Class D amp long term reliability

[Buckeye Amps]

Dylan, with all due respect, while I appreciate your input, it's important to put things into perspective.

Without turning this into a "pissing match" (closest phrase I could think of), you may be under estimating how many MP series amplifiers we have sold and shipped in the last 4.5yrs.

My response was to show that using another sample size that consists of a few thousand modules each of the NC252 and NC502, the failure rate we have seen is nowhere near 10%

 

[Apollon Audio]

Without turning this into a "pissing match" (closest phrase I could think of), you may be under estimating how many MP series amplifiers we have sold and shipped in the last 4.5yrs.

My response was to show that using another sample size that consists of a few thousand modules each of the NC252 and NC502, the failure rate we have seen is nowhere near 10%

I fully respect that Dylan, and I’m not here to turn this into a numbers contest either.

But given your experience with a substantial number of units, would you agree that, in general, the MP series modules tend to fail more often compared to the higher-end Hypex modules (like NCx, NC500, NC1200, NC2K) or Purifi designs?

That’s really the core point I’m trying to make, not that MP is bad, but that it’s objectively more prone to failure due to its design and component choices. Curious to hear your take on that comparison.

 

[Buckeye Amps]

I fully respect that Dylan, and I’m not here to turn this into a numbers contest either.

But given your experience with a substantial number of units, would you agree that, in general, the MP series modules tend to fail more often compared to the higher-end Hypex modules (like NCx, NC500, NC1200, NC2K) or Purifi designs?

That’s really the core point I’m trying to make, not that MP is bad, but that it’s objectively more prone to failure due to its design and component choices. Curious to hear your take on that comparison.

That I can say yes, though I also need to add a caveat that we didn't start carrying Purifi models until 1.5yrs into our business (whereas MP has been carried since day 1).

Going by some preliminary numbers I'm looking at, I would put the failure rate of an MP series module around 1.5% (between the NC252 and NC502) for any of our amp builds.That's even counting the two modules from this thread that may have been related to a surge issue, along with a few builds that used a 3rd party case/kit back in 2021.

The NCx500 and Purifi 1ET400A and now 1ET6525SA is somewhere around 0.5%. Nearly all of these failures were early on in the amp life/usage rather than later in time.

 

[RickS]

I fully respect that Dylan, and I’m not here to turn this into a numbers contest either.

But given your experience with a substantial number of units, would you agree that, in general, the MP series modules tend to fail more often compared to the higher-end Hypex modules (like NCx, NC500, NC1200, NC2K) or Purifi designs?

That’s really the core point I’m trying to make, not that MP is bad, but that it’s objectively more prone to failure due to its design and component choices. Curious to hear your take on that comparison.

Would suggest that time in the market is likely the key difference, perhaps in different segments too.

Your MP rate is quite high though. Are you repairing them or sending back to Hypex for repair?

 

[sceptical1]

Sample size = 1 is never a good basis for forming an objective opinion.

That depends if we are talking about your amp or mine. lol

 

[Apollon Audio]

Would suggest that time in the market is likely the key difference, perhaps in different segments too.

Your MP rate is quite high though. Are you repairing them or sending back to Hypex for repair?

Yes I agree, time on the market is definitely a key factor, and the application segment plays a big role as well. We are implementing Hypex MP series modules in our amps since 2017.

In our experience, the highest failure rates with the MP series were seen in the early revisions. Things have improved somewhat with the newer versions, but the failure rate is still significantly higher compared to Hypex’s high-end modules or Purifi designs.

We’ve noticed the higher failure rates in setups where the modules are pushed harder, such as subwoofer applications or other high-demand, high-output environments. Even though we mostly build custom fan-cooled amplifier solutions for pro applications, which are thermally optimized, the MP modules still showed noticeably more failures than NC500, NC1200, NC2K, NCx, or Purifi platforms.

Most failures tend to occur after 1–4 years of use and more, which brings up another important point: usage hours. The capacitors on MP modules are rated for 2000 hours @ 105°C, which is fairly minimal compared to what’s used in higher-end modules. For instance, NCx and Purifi modules use Rubycon capacitors rated at 10,000 hours @105°C, which makes a huge difference in long-term reliability, especially in systems that run continuously or under thermal stress.

