Class D amp long term reliability

[antennaguru]

Hi,

Looking for 2 channel amp to play a few hours 3-4 days a week. Would like to keep it for the next 10-15 years. Are class D amps today reliable enough to last that long without issues? Or should I go with AB amp? Don't really care one way or the other, but obviously my choice would be limited.

Are there any modules that are more reliable than others as far as D-amps go?

Thanks

I have personally had very good experiences with the ICEpower 125ASX2 modules (125 WPC into 4 ohms). In the four (4) that I have built into various chassis zero (0) have failed. I did pay attention to the datasheet mounting requirements and I did NOT use any forced air ventilation - only convection airflow across the modules (cool air entering from below the chassis, flowing over the module, with the warmed air exiting out of the top of the chassis). Having said this the first ones I used now date back to a little over 10 years ago, with no failures. I don't want to jinx them but I think they will probably make it to 15 years. To me that is enough product life to justify the current low cost of those 125ASX2 modules. Nevertheless, most Class D modules are not very easy to troubleshoot and perform board level repairs on, as they're built for OEMs to simply remove and replace when they do eventually fail - like the AGA plate amp I am replacing now which failed at the 9 year point.

Class AB amps on the other hand were discrete component or chip builds with linear power supplies dating back several decades with zero (0) failures. I can't speak to Class AB amps available today as I'm not building them for audio any more - simply because I already have a large collection of them and cannot justify building or buying any more. Lately I am having fun building very high power non-audio amps around LDMOS transistors.

 

[antennaguru]

They're an active speaker system. There are no active components in the speaker itself. "A system is a group of interacting or interrelated elements that act according to a set of rules to form a unified whole".

By this vague definition EVERYTHING is "an active speaker system" - including my clock-radio. I guess, since the speaker, radio, and amplifier are inside one box it's even an active speaker at that.

Probably a good time to stop defining terms, and other wildly off-topic discussions, and get back to the thread topic of: "Class D amp long term reliability".

 

[Geert]

By this vague definition EVERYTHING is "an active speaker system" - including my clock-radio.

According to my definition your clock-radio is NOT an active speaker system, as it has the active components inside The term has been used in the audio industry for more than 40 years, like it or not.

 

[MAB]

Hmm...
Infinity IRS Beta.
They do have an active crossover with servo control. I sold them, called them active to the customers, as did the Infinity rep when describing them to me and the other sales people. Same for the JBL XPL-250, which also had an active crossover. That's what we called it back in the day, 'active'. When Meridian showed me the new active speakers they came out with I didn't have a debate with them over the use of the word active.

 

[fpitas]

Durability is just a question of development and component quality. If you save on it, the technology doesn't matter, because trash remains trash!

This. It's bogus to extrapolate from lowest common denominator amps.

 

[rdenney]

To me, an active speaker is one to which one runs line-level audio and a power cord, versus one that gets speaker cable. But I'm a simple guy.

Of the amps I've owned, the failures have all been with AB designs. But that only makes sense, because all the amps I've ever owned until I bought the Buckeye have been AB designs. Believe me, AB amps with discrete components can go nuclear as well as any other kind of amp. Just picking one example, I had an old and obscure Spectro Acoustics amp that was over 200 wpc back in the late 70's when that meant something, but it released its magic smoke on more than one occasion without any particular abuse from me. As with most of those amps, the issue was power supply capacitors, and what they took with them when they arced over.

Rick "any amp can fail" Denney

 

[Blumlein 88]

To me, an active speaker is one to which one runs line-level audio and a power cord, versus one that gets speaker cable. But I'm a simple guy.

Of the amps I've owned, the failures have all been with AB designs. But that only makes sense, because all the amps I've ever owned until I bought the Buckeye have been AB designs. Believe me, AB amps with discrete components can go nuclear as well as any other kind of amp. Just picking one example, I had an old and obscure Spectro Acoustics amp that was over 200 wpc back in the late 70's when that meant something, but it released its magic smoke on more than one occasion without any particular abuse from me. As with most of those amps, the issue was power supply capacitors, and what they took with them when they arced over.

Rick "any amp can fail" Denney

My worst amp failure was when some caps let go on a Classe 25. Lots of foul smoke and then it put out something activating the crowbar protection in the connected Quad ESL-63 speakers. Happened a couple days after a big lightning storm so I think that had something to do with it.

 

[antennaguru]

To me, an active speaker is one to which one runs line-level audio and a power cord, versus one that gets speaker cable.

^^^ This is my definition too!

My IRS Beta subs are therefore NOT "active" because speaker cable/wires go to them, and the amps sending signals to them over the speaker cable/wires connected to them are external to the subs, and stacked in the equipment rack. Their amps are in fact Class D ICEpower 125ASX2 amps which I installed into chassis with adequate convection cooling, and so far no failures in many years of operation.

