Voltage trippling.

[Wakculloch]

Someone gave me a very early transistor spring reverb unit that is awful, but the springline and box are good, so am gonna rebuild with valves.
Have a power supply idea that i'd like comment on before i start.
Using a 0-24, 0-24V transformer connected in series then rectified and smoothed to 65v for 3x 300ma valves(PCL85, ECC83, ECC82) with series heaters through a dropper resistor; then using the same raw AC trippled to get 200V for the HT.
In my head it should work, but i may be overlooking something!
Has anyone tried this arrangement?

[Wakculloch]

ie

[bbartilson]

Someone gave me a very early transistor spring reverb unit that is awful, but the springline and box are good, so am gonna rebuild with valves.
Have a power supply idea that i'd like comment on before i start.

My thoughts:

I wouldn't bother with a tripler at all. You can buy a decent 120V/12V CT transformer quite inexpensively. Add one of the little B+ transformers from Weber's store:

http://taweber.powweb.com/store/magnetic.htm (at the bottom of the page)

And you have 12V with CT to drive your heaters without any dropping resistor, and plenty of B+ to do whatever you'd like.

But that's just me - I'm into conventional solutions. The extra filtration required to get the excessive ripple out of the tripled B+ would probably negate the economy of avoiding the proper off the shelf parts. At least it would cause me to avoid the solution you're suggesting.

Secondly, what kinda reverb tank is in this thing? Is it Accutronics? If so, what's the code on it? It would be something like 9B1C3B, it might start with a 4, but it should have a series of letters and numbers. Those numbers denote, among other things, input and output impedance of the drive and return coils. In any case, you'll likely end up needing a transformer to drive the front end of the tank. So add another transformer to the equation.

If it sounds crappy in the first place, you may be talking about scrapping the reverb tank as well. Sounds crappy with transistors probably equals crappy with tubes as well. But there's nothing wrong with having a nice old box and putting all new parts in it. That is, if a nifty sounding tube reverb is the goal.

Cheers,
Bill

[Wakculloch]

Codes

Thanks for input Bill. Looked up codes and found the tank has an input impedance of 1.5K, which as i have an output transformer to drive into eight ohms would have stuffed things up. Luckily i have an 8ohm tank one knocking about.
The power supply design is not just me being awkward (although i am), its because i have a large supply of PCL85's, and the heater supply to them is 18V at 300mA, so having the heaters in series makes sense to me, and i'm hoping that as its DC it wont cause too much hum, but am worried about heater/HT interaction.
I've previously built some preamps using voltage trippling circuits, which have all worked well, but they had the heaters taken from a seperate 6v transformer.