When Suzy answers 8 after being asked "what's 5x3?" you don't tell her she's "incorrect and misleading". That'd be something more likely to be said by someone who thinks Suzy knows the answer and some of the other kids (who are trying to learn) don't, and she wants to screw them up! "Mislead" has the strongest connotation to deliberate deception of all its synonyms.
Onto business:
View attachment 426988
www.toppingaudio.com
Click specs, page down 3x, and the chart you see will include this bit I snipped out of it.
View attachment 426991
On the top of Page 5, 7.5: Electrical Characteristics
Highlighted above is the maximum voltage output capability of the TPA6120A2 connected to (+15V / -15V). We can either add those together or halve Topping's 37 Since
37 / 2 = 18.5
15 + 15 = 30
Can a linear amplifier running on 30 volts cause its output to be 37 volts?
Not last time I checked.
Does any manufacturer claim on their amplifier datasheets that the output voltage swing of their amplifiers
exceeds supply by 23 percent?
No, the standard amount amplifiers can swing past their rails is 12%..................
You say that 15 turns into +23V / -23V
That's misleading, sir: 15 multiplied by the root of 2 is 21, so
How much should we expect to droop to on those 35V bulk caps when the E30 II (or E30..) is doing easy work as usual, something like 30mW (98% of everyone everywhere's dissipation with dynamic drivers)
I think remember measuring power draw of the E30 II with my meter while idle, and it was like 3-4W
E30 II 15VAC 1A adaptor AC voltage at rest: 19.3V with 120.1V in
19.3-15 = 4.3V
15V * 1A = 15VA
3.5VA/15VA = 0.2333333
4.3V * 0.2333333 = 1.00V
4.3V - 1.0V = 3.3V
15+3.3 = 18.3V
18.3VAC = 25.9V peak
Bringing 25.9V down to 15V is a ha-uuuuge drop
10.9/25.9 = 42%
15/25.9 = 58%
###solution for above: When E30 II is running normally (ie. listening to a tv show through earbuds in a quiet room):
42% of its power dissipation is due to the regulators...
###solution for below: When E30 II is running normal efficiency headphones at 105-110dB level (headphones are 92dB/mW) it uses 1W more power than on and idle:
41% of its power dissipation is due to the regulators...
Instead of the voltage on the caps being 18.3V, the extra watt brings it down to 18.0V (18.01V to be exact...)
25.9V peak turned into 25.5V peak
Standard, nothing special regulators are usually designed keep the AC at least 2V about their output.
If we run on 15V DC, that means we need a minimum of +/- 17V to the regulators
27.2 open turns to 21.2 with 1 full A drawn
How many amps drawn required to drop further to 17?
21.2 - 17 = 4.2
4.2/6 * 1A = 0.7A
Total max draw design is 1.7A, but adaptor is 1.0A!
This is ... at least uncommon. It could be due to the transient nature of music that the transformer can be undersized like this, but looking at everything together, it makes more sense the adaptor is correctly sized and the internal voltage the 18.3VAC (25.8V peak) {(idle)} and 15.0VAC (21.2V peak) {(full load)}
Put another way, it doesn't make sense to leave an entire 6.2 volts above the regulated rail... we need 2, not 6.2.
The way it works out, the regulators, being fed from a 15VAC transformer, burn an extra watt when the 6120 amps draw somewhere between 60-150mA more than they do when idle (this would be during semi-loud music), than the would if a 12VAC transformer was used instead. Keep in mind, this is only
if 15V is what the 6120A2s are getting....
If that 12VAC transformer powering the E30 II with its + / - 15V rails was also rated for 1A, there would be no change in amp performance
The 6120A2 must be higher inside...
I don't see how the 6120A2's Vcc regulation can be done to
anything under + / - 21.15 volts!
Why? Because 37V peak to peak is 18.5V (one way). The 6120 datasheet
shows that you need to give it 2.5 to 2.8V more than you from the output, so:
18.5 + [(2.5+2.8) / 2] (unnecessary squares - just to make it clear
18.5 + 2.65 = 21.2V
Wait a second.... 15 * sqrt2 = 21.2
What a coincidence...