OTOH, my 4 "active" subs that failed all had internal amps with AC power cord connections on the back of the subs. All were fed with low level audio signals, 3 by RCA interconnects from the respective preamps, and 1 by picking off low level audio signals to then amplify with dedicated internal amplification from the main amp's speaker cables. There is a view that it can be better for subs to derive their input audio signals by picking off low level signals from the main system speaker cable/wires on their way between the main amp(s) and the main speakers. That is the way my AGA sub is fed and was the specific recommendation of AGA, even though that sub also has RCA inputs.

 

[RickS]

^^^ This is my definition too!

My IRS Beta subs are therefore NOT "active" because speaker cable/wires go to them, and the amps sending signals to them over the speaker cable/wires connected to them are external to the subs, and stacked in the equipment rack. Their amps are in fact Class D ICEpower 125ASX2 amps which I installed into chassis with adequate convection cooling, and so far no failures in many years of operation.

OTOH, my 4 "active" subs that failed all had internal amps with AC power cord connections on the back of the subs. All were fed with low level audio signals, 3 by RCA interconnects from the respective preamps, and 1 by picking off low level audio signals to then amplify with dedicated internal amplification from the main amp's speaker cables. There is a view that it can be better for subs to derive their input audio signals by picking off low level signals from the main system speaker cable/wires on their way between the main amp(s) and the main speakers. That is the way my AGA sub is fed and was the specific recommendation of AGA, even though that sub also has RCA inputs.

If your struggle is that I called left the word crossover out of the reference to my active speakers, I have active crossover speakers.

Unless the speaker would be useful without power. it seems pointless to get too twisted up over where the amp is physically for an active speaker. If you do not power the active speaker crossover, you get no sound. This is not the case with a passive speaker, so seems the real question is how the speaker operates as part of a system. Someone previously posted that another approach would be to call it an active speaker system. If you have a better idea, please feel free to share. Am pretty sure most ASR members know what I meant by an active speaker though.

 

[LTig]

To me, an active speaker is one to which one runs line-level audio and a power cord, versus one that gets speaker cable. But I'm a simple guy.

This is a powered speaker: electronics is inside the box.

Active means line level crossover (analog or digital) feeding separate power amps for the individual drivers (also true if one power amp feeds multiple drivers of the same kind) without passive crossover parts in between.

Passive means one amplifier feeding all drivers through a passive crossover.

Most studio monitors hence are active powered speakers. Some big ones use external electronics (like the JBL M2) so they are active but not powered. Some offer both as an option (AFAIR Neumann KH420).

There are also hybrids which have all the electronics inside the box where one amplifier feeds the woofer and another amplifier feeds mid and tweeter through a passive 2-way crossover. You could call them powered active passive.

 

[Roland68]

For me, an active loudspeaker is only real if each chassis (or several in parallel or in series) is powered by its own amplifier, which is controlled by an active crossover, regardless of whether it is built-in or external.
This is also the original definition of a true active speaker.

But now it goes from a built-in amplifier in a speaker that feeds both speakers via passive crossovers (which are then called active monitors) to speakers with an amplifier in each speaker, regardless of the type of crossover.

And so the definition of today's active loudspeaker is quite simple.
Either the loudspeaker is completely controlled via an active crossover, or an amplifier is built into one (of 2) or each loudspeaker.
This is what is sold today as active speakers.

But that has nothing to do with “Class D amp long term reliability”.

 

[antennaguru]

Yet another failed Class D subwoofer plate amp! This latest one was on a system in our mountain house and was purchased new directly from the manufacturer, Anthony Gallo Acoustics in 2014. It was never abused and was sparingly used on a very nice sounding stereo system with passive wall mounted AGA Strada 2 main speakers ($2000 for the pair). The AGA TR3 subwoofer had cost $1000 new 9 years ago, and my KUDOS to AGA as they are still able to support the customer with a replacement plate amp for $210 shipped. I'm looking forward to receiving and installing it so I can get that system fully operational again.

This latest Class D amp failure brings my total of failed subwoofer plate amps up to 4 out of 6 subs. 3 of those 4 failures were Class D subwoofer plate amp failures, and 1 of the 4 failures was a Class AB subwoofer plate amp failure. The remaining 2 subs don't use plate amps, and have had no failures of any kind. In other words every single plate amp active speaker (all were subwoofers) that I own has failed. One even took out its woofer as collateral damage when it died. This latest one lasted the longest at 9 years before failing, and this one is the only one that is still being supported by the OEM. JBL and EV were not able to support providing replacement plate amps for their subs, and I had to adapt alternative generic plate amps from Parts Express to those subs, which required me making sheet metal filler plates in my metal shop to adapt the OEM sub cutouts (holes) to the dimensions of the replacement plate amps - as there is zero standardization in plate amp dimensions.

Upon visual inspection of this latest failed Class D plate amp I can see a few caps that look bad, but there is a lot of brown Glyptol and white RTV on the board securing components and making board level component replacements too cumbersome an exercise. Thankfully the woofer is fine.

