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If you want to build it, what you mustn’t miss is the opt primary must measure 250 ohms primary resistance. Most cheap small 5k transformers are in range. 10 ohms either way likely, 20 might not matter. Hook it up bring up on variac testing at each step, if that goes well take you’re final voltage readings at b+ identified by Raymond, otherwise adjust resistors on test if you can settle where it’s comfortable.

Someone who built it commented.

“Polite” eh.
I know all about that. IME politeness seems to be a function of lack of power output or an inadequate gain structure. My 60W NVA thingy kicks ass and takes down names. Often it’s been far too much for my lily white ears in my tiny box of a room. Not polite by any means until I attenuated the input levels. It’s now powerful and neutral.
The 2W 45 is utterly exquisite on simple music and melts the soul: however, Deep Purple on the 45, even through 98dB/W speakers, sounds like Ian Paice has been replaced by the reverend Richard Cole playing with brushes. All depends on the musical programme you feed it with, but I wouldn’t be without it. At it’s best, it’s mesmerising.
The 6-8W (depends on the output valves) E-Linear breadboard I’m playing with, takes a more middle-of-the-road approach and sounds good on a wider range of music than the other two do in my system. Doesn’t mean in absolute terms that it’s the best of the three, just that it is the most accommodating one with my speakers.

Too polite may or may not mean that the guy on the asylum is running out of steam with the speakers he’s using. You won’t know until you’ve finished, whether it suits your system. The speaker/amp interface is where the action is. Didn’t really appreciate that until recently. More fool me. Been told about it long enough.

Cressy Snr wrote: ↑Sat Jan 22, 2022 10:13 am
The 2W 45 is utterly exquisite on simple music and melts the soul: however, Deep Purple on the 45, even through 98dB/W speakers, sounds like Ian Paice has been replaced by the reverend Richard Cole playing with brushes. All depends on the musical programme you feed it with, but I wouldn’t be without it. At it’s best, it’s mesmerising.

My px 25 amp was described at the wam harrogate show as reproducing led zeppelin the best someone had ever heard, and everyone in the room agreed, their son was a drummer
And said how lifelike the drums where.
The main difference is the power supply...

steve s wrote: ↑Sat Jan 22, 2022 11:23 am ….The main difference is the power supply...

Having 107dB/W speakers, with 2x18in bass units per side also helps. They are 8x louder than mine

There's not much difference between mine and your speakers Steve
If it where the speakers fault the amp wouldn't matter

When the signal gets more complicated and also with increased volume, the ac signals are spread through the power supply and the sound folds.

Yes, well the man on tubediy may not have had a strong enough power supply. Mine will be stronger than whatever he had Im confident, so were not limiting with our power supply here, and the ac on complex bits wont have a chance to be lost in the pwer supply because the 572b shall shunt regulate as much power as the signal section plus a little, and the shunt reg together with the amp will play the music.

On the subject of speakers and power amp. Not meant to be too negative to Steve Cressy but the Barbaric just couldnt drive these speakers. The 14 watt 801@ addressed that shortfall. The problem with the speakers is the drivers are totally inefficient and not full range by any stretch of the imagination. But their being told what to do by a boss amp! Yet with sosundstage imaging and delicacy where needed. Speakers have completely changed.

I'll get me coat.

If the speakers are those big white mets paul, they didnt really get on with the kt77 amp i was using but came alive with a solid state pa amp up them. I never tried to work out why, they were most pleasant with the f5 up them

That circuit looks simple but it's not. Those PS drop-down resistors ( R5,6,7 ) don't have any caps associated with them, so there must be feedback effects going on there.

What happened to breadboards and clipleads?

Great progress Paul...

Wow..

Cressy Snr wrote: ↑Sat Jan 22, 2022 1:47 pm I'll get me coat.

Don't you dare !

Nick wrote: ↑Sat Jan 22, 2022 3:56 pm What happened to breadboards and clipleads?

well it’s planned as the house amp, so worth making nice.

Ant, yep.

Steve Cres, oops

Mark, yes must be feedback there. Probably if someone didnt have 250 ohm opt bias of 6v6 could be adjusted wih 6sj7 plate load, within reason wouldnt damage the setup of 6sj7, but no drama, 251 ohms is great.

Ultimate dream is substitute 1619 for 6v6 but not yet. I had a lot of trouble trying to get the filament voltage right and just decided go 6v6 first. Battle with filaments next time.

Nice little Hammond case, only just big enough. Couldnt fit power supply in, unless I went switch mode.

steve s wrote: ↑Sat Jan 22, 2022 4:55 pm
...Don't you dare !

Only joking Steve/Paul Should have used a smiley.
Excellent progress on the Bates!