Bottlehead Forum

Bottlehead Kits => Mainline => Topic started by: hpleung on March 15, 2025, 12:36:16 PM

Title: 417 tube
Post by: hpleung on March 15, 2025, 12:36:16 PM

Hi,

I wanted to check if the 417 tube can be used on the mainline. With an adapter.

Thanks

Title: Re: 417 tube
Post by: Paul Joppa on March 15, 2025, 02:57:21 PM

Probably. Some issues are:

* The plate impedance is a bit more than twice as high, so it won't drive low-impedance headphones quite as well

* The parafeed capacitor might need a different a different value

* Both tubes are highly prone to oscillation at very high frequencies, so lead dress is critical. It may not be possible to make an adapter that does not oscillate.

Title: Re: 417 tube
Post by: hpleung on March 15, 2025, 04:00:05 PM

Thanks. I will try and see.

Title: Re: 417 tube
Post by: 2wo on March 15, 2025, 05:57:48 PM

If you're making the adapter yourself, you might be able to add some stoppers or maybe some ferrite beads internally. Might help a little. I have only tried this on a 6sn7 adapter