Amplifiers weight

I reckon you guys ain’t heard of the ultra-low mass amp craze that’s sweeping the nation. I use an ultra-low mass portable CD player with headphones. Total mass less than two pounds. No big honking transformer, or big honking capacitors, monster power supply, no big old power cord, no fuses, no interconnects or big honking speaker cables. Or their attendant noise and distortion. No more pencils, no more books, no more teacher’s dirty looks. 🤨

While your question was poked fun at by some, this exact question came up for a friend and I yesterday. Why? Because weight is touted as a "pro" for some amps and we didn’t know why.

Its called: marketing. 
See: Mark Levinson.

I just paid $142.85 a pound

Let me see.... two plus... carry the one... Holy crap! $2278/lb! I knew the iPhone was overpriced but this is crazy!

Power Supplies: Commentary for Consumers. by Nelson Pass

Power transformers

The best power transformers are toroids, with donut shaped magnetic cores. They pack the most power for weight and size, and they make less noise. Toroidal transformers have to be rated at a minimum of several times the intended wattage because the power is delivered in short pulses to the capacitors.

Typically, a Class AB stereo amplifier rated at 200 watts per channel continuously should be capable of delivering 700 watts or so, and this means a transformer rating of about 2000 watts. Anything less means non-continuous operation. This might be alright for a class AB amplifier where maximum continuous operation is not required.

If the stereo amplifier is rated 200 watts per channel pure Class A, it will draw about 1000 watts all the time, meaning that about 3000 watts of power transformer is called for, no less.

Now a toroidal transformer delivers about 30 watts per pound, so a 3000 watt toroid will weight about 100 lbs, maybe more. The rest of such an amplifier will probably weigh about as much, so if you are looking at a 200 watt per channel stereo Class A amplifier, you will want to see if it weighs at least 200 lbs.

One pound of weight for every 2 watts is a good litmus test for evaluating Class A amplifiers. An amplifier weighing less might not be pure Class A. It might be almost Class A, or it might be one of the many products which achieve a Class A designation through trick circuitry.

To lower noise still further, toroids are sometimes encapsulated in metal cans. To reduce magnetic radiation, these cans are usually, but not always, made of steel. This is good, but be aware that in the past, at least one company has used a small transformer in a big can, and made up the difference with sand.

The answer is, in other musings from Nelson, is that a 200watt class a/b power amplifier, should weigh at least 50lbs. The larger part of that mass being the transformer. As in a good 25lbs.

Heat sinks, about 7-8 lbs per channel. maybe 10lbs per channel. then the chassis, about 10-15 more lbs.

Faceplates of solid aluminum cost a lot to make,and weigh a lot... so don’t waste your bucks on them and don’t make the manufacturer do it, just because it looks cool and makes you rub your nipples in excitement. circuit bards weigh the least, a few pounds. Capacitors in the power supply another 7-8-10lbs. so we end up near or at +60lbs for a proper 200 watt per channel class a/b power amplifier. Which is why, if one minimizes but tries to meet the proper spec, we end up at Nelson’s stated low end of ’at least 50 lbs’.

Here we see a 1500va transformer, coming in at 30lbs shipping weight, most of that being the transformer itself.

https://www.antekinc.com/an-154115-1500va-115v-transformer/

When we look inside a classic Adcom GFA-555 power amp, we see a 600va rated power transformer, which is actually quite pitiful, with regard to current delivery. No balls at 4 ohms. We could drop the afore shown 1500va transformer in there, and then do some mods to the amp, so it can belt out full proper power at 4 ohms. the work would be extensive and flakey, ie subject to failure as the thing is not really built for it.

Just buy a ballsier amp with a proper power supply, if we feel we need the extra but proper power at 4 ohms...

to be blunt, the vast number of 200 watt per channel power amplifiers will NOT have that 1500VA rate transformer in it, they will poses something much lighter and wimpier. the only middling one that actually delivers that, that I know if, is the belles 450, where David Belles, added in a 1500va transformer. It looks like a undersized curling stone. I'm sure there are many more amps like that, this is just one I remembered at the moment and have owned 4 of over various times. Belles 450, no wasted mass, and half of the 57lbs, is the transformer. As it should be.

To go to the right area, where it is all ’done right’, we have to move up to the big boys and their extreme power supplies, all done for mucho cash outlay.