounds fantastic. Big thanks for all the help on the forum and website here, Rob Robinette's site is an absolute gold mine, and the TJ Adamowicz (Green Eagle) site was a big inspiration.

[sluckey]

Wiring and voltages look good.

[stratomaster]

Some ideas for cleaning up the power supply wiring:

AC neutrals can be directly connected.  Instead of switching both hot and neutral you can just switch hot and save yourself some spade connectors and jumpers.
--Alternatively you can land your neutrals on the NTC. You'll still preserve it's function, and clean up your wiring more.

Rewire your standby switch to break the output of your diode rectification to the first filter cap. You'll have to move your plate wire one post to the right to share with the cap.  You can get away with this type of hot swapping on solid state rectifiers.  This way your HT tap doesn't take the tortuous path it is currently taking. You can go direct to the diodes.  You'll eliminate a foot or so of wiring and several spade connector splices. UPDATE: I had a second thought after submitting this post.  See the attached markup. If you wire your standby here (splice in where green lines are drawn) you'll take advantage of the soft start provided by the NTC to ramp the voltage into and out of the rectifier and charge up the reservoir caps, provide voltage to the plates, and minimize the current at inrush when you do flip from standby to play).

Solder direct wherever possible.  The fuse holder lugs are easiest place to do this. The power switch hot connections and standby are the next obvious choices.  You can even sub the switches for SPSTs to gain more space, but you don't need to go that far.

UPDATE 2: Sorry I couldn't help but keep thinking about this.  If you have a tag strip you can move the NTC to it and land your (now unswitched) neutrals there.  You can repurpose the NTC turrets as bias supply landings.  I crudely mocked up what this would look like.  I moved the NTC to the left of the power switch to clearly illustrate the idea.  You can put it anywhere and even reuse the PT mounting hardware to secure the tag strip since you're not creating a ground of any kind. I didn't draw twisted pairs, but you'd twist these in reality.

[emerson909]

Thanks, yes there’s definitely some opportunities for optimisation there. It’s my first build tho so I really didn’t want to go off piste with the power supply so stuck to the original schematic. I picked up another hot rod deluxe chassis on eBay last week tho so already planning the next build ! I think the tag strip on the chassis near the pt will be the way to go

[emerson909]

Here's a photo of the current build, I went with the tag strip option and just finished wiring the PT. Also decided to move the rectifier off the board and onto an octal socket. Quite please with it so far so think I'll rewire the Bassman to match once the new build is up and running.

[stratomaster]

Much improved.

I'd recommend moving the standby after the first reservoir cap to extend its life.  Merlin the valve wizard has an excellent page on this. 

[emerson909]

Thanks,

I had read the Valve Wizard page, I should have said I will be keeping a bridge rectifier with components  mounted on the valve socket so standby will be switching the AC per this diagram at the bottom of the page

https://www.valvewizard.co.uk/standby.html

[emerson909]

Finally got round to rewiring the power supply but ended up completely rebuilding the amp :) Pictures attached.

I've changed the tone stack to 100k slope resistor and 0.1uF bass cap, removed the ground wire soldered to the pots, and move the screen resistors to the tube sockets but otherwise same as before, just neater!

[stratomaster]

Very slick work. My only criticism is not liking nylock for chassis grounds.  I keep k-lock nuts around for that particular connection.

I hope it sounds amazing, loud, and noise free.

[emerson909]

Thanks man, the nylock nuts have got serrated washers underneath so should be the same as to the k-lock. I don’t know if we can get the k-lock here in the uk (I’m probably wrong and just not found them!)

Yes it’s brutally loud with zero hum so really pleased with it!

It’s mostly your suggestions gone into the power section so thanks again