Thread: Transformer Info – Lundahl 1550 “amorphous” core

Originally posted by Flatpicker:

What is “the low frequency resonance with external capacitors” referring to, or why would you use external capacitors with and input transformer?

They might just be saying that this core material doesn't ring even into capacitive loads.
Joe M. did do some graphs with various trafos and an impluse test ... (or was it a square wave ? ). Perhaps these were all output trafos.

Manley and my good buddy Pat are very big on this amorphus core thing. Been wanting to try one to see what all the hub bub is about.

Originally posted by cjenrick:
.... my good buddy Pat ....

:D
you guys do make me laugh.


Chris , talk to me about that T4B PDF.

Amorphous cores don't sound like fat iron. There you have it!

Originally posted by cjenrick:
...my good buddy Pat...

I take it I missed something exciting here. ;)

I’ll admit, Pat’s web site is what got me to researching the amorphous core material. Someone at another forum said he thought Pat’s “custom wound amorphous core transformer from Lundahl” was the LL1636, but looks like to me the LL1550 is a better match for the Forssell Fet Opamp. (Funny, Pat misspelled Forssell :D ) I’ve also heard that his design uses a cap on one of the center taps ( ) and switches between phantom powered primary coils to un-powered primary coils for dynamics and ribbons that don’t need it. Weird, but maybe it works...

I plan to research these amorphous core transformers when I find the time (an expensive commodity right now). If I find anything interesting that hasn’t been covered, I’ll post it.

Originally posted by Shalimar:
Amorphous cores don't sound like fat iron. There you have it!

Sounds (no pun...) like a decent substitute for the Jensen JT-16 for over half the price.

As always, thanks for all the input, guys!
[img]graemlins/beerchug.gif[/img]

Well, anymore daft enough to pay for his 'kits' should do some research on just what you get and the actual cost. 'Nuff said.

Nope. It's not a substitute. Lundahls are pretty unique, imo. They're highly 'invisible', you'd be hard pressed to hear a LL1517 in any kind of line circuit. It's likely more the effect groundlifting, CMMR and galvanic seperation. Makes 'em great for stuff like balancing and phase inversion without sonic penalties.

Jensens are not transparent in my book. More like Sowters. Fat iron. Very different overload sound compared to a Lundahl. Some folks even get dissapointed with Lundahls.

I would choose Lundahls for an entire console, but I like coloured stuff like Beyer, Monacor, JS & Telefunken for my outboard and micpres.

YMMV

Originally posted by adrianh:
Yes "My buddy Pat" does use the LL1636
as the input transformer in his kit.

Adrianh

Chrissugar,
Change that 99% to 100%. ;)

Originally posted by Shalimar:
Nope. It's not a substitute. Lundahls are pretty unique, imo. They're highly 'invisible', you'd be hard pressed to hear a LL1517 in any kind of line circuit...

So even though the "Amorphous cores don't sound like fat iron" ,the mu-metal ones are still not as colored as the Jensens? Are the mu-metal Landahls colored at all?

Right. I dunno 'bout all of them. I've tried five or six and none of the big tube output trafos. But the ones, LL1517, LL1577, LL1550, LL1538(XL) and some of the 79XX ones sound pretty different than all other trafos I've used.

Higher ratio always seem to make the trafo more sonically visible. But that's me, try for yourself.