L'Amp: A simple SIT Amp

[generg]

thank you very much, BTW for asking.....bulb rolling, he,he sounds good....!

[generg]

Originally Posted by Salas

That's what I found in Wikipedia about that phrase:

steely-eyed missile man
English

.........
1. (US, slang) A NASA astronaut or engineer who quickly devises an ingenious solution to a tough problem while under extreme pressure.

Hi Salas,

perfect, that is exactly the way I feel the last two years when I retired and started to work with the Pass "Apollo" Forum.....every year two or three new rockets (F5 turbo, F6, SIT, M2, J2....) published by the Amp committee in Foresthill.

I reflect to change to the Russian side maybe there is less stress and more vodka.....

[Salas]

Yes, switch to Energiya rockets!

[generg]

O.k. The SIT with the four 3,3 ohm resistors is the best!

NO doubt! All shyness is gone! Precise, powerfully til the bottom. With my quick B1 now a bit bit too sharp wit my Lowthers.
Maybe for Lowthers characteristic I preferred in the past darker sounding amps.....

What a change! Of course I will look for the distortion spectrum, maybe I have dominant k3....
Unfortunately I have now a good hum, is it possible that the placing of the resistorloop in the case nearer to the xformer is hum susceptible? I suppose so... Because I put away the second channel, crippled F4, to lower the current and the hum remained on the same level.

Mike you are right to persist on the try with the bulbs or resistors, they set the level for other solutions like CCS or Mufollower!

Salas please another CCS, still better than the last....

Best Gerd

[Salas]

See solving the hum issue first, if the hum won't go no matter what resistor loop care, its about PSU breakthrough including its higher harmonics. That cascode CCS gives great PSRR up very high, I could present you a single Mosfet one with a TO-220 having a faster gate for mid way results you may prefer, and less components, but try solve the issues when using a resistor first, since you gravitate towards that one. And let me know.

[Franz Gysi]

Gerd

You are using for resistors in series, right?

What wattage did you choose?

Franz

[generg]

Hi Salas, thanks!

yes I will look for the hum by placing the resistors in other way....

the bulbs have a good place on the top of the case, less hum.
o-k- with your CCS the hum was really absent...

I am still not happy with so much wattage in resistors......

so I am open to try another CCS solution, really!
" its about PSU breakthrough including its higher harmonics." What do you mean by this? I use an 500W xformer and the normal First Watt pcb with 8x22.000uF, not sufficient? even for one channel? of course I combined the two +-24V to 48V.

hi Franz,

I used three 3,3 and some 1,5 and 1 Ohm Vishay metal combined, I got them here

50 Watt, axial bei reichelt elektronik

I suppose this non inductive Vishay should be better......?

RTO 50F 10 - Dickschichtwiderstand 50W TO220 10 Ohm, 5 - Dickschichtwiderstände TO220 bei reichelt elektronik

[Salas]

I wrote IF its not due to loop hum then its about PSU breakthrough. Don't be surprised if there might be charging cycle products in heavy PSUs also. Very low impedance goal in such PSU is another thing. SE power stage has no cancellation like PUSH-PULL, plus some gain here. Remains to find out if its due to loop sensitivity for transformer field. I will see about another CCS for you to try soon enough then.

[Michael Rothacher]

All my copies are fairly quiet.

Part Deux has around 30uV of noise.

[Michael Rothacher]

Hello Gerd,

I'm glad you tried it. Are your Lowthers 16 Ohms? What is the supply voltage?

I'll have some data and info on various CCS's later, after Part Deux comes out and I finish my current project. But, by all means, full speed ahead.