Schottky diode with low forward voltage

[Felice]

Hello
Yesterday I ordered the last Limited Edition BeePre 300B  Preamplifier Kit.

Our mains voltage in the Basel / Switzerland is 232-236 volts wavering.

My question, could you replace the Schottky 80SQ045N or 1N5820 with other types that have even lower forward voltage?
After all, it's about every millivolt profit that the LM 1085 works clean.

Best regards
Felix

[Paul Birkeland]

235V is going to work quite nicely, it's the 220V countries where things get a little low.

You might also consider picking up a 230:6 transformer and wiring it as a boost transformer, which will nudge up your line voltage a bit more and give you some extra headroom.

While there are lower voltage drop Schottky diodes, they are mostly in TO-220 packages that aren't going to work super well with the BeePre layout. 

[Felice]

Hello
Thanks for your answer. I still have an auto-transformer. However, 1000VA with Prim 230 volts to 246 volts. According to the data sheet. Let's see if that's not too much of a good thing. Will it then measure.

  Another question,
I already read, or in other words, it is recommended that in a pentode, when switched to triode, between anode and sreen grid ( g2) resistor, a UF 4007 is switched.
Apart from the layout, so in this case between R 215 and C9 / D9.
I do not know how far this changes the circuit. And if something really brings an advantage.
Has this been done before?


Best regards
Felix

[Paul Birkeland]

I would not recommend that alteration.

[Felice]

So the Bee Pre is finished today. Switched on and playing for 4 hours now. The sound is excellent.  Unfortunately, there is a problem. At about 6:00 pm the mains voltage fluctuated, so there was something unpleasant hum. Short measured. 230V. Accordingly, the sec voltage was 5.6 volts AC.

Now I'm thinking about buying the PVEA2000 230 / 200-215V auto-transformer 230VAC 200VAC, Tufvassons transformer.

[url]https://www.distrelec.ch/Web/Downloads/he/et/PVEA2000_eng_datasheet.pdf/url]


The datasheet shows sec 246 volts. This must be withstood by the two transformers.
After all, there are + 10% in the UK. Hope the power transformers do not go up in smoke right away.
Felix

[Paul Birkeland]

246V AC will work great with the 240V BeePre.

[Felice]

Hello
In the scheme, a 215 Ohm grid stopper is located.
Have I overlooked the instructions or does not it matter if he is missing?

Otherwise, the upgrade BEE QUIET is a quite outstanding fine thing

[Paul Birkeland]

If you leave that part off one of the 9 pin sockets, you will destroy one of your EL84s pretty quickly.

[Felice]

I'm sorry about it. I mean before 300B a grid stopper is located

[Paul Birkeland]

Not a problem.