Amplifier Power Question

[PENG]

Great! Really great!

You see, Here people often talk about the importance of having substantial power in a well designed amp. Then again, other than being overpriced, I never heard one bad word about these high-end Japs like Accuphase:
View attachment 19923

Most of people seem to agree that these are not mere objects of desire and beauty, but really well engineered units. Now, the one in the picture has 2x30Wpch into 8 Ohms. THIS is why I asked all those questions. I wanted to know is it 'much ado 'bout nothing'.

The description says this:
In the output stage, power MOS-FETs renowned for their excellent frequency response, sonic performance, and superior reliability are used in a triple parallel configuration and driven in pure class A. This is sustained by the strong power supply featuring a massive transformer and two large 47,000μF filtering capacitors. Output power in each channel is rated for an impressive 150 watts into 1 ohm, 120 watts into 2 ohms, 60 watts into 4 ohms, and 30 watts into 8 ohms. Even speakers with ultralow impedance or drastic fluctuations in impedance curve can be driven reliably by this impressive amplifier.

OK, I see there's some 'sonic performance' talk, but you gotta have a wee bit of marketing. They also say that it could run difficult speakers. I guess it could.

If it is a pure class A design, and I am confident Accupase knew how to do it right, then the sonic performance talk were valid in the old days and even now, in theory. Modern class AB, D and other designes can just be as good in terms of distortions of any kind including IMD. I still prefer Class A just for the sake of it, not that I can hear the benefits. Too bad they are so heavy and relatively expensive, and run hot. For preamps, I would always go class A as there is almost no down side.

 

[sterling shoote]

I have a JBL B-380 Sub in my system. This sub was powered by a 300 watt amp; but, I had clipping when playing dance music at high SPL. This sounds like a sledge hammer hitting concrete. I moved up to 600 watts and now no problems. Some subs would not begin to work however on 600 watts. At any rate, 100 watts on all other channels of my HT seems to be adequate.

 

[ski2xblack]

That Accuphase is an example of one with "regulated" power supply that doubles down; it has no dynamic power reserves above those power ratings, so if one had speakers and listening habits such that they never needed more than 30@8/60@4/120@2/150@1 peak output, then it would suffice. The low power reflects the practical limits of class A amps, which are all invariably toaster ovens. The price reflects the more expensive power supply, heat sinking, robust (more costly) parts, the fact that they are hand made in Japan by audio fanatics, and years of marketing to cultivate a cult status. Accuphase seems to me to be Japan's answer to McIntosh, as far as prestige status within the market...they even have power meters.

 

[Dave Blount]

Accuphase ........a beautiful piece of kit for sure !

 

[ChGr]

.

 

[Bob Leonard]

Technical specifications

Class

A

Type

Stereo

Gain (dB)

26

Full Pwr @ 26 dB gain (V)

0.77

Low Frequency Response

1.5 Hz

High Frequency Response

100 KHz

Power Output/ch (8 ohm)

30

Power Output/ch (4 ohm)

60

Distortion (1 KHz, full power)

1%

Input Impedance (SE & BAL Kohms)

30/20

Damping Factor

150

Output Noise (uV)

200

Power Consumption (Watts)

200

Temperature (deg C.)

53

Number of Chassis

1

Dimension (W x H x D) (In.)

19 x 7 x 19.2

Unit Weight (LBS)

62

 

[Bob Leonard]

Which amplifier has more head room? the Pass Labs or the Denon AVR-X3300W.

Number of Power Amps 7

Power Output (8 ohm, 20 Hz - 20 kHz, 0.08% 2ch Drive) 105 W

Power Output (8 ohm, 20 Hz - 20 kHz, 0.05% 2ch Drive)

Power Output (6 ohm, 1 kHz, 0.7% 2ch Drive) 135 W

Power Output (6 ohm, 1 kHz, 10% 1ch Drive) 215 W

 

[highfigh]

View attachment 20806


Technical specifications

Class A

Type Stereo

Gain (dB) 26

Full Pwr @ 26 dB gain (V) 0.77

Low Frequency Response 1.5 Hz

High Frequency Response 100 KHz

Power Output/ch (8 ohm) 30

Power Output/ch (4 ohm)

60

Distortion (1 KHz, full power)

1%

Input Impedance (SE & BAL Kohms)

30/20

Damping Factor

150

Output Noise (uV)

200

Power Consumption (Watts)

200

Temperature (deg C.)

