Is powerfull Amps only for low sensitivity speakes?

Thank you all for your contributions.
Dear Pokee thank you also for the example.
regards

We'll start with i design amps - and have done some in hgih end commercially.

Your question is a little bit vague, os let me re-pose it two ways:

1. Is the primary benefit of powerful amps the ability to drive inefficient or power hungry (big room, big capability) speakers?  Yes.

2. Is there any *disadvantage* to powerful amps with efficient or small speakers?  No.

There is nothing about a powerful amp that is inherently a compromise of sound for power except for one thing: the cost of a big transformer, many transistors, and heat-sinks necessary for big power.  So in that sense there *is*  a trade off; yet in those many-$1000 power amps, no such trade off has been made.

I have built my primary design in two formats:  low power class-A (almost) and high power class A/AB, using nearly the same parts. They sound very similar, until one runs out of power and either clips or compresses. But that usually happens after my ears or the speakers are in distress.

Let's look at the flip side: modest power on large full-range speakers.  I currently drive huge, 89 dB efficiency speakers (Mahlers if you care, very fussy) with the 60 wpc version with no problem. Most would select a higher power amp.  I see no need, even though 3-4 are lying there idling, free for my use

So, within reason, select simply the best sounding amp.  Also remember that there is more to "power" than rater power into an 8-ohm resistive load. Most speakers are FAR from an 8-ohm resistive load, and it may take some serious muscle to control them.  That means low output impedance and ability to drive high current into a load that might drop to 2-ohms., or in many cases (read this carefully: negative impedance for  a brief moment when the voice coil is traveling backwards). Electro magnets work both ways :-)  And speakers are electro-magnets at their core.

Funny, on my moprning run, before reading your note, i was thinking about the best price/performance way to build a great, low cost (ok, maybe < $1000, so not that low), low power amp.

Happy listening.

G

My speakers are 94db and I have twin magtechs (2 X 900 watts).  They sing, they breath and sometimes, they even cry.

I took a look at John Atkinson’s measurements of your speakers and at the description and specs of the GS150, and as far as I can tell from those documents the speakers and amp should be a fine pairing.

I assume that your preamp can provide balanced signals to the power amp, because like many ARC balanced power amp designs I’m pretty certain the GS150 will not work properly if provided with single-ended inputs via RCA-to-XLR adapters (or, for that matter, if the preamp provides single-ended signals via XLR connectors, although that would be unusual in a high quality design).

To address your initial question more generally, IMO using an amp that is more powerful than necessary can raise at least two concerns (although neither appears to be applicable in this case):

1)There tends to be a **loose** correlation between the power ratings and the gains of various amplifiers. If the overall combination of speaker sensitivity, amplifier gain, preamplifier gain, and source output level is too high, the volume control on the preamp may have to be used at very low settings, where various undesirable effects can occur.

2)Everything else being equal, more watts = more $. So with a higher powered amplifier a greater percentage of the dollars one chooses to spend may go toward power rather than quality, compared to spending the same number of dollars on a lower powered amplifier. Assuming at least that the topologies and class of operation (A, AB, or D) are similar between the amps that are being compared.

Good luck. Regards,
-- Al