Also worth mentioning: since Hypex only provides a 1-year warranty on these modules, we end up covering the cost of failed modules ourselves when they fail within our warranty period. And for customers outside the warranty period, we offer replacement modules at our internal purchase price, with no markup, to keep things fair and transparent.

 

[Sokel]

Yes I agree, time on the market is definitely a key factor, and the application segment plays a big role as well. We are implementing Hypex MP series modules in our amps since 2017.

In our experience, the highest failure rates with the MP series were seen in the early revisions. Things have improved somewhat with the newer versions, but the failure rate is still significantly higher compared to Hypex’s high-end modules or Purifi designs.

We’ve noticed the higher failure rates in setups where the modules are pushed harder, such as subwoofer applications or other high-demand, high-output environments. Even though we mostly build custom fan-cooled amplifier solutions for pro applications, which are thermally optimized, the MP modules still showed noticeably more failures than NC500, NC1200, NC2K, NCx, or Purifi platforms.

Most failures tend to occur after 1–4 years of use and more, which brings up another important point: usage hours. The capacitors on MP modules are rated for 2000 hours @ 105°C, which is fairly minimal compared to what’s used in higher-end modules. For instance, NCx and Purifi modules use Rubycon capacitors rated at 10,000 hours @105°C, which makes a huge difference in long-term reliability, especially in systems that run continuously or under thermal stress.

Also worth mentioning: since Hypex only provides a 1-year warranty on these modules, we end up covering the cost of failed modules ourselves when they fail within our warranty period. And for customers outside the warranty period, we offer replacement modules at our internal purchase price, with no markup, to keep things fair and transparent.

Don't think that caps are a serious or primary cause.
As you said, you have seen 1200as2 fail as much as Hypex MP but they too use Rubycon, WIMA, etc. (at least the genuine ones, lots of fakes around)

So, what's the underlying cause? What I suspect is heat. What I see around are simply failing to meet the real estate needed for high power applications.
Your bigger premium cases may be adequate, smaller ones though...

 

[Apollon Audio]

Don't think that caps are a serious or primary cause.
As you said, you have seen 1200as2 fail as much as Hypex MP but they too use Rubycon, WIMA, etc. (at least the genuine ones, lots of fakes around)

So, what's the underlying cause? What I suspect is heat. What I see around are simply failing to meet the real estate needed for high power applications.
Your bigger premium cases may be adequate, smaller ones though...

I’m sorry, but it seems you may have overlooked a part of my earlier comment.

“We’ve noticed the higher failure rates in setups where the modules are pushed harder, such as subwoofer applications or other high-demand, high-output environments. Even though we mostly build custom fan-cooled amplifier solutions for pro applications, which are thermally optimized, the MP modules still showed noticeably more failures than NC500, NC1200, NC2K, NCx, or Purifi platforms.”

 

[JSmith]

In our experience, the highest failure rates with the MP series were seen in the early revisions. Things have improved somewhat with the newer versions, but the failure rate is still significantly higher compared to Hypex’s high-end modules or Purifi designs.

Interesting... so what would be the further breakdown then of that general 10% figure, comparing early modules to the more recently produced versions? The open discussion here by all parties is appreciated.


JSmith

 

[BeeKay]

But given your experience with a substantial number of units, would you agree that, in general, the MP series modules tend to fail more often compared to the higher-end Hypex modules (like NCx, NC500, NC1200, NC2K) or Purifi designs?

If you compare failure numbers between MP and non-MP modules it would be fair to include SMPS failures on the non side. The way you do it‘s apples and oranges.

 

[sigbergaudio]

I'm surprised either Apollon or Hypex are still selling a product where 1 in 10 fails if that is indeed the case.

We are certainly not into thousands of amps shipped yet, but with our active speaker products based on the Hypex fusion amp which uses the MP modules, which we started shipping back in 2020, we have yet to have a single failure that wasn't due to external causes (power surge tripping the internal breaker circuit / fuse).

 

[JeremyFife]

Cautionary tale indeed. I fully accept that most *MP Amps will be just fine.
However, as a risk averse type, I'm thinking that it's better to go with cheaper TPA325* units or splash out on Purifi/Ncx.
Am I reading too much into this?

