New 5F4 build-transformers

[Travst]

Excellent points, Tom and good advice that I'll take note of. I have read quite a few threads that agree with your thoughts and it makes perfect sense to me to add improvements. I'm not locked into the 'stock' design' by any means. I'll take the time to read up on screen resistors. I've built an 18 watt, modded a couple of VJs and fixed several amps. It's all a learning experience to me right now, but the way for me to 'get' things is to dive in and do it and ask for advice from those who know much more. The point about the choke is well taken, and I'll see if Triode can provide the package with a choke for the higher current.

[Tom Phillips]

Yes, I thought the Supers had smaller iron as well, but MC seems to recommend the 40/50 watt transformers. I wouldn't mind finding a match in the MC line that's a lighter wattage. Any recommendations? I'm using 2x12" speakers at 8 ohms, so only the 4 ohm impedance is absolutely necessary.

It’s really your call about what you want to build. As has been mentioned above, the transformer set will work except the choke may be underrated since the Super places the choke in the power tube plate supply where the current is highest. The choke needs to be rated for higher current or you will experience excessive sag and eventually failure of the choke. You could move the choke to the screen supply and it should work fine. However, now you are deviating from the 5F4 design. If your goal is to build an exact clone of a 5F4 super then it’s a different story and you would probably need to locate individual transformers from specialty sources. Total cost would be much higher. I took a quick look but I did not see an exact match for the 5F4 in the MC line.

If you build with the proposed transformer bundle & mods you will still have a nice sounding amp and you will get a little more power because of the PT & OT upsize. The bundle price is good and MC quality is excellent. The 40/50 watt transformer set is just what they have settled on to satisfy the need for several amps.

The Ceriatone layout does not include screen resistors. If you really like to crank your amp into power amp distortion I recommend that you add them to your build.

And now a little rant about the Ceriatone supplied layout:
The cookie cutter copying of old circuits leaving out improvements such as the screen resistors is just dumb. It demonstrates that the people running these companies do not understand the technical aspects of what they are doing. I suppose that’s OK as long as they don’t claim otherwise and you can participate in this forum for technical advice.
End rant.

The 5F4 Super was designed at a time when the tubes were cheap and generally higher quality and, most importantly, when the amps were played clean. Fender soon added the classic 470Ω screen resistors to their designs. You can do that too. 1kΩ / 5W screen resistors would be even better. Their purpose is to reduce the steep rise in screen power dissipation that occurs when the power tubes are driven into distortion.

Regards,
Tom

[Travst]

Yes a significant difference is the smaller OT used in the Super. Here are a couple of comparison photos.
Both models sound great. The Magnetic Components OT has a multiple impedance secondary which is nice.

Yes, I thought the Supers had smaller iron as well, but MC seems to recommend the 40/50 watt transformers. I wouldn't mind finding a match in the MC line that's a lighter wattage. Any recommendations? I'm using 2x12" speakers at 8 ohms, so only the 4 ohm impedance is absolutely necessary.

[Tom Phillips]

The bassman iron should work, but i think the original Supers had smaller iron. If that a consideration.

Yes a significant difference is the smaller OT used in the Super. Here are a couple of comparison photos.
Both models sound great. The Magnetic Components OT has a multiple impedance secondary which is nice.

[ThermionicScott]

The bassman iron should work, but i think the original Supers had smaller iron. If that a consideration.

[Travst]

Joe, I should have specced which layout I'm using. I'm going by the Ceriatone layout in general. Thanks for the tip, I'll talk to Triode about the choke.

http://ceriatone.com/images/layoutPi...one_100508.jpg

John

[JoeM]

Are you doing an exact copy of the 5F4 power supply? The 5F6A has the choke in a different location, (like other later Fenders), but the 5F4 has it earlier in the PS. You might contact Triode and see if they carry the larger choke.

I used the choke in that set in my 5F6A clone, and have used a Magnetics Components OT for a DR in my Princeton. Very happy with them, and Triode was a great company to deal with.

[Travst]

Hi all, first post here after lurking for a time.

I picked up a nice tweed cab in a trade and a 5F4 Victoria chassis on Ebay. My parts will be arriving over the next few days to start this build. With regard to transformers, I'm looking at the Magnetic Components Tweed Bassman set from Triode:

Fender Tweed Bassman Transformer Bundle

I want to make certain I've made the correct choice before ordering. Do these fill the bill? If anyone's used them, how do you like them? The reviews seem very positive here and elsewhere.

John