Re: Insight into "U47-inspired" with EF12 tube?
« Reply #180 on: October 16, 2012, 10:00:30 PM »
Hi Brad, I know this post is old but I had a question on your PSU. I decided to make a U47 clone like you, and I'm going to go with an EF12 tube. I actually had the privilege of speaking with Andreas Grosser today and he suggested this tube. I'm going to buy it from him, tested, for a good price.

I wanted to ask what you would do differently on this PSU - I know you originally had envisioned using an EF12 as well.

Additionally, I had a question about the orange symbol that looks like a circle with a cross in it. I'm not a total newbie, but I've never seen that symbol before.

So, if you had to do it over and use the EF12 after all, knowing what you now know, what would you do differently? I'm reposting your last schematic.

Also, had you considered adding some kind of soft-start to the psu?

Thanks for your time, or anyone else who wants to chime in.

** * Kablooie!


Re: Insight into "U47-inspired" with EF12 tube?
« Reply #181 on: October 20, 2012, 05:47:13 PM »
Right.  This is actually not my first tube microphone, but I believe you.  My experience with audio circuits (mostly guitar and hi fi amps, a couple microphones, a couple mic preamps) has ALWAYS been that the power supply is anything but an afterthought.

In a tube mic PSU, what are some of the "critical details" in your opinion, Gus?
Remember, an amplifier is really a power supply modulator.

Re: Insight into "U47-inspired" with EF12 tube?
« Reply #182 on: June 27, 2013, 01:08:03 AM »
From what I've read, the EF12 was sort of a precursor to the EF86.  Can anyone validate?

That's what I understood too. . That's where I started out with my STU-47 - I used Max's EF86 circuit and then tweaked (paying attention to heater current and max voltages). Best thing is to look at the data sheets.

Where is the circuit at???


Re: Insight into "U47-inspired" with EF12 tube?
« Reply #183 on: June 27, 2013, 02:16:51 AM »
Well, the one I used for my 'Stu47' is in the thread which I linked in my first post...

By "Max's EF86 circuit" I meant IOaudio's MK7 or MK47 project. I get confused by his numbering but the earlier one that uses the EF86.

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