Why are some Amps so heavy? Are they better? Are Toroidal transformers must be the best?

[SonomaComa]

I am now trying to setup my first ever 5.1 surround sound but I am going to start with front tower speakers and a really good Receiver and Amp. Why are some Amps so heavy? Some are over 70 pounds! Like the Emotiva XPA-5
XPA-5 | 200W x 5 | Emotiva Audio | High-end audio components for audiophiles and videophiles, spanning 2-channel music systems, as well as 5.1 and 7.1 home theaters. Products include multichannel amplifiers, stereo amplifiers, and monoblock amplifier

The Marantz MM 7055 is less than a wimpy 35 pounds and cost 300 dollars more!
Marantz US | MM7055

How do the lighter Amps compare to the heavy weight Amps is terms of quality of sound, heat build up during long operations, and overall longevity? I thought the heavier ones would be better. Is that the case with the Amps? If you won a raffle and could only pick one of those two, which would you pick? And why?

[lsiberian]

The heaviest part of most amps is the transformer the size and weight of these can tell you a lot about the capable power, but in more traditional amp there are other components that contribute. With the advent and maturity of class d you don't need a heavy amp to get high power anymore. Judging a receiver by weight is not the most reliable method. Instead pick brands that are reputable. Adding useless weight isn't hard to do so don't make it an important spec.

[SonomaComa]

Thanks Isiberian for the insight. The picture of the inside of the Emotiva XPA-5 sure looked extra beefy. The Marantz MM 7055 doesn't show what it looks like inside. I thought they might be afraid to show what's inside. Today's receivers may be jam-packed with the latest technology, but it seems they they lack the muscle of high-end power amplifiers. I also read that most receivers, even big-ticket models, can't spare enough internal real estate to house humongous transformers and hefty power supply capacitors that powerhouse amps need. Separate power amplifiers have room for all of that good stuff.
Can somebody recommend a good Receiver and a separate Amplifier?
I was thinking of floor speakers like the Yamaha NS-777's NS-777 - Home Speaker Systems - Speakers - Audio & Visual - Products - Yamaha United States
Or the JBL Studio L890's Studio L890 | 4-way, dual 9” floorstanding speaker | JBL US

[Irvrobinson]

How do the lighter Amps compare to the heavy weight Amps is terms of quality of sound, heat build up during long operations, and overall longevity? I thought the heavier ones would be better. Is that the case with the Amps?

Weight can be an indicator of quality, but you have to know what you're looking at. I'm also going to assume this discussion regards Class AB amplifiers, because switching amplifiers or those with innovative power supplies can weigh a lot less and not suffer any in quality.

As lsiberian brought up, for Class AB amps the transformer is typically the heaviest component, especially if there's more than one of them, but there can be other components that contribute significantly to weight. For example, heat sinks. Most amps are passively cooled, so they often have heavy heat sinks to absorb and dissipate heat. On lightweight amps it might be cooling that was skimped on. On some amps the chassis and case can be very heavy, and for little practical reason. Sony used to be famous for this, getting even some of their CD players to weigh over 30lbs. Many very expensive amps have needlessly fancy cases and facias that add a lot of weight, but no practical value. Other components of the power supply can also be pretty heavy, like if the amp uses solid buss bars for power distribution, or large arrays of smoothing capacitors.

So, if an amp has a modest chassis and case, yet it weighs more than other amps of similar power ratings, there is a reasonable chance that the manufacturer of the heavier amp gave it a more robust design. It may be a higher rated power transformer, it may be a more capable power supply, or it just may be more heat sink mass to keep the amp cooler under high load conditions, but there's a reasonable chance it's something good.

That's not to say that weight should be a primary indicator of amplifier quality, especially sound quality, just that in some cases it can mean something.

Another factor to consider, unless you have *very* good speakers that can play very loudly without distortion, and you have a large room to let them breathe (and use a lot of power), you are unlikely to hear differences between any two properly functioning solid state Class AB amplifiers.

[SonomaComa]

Wow, so they might try and trick somebody with the extra weight. But it seems i f they put that weight in the right places it could be very beneficial. It sure looks like Emotiva did a good job of making their XPA-5 pretty hefty. It looks like they use 1 toroidal transformer for each channel. Have you seen that picture of the inside of it?

[PENG]

Wow, so they might try and trick somebody with the extra weight. But it seems i f they put that weight in the right places it could be very beneficial.