53

Number of Chassis

1

Dimension (W x H x D) (In.)

19 x 7 x 19.2

Unit Weight (LBS)

62

I started, go ahead and finish. Thanks

 

[PENG]

Which amplifier has more head room? the Pass Labs or the Denon AVR-X3300W.

Number of Power Amps 7

Power Output (8 ohm, 20 Hz - 20 kHz, 0.08% 2ch Drive) 105 W

Power Output (8 ohm, 20 Hz - 20 kHz, 0.05% 2ch Drive)

Power Output (6 ohm, 1 kHz, 0.7% 2ch Drive) 135 W

Power Output (6 ohm, 1 kHz, 10% 1ch Drive) 215 W

There is no comparison but the Denon offers much more power for 2 channel use.

 

[Verdinut]

IMO, Class AB is the best compromise:
1. Consumes less power than Class A
2. Heats less than Class A and will therefore outlast most Class A amps
3. Can put out a lot more power in a chassis not as heavy as a Class A unit. You stand less chance of being short of amp headroom with AB
4. Costs less than most Class A amps.
5. A well designed Class AB will meet the specs of most Class A amps, in which case, you won't be able to hear an appreciable difference between the two designs.

 

[Ampdog]

Just a practical point of comparison, if I haven't missed it: It is mostly agreed that while audible, a 3dB difference in output is slight, as in 'not worth writing home about.' 3dB is a factor of two in power. Thus, it is generally not worth vacillating about amplifiers with less than factor two in output. As in: It is hardly likely that an audible difference will be noticed between amplifiers of maximum outputs 100W and 150W.

Regarding 'stiff' power supplies, I would mention that for general music reproduction, a supply with a large value storage capacitor would not perform much different from a fully regulated one. This because of the nature of most music having a relatively long time between peaks of quite low amplitude. The cost of such capacitors may not be much less than a regulated supply; the reliability tends to swing my vote thataway.

 

[Ampdog]

Regarding class A vs class AB, it needs to be realised that class A is not necessarily better as in having inherently lower distortion - it depends on the design. Hopefully the old problem of possible cross-over distortion with class AB has long since been buried. With correct design there should not be any audible cross-over distortion in class AB topology. (See articles by Douglas Self, Rod Elliott and others regarding this.)

 

[Verdinut]

If it is a pure class A design, and I am confident Accupase knew how to do it right, then the sonic performance talk were valid in the old days and even now, in theory. Modern class AB, D and other designes can just be as good in terms of distortions of any kind including IMD. I still prefer Class A just for the sake of it, not that I can hear the benefits. Too bad they are so heavy and relatively expensive, and run hot. For preamps, I would always go class A as there is almost no down side.

No down side except for higher heating, more electric consumption and stiffer price.

 

[PENG]

No down side except for higher heating, more electric consumption and stiffer price.

Stiffer price, generally true, so is power consumption but that's minimal considering the inherently low consumption of pre-amps. That's why I qualified it with the word "almost".

 

[Johnny2Bad]

Output power depends on two factors ... the input sensitivity of the power amplifier (which you should be able to determine from the specification sheet) and the voltage output of the preamplifier or other source with volume control.

The actual location of the volume knob is irrelevant, as it indicates the difference between minimum and maximum output, but the maximum output is not a fixed value; it depends on the source output.

So your preamp may provide 1V output, and your power amp may produce it's maximum rated power with 1V input, but a phono preamp and optical disc player are unlikely to generate the same output voltage. So for example the amp may clip at 11:00 with a CD in the drive and not until 3:00 with a record on the turntable.

All of the above is also dependent in impedance matching between components, as this also affects voltage outputs of preamps and sources, but for the sake of discussion, it can be ignored provided the components are considered compatible.

You are supposed to use your ears to determine the Sound Pressure Level and to detect distortion, not the relative location of a volume knob.