crazy high rail voltage = better????

[tv]

"Hi-railing" the opamps can be used for "sag emulation" as well if a certain mod is performed ...

Using heroic rail voltages seems to me to be the "last cheat"

Let's see about that :twisted:

http://moosapotamus.net/IDEAS/F2B/alembic.htm

Replace the tubes with 2×IRF710. Sources must now have separate low negative rail (maybe from heaters), i.e. bottoms of catode resistors/caps go to negative rail.
(Or re-bias the gates.)

If it smokes, it's your expense ...

 

[tv]

Voltage alone is bogus.

Everybody knows "bigger is better" ...
(thong in chick)

 

[JohnRoberts]

S/N is a ratio so this can be a ratio between voltages or powers. Purists argue dB is only valid terminology for power ratios, but I embrace it (dB) for its convenience when cascading voltage ratios, with the only exception transformer turns ratios whose power ratio is roughly unity (but even that is tempting).

Transformers allow you to scale S/N voltage ratios while holding the power ratio constant, so this may be the basis of PRR's statement. While power is certainly a more complete characterization of noise sources, integrity of audio signal transfers in modern solid state electronics is more about voltage transfer, and S/N is the ratio between signal voltage and noise voltage.

While it seems logical that pushing rails to the sky will increase headroom, for perspective keep in mind that modern A/D convertors are routinely running from 5V supplies, with newer generation chips running at 3.3V PS.

I am not convinced that we really need +/- 15V rails to deliver good S/N but it sure is easier than trying to cleanly route signals all around a console with only a single 5V rail. I recall doing an analysis years ago between +4 dBm and -10dBV recording gear. There was no inherent advantage inside the box, with slightly better noise rejection in interfaces between boxes.

In the game of merchandising products you look for differentiating factors that "seem" like they should make a difference. Many consumers are thirsty to believe that audio is not a mature technology, and looking for simple changes to put their faith and money into.

JR

 

[Guest]

John;

15V is more than 5V if to compare to Vbe.

Join our fashion! :thumb:

Let's invent a loud slogan, something like "Higher Voltage means Higher Life Standards", or something better.

 

[JohnRoberts]

I appreciate the humor but have spent my entire career tilting against such windmills. Back in the '80s I even wrote a column called "Audio Mythology". It seems the old myths are still with us, and new ones keep popping up.

I blame the weak science education of the general public, but audio seems to attract a near religious faction of true believers in such nonsense, and a subindustry to profit from their poor judgement. [/rant]

JR

 

[Guest]

John;
audio is based on beliefs, and you know that.
We propose to support new beliefs that help to get better sound.
Join us!

 

[thermionic]

[quote author="Samuel Groner"]

I should have worded it as a 'complementary design', in which case you could run them @ +/- 120 V.

Can you elaborate? With signal just below clipping a transistor in the voltag amplifier stage will see the full power supply voltage, complementary or not. The input stage is another matter for a power amplifier as CM range is limited, but for opamp-like circuitry we want full CM range so the transistors might see the full rail voltage there as well.


Samuel[/quote]

I have to be honest and say that, whilst I've built many pre and power amps, I have never run the transistors (I've always been told it's bad practice - probably for the reason you cite) anywhere near their quoted Vceo or Vcbo - I tend to choose parts for noise and Hfe, so I stand corrected.

Modern MOSFETs and BJTs have generous ratings, but I have never needed more than +/-24v or +/-75v from anything I've built.

Even with a Rail-Rail op-amp, from what I can gather, you'll never get the full P-P rail voltage.

Justin

 

[thermionic]

[quote author="JohnRoberts"]I appreciate the humor but have spent my entire career tilting against such windmills. Back in the '80s I even wrote a column called "Audio Mythology". It seems the old myths are still with us, and new ones keep popping up.

I blame the weak science education of the general public, but audio seems to attract a near religious faction of true believers in such nonsense, and a subindustry to profit from their poor judgement. [/rant]

JR[/quote]

Is there any other industry that one could compare to audio in terms of the sheer amount of voodoo? IMO, mythology holds back the consumer from getting better hardware. Can anyone tell me of one positive thing that subjectivity has given the world? Why has no one claimed Randi's $1-mil prize?

If someone comes to you with a reliable empirical observation, there's a reason for it - I don't believe in the supernatural.

Justin

 

[JohnRoberts]

There are always slime balls standing ready to profit from peoples ignorance. (Hey wanna sub prime loan..? No money down, you pay interest only... what could go wrong?)

The biggest in dollar terms is probably the diet industry. While I love those "effortless" exercise machines (effort is the whole point of exercise). My new favorite is the "eat all you want and lose weight diet... we couldn't say it on TV if it wasn't true!". Perhaps it's eat all the sawdust you want, or something like that?

Fools and their money... As long as fools have money there will be shysters to separate them.

JR

 

[dale116dot7]

.... I knew there'd be a first taker on this album somewhere.... :wink:

 

[Guest]

Ok John; I remember an year ago you were arguing against power amplification; you told something like real modern well educated smart engineers don't amplify power today, they amplify a voltage only. Why you do not support a voltage anymore? However, it is dangerous to touch high voltage wires, and an appropriate means have to be applied working with dangerous voltages, but it is a theoretical discussion! Please look at Vbe compared to powering voltages, please look at Cgs, is not it impressive?

 

[JohnRoberts]

Not sure there's any argument, but I would have used different words.

Probably more like "modern audio engineers capture input voltages and after manipulation deliver output voltages. Even the imprecisely named (solid state) "power" amp actually puts out a voltage waveform not a power waveform. Any power generated in a speaker load is is a consequence of that robust voltage source being terminated by a speaker impedance.

Of course YMMV as usual.

JR

 

[tv]

IMNHO hivolt solidstate audio equipment that isn't power amps is primarily targeted @ "headroom" people. Edit: with wallet "headroom" as well.

 

[tv]

That's what I meant, yes. Lost the link though (**** happened ).

 

[tv]

I remember those "16" BD's. From my early 80's "100w in 4ohm" amplifier days .

 

[tv]

Thanks. Saved to HD.

You can abuse very similar circuit (if: single supply AND lower transistor network omitted; PLUS a certain diode/resistor/cap network pulling down the upper transistor when output signal present) for mimicking "tube rectifier sag" ...

I think peavey has some patents in this field, I have built 3 prototypes in 1989-1992 (I think that was before patents, might be mistaking, but anyway it's simple to pull off) which were succesfully used in studio recordings at that time despite being stuffed in plastic "soap" boxes.

 

[Guest]

Mediatechnology;
iIt appears to me that you've lost the point. Modern crystals are not necessary dirty so they survive high voltages without such bootstrapping that adds phase delays. It was excusable in 741 era, but now semiconductors can be powered by higher voltages so may be used on more linear parts of their transfer functions. However, BJTs are still current amplifiers. However, MOSFETs are device with capacitive inputs, but when Vsd is high enough their input capacitances are pretty linear.

[quote author="mediatechnology"]

Snatched this pic from some mic-pre design webpage which I can't remember. Likewise it looks like I can have a badass hi-volt 5534an for cheap ...

http://www.groupdiy.com/index.php?topic=18134

I posted that one. Yes, wavebourne is right about the 741 but again he misses the point completely and probably intentionally to just to attempt to tweak everyone and derail a thread. If you look further down the page you'll see the MCI swinging op amp link that used the 5534 (2003).

The EDN cite is limited because the non-inverting input is grounded thus limiting the input common mode range.[/quote]

 

[tv]

Just add the special Rinkwitz Liley 4th grade filter and it will SING !

 

[bcarso]

[quote author="tv"]... Rinkwitz Liley ....[/quote]

Are you smarter than a 4th grader?

I have to laugh as this reminds me (delairing thlead heele, solly) that in a recent book I discover that 1/f noise is now being called "flick" noise in certain texts by authors who might be supposed to have difficulty pronouncing l's and r's.

 

[tv]

http://www.rane.com/pi14.html
Last sentence @ 3rd paragraph.

It's the harmony, mann. The harmony!