You are quite right. For example, I would expect a well designed toroidal transformer lighter, not heavier, and just because an amp uses toroidal does not mean it has a better power supply than one that uses an EI core type transformer. In the entry to mid range group, that may be generally true though. Even within the class A/B group, there are no shortage of robust amps that weigh quite a it less than Emo's. Immediately come to mind are some Bryston and Anthem models, that weight quite a bit less than Emo models with similar output ratings. You can get high quality power transformers that weigh less than some cheap lower grade ones, likewise for heat sinks. The chassis/enclosure design also influences the final weight, example: ALuminum vs Steel vs Plastic (certain part only, the Marantz you cited probably has some plastic content). Aluminum costs more than steel, and it can be used for heat sinks, along with a chassis/enclosure design that helps dissipate/vent heat, could also reduce weight.

North American cars used to be built with the body on frame design, when the unit body design first came out there were all kinds of skepticism about their body integrity, but now, as far as I understand, unit body actually is generally (as usual not always) stronger in the sense that it protects the passengers better. So a lot depends on the design, heavier does not always mean better.

It sure looks like Emotiva did a good job of making their XPA-5 pretty hefty. It looks like they use 1 toroidal transformer for each channel. Have you seen that picture of the inside of it?

I highly doubt that, but you got me curious enough to check it out. Could you kindly post that picture of the inside that you have taken? I love to see those 5 transformers.

[Adam]

If you won a raffle and could only pick one of those two, which would you pick? And why?

I'd pick the Marantz. I like the looks better, I've had a craving to get a Marantz component for a while, I actually prefer lighter-weight components, I hate the hum coming from the toroidal transformers in my Emo amps, and I've learned that I don't need more power than what the Marantz can provide. My only concern would be how quiet the fan(s) in the Marantz are - or will stay as time goes by.

Fans bring me to heat sinks. I'll chip in a bit on heat sinks, but these guys have already covered most of it. Heat "sinks" as used in these amps are not only sinks, but also heat spreaders and heat exchangers. All of those fins that you can see on the Emo heat sinks are there to move heat into the air. The big difference between the Marantz and Emo is that the Marantz has forced air cooling, so it uses at least one fan. A fan can easily drop the required surface area of a heat exchanger by a factor of five or more. There's an added bonus to that due to something called fin efficiency - as you move along a fin away from the base where the hot components are, the less effective that part of the fin gets because it isn't as hot as the base. So, you can design in the required surface area, but you also have to consider fin efficiency - which might drive your area up further depending on the material you use and how long your pins are. So...fans drop the required area, which equates to dropping the required weight. Aluminum spreads energy about four times as well as steel (and about ten times as well as stainless steel), so you need less volume of aluminum to spread energy. Aluminum is less dense, too, so it weighs less even if you use the same volume - double winning. There are other materials that spread energy better, but aluminum is a great choice for most applications due to a combination of cost and effectiveness. So, as they said, weight isn't everything.

[Steve81]

My only concern would be how quiet the fan(s) in the Marantz are - or will stay as time goes by.

FWIW, the reason I passed on Marantz when I was picking was the lack of rating into 4 ohms, which didn't give me much confidence as to how it would handle a difficult load. Of course, if I were to do it all over again, I'd probably reconsider the Outlaw 7125, which I'd also probably pick over the XPA-5 for various practical reasons (the weight and 19" depth on the Emo amps is tough to accommodate in most AV cabinetry for starters) and that it's USA built is nice.

[PENG]

FWIW, the reason I passed on Marantz when I was picking was the lack of rating into 4 ohms, which didn't give me much confidence as to how it would handle a difficult load. Of course, if I were to do it all over again, I'd probably reconsider the Outlaw 7125, which I'd also probably pick over the XPA-5 for various practical reasons (the weight and 19" depth on the Emo amps is tough to accommodate in most AV cabinetry for starters) and that it's USA built is nice.

I know you own an Emo amp, and I wish I own one too just to find out why they are so heavy when they seem to standardize on a relatively lower tranformer VA to Watt output ratio until you hit the XPA-2 level and up. I mean relative to Outlaw (actually let's use ATI as they made amps for so many including Outlaw apparently). If I were to guess, I could only think of one word, material, ....for everything else except the electronics.

[PENG]

I'd pick the Marantz. I like the looks better, I've had a craving to get a Marantz component for a while, I actually prefer lighter-weight components, I hate the hum coming from the toroidal transformers in my Emo amps, and I've learned that I don't need more power than what the Marantz can provide. My only concern would be how quiet the fan(s) in the Marantz are - or will stay as time goes by.

Look, may be, but weight? It depends..





My 30+ year old, 140W thing weighs 42 lbs. I wish it had a lighter toroidal in it.