I'm happier with my 336i now that it's running DC heaters. Much, much less hum regardless of whose 6SN7 I run it with. Now I'm giving some thought to those 10uf caps. They're paralleled to 30uf. I'm thinking a single 33uf Obbligato film cap on each side would be a major improvement. Before...

Yep. It's those AC heaters. I'm not happy with the build--the 35v 2000uf electrolytic cap's too large and the 250v 1uf polyester's almost as large. That forced me to locate the bridge rectifier and it's caps at the rear of the amp with twisted pairs running from the AC source on the PC board...

About 10 days ago I dropped a note here asking if anyone had seen this HA: Single End Tube Head Phone Amp Kit - Plug and Play I didn't get any responses but then I'd never seen mention of it so I wasn't surprised. The vendor's got good feedback, charges very reasonable shipping from HK...

I bought this via eBay. I did a bit of searching here but came up empty. It was cheap enough (95 bucks shipped). The HK seller has very good feedback and charges reasonable shipping. He also sells the PCB for 14 bucks shipped but I didn't feel like sourcing the parts, etc. After giving it a...