EI-625 Lam Outputs

Thanks Mike,
I have a good working prototype 45 headphone amp and I'm ready to take all the good things learned from it and move it over to a wife approved chassis. I came across a mention of the EI-625 lams in an output and wondered if they were available to try. The power supply question was because I'm using a big Hammond to have extra taps in case DC was needed. Not using DC filaments now and I think with better routing I won't need such a big transformer.
I'll stick to the 404's.
Thanks,
Alonzo

RE: EI-625 Lam Outputs, posted on August 25, 2016 at 20:21:26
OldNuke Audiophile Posts: 141 Location: Silicon Valley Joined: November 18, 2014	Bottlehead just announced a sale on it's Mainline headphone amp, could an EI-625 output be commissioned at 4K? Alonzo

RE: EI-625 Lam Outputs, posted on August 26, 2016 at 17:58:12
mqracing Manufacturer Posts: 4323 Joined: June 29, 2000	Yes. But i suspect your putting entirely too much emphasis on a core size in isolation. Not too be a wise guy... but why would EI-625 be magical as contrasted say with EI-50 or EI-75? MSL Builder of MagneQuest & Peerless transformers since 1989

RE: EI-625 Lam Outputs, posted on August 26, 2016 at 20:46:19

OldNuke
Audiophile

Posts: 141
Location: Silicon Valley
Joined: November 18, 2014

I would have no idea. :) I'm just a hack guessing on what may or may not sound good. I'm no where near your level of knowledge in developing parts or the synergy of assembling the right output in the right circuit.

I picked out the EI-625 because of a mention from Paul Joppa in another posts, because I'm finishing up my current build (at least the experimentation part of it), I'm looking for my next project.

RE: EI-625 Lam Outputs, posted on August 30, 2016 at 18:40:38
Paul Joppa Industry Professional Posts: 7296 Location: Seattle, WA Joined: April 23, 2001	I don't recall anything, but if you can find or quote the reference to me I might be able to clarify. FWIW the stock (Bottlehead) Mainline outputs use EI75 lams, nominally 4K primary impedance. This is the same size as Mike's excellent EXO-35/36 and EXO-45/46 outputs, which are spec'd at 2.5K and 5K ohms.

RE: EI-625 Lam Outputs, posted on August 30, 2016 at 19:50:45

OldNuke
Audiophile

Posts: 141
Location: Silicon Valley
Joined: November 18, 2014

Hi Paul,
You mentioned a stack size and info after Mike mentioned he had these vintage low nickel lams and needed to complete the design and get them in the catalog. Copy below:

Posted by Paul Joppa (P) on February 18, 2015 at 19:22:01
In Reply to: Teaser Post posted by mqracing on February 17, 2015 at 00:57:27:

You know, Mike ... a 1.25" stack of 0.625 lams is about the same area as an EXO-35, and the same core geometry as a TFA-204. Just a thought ... :^)

I like the other vintage items I've gotten from Mike and thought these would be a good one to try to design a headphone amp around.

My Mainline is finished (never to be touched as to not let out any magic dust) with TL-404's in it. I have a 45 SET amp with Mike's EXO-45, well they are 145's with Litz wiring.

RE: EI-625 Lam Outputs, posted on September 2, 2016 at 12:23:15
Paul Joppa Industry Professional Posts: 7296 Location: Seattle, WA Joined: April 23, 2001	I was just making a somewhat goofy idea. The TFA-204 is a slightly unusual core geometry, the stack is twice the leg width. There is a theoretical reason to choose that, but as Mike says it's only one of many considerations. In case it's not clear, the 625 just means the leg width is 5/8 inch. There is no other magic to it!

RE: EI-625 Lam Outputs, posted on September 2, 2016 at 23:11:35
OldNuke Audiophile Posts: 141 Location: Silicon Valley Joined: November 18, 2014	No worries, I didn't expect it to be a given idea. Experimenting with different things is how we find that magic combination. It's not guaranteed to be good but it's not guaranteed to be bad either.

RE: EI-625 Lam Outputs, posted on August 26, 2016 at 18:00:44

mqracing
Manufacturer

Posts: 4323
Joined: June 29, 2000

Best way to proceed is to start with what pri andsec impedances you would need and the max operating level.

I just finished up a custom headphone output for Wavelength Audio. Many hours put into this design but it is pretty trick.

MSL

Builder of MagneQuest & Peerless transformers since 1989

RE: EI-625 Lam Outputs, posted on August 26, 2016 at 20:50:56
OldNuke Audiophile Posts: 141 Location: Silicon Valley Joined: November 18, 2014	Okay, I'll nail down a project schematic or 3/4's of one and get your assistance on the right iron.

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EI-625 Lam Outputs

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