What all of these plate amp failures have in common is that they all lived their lives inside a speaker cabinet with poor ventilation and plenty of vibration. This just adds further fuel to my belief that active speakers, subs or mains, are ALL destined to fail in a vastly shorter timeframe than passive speakers. These failures will be the electronics, unless they fail in a manner that also kills the driver. To be sure, I own several sets of passive main speakers that are over 30 years old with no failures.

I am very appreciative that Anthony Gallo Acoustics is able to support providing a replacement plate amp for my 9 year old AGA subwoofer!!! They are very customer focused, unlike JBL and EV who could not support providing replacement plate amps for subs that were quite younger than 9 when they failed. Anthony Gallo Acoustics was acquired late in 2022 by Pulse-Eight.

I received and installed the new Class D plate amp from Anthony Gallo Acoustics, and it sounds great - just like the last one. I am very happy that my $1000 subwoofer is back on line with only a $210 repair! The system sounded a but anemic without it. Hopefully this new replacement plate amp will last another 9 years, or longer!

A valuable lesson for me was that AGA continued to support their product with the availability of a replacement Class D plate amp, unlike my past experiences with JBL and EV who stopped supporting their customers after only a few years.

I was using an ICEpower 125ASX2 Class D main amplifier on this system for a number of years, whose high level signal was passed thru the AGA Sub's high level connections to drive efficient and crossover-less AGA Strada2 wall-mounted main speakers. The Sub just picks off and attenuates a tiny bit of high level signal for amplification in its plate amp. After hooking everything back up I noticed some more Class D high frequency noise than I remembered. For a sanity check I swapped in an old Class AB Naim NAP250 main amplifier instead of the Class D main amplifier, and it completely solved the problem of high frequency noise from the main system tweeters. My wife even made an unsolicited comment that the Naim amp sounds better, as I think she is more sensitive to Class D high frequency noise than I am. In the end this system sounds better than ever to us both, and far better than I would ever expect a system with wall mounted main speakers to sound! Wall mounting the mains truly works best in this room due to the layout and other functions of the room (traffic, wood-stove, etc.)

 

[C lem]

I just bought a Behringer NX6000 class D amp for my subwoofers because my class A/B amp was starting to have problems, it weighs a ton and is a monumental pain to get out of the equipment rack. I bench tested the Behringer yesterday before installing it and yes, it has loads of power, but that power is trashy as hell. But that doesn't matter for subwoofer use, and the amp cost under $500 from Amazon (of course, Amazon in the age of Covid). I took a look inside the amp and I have to say I was impressed with the extremely clean and orderly layout - and I was struck by the utter sterility of it all. Might as well have been a motor controller on some industrial assembly line.

We'll see how the reliability is!

I will be testing one on a pair of JBL srrx 718 subs. The xls2502 is not cutting it and I need raw power.
between ,30 and 88 Hz.
at first glance, the nx6000 has some very huge capacitors in amp and power supply.

 

[EJ3]

Once you have a hole you have a hole. You're going to have to fill it with something, otherwise you still have a hole...

And a cave is just a hole turned sideways. Do with it what you need to do. Vertical or horizontal? That is the question.

 

[Deleted member 48726]

I will be testing one on a pair of JBL srrx 718 subs. The xls2502 is not cutting it and I need raw power.
between ,30 and 88 Hz.
at first glance, the nx6000 has some very huge capacitors in amp and power supply.

Watch out for those Behringer watts. They don't scale correctly.

The iNuke should have identical internals as the NX one.

 

[pseudoid]

To me, an active speaker is one to which one runs line-level audio and a power cord, versus one that gets speaker cable. But I'm a simple guy.

All well and dandy but... with the exception of "active" speakers which also handle other types of audio signals that are not analog and/or 'line-level'.
We got network'd audio, we got digital audio, we got audio in the airwaves (WiFi/BT), we got the Mensa-grade smart speakers, that will listen and even talk back to/at you, we even have speakers that speak to each other.
We don't call a semi-conductor a passive-aggressive, because it is sometimes in its off state and may not draw any power.
I think what an "active" speaker should really mean (or was intended to mean) is that it was not a "passive" speaker.
"Passive"; as made to work using passive components, like RCLs and magnets and maybe even some pixie dust.

Soon, the AC power-cord will also disappear and speakers will just run on your emotions (both for audio and power).

 

[DonH56]

<elided>

Soon, the AC power-cord will also disappear and speakers will just run on your emotions (both for audio and power).

Well, crap, as an engineer, old-school guy, and mostly objective type my speakers are probably going to be really, really quiet. Guess I'd better get more emotional, more subjective, if I want to be able to hear them in the future.

 

[fpitas]

And a cave is just a hole turned sideways. Do with it what you need to do. Vertical or horizontal? That is the question.

This conversation is getting deep. And troglodytic.

 

[antcollinet]

This conversation is getting deep. And troglodytic.

Well troglodytes do need deep caves.

 

[DonH56]

Around here a vertical hole is a mine shaft. In the midwest, it's a well. Don't know if either is significantly better or worse on average than a class D amp for reliability.

Crawling back into my cave now - Don