Mullard EL38 Triode connected.

[Nick]

From the original PSUD page

PSUD2 has moved! You can now get the latest downloads and support from the Groups.IO page at https://groups.io/g/duncanampspsud
This page will stay live for the foreseeable future to host older versions

If you go to the new link, it looks as if its still active.

[Paul Barker]

Ive failed to download the program even though Im in the group. the program is highlighted in blue I press download, nothing new appears in Downloads.

could someone with the exe file please email it to me at my this account paulv1505@gmail.com

[Nick]

http://www.lurcher.org/nick/psud2_build79.exe

I would think emailing an exe is likely to to be blocked.

[Paul Barker]

OK I finally have it it seems the Microsoft protections are restrictions require a whole load of hoops to jump through where in the old days you answered one question and it loaded.

i left my laptop turned off through all that period when there was a problem and turned it back on for the first time to do this. seems it wasnt affected by that issue. i barely use windows. only require it for Duncans stuff, and barely need that. Ipad is leagues ahead of windows for everything else.

thankyou Nick. the route to the download is very hard to navigate correctly when you are dyslexic. might seem simple to neuro typlicles, like getting a battle ship through a minefield to me.

[Nick]

I am conflicted between two answers to that post:

1. "neuro typlicles" Thats easy for you to say.

2. "neuro typlicles" who are you calling neurotically?

[Paul Barker]

Nice.

[Mike H]

Interesting!

[Paul Barker]

[Paul Barker]

Also note the right most voltage is where the lower drawn grid line intersepts the imaginary extent of the loadline off the chart. No idea where the 2nd harmonic is now but it sounds a lot better after the change to EZ80 one anode bias. Rught now anode voltage is 405v so I shall drop it to within max dissipation 390v position by means of my big blue variac.

The power supply is choke input 5R4 GY potato masher one (two anodes) per side. 1uF paper in oil then 30 h choke then Two 200uF (100 + 100) 500v Black Gates WKZ in parallel. No noise. The Geremy Epstein method seems OK this time.

Doing the changes threw my left hand out, it spasm’s violently if I try to continue. So I am resting it until another day when I will change the ECC88 bias to 6al5 diode bias. Also because of stroke I cant change cartridge to MC, so listening on a mm no name cartridge, but new and silver litz wired supposedly the original cartridge fitted by Hitachi.

I dare not fit the Ortofon 25FL in top condition, may left hand will probaby smash it to bits.

Baby steps.

[Paul Barker]

On the stroke unit day the OT’s asked if I had any hobbies? They were grinning from ear to ear when I told them. “Do that!” So I am doing it best endeavour. The soldering is shocking uggly! Maby after a week of not challenging the left hand I can do the next change.

I am no longer limited to 30 days before I am permitted to drive. Now my not having permition extends due to on going ‘Amyloid Spells’. Now I cant request permition to drive until I’ve seen the Neurology team’s Physios, who according to the GP will be the key to giving proof to dvla I am safe on the roads. Well since if I tried to mount an MC cart it would get smashed to bits violently, thats a long way off.

The stroke consultant’s last word is “We will review Mr Barker again in due course. “

I am happy and alive.

[Paul Barker]

OK so this amplifier is now all change. I need more power so I looked at PX25 but no appreciable power increase and 4% distortion.

So low power GM70. The driver same original ECC88 but as SRPP so CF output to drive GM70.

On the compound curves the operating point of 100v -2.2 bias 10mA shows ri 3k mu32 s 10.5 so it in this instance serves as the volt amp and driver. (Edit, I soon realised this wont drive the GM70 so got to work and came up with the schematic below. Further down in the thread.)

[Paul Barker]

[Paul Barker]

Forget it. The opts just dont suit the gm70. But its stupid to try put the Tributes on the el38 amp. So to improve the EL38 amp I shall sub in the 300b which on these 5k6 transformers should get me 12 watts at 4% thd. That is all Im going to make this amp do. So that will be a fairly quick adaptation. Then I can get on with the real Man’s amp. The GM70.

[Paul Barker]

Probably now converting this amp to 300b. 8 watts 2%thd.

This circuit ends at 5k interstage transformers, 300b takes over from there and terminates at same 5k6 opt’s.

Because I’m upping the b+ and have to voltage drop to the former parts of the amp, its a bit of a juggle. So best if I hook it up and adjust on test before publishing it. It should all fit on its own chassis.

[Paul Barker]

So this amp is simpler than building new monoblocks. I just have to add two 5k//5k interstage transformers, and two 300b’s The rest is all in there, just needs changing connections and some added resistors.

So this isnt too difficult an objective.