Anecdotal observation 1: TPA3255 ampifiers have varying heatsink solutions. And they do heat up!
Anecdotal observation 2: Companies have clear incentives to reduce component costs and increase profits.
Anecdotal observation 3: Longevity of products is almost always not a company concern.
Question: So why didn't manufacturers give us ampifiers WITHOUT heatsinks? Reducing heatsink use can increase profits!
Most Likely Answer: Because the products will fail before warranty window ends. This is a problem if their resellers get too many product returns and start refusing to carry their products anymore, or too many bad reviews.
Manufacturer's Action: Give cheapest heatsink solution that honor the warranty.
Simple takeaways:
Less heat in most cases is almost always better.
If manufacturers can cut cost, they will (unless they're operating in luxury good category, then they are incentivised to give you robust solutions that you will pay excessively for).
The 3E Audio A5/A7 cases completely refute your argument.
It would have been much cheaper and easier for 3E Audio to use a simpler, less expensive case, cheaply cut ventilation slots, a cheap heatsink, and forced-air cooling. That would have significantly reduced manufacturing costs, and the direct (albeit uncontrolled) cooling performance would have been many times higher.
Either they are stupid, or they know a lot more than you think.
Yes, and how many of those hundreds of thousands of amplifiers produced 20-30 years ago have you seen survive till now? Could more of them have survived if they have had more robust heatsink solutions with internal temperatures of 30-35°C instead of 45–50°C (which implies higher component temps)?
Note also in ASR, we do have SINAD hysteria and ultra-low distortion expectations. Similarly, products 20-30 years ago didn't have such SINAD.
Physics HAS shown heat to be the enemy. Why is adequate cooling for product longevity and expecting products to run as cool as possible be unrealistic or fearmongering?
It is precisely posts like this that show most users have absolutely no idea about this subject.
First of all, most older amplifiers are Class AB (or similar) designs, where the stability of the operating point at higher temperatures is a major factor—influencing issues like the tendency to oscillate.
I have refurbished many of these old amplifiers, and in most cases, the problem is the age of the capacitors, not the heat.
In reality, more capacitors in these units fail due to age—for example, through electrolyte drying out or loss, or the breakdown of the oxide layer caused by infrequent use. Turning a unit on for 3–4 hours every 1–4 weeks is just as damaging as running it for 8 hours a day (or 24/7). Rising resistance and decreasing capacitance over time are other factors leading to age-related failure. The resulting increase in heat generation during operation (which is unrelated to the capacitor's ambient temperature) leads to gas formation, bulging, and electrolyte leakage. In rare cases, the capacitor bursts.
Therefore, lowering the temperature would not extend their lifespan.
Modern Class D amplifiers—at least well-designed ones like the Mini 300 and 3E Audio models—run significantly cooler than older Class AB amps (10–15°C cooler on average), which effectively doubles their lifespan.
However, since the capacitors are already failing due to aging, this makes no difference in practice.
It is only at significantly higher temperatures—such as 60°C or 70°C in Class A amplifiers—that the balance between lifespan and heat-induced aging shifts, necessitating a refurbishment after just 7–14 years.
You can work backward from that scenario as well. Since every 10°C change—up or down—halves or doubles the lifespan, empirical data suggests the following: 70°C = 7 years, 60°C = 14 years, and 50°C = 28 years. There is no need to calculate further at this point, as the age-related lifespan of electrolytic capacitors is roughly 25–30 years.
By now, it should be obvious to everyone that modern Class D amplifiers cannot have a temperature-related problem, given that all reasonably well-designed units operate well within safe limits.
My experience with many older, refurbished amplifiers aligns with my professional background regarding capacitors and other electronic components in the industrial sector.
Since our high-energy products are used in long-term, aging, and stress testing for electronic components—including capacitors, assemblies, and devices—we possess a vast wealth of experience in this area.
