Does a good amp have to be heavy?

Question

In my (pretty limited) experience, electric guitar amps seem to get heavier as they get more expensive... is this a general rule and if so, why? What makes even a relatively small amp (like a 50W $2000 Mesa) so heavy (~25kg) and how is this linked to quality?

Answer 1

There are mainly three factors to this:

• Powerful speakers need (or at least used to need) heavy magnets.
• Lightweight cabinets tend to be less “acoustically stable” than heavy ones. And more easily damaged when handled roughly.
• 50 Hz transformers need a lot of windings around fat iron cores. (Plus, tube amps also need output transformers. And, the more power you want, the more cooling you need...)

These points have gotten somewhat less relevant as technology marched on: there are now pretty light PA speakers and bass cabinets available, which use neodymium magnets and clever structural engineering to get loud levels and even sound properties. And, switching power supplies can be built much lighter than traditional transformers at the same power ratings. Class-D amplifiers need almost no cooling. And a light composite chassis can be quite as sturdy as a heavy wooden crate.

However:

• Guitarists have something of a tendency to avoid modern technology in favour of “vintage”, regardless if that makes any sense sound-wise
• Guitar cab's aren't meant to sound good in the HiFi sense, but colour the sound in certain manners. Both naïvely designed light and simple heavy-duty cabs will do this, in different ways (cheap & light ones often in ways that even guitarist don't like), whereas PA speakers that are more or less trimmed for linear response just sound boring for guitar (though this can of course change when combined with a good digital cab sim).
  Similarly, non-switching power supplies (in particular with tube-diode rectifiers) have certain properties which are technically non-optimal, but actually work out positively musically.

Answer 2

I used to associate quality = mass for most things, including PA systems and (tube-powered) guitar amps.

Now that I'm my 50's I've looked for ways to get that sound without so much weight, and thankfully, new neodymium magnets have helped a lot.

My current favourite is a Hughes & Kettner Combo 18. At 21 lbs it is easy on my back, but a monster for tone, and if the house needs, more they can mic it!

Answer 3

What makes even a relatively small amp (like a 50W $2000 Mesa) so heavy (~25kg) and how is this linked to quality?

Those amps use cast frame speakers, specifically an OEM variant of the Electro-Voice EV12L, which is probably the second loudest and second heaviest guitar speaker in the history of time (the JBL F120 is a bit louder and heavier). Heavy magnet Celestions like Vintage 30s weigh around 12-15 pounds, the EV easily weighs 25 pounds. Quality? They almost never blow out and the cast frame does not bend or warp. And they are absurdly loud at about 103 spl.

In audio gear in general the bigger and better the transformer, typically the better the sound and more reliable the amp. Black and silver face Fender Bandmasters have tiny transformers that will blow if pushed too hard, the Fender Bassmen from those eras have big transformers, are near indestructible, and give you a tight controlled low end even though they are otherwise nearly the same amp.

The transformer is the one thing that cannot be replaced or upgraded. If it is, it is no longer considered the same amp.The transformer is the engine, the tubes are the spark plugs.

electric guitar amps seem to get heavier as they get more expensive... is this a general rule and if so, why?

The reason is that larger more powerful transformers require more raw materials to produce, must be produced on higher precision tooling, and the increased weight incurs higher shipping costs both during manufacturing and when delivering the finished product.