Rouge Un - a red preamp featuring Lundahl , 5534 & pumpkin output

[Dylan W]

Hi guys, here it the guy, winded back (still with the white top insulation) but it goes well with the winding job.View attachment 143780 I still wait for the exact core material and shield tape but it will happen. Stay tuned!

Amazing work.

Guessing core material should not be super critical because of the amount of feedback around it. TBH I have always guessed that Rupert did it this way as a cost-saving measure, an audio transformer wound on a cheap power transformer core with lots of feedback is cheaper and easier to mass-produce than a layered audio transformer.

Can you share some details about the construction? Is it a ferrite, a strip of GOSS (like a power tx), or something higher perm?

 

[thomasdf]

Looks like a glazed doughnut!

Even more when sipping on my morning coffee !

 

[Moby]

Looks like a glazed doughnut!

Should I keep it like this? I like it And to rename it to the "doughnut".a? If many people like this reply I will understand it as "yes"

 

[Moby]

Amazing work.

Guessing core material should not be super critical because of the amount of feedback around it. TBH I have always guessed that Rupert did it this way as a cost-saving measure, an audio transformer wound on a cheap power transformer core with lots of feedback is cheaper and easier to mass-produce than a layered audio transformer.

Can you share some details about the construction? Is it a ferrite, a strip of GOSS (like a power tx), or something higher perm?

It's grain oriented steel, heavilly shielded everywhere possible. Shielding material is something unusuall and it has to be custom made. Otherwise it's not so complicated. I already tested 6 diferent core materials and I wait for two more. One is close enaugh. I will reply as soon I recieve the rest of the samples.

 

[JMan]

Should I keep it like this? I like it And to rename it to the "doughnut".a? If many people like this reply I will understand it as "yes"

That re-name is cute But everyone know orange sounds better! In all seriousness though, while I think the orange gives the pumpkin a unique look, I vote for whatever is easiest and most cost-effective (if there is even any meaningful effect on cost).

 

[tk@halmi]

Should I keep it like this? I like it And to rename it to the "doughnut".a? If many people like this reply I will understand it as "yes"

I can’t speak for everyone, but the color really should not matter. We all know it is a replica. I kind of like the glazed doughnut look and designation.

Great progress, Thank you!

 

[thomasdf]

I think JMan gets an extra vote since they’re the owner of the sacrificial pumpkin !

 

[inf0]

Courtesy of google AI . Now I'm hungry

 

[JMan]

I think JMan gets an extra vote since they’re the owner of the sacrificial pumpkin !

You know, during autumn where I live, pumpkin donuts are a widely available specialty treat!

 

[Brian Roth]

Speaking of pumpkins, I ran across this pic from maybe 20 years ago. It shows a modified Neve 5106 desk (now retired). In the card cage to the right side, near the floor, you can see all the pretty pumpkins all in a row. <g>

 

[tk@halmi]

Speaking of pumpkins, I ran across this pic from maybe 20 years ago. It shows a modified Neve 5106 desk (now retired). In the card cage to the right side, near the floor, you can see all the pretty pumpkins all in a row. <g>

A whole pumpkin patch that is.

 

[gyraf]

Very interesting indeed - fantastic work, Moby!

I have all the parameters and the winding details

There's a whole series of questions that I'm exited that we to finally can have the answers for - we've been wondering about this for a long time now, and I didn't find these yet in this thread:

- The total DC-resistance and inductances of each winding before hack-sawing?
- The exact dimensions of the core once excavated?
- The dimensions (diameter) of the pri and sec copper wire?
- The order of the different winding layers, and where was the screening(s) put in?

It's grain oriented steel, heavilly shielded everywhere possible.

- How exactly do you know that it's grain oriented? That's a rather complex thing to deduce, unless there is a referenced part number on the core?
- By "heavily shielded" you mean the windings, not the core presumably? Heavily shielded just how? (Actually, come to think of it, I don't see any magnetic shielding band in your "exploded view")

Shielding material is something unusuall and it has to be custom made.

- Can you explain in more detail? How is it unusual, why would it require a "custom made" solution?

I already tested 6 diferent core materials and I wait for two more. One is close enaugh.

- We'd really like to know exactly what sort of core materials you tried, how you evaluated them, and how exactly you conclude what is close enough?
- What exact parameters did you measure for these different types? Can we know your source(s) for these six or eight different core materials?

It would be really educative and eye-opening for people around here to be able to expand this experiment on their own..

Goes without saying that I'm a big fan of this whole process - and I'm really sorry about missing PM's from some of you about the topic!

/Jakob E.

 

[Moby]

Very interesting indeed - fantastic work, Moby!



There's a whole series of questions that I'm exited that we to finally can have the answers for - we've been wondering about this for a long time now, and I didn't find these yet in this thread:

- The total DC-resistance and inductances of each winding before hack-sawing?
- The exact dimensions of the core once excavated?
- The dimensions (diameter) of the pri and sec copper wire?
- The order of the different winding layers, and where was the screening(s) put in?



- How exactly do you know that it's grain oriented? That's a rather complex thing to deduce, unless there is a referenced part number on the core?
- By "heavily shielded" you mean the windings, not the core presumably? Heavily shielded just how? (Actually, come to think of it, I don't see any magnetic shielding band in your "exploded view")



- Can you explain in more detail? How is it unusual, why would it require a "custom made" solution?



- We'd really like to know exactly what sort of core materials you tried, how you evaluated them, and how exactly you conclude what is close enough?
- What exact parameters did you measure for these different types? Can we know your source(s) for these six or eight different core materials?

It would be really educative and eye-opening for people around here to be able to expand this experiment on their own..

Goes without saying that I'm a big fan of this whole process - and I'm really sorry about missing PM's from some of you about the topic!

/Jakob E.

Hey, I will try to answer your questions as soon I finish my homework. But I do my best to make it exactly as the original. Stay tuned