What's the Sonic Character of Accuphase Amps?

Bob! Thank you for the reply. I get a feeling you really enjoy the Accuphase equipment you've purchased. I am leaning toward the P450 simply because I am unsure about the pros & cons about Class A (lower wattage) vs. Class A/B (higher wattage). My ultimate goal is to find an amplifier capable of producing the micro-dynamics of music with delicacy and finesse while at the same time being able to produce music's wide dynamic swings with ease. I could be wrong but to do this well, I figure power is a big factor - and requires more than the 50 watts provided by the A50V.

Now, my purchasing decision becomes one based on quantity of distortion produced by the amp vs. the dynamic headroom provided.

Perhaps this should be for another thread.
Someone explained this to me once and it is my understanding that speaker efficiency vs. power required is generally based on the following:

0 db is a power ratio of 1. Records and tape have dynamic ranges of 30-40db. To achieve a 30db dynamic range requires a power ratio of 1,000:1 and 40 db requires 10,000:1. So if you assign 1 watt of power to a speaker yielding 90db SPL, you need 1000 watts to deliver a true 30db dynamic range. With digital material we find dynamic ranges of 60-70db requiring power ratios of 1,000,000:1 & 10,000,000:1 respectively. Power amps of 1-10 million watts are not feasible today but the point is, more power offers more dynamic realism. Forget power vs. loudness because that really is not a factor in the overall scheme.

I really hope that "math" is incorrect.

Thoughts?

bwhite: i don't know whether the figures in your quoted piece are correct or not, but i can tell you this: tho the a-50v has a rated output of 50w/channel (into 8 ohms), it drives my eidolons to damn near the same levels as my jrdg 8ti, which has a rated power output of 250w/channel(also into 8 ohms). both of these amps produce high current and provide peak power far exceeding their rated output figures. i don't know what speakers you're using but the a-50v is specifically designed to remain stable with loads as low as 1 ohm. -cfb

Hi Kelly,

I don't know if the math is right either - the more I look at it, the more I question the accuracy of that statement. I plan to post a thread to the forum for discussion.

I use Wilson-Benesch Act One speakers. They are a bit more efficient than the Eidolons - but really like power. Guess I should just try to demo several different amps vs. buying/selling/buying/selling until I find the right match.

Bryan my method for figuring out desired headroom is simply 20dB (times 100) over your average listening power level. I have run that way for nearly 30 years now with very acceptable performance (and only 1 blown tweeter when we once got really carried away). My 100 watt rated horns become quite loud at only 2 watts/channel drive level, so for a rated 200w/ch amp I then have at least 20dB of headroom available (most high quality amps are conservatively rated & do produce around 10% over rated power before clipping). Of course this large amount of power is only used when really pushing it hard, but it does happen (albeit rarely) so I want that capability available. However when I have run with a high quality lower power 100w/ch amp (an Ayre V3 class A design) I found that to be inadequate even with these 104dB sensitivity speakers. The P450 will definitely satisfy your requirement for controlled finesse with dynamic capability, and will do so efficiently (idle power consumption is just 125 watts - not too bad at all). Considering that your speakers also like lots of power, I don't think you can go wrong with that combo.
The thing about pure class A amps like the A50 is that, as Kelly advises, they do have a lot more drive available than their rating would suggest; the peak current capability of these designs definitely belies their lower power rating. Although I've never heard the A50 amps, their price point is simply more than I'm wanting to spend for an amp so it's doubtful that I'd ever actually audition one in my rig. Although I rather doubt that the A50 has near the headroom capability of the P450, its sonic qualities may more than make up for that descrepancy, being a class A design. So don't fuss over the theories & the numbers, just TRY one. As I said previously, if your pockets are deep enough for the A50 (or for two - they are bridgable) then certainly do audition one. If the P450 is more in line with your budget then go with that or one of the other less pricey Accuphase amps.
Another factor to keep in mind is waste energy; class A amps burn a lot of power & produce a lot of waste heat in your room even when sitting idle. In your temperate San Francisco climate, extra heat in your house is fine in the cooler months, but is ceratinly unwanted when it's warm outside as it can significantly increase your cooling bills. If I have a class A solid state amp in my rig during hotter weather then it's often left powered down, & therefor doesn't sound its best even when it is turned on in the evening. Normally I will then change it out for an A/AB design such as the P450, but even that won't be left on continuously if it's much over 80 degrees outdoors. The waste heat factor is another one of the tradeoffs that you'll have to juggle when making your amp decisions. Oh and yes, you do correctly surmise that I'm certainly quite happy with the product line. The manufacturer product support is impressive enough that I'm not worried about a failure in 5 or more years turning the equipment into some very expensive boat anchors. This has always been a problem with my Luxman setup; much as I loved it, I absolutely wouldn't make that mistake again.

Hi Bob,

Thanks for that outstanding reply! From what you say, it seems like the P450 will be perfect for my use. I recently had a 100 watt amp in my system and while it clipped only once, it could easily go louder than I (or the neighbors) care to listen. I am only hoping that a more powerful amplifier will control the speaker better - volume is not a issue.

Thanks again Bob!!