(Don't need one now, but I expect my PA5 to die eventually)

 

[Apollon Audio]

If you compare failure numbers between MP and non-MP modules it would be fair to include SMPS failures on the non side. The way you do it‘s apples and oranges.

The failure rate of Hypex SMPS in our experience is consistently below 0.1%, making them exceptionally reliable over time. We implement these power supplies since 2012.

 

[Apollon Audio]

I'm surprised either Apollon or Hypex are still selling a product where 1 in 10 fails if that is indeed the case.

We are certainly not into thousands of amps shipped yet, but with our active speaker products based on the Hypex fusion amp which uses the MP modules, which we started shipping back in 2020, we have yet to have a single failure that wasn't due to external causes (power surge tripping the internal breaker circuit / fuse).

Thanks for your input. I can understand your surprise, but there are a few important points to consider.

First, it seems you haven’t had experience with the earlier revisions of the MP modules. As I mentioned before, the first revisions had a lot higher failure rate compared to the newer versions, which have improved, though they still don’t match the long-term reliability of the high-end Hypex modules or Purifi designs.

Second, it sounds like your application might not be pushing the modules as hard as in some of our custom installs. We also use MP modules in high-demand environments, including PA systems and large-scale speaker installations, where the modules are regularly driven near their limits. Even though we design fan-cooled, thermally optimized enclosures for these scenarios, we still observe higher failure rates in MP modules under these conditions, compared to NC500, NC1200, NC2K, NCx, or Purifi modules.

As also mentioned, we’ve seen a lot less failures in the newer revisions, but they still don’t reach the level of reliability we’ve consistently seen with higher-end modules over the years.

So yes, context and application matter greatly, and our feedback reflects a broader range of demanding real-world use cases.

 

[-Matt-]

Maybe someone should make an MP module based amp for the pro market where the modules are hot-swappable like a raid array!

(Sort of joking, sort of not)!

 

[Apollon Audio]

Maybe someone should make an MP module based amp for the pro market where the modules are hot-swappable like a raid array!

(Sort of joking, sort of not)!

Great idea!

 

[markstein]

I find this thread highly interesting - thank you all for your input, especially all manufacturers for sharing their experience.

This may influence future buying decisions.

Currently running Neumann KH310 and KH810 since > 10 years without issues, looking forward to the new @AsciLab C6C and S6C, however, if these Hypex amp modules are using low quality components with questionable long term reliability, this might be a reason to look somewhere else...

 

[sigbergaudio]

I find this thread highly interesting - thank you all for your input, especially all manufacturers for sharing their experience.

This may influence future buying decisions.

Currently running Neumann KH310 and KH810 since > 10 years without issues, looking forward to the new @AsciLab C6C and S6C, however, if these Hypex amp modules are using low quality components with questionable long term reliability, this might be a reason to look somewhere else...

As a manufacturer using the same amps, if I may chime in;

A) As mentioned we haven't had any issues
B) As it is an OEM amp, both the amp itself and the modules on it can be easily serviced and repaired, and is likely to be available a long time. So this is at least a better bet than a proprietary amp of unknown origin custom ordered by a small manufacturer.

 

[respice finem]

Maybe someone should make an MP module based amp for the pro market where the modules are hot-swappable like a raid array!

(Sort of joking, sort of not)!

This would really be nice, esp. in active speakers. Mailing them is always a risk.

 

[markstein]

As a manufacturer using the same amps, if I may chime in;

A) As mentioned we haven't had any issues
B) As it is an OEM amp, both the amp itself and the modules on it can be easily serviced and repaired, and is likely to be available a long time. So this is at least a better bet than a proprietary amp of unknown origin custom ordered by a small manufacturer.

Understood. However:
- How long is your horizon of experience? You are relatively new in this market.
- Meaning: How meaningful is your experience?
- If long term reliability is the main issue, most failures will occur after warranty phase, and repairs will be subject to a charge.
- In this case, repair processing, repair charge and general availabilty of the spare parts and of course the manufacturer are important arguments for a purchase decision.

In my personal case I would therefore definitely prefer (for active speakers)
- manufacturers for the pro market, already long in business
- manufacturer with service centers in my home country (Germany)