Poll

Your daily use amplifier's output per channel

1-10 Wpc
6 (5.8%)
11-25 Wpc
6 (5.8%)
26-60 Wpc
17 (16.5%)
61-120 Wpc
36 (35%)
120+ Wpc
38 (36.9%)

Total Members Voted: 91

Author Topic: Average amplifier power  (Read 2197 times)

Offline Hi-Phibian

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Re: Average amplifier power
« Reply #60 on: June 12, 2018, 03:41:46 PM »
That is also very interesting. Some years ago, I remember reading a review of 8 Japanese amps. The main criticism with regards to the volume pot. was that without exception all amps would run out of steam at the 12 o'clock position. From this position to the "maximum volume" position all you could get was more distortion! One might think that this was a marketing ploy for the consumer to think that the amp was very powerful, more that the claimed power rating.


Or just the fact that a tuners typical 200 mv will need more gain / less attenuation applied by the pre amp then 2000 mv from a typical CD player.
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Offline Ampdog

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Re: Average amplifier power
« Reply #61 on: June 13, 2018, 05:30:11 PM »
Posted by King_Julian_S   
Quote
Wow some really nice food for thought here

I totally agree.

Somewhat OT, but a pet moan from me:
-Stay away from speakers that are difficult to drive and for example, have an impedance dipping below 4Ohm with difficult electrical phase angles,...

Amen

This might be difficult, as this information is not always at hand.  But expecting from designers of amplifiers to bend over backwards to eliminate problems caused by other components has a limit.  From my modest knowledge of networks, these peaks can be avoided or at least compensated out by driver manufacturers. Perhaps egotistical, but there are loudspeakers out there with excellent response, offering a comparatively 'docile' impedance characteristic.

(At most, an amplifier can be designed to compensate for a particular 'difficult' driver load. But how many amplifiers must I design for how many different loudspeaker queers?)



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Offline BJ

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Re: Average amplifier power
« Reply #62 on: June 13, 2018, 07:53:23 PM »

-Stay away from speakers that are difficult to drive and for example, have an impedance dipping below 4Ohm with difficult electrical phase angles, Same applies to speakers with low sensitivity/efficiency


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« Last Edit: June 13, 2018, 07:57:59 PM by BJ »
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Offline Nidri

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Re: Average amplifier power
« Reply #63 on: June 13, 2018, 08:02:43 PM »
-Stay away from speakers that are difficult to drive and for example, have an impedance dipping below 4Ohm with difficult electrical phase angles, Same applies to speakers with low sensitivity/efficiency.

Which is the more important consideration - Sensitivity or Impedance?
My Spendor A2's are rated at a low-ish 85dB Sensitivity but the Impedance is rated as 8 Ohms*.
(25-125 Watts Recommended)

In practice they've proven fairly easy to drive.
They've made beautiful music with anything from 60W to 250W amps.
Even a 6W-rated 6L6 amp made them sound pretty good, though it's not an ideal setup obviously.


* A comment from the manufacturer (From a Hi-Choice review):

Did you opt for more extended bass, rather than sensitivity?
Yes. Many loudspeaker designers lift midband output to get a high sensitivity figure. A resonant reflex port or line is used to add back missing bass. Unfortunately the extra bass is usually out of phase/time with the original bass and listeners find that very distracting. By contrast, the Spendor A2 consistently delivers articulate, coherent bass. The freedom from spurious cabinet or cone resonance is important. Dynamic contrasts, from silence to loud, are reproduced very accurately. That makes the perceived sound output noticeably (2-3dB) higher than simple sensitivity measurements would suggest. A 4ohm loudspeaker will measure more sensitive than an 8ohm equivalent. Many loudspeakers are awkward-to-drive 4ohm designs. We engineered the A2 to be an easy- to-drive 8ohm load.

Offline Ampdog

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Re: Average amplifier power
« Reply #64 on: June 14, 2018, 01:11:35 AM »
A reminder:

As Hi-Phibian stated (post #60), it is often meaningless to use the position of a volume control as a reference of anything. The volume control position is entirely dependant on the magnitude of the input signal.

