- Feb 3, 2020
- South East Asia (not China or SAR's)
Unfortunately, my EL156 pentode Regulator produces more than the regular noise. So first trying to bring this down.
I suggest you learn to use a simulator and read up on the Tube Regulator.
Need this Low noise voltage for the phonostage Experiment. It does now hum Like hell.
I would use an LC Pre-filter and then work out the kinks. There is no reason for regulators to hum, but watch heater-cathode leakage and the parasitic heater-cathode diodes.
Compared with the EL34 triode Regulator of the Fairchild 670, which one will be better suited for an audio PSU, pentode or triode regulator?
I have only use Triodes as pass elements, generally speaking "high perveance" types.
Use a pentode as Error Amplifier.
If connecting the load as I show, the load will be bootstrapped by the pass element and gain is maximised, plus noise is minimised, as the error amplifier is supplied from the regulated output to lower noise.
Supply the screen and the reference from the regulated supply as well.
I thought a triode regulator has lower Output impedance, but might be wrong on this.
Both regulated PSU needs extra 200V, means the Transformers have to supply this extra voltage. If I would use my Siemens Tube E235L regulated PSU, it would only need 100V extra voltage in triode mode. Much more efficient.
Use 6AS7/6080 which were designed as regulator pass element, or why not go hybrid and use a MOSFET?
P. S. Nice amp! My F2A uses EL84 driver, too. Thats quite the Sakuma principle, beefy driver section for good sound.
It was one of the first 300B Amp'd I build I felt was good enough to share AND reliable and simple enough to build.
He liked to use cheap TV or Radio set tubes, so why Not cheap B+ regulators, too? LOL
Indeed. As said, sometimes excessive 2nd guessing is useless.
You think he destroyed the advantages of achieving a Low impedance B+ Output with heavy filtering after the IC?
Well, the chokes add a lot of DCR AND impedance. So the low output impedance will be swamped out by this.
Say a regulator has 100mOhm ouput impedance, we use a 10H/100Ohm Choke.
At DC the output impedance of the combination will be 100.1 Ohm (basically Choke DCR) at DCR and 6,283.3 Ohm at 1kHz.
And yes, changing the regulator one one with 10mOhm will not have a relevant change and having a 10 Ohm output impedance will still have minimal effects.
So any Choke Filters should be placed prior to the active component?
Depends on your goals.
I suggest that a first bulk filter first, solid state regulator and RC filter chain with relatively low value resistors and film capacitors preserves the classic "tube sound" without "the sound" of the regulator interfering, while getting good operating condition stability, minimal noise etc.
So hence my setup of:
CLC -> active Reg -> RC to tubes
for my stereophile Class A rated 12,000 Euro tube/Hybrid phono stage.
I really think he put passive filtering behind it, but its no safe bet.
I think so, because my experience is that even tube regulators with high feedback tend to cause what I'd call "overly tight" solid state sound to classic low/no feedback tube circuitry.
Prior to His IC are just Caps and a resistor, means the active Filter Starts very near after rectification.
Yes, have a first bulk capacitor to hold up line, use modern electronics for a bulk of noise rejection (this has penalties) and then a classic LCRC filter chain will give the most classic tube sound.
He could have applied it the wrong way, Just because to His ears it meant sounding better.
There is no "wrong ways", there are different goals and different ways of achieving them.
Will this, technically speaking, be the best serial Tube regulator? A pentode? Maybe I got this wrong? Please explain. Thanks.
What I showed is a high power tube rectified and regulated regulator with up to 2 X 100mA @ 450V output and avoiding any electrochemical capacitors (that's a hobby horse of mine).
It was one of my earlier attempt's when I was still overly influenced with a Pro-Audio and Industrial Electronics designer mindset and more of a Technocrat and given to achieving my design goals using orthodox "brute force" feedback based methods. I didn't know better.
Over the years I tended to avoid using ANY regulated supplies where this is possible. Yes, it needs more inductors and capacitors to get low noise, more size, weight, cost but to my ears I preferred the sound. You do need stable mains for that of course.