Anvil kit transformer

  • The transformer in mine doesn't support 120V. But it already is many years old ad the transformer has been updated possibly. You could contact Klaus at Musikding and ask him. Maybe, he can also make you a special offer for a kit without the transformer and you get a suitable one by yourself?


    Best regards,
    Alex

  • Yeah, ended up e-mailing them and unfortunately it doesn't support 120V. I've been looking at transformers but haven't been able to find one with the same specs. Might just end up getting a step up transformer but unless you pay out the ass for a big one I'd be somewhat concerned with reliability.

  • The specs I was given for the secondary side are:


    270V @ 0.08A
    14V @ 2A


    Most of the transformers I'm seeing either fall short on the 270V or they have the typical 6.3V winding for the filaments. I'm not well versed in transformers, so maybe I'm looking for the wrong thing here.


    Looking through catalogs of manufacturers here in North America for transformers and not seeing that combination. If I fall 10V short on the high voltage side, how disastrous is that? If I had to guess from the little I know I would say it would probably sound pretty crappy if it even worked at all.


    I'm not terribly experienced, basically just modded an ADA MP1 and my VHT preamp, have a couple AX84 amps I'm going to build.


    At this point I'm thinking the step up transformer is the way to go, one of the toroidal transformers I saw that came somewhat close to the specs was over $100 USD, and I could save $35 USD by not getting the transformer with the Anvil kit. So, that's still ~ a $70 difference if I had to pay that much. I'm sure I could probably score a step up transformer for a less than that.


    Looked at the power draw specs of my VHT GP3 preamp which I'm assuming would draw roughly the same, I think total power draw was ~ 35W, so thinking a 100W step up transformer would handle any spike in power draw when switching the amp on.

  • The 14V secondary is quite important/restricted since it feeds a 12V power regulator for the switching electronics and the filaments (high current!).
    The 270V secondary is more flexible: you can use a deviating voltage here and adapt the resistor R2 so that the voltage after R2 becomes 337V as given in the schematic. Maybe that helps?

  • Alright, so did a bit of homework and reading up on transformers and looking at the schematic.


    This is about the closest I could come up with:


    https://www.antekinc.com/as-05t280-50va-280v-transformer/


    So, my thinking is since it has 2 6.3V windings @ 2A I could wire those in series to get 12.6V @ 2A.


    Looking at the schematic for the Anvil, I don't actually see the portion for the heaters in there. Are they before or after the voltage regulator I see in the second page?


    A quick Google shows that 12.6VAC would rectify to 17.8VDC, which should be enough for the LM2940CT12 voltage regulator. So if the heaters are being fed DC after the voltage regulator I think I would be fine.


    Size wise, unless the transformer is crammed into a corner and space is really tight in there I don't think it should be an issue.


    The Antek is rated at 50VA, a quick calculation on the one with the kit shows it's around the same, without accounting for load of course.


    Thoughts, ideas, concerns?

  • I think I would try it in your case. The current rating should be fine since the LM2940 cannot handle more current anyway.


    The heaters get the current from the current regulator, which is why the Anvil is so silent btw (no heater hum!).


    Please make sure that you can wire the two 6.3VAC in your transformer in series, though.

  • What would be the determining spec that would allow for that? On the product page in the second pic it shows 2 seperate 6.3VAC windings @ 2A.


    Would be there a spec that wouldn't allow the secondary to output that? The 2 windings terminate at blue and green wires, I assume I take the middle green and join that to the middle blue.


  • From my (strongly limited!) knowledge, you have to take care of two important parameters when wiring transformer secondaries in series:
    1. the maximum current drawn from the resulting transformer output must not be higher than the individual secondary maximum rating (2A here)
    2. The maximum power must be below its maximum rating. From what I see, this is 50VA as given on the website. When you wire the two 6.3V secondaries in series, the resulting maximum would be: (280V x 0.09A) + (12.6 x 2A) = 50.4VA.
    This is quite close. However, I assume you won't need the full 0.09A from the 280V secondary, hence this may be ok.
    Long story short: I would simply write an email to the shop or manufacturer and as if serial wiring of the 6.3V windings is allowed.


    Yet, again: I am definitely not an expert in this field...


    Hope this helps!

  • You've been a huge help, thanks!


    Part of my issue initially when shopping was the power rating of transformers, I was looking for ones rated 300VA, not understanding that that's not the max voltage it can output. Once doing a bit more research and realizing that that's not how they're rated it made it a lot easier to find something that wasn't huge and had close to the right voltages.


    Again, fairly new to this, but have to start somewhere. Just got me a good multimeter that won't blow up in my hand when measuring high voltages/currents and about to start on my AX84 builds, then snag the Anvil kit and transformer in another payday or 2.

  • Cool, hope this turns out well.


    btw: if you're new to this territory, I propose to realize other kits first. There are less complex ones (also with tubes) with a more newbie-friendly documentation. Just saying, don't get me wrong here... ;)

  • I get what you're saying, but don't want to spend money on something that won't get used. I'm a metal head and use a clean channel like 1% of the time.


    I've modded lots of stuff, ADA MP1, VHT GP3, working on a Marshall JMP1, etc, so it's mostly scratch built stuff I'm new to. I've poked around lots of PCB's and whatnot.


    Going to build the AX84 stuff first, just have to go somewhere to print off drill templates and whatnot while avoiding the plague.

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