Diode to 5AR4 rectifier conversion - Best method?

[GuitarPilot65]

Forgive me if I missed something here at EL34World.  I have Gerald Weber's green book, to which he devotes a chapter to this mod; just wanted a second opinion.  It's for my newly-acquired '63 VVRI.  Going with the separate fillament xformer rather than power xformer upgrade.
Thanks.

[Dave]

I can only think of two methods and the only difference between the two would be where you get your 5 volts from.
I used to sort of think that bottle rectifiers would universally make amps better, but have since changed my mind.
The only reason (anymore) that I would bother adding a tube rectifier to anything (not talking about scratch builds) would be if I needed my b+ a little lower.

Especially in the case of a 5AR4, you are not likely to experience any noticeable sag or any other "complimentary" new characteristics to the tone of the amp.

Not saying don't do it, I don't care if you do or not, but weigh the pros and cons.
Cons:
1. reduce the value of an otherwise stock amp by modifying it
2. add one more component that can fail (tube rec) to the amp.
3. take a chance of making a mistake in the modding process and dammage something else.
4. spend money
5. spend time

Pros:
1. ?

Dave

[firemedic]

Pros:
1. Having a tube socket for a rectifier gives you more options w/ the amp's responsiveness & "character"
2. You can always put a SS plug in it.
3. My TOS sounds way better -to me- with a 5U4 than a GZ34. And my "Tremolux Reverb" (basically a Vibroverb) sounds better with a GZ37 than a GZ34. It's probably just a matter of lower B+ voltage, but with a tube socket you have options. That's the same as Pro#1 but it bears repeating.
4. They look cool.
  
Just look at any rectifier socket wiring diagram- it's pretty simple. Someone posted a "universal rectifier" wiring diagram in the forum somewhere which gives you even more rect. tube options.
Also make sure you get a 3A minimum rated filament transformer. I got mine from mouser, works great.

[bluesbear]

Doug has 3 amp, 5 volt filament transformers for $22. I keep one around... just in case! I know there isn't a lot of difference between SS recto and 5AR4, but there is some. The big difference is that with a recto socket, you aren't stuck with a 5AR4. There's 5V4 or 5U4 or 5Y3. You can tell those tubes from SS. More options is always a good excuse for a mod, unless the amp being modded is worth more than the price of building what you want from scratch, of course.
Dave

[GuitarPilot65]

Good points re: versatility of tube choices; hadn't thought of that since the original '63 had the 5AR4.
I will most likely be ordering the filament xformer from Doug, rather than upgradet the power xformer.
Just noticed the diodes on the Custom Vibrolux Reverb OT (schematic excerpt attached).  Anyone know what those are for?

[Dave]

Those are called flyback diodes. You can do a websearch on that term and read all about it.
Essentially they are there to protect the OT against certain types of power tube shorts.

Dave

[topbrent]

Save your money and effort.  
- The fountain that brings forth the living water of tone, is not a tube rectifier.

If you want some sponginess you can add an inexpensive 150ohm 25 watt sag resistor right off of the rectifier diodes before your first filter cap to accomplish the "feel."

Vishay/Dale 25w 150ohm wirewound = $3.78 from Mouser:
http://www.mouser.com/ProductDetail/Vishay-Dale/RH025150R0FE02/?qs=sGAEpiMZZMtbXrIkmrvidDNaDpN5VXc5wY5QUumMGTg%3d

[Dave]

Great point about the "sag" resistor. Win Win and it is fully revesible without a trace of its existence if you decide to undo it.

Dave