Furthermore, earlier I tried to indicate that small increases  in perceived volume might easily mean a doubling in output power. To put it differently, the following succession of output watts equals a just noticable audible increase in output energy:  3,  6, 12, 24, 48, 96, 192, 384, 768 watt and so on.  In other words, an increase in output from 400W to 800W is just perceptable - or put it in any other way you wish. Also meaning that the same differences simply does not allow any useful headroom!  Such (a useful headroom) may be portrayed as at least output X 4.
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Offline Gerlach

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Re: Average amplifier power
« Reply #65 on: June 14, 2018, 08:12:22 AM »
Ney man Bru....jhy ka mossi sulke recless statements maki....hie onne inni Cape luister en sell ons nog lekka Panels met Welding Masjinne

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Offline Shonver

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Re: Average amplifier power
« Reply #66 on: June 14, 2018, 09:14:52 AM »
...and then there's the belief that a good amplifier will double its power output every time you halve the load impedance. Like:

8R->200W
4R->400W
2R->800W
1(!)R->1600W

Others need not apply.

The truth is that _every_ amplifier can do this, until its limits are reached.*  The problem is that specmanship dictates that manufacturers have to express maximum output to look impressive. So, here it is, with max numbers in brackets**:

1R->hEllooOOoo... anybody home?
2R->150W(150W)
4R->75W(100W)
8R->37.5W(60W)

Unless a dedicated control circuit is in action in the first amplifier, it will similarly have non-linear maximum output figures:

1R->1600W(1600W)
2R->800W(1100W)
4R->400W(510W)
8R->200W(275W)

*Maybe not 2R or 1R, but Ampdog has already addressed that in post#61
**The figures quoted are hypothetical, though the effect is real.
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Offline Neil

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Re: Average amplifier power
« Reply #67 on: June 14, 2018, 10:10:25 AM »
Quote
A powerful amp playing only two watts is a totally different and an amazing sound compared to a flea powered amp playing at two watts.
+1

Nothing wrong with having a bit more oomph, you want to amp to CONTROL the speakers not the speakers CONTROL the amp, so yes that's why you always buy the most powerful amp you can at the time, dont always just settle on bottom of the range just to get by.

That 16 year onkyo amp i bought for the bedroom - so glad i did - 100w/ch for 6 ch - always enough power, its great!
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Offline Moog

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Re: Average amplifier power
« Reply #68 on: June 14, 2018, 12:00:20 PM »
 I am sure the reviewers were aware of all the reasons given above before they came to their conclusions.  Unfortunately i no longer have a copy of the review to elaborate in which context the concerns were raised.  The review was in an one of the editions Hifi for Pleasure in the mid eighties, a magazine which is no longer in production.
« Last Edit: June 14, 2018, 12:06:51 PM by Moog »
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Offline Hi-Phibian

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Re: Average amplifier power
« Reply #69 on: June 14, 2018, 12:05:46 PM »
If you are Krell.  You make a 330 watt amp in to 8 ohms.
You rate it 250 and quote that it doubles all the way down to 2 ohms. Ie 1000, not 1320. 







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Offline xumbug

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Re: Average amplifier power
« Reply #70 on: June 14, 2018, 12:44:42 PM »
In most cases that i know, its not the quantity of watts, but the quality of watts. A really good 211, 845 or even 805 delivering 20, 40 or 50 watts can be much better than 200, 300 iron fist watts!
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Offline moloels

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Re: Average amplifier power
« Reply #71 on: June 14, 2018, 03:27:30 PM »
When I see this post I always think of this Krell Amp (700 watts) and wonder whether it is made to drive certain type of speakers only.





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Online fdlsys

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Re: Average amplifier power
« Reply #72 on: June 14, 2018, 05:58:23 PM »
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Offline Ingvar Ahlberg

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Re: Average amplifier power
« Reply #73 on: June 14, 2018, 07:17:02 PM »
Quote
and then there's the belief that a good amplifier will double its power output every time you halve the load impedance.

Quote
The truth is that _every_ amplifier can do this, until its limits are reached.

That is totaly untrue, extremely few amps manage that, the average ss amp speced as 50 w in 8 ohms does not double into 4 and can not drive 2 ohms, period.
To deliver 2x200W into 2ohms that 50W(into 8 ohms) ss amp must have a 500VA transformer, not that common, and that is a physical fact

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Offline Shonver

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Re: Average amplifier power
« Reply #74 on: June 14, 2018, 09:44:48 PM »
That is totaly untrue, extremely few amps manage that, the average ss amp speced as 50 w in 8 ohms does not double into 4 and can not drive 2 ohms, period.
To deliver 2x200W into 2ohms that 50W(into 8 ohms) ss amp must have a 500VA transformer, not that common, and that is a physical fact

Ingvar

Respectfully, maybe take a breath and re-read what I said.
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