This is the second one of these preamps I have owned. The first I sold and regretted it and as it's hand built I was resigned to the fact that I wouldn't find another until I was browsing on Audiogon and I found this one 
It uses the 01A valves for output and a 6BY5GA for rectification. Rod Coleman filament boards and Ale Moglia gyrator boards so no output transformer. Parts used are good, mid level quality. The volume pots will be changed at some stage but I'm still deciding which direction to go and it's rather costly. Maybe transformers would be good?

I'd been lucky enough to find a Lundahl C-core mains transformer that came from an Absolare preamp and the 2x split bobbin filament transformers I ordered from Hammond. Once all parts arrived I sent it down to Dark Lantern member Colin for installation.

So it's all converted to NZ voltage now and Colin was great to deal with. Shame he moved back to the UK 

I was also lucky enough to score a pair of Duelund caps for the gyrator boards which I'll install when they arrive as the Dynamicaps are kinda hard sounding. 

Below is an Amorphous C-core choke to replace the Hammond choke that a chap in Singapore made me. I hooked it up and liked it immediately (I wasn't expecting the difference that a choke could make) but it wouldn't fit with the mounting bracket that was attached so I thought I'd cut it down so the the overall height would be lower and it'd then fit no probs. Well that didn't work as the bracket was very soft material and warped so this is now no use and I'm unsure of how to mount it.








Any ideas on how to mount this choke? Should I just cut the rest of the bracket off and use a large jubilee style clip round the outside of the whole thing and tighten it with a bit of wood between the choke and top plate of the chassis?

It'll need to go in the space where the Hammond choke resides in these pics. When I temporarily installed the amorphous choke to have a listen I noticed that it caused some hum which I'll have to try and remedy. I'll do this once I have the mounting sorted by using a bit of steel which I'll connect to earth and place in different positions around the choke and listen to see if the hum stops. Hopefully I can fix it.









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Here are a couple of pics showing the new transformers installed and the overall layout internally





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You could try bending a 'U-clamp' out of alumin (not steel) & clamp the c-core choke down onto the chassis - laminations flat on chassis or standing up on edge, but long-ways to lower height.
You might try to utilise the existing 2 screw holes to attach your new U-clamp.
With some compressible material betw clamp & choke.



Ideally it's lams should run 90deg to the PTX lams above, to minimise AC EM hum coupling.

Keep us posted!

Oh, twist all your AC wires (including signal wires) & keep away from signal wiring.

DarkLantern blog - darklanternforowen.wordpress.com

Some times my questions seem trivial but I learn every time so thanks!

I'll look into the clamp idea and let y'all know.