audio-talk

Yep

It’ll take quite a while to mod, but I’ll report back once I’ve got it sorted.

I can rig up my other headphone amp with 6EM7 if you're curious Paul

0.9W is incredibly loud on headphones.

Newest audio circuit:

A bit more work on the power supply and we're within 1V of the previous bias of 10.5V on the power tubes:

There was a bit of residual ripple in the earpieces of my phones, but a mod to the power supply sorted that one: Voltages are lower but there is no difference to the sound that I can hear. It's still fab.

Yep, they're bloody good valves! :D

I've solved the gain problem by using 1/2 an ECC82 per channel. It is fine now in terms of volume control travel.
I've wired the valves so that triode 1 of one envelope is active on the left channel and triode 2 of the other envelope is active on the right ...

I've gone triode on the input stage in an effort to reduce the gain, but there's going to have to be a rethink in that department in order to pull the gain down some more.
Nevertheless the sound is great. I can certainly see why Paul likes the sound of this valve.

And the PSU:

Here's the audio cct:

Well, it's playing music as I write and what a superb sound!
IMG_0626.jpeg
Gain is a bit high at the moment so I might have to do triode mode on the 6BR7 input stage and forego the pretty little glow tube.
I found a nice set of curves for the 6BS7 in triode mode on Ale Moglia's site. The 6BS7 is ...

After a bit of re-wiring in a series/parallel arrangement off the 12V DC heater supply, we now have 6.3V at the EL38s and 6BR7s:

The postie brought these handsome devils this morning:

Mirror System - Route 77 (2024)

Well hopefully, they'll fit. I've looked at the dimensions on the Mullard data sheets and they should be OK. They are not the older, Philips "fat bottle" versions. They're more "thin bottle" GZ37 dimensions in width, like the later versions of the EL37.
I'll be using them triode strapped as per the ...

Got a pair of EL38 coming tomorrow.
Watch this space.