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Trevor Wilson[_3_] Trevor Wilson[_3_] is offline
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Default More than 30W per chanel Class A transistor amps

On 4/03/2019 11:45 pm, Peter Wieck wrote:
On Sunday, March 3, 2019 at 7:21:11 PM UTC-5, Howard Stone wrote:

Everyone says that I should try it with am Audio Research valve pre -- but how can this possibly be an improvement over no pre at all???


It is called "Gain" and "Transient". For the sake of simplicity and discussion, let us agree on three things:

1. Whatever amplifier is in use, it is rated at its full RMS output against a 2V input at 1,000 hz.


**Just a nit: There is no such thing as RMS power. It is either
continuous Watts, or just plain ole Watts. The moniker RMS can be
applied to Volts or Amps, but not to the product of the two.


2. It is a well-designed device using quality parts and assembled with great care.

3. The speakers in use are also good, well-made and rated at 90 dB @ 1 meter @ 1 watt. And rated at an 'average' of 50 watts.

Some basics: The transient associated with a snare-drum rimshot is approximately 120 dB. The transient associated with the onset of the organ Bombard pipes in the Saint-Saens organ symphony on a well-made recording very nearly, or actually peaks at 30 dB over average.

Most amplifiers are capable of momentary peaks and transients far above their rated RMS.


**Most amplifiers that employ crappy power supplies, yes. The Krell
KSA50 is not such an amplifier. It's CONTINUOUS power rating is very,
VERY close to it's transient power rating. The continuous power of a
KSA50 is around 75 Watts. The transient figure is something like 76
Watts. Had Krell decided to skimp on the power transformer, then the
difference between the transient figure and the continuous figure would
be far greater. The weird thing is the manufacturers make a big song and
dance about the size of the transient number vs. the continuous one,
when the bigger the difference, the crappier the amplifier.


Most speakers can handle transients and peaks far above their
'average' rating.

**Oh, absolutely. One need only examine the voice of a typical bass
driver and relate that to the power handling. Almost all domestic
speakers are rated to be connected to an amplifier of XX Watts and being
driven with music. Since music has, at worst a peak to average figure of
around 10dB, then one may assume that the average power applied to a
speaker is always somewhere less than 10% of the continuous power rating
of the amplifier.



If a pre-amp has no gain over the original signal source, which is a nominal 2V, the peaks and transients will not be expressed - unless the actual listening level is a minimum of 30 dB below the average.


**Well that depends on the sensitivity of the amplifier.


Pre-amps are awful things, just like democracy. Except for the alternatives.


**A decent preamp need not be expensive.


--
Trevor Wilson
www.rageaudio.com.au

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