Hi folks,
I have a question for you experienced DIYers: does a freshly built power amp need burn in time to sound right and if so, how many hours roughly (ballpark)?
Background: I have a premium ACA here which was for a long time my favourite amp and still is very high up. For the price, amazing. Now I borrowed a 50wpc Class AB Apex FX8 Muse from a friend (chermann) which i really enjoyed now for many weeks and wouldn't want to go back to Aca necessarily due to more power and punch and wider soundstage. It frankly sounds stunning through my system, which consists of a Wiim Pro, feeding a Lampucera Tube DAC and speakers are ALR Number 2. Recently Chris and Harry (thanks again so much guys!!!) helped me build my first own Class A power amp, a M2 OPS with OPA828 Opamps (see picture) in a 4u400 case and 500va toroid. It has only played for 10/20h but I am missing a certain attack/rhythm/forwardness (not sure how to describe it accurately, but with many songs it just sounds slow in a way... Like I wanted to "help" a little and push it to get going... I think sluggish describes it best), that I get from the other two amps (more from fx8, but also aca has it). I am asking myself now whether it is that the amp needs time to settle and play some 100/200h or the synergy of the system is gone somehow (maybe I need new speakers?) or maybe this is just how the amp sounds (which would be worst case for me). So maybe you can help me out here and tell from your experience if this is something that just needs time? Thanks a lot!
I have a question for you experienced DIYers: does a freshly built power amp need burn in time to sound right and if so, how many hours roughly (ballpark)?
Background: I have a premium ACA here which was for a long time my favourite amp and still is very high up. For the price, amazing. Now I borrowed a 50wpc Class AB Apex FX8 Muse from a friend (chermann) which i really enjoyed now for many weeks and wouldn't want to go back to Aca necessarily due to more power and punch and wider soundstage. It frankly sounds stunning through my system, which consists of a Wiim Pro, feeding a Lampucera Tube DAC and speakers are ALR Number 2. Recently Chris and Harry (thanks again so much guys!!!) helped me build my first own Class A power amp, a M2 OPS with OPA828 Opamps (see picture) in a 4u400 case and 500va toroid. It has only played for 10/20h but I am missing a certain attack/rhythm/forwardness (not sure how to describe it accurately, but with many songs it just sounds slow in a way... Like I wanted to "help" a little and push it to get going... I think sluggish describes it best), that I get from the other two amps (more from fx8, but also aca has it). I am asking myself now whether it is that the amp needs time to settle and play some 100/200h or the synergy of the system is gone somehow (maybe I need new speakers?) or maybe this is just how the amp sounds (which would be worst case for me). So maybe you can help me out here and tell from your experience if this is something that just needs time? Thanks a lot!
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Isn't that board meant to use the high voltage OPA551 opamp? OPA828 is maximum +/-18V to my understanding. Maybe that's what your rails are, my crystal ball is very hazy and I just can't see anything. I'm familiar with tombo's OPA828/LME49600 "Blasphemy" pcb's but those are meant to properly drive a signal transformer that in turn drives an output stage. Perhaps it's just a lack of power and damping factor with your particular load that's needed with this desired attack/rhythm/forwardness thing. But, those red caps will need at least 1,000 hours of burn-in as everyone knows.... that's probably it.. 😀
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I actually think the term ”burn in” is unreal overkill and sligtly ridiculous and decieving.
But:
”Amplifier long term Warm up, stabilize, and settle down.”
That It is for sure a real thing for every real deal good sound and not tone deaf dude, who have actually built, actually listened to, and actