Build Basics FAQ : #2. POWER TRANSFORMERS!!

Second in a series of FAQ build basics. Here I discuss and outline how to go about choosing a power transformer for your build.
0:00 Intro
3:19 Two phase rectification
4:48 Full bridge rectification
6:50 Marshall schematic examples
10:04 Reading PT spec sheets
13:31 Configuring your Headfirst PCB rectification section
17:24 Setting up your DC relay and/or heater supply
21:35 A word on chokes
22:45 Hunting for Power Transformers
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[@docdeens4030]

Man, I've learned so much from your channel, I feel like you should be charging. If only you weren't halfway across the world, you would be getting a lot of free beer in trade for answering my stupid questions

[@soapboxearth2]

These videos are just amazing, Jason. Thanks for taking the time.

[@HeadfirstAmps]

Glad you like them!

[@russiangoose7053]

I'm loving this build basics series, please keep them coming! I'm eager to get building but I have a lot more I need to learn first before doing a scratch build

[@clintn6677]

You should do a video series on a build from start to finish and sell it. Most youtube channels have vids on stuff like mixing, songwriting, programming drums etc. Having one on building would sell IMHO.

[@fabronaut7478]

thank you for sharing this knowledge! I've only had older modelers / solid state amps, but have always been curious about tube amps. took me awhile to realize that many of my favourite crunch / distortion tones were associated with JCM 800 hot rodded Plexi style circuits, many of which probably had further modifications under the hood. I used to think I couldn't get anywhere near that "sound in my head" without spending way more than I can justify as a tinkerer and rusty bedroom player. being able to do a DIY scratch build or modify a used example as you've demonstrated will likely go a long way to getting there! even if I don't go that route any time soon, it's cool and I'm learning interesting things along the way. cheers from Canada!

[@dr.danamplifiers1753]

Another great video. Excellent pertinent points ✌🏼

[@johnmarshall3903]

Great info as usual, thanks Jason.

[@prook2001]

Thanks for this Jason just what I was looking for.

[@lechstryzewski9350]

Awesome video - Thanks Jason !!!

[@geraldstewart9399]

Great video, Thanks!

[@jedishaw6771]

Great info thanks!!

[@DJ33]

Definitely learned something, thanks

[@matthewf1979]

I miss the hell out of Classictone too. I buy Mercury iron now. They’re the only other company I trust with stated specs. Hammond and Heyboer are all over the place on 120v primaries.

[@HeadfirstAmps]

Oh wow, I haven’t heard that before. You ok with the Mercury pricing?

[@matthewf1979]

@@HeadfirstAmps I have to be ok with Mercury pricing. They’re the only ones making commonly available iron that does what I want. As you know, amps designed for a specific voltage range don’t sound right if it’s outside of that range. I don’t have any problems with Hammond or Heyboer OT’s, chokes or reverb drivers though. They all sound fine and operate noise free. I usually just buy everything from Mercury though. High volume, group buys from Mercury are the way to go if you want to bring the price down.

[@eyedunno8462]

How about Torodial Transformers?

[@buzzedalldrink9131]

I read Hammond makes direct replacement transformers ,their 290 series, for guitar amps that were reverse engineered from classic tones

[@HeadfirstAmps]

The Hammond stuff is ok mate

[@terribleligadelmal4541]

so... the 50w example works for the relays or not? i didnt get that part...

[@Frankentoane]

I can still use a pt rated for 100w for a 50w mc2 build right? Granted i wire it in full bridge rectifier with the ct connected in between the first series filter caps, as mentioned here?

[@HeadfirstAmps]

You absolutely can!

[@johnmiller9219]

lots of inexpensive options for Fender PT replacements. Can these be used? Many of them are for 2 or 4 6L6

[@JohnWiku]

Anything can be used, depends on your requirements of course!

[@johnmiller9219]

@@JohnWiku I'm referring to the Headfirst boards. Will they accept for example a Supersonic Power transformer or a Hot Rod deluxe Power transformer and run 6L6's ? I ask this because transformer replacements for Fender are plentiful and dirt cheap

[@JohnWiku]

@@johnmiller9219 As was explained in the video, that is not a problem at all

[@johnmiller9219]

@@JohnWiku I guess i'm questioning what will picking a particular PT determine aside from B+ voltage? Power tube type? If i use a Hot Rod Deluxe PT must i use 2 6L6 or can i use EL34 or KT77 ?

[@JohnWiku]

@@johnmiller9219 Regarding different tube types and how many you're running, what you need to pay attention is the heater filament current needed to power them, and spec a PT suitable to handle it. These board seem to be fine for whatever PTs you might throw at them, it all depends on the components you use to populate the board, as these have to be rated, and preferably overrated for the voltages you'll be running them.

[@natehaiden]

I'm actually just trying to search for information on how power transformers change the feel of using your tube amp. Perhaps you're a good resource.

[@HeadfirstAmps]

It’s the mA supply rating of the HV secondary, internal resistance - yeah all kinds of things