Regulated Vs Unregulated chipamp power supply sound

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#23
It's difficult to design audio stuff, because you design against a background where some people want to insist that any or all parts of a system are the absolute best availailable regardless of cost, inconvenience, size or any other impediment.

This is unfortunate, in that it tends to produce designs that have no aesthetic of efficiency, any consideration of elegance is abandoned.

It is possible to discover the PSRR of many amplifiers purely by looking it up, in other cases simulation or even an estimate can be used. Then you can use whatever value of PSU noise produces whatever value of output noise you consider acceptable to generate a PSU design which is elegant if only in terms of employing the minimum number and most cost-economic components.

Or you can build some ugly old ****.
 
#24
It's difficult to design audio stuff, because you design against a background where some people want to insist that any or all parts of a system are the absolute best availailable regardless of cost, inconvenience, size or any other impediment.
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or the inverse case were the OP is limited to only using parts on hand.
Eg chip amp samples and found XFMR.

or designing halfway decent +/-regulators is harder than it looks.
 
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#25
^ Right. So either unwinding or finding another, easy way to manage the voltage on the xfmr are the two best solutions. Both have their value. Regulating + chip is harder than a small discrete kit and worse performing. Unwinding has the best bang/$ if the parts are already on hand.
 
#27
infinia said:
2,200uF per amp for 1V ripple RMS
20,000 for 5A is not unreasonable for a fully loaded transformer

30W amplifier peak draw at 8 ohms I = (1.414*(30/8)^0.5) ~ 2.7A
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STA540 data sheet says Vrail = 22, Prms = 34 W is RMS into 8 ohms...

So Prms = Irms* Vrms and Irms = Ipk/sqrt(2) Vrms = Vpk/sqrt(2)

Meaning that 2 x Prms = Ipk * Vpk.

or Ipk = 68/22 which is a bit more than 3A peak. ( 1KHz sine wave)

EDIT: My guess as to the "muddy" highs is that the tests are not level matched. Afterall, we're talking about 10% distortion at these levels. The cleaner one is likely putting out less power.
 
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#28
as Arty pointed out not using regulated supplies have increasing ripple and sag under heavy amplifier loads so the effective rail volts and accordingly the output power drops. so if you want to squeeze the last 1dB out, use regulated supplies set to stun but on the other side when he hooks up at 4 ohm loads the amp most likely chokes off on peak currents sooner.
tradeoffs -tradeoffs
 
#30
IMOP an amplifier IS a regulated power supply, so whats the point of having two of them in cascade, none except excessive complexity and potential interaction of both protection circuits and control loops!! However there are two circumstances where they are useful or mandated, one is where the power supply is in fact a direct offline switcher for weight or space saving, the other is where inadvisedly you are trying to push the absolute maximum output from a chip amp without exceeding its voltage rating and cannot absorb mains voltage variations, ripple and misstaps. If you are designing in the latter case it would be better to choose components allowing a more relaxed regime and some headroom. In short, no regulation unless absolutely unavoidable 🙂
 
#31
Dan Joffe at his LM3886 amplifier uses regulated power supply: Akitika GT-101 Stereo Power Amplifier

-> Big image of the regulated: http://www.akitika.com/pictures/pwr_supply_pcb_assembled_closeup.jpg

Class AB with a Regulated Supply...Approaching Class A?

The GT-101 has an electronically regulated power supply. That makes it unusual among audio power amplifers. But in some ways, it offers an advantage similar to class A operation.

Class A amplifiers can be among the most linear of amplifiers, and the least efficient. They draw a constant current from the power supply, no matter what signal is being delivered to the speaker. That says that a Class A amplifier doesn't modulate the supply rails..constant current drain produces a constant load on the power supply, and hence a constant voltage.

Is a Class AB amplifier with an electronically regulated power supply almost as good in that respect? If the power supply's output impedance is low, then the output signal minimally modulates the rails. That should cause less distortion at the output. In that sense, the Class AB with regulated power supply should be about as blameless as a Class A amp.

The one way that the Class A amplifier still has it over the Class AB is that at low listening levels, the output device has nearly constant current. That is, its operating current is the large class A bias current with the small signal modulations. Of course, at high output levels, the Class A advantage diminishes, as the output device then experiences wide swings in operating curren.
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#32
Class A amplifiers can be among the most linear of amplifiers, and the least efficient. They draw a constant current from the power supply, no matter what signal is being delivered to the speaker. That says that a Class A amplifier doesn't modulate the supply rails..constant current drain produces a constant load on the power supply, and hence a constant voltage.
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except this repeats the same erroneous claim that ClassA is constant current draw on the dual polarity supply rails.
 
#34
i have efficient speakers, i do not need the sta540 to produce its maximum to make it uncomfortably loud.

yes an amplifier is a kindof voltage controlled regulator.
i do not have empirical evidence, both i and others who had no clue did notice the difference between regulated and unregulated versions.
both my regulated and unregulated supplys are reasonably sized, along with the tank capacitors.
i did this comaprim with simular chips, tda1554q and tda8560q, same conclusions.
tda 2052 and 7293 did not have any noticable ( by me, naturally) difference between regualted and non regulated versions.
however, regulated sta540 does sound far sharper than tda 7293 or tda 2052.
i'm quite sure the 2052 ics are fake, i must add. the sounds is blurry, and it should not be at all.
 
#35
AndrewT said:
I have opened up the outer insulation of many different manufacturers' toroids.
All are bifillar, expect for the one trifillar.
I have found that they sometimes adopt slight variation in colour of the enamel coating between the two windings.
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good to know
should make DIY custom transformers a snap.
find some pretty 1" mylar insulating tape and should look pro.
 
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#40
got no other idea then.
when i test something i don't trust my ears, usually i ask people who are clueless about audio to have a listen and tell if A or B sounds better. so i'm sure the difference is not imagination at all. with any load any powersupply rail does sag some amount, maybe this "modulation" can somehow sneak into the chip and get amplified. but this is like shooting blind at the moon hoping it will fall and we all have cheese.

i'd be interested to find out why it sounds far better with regulated vs unregulated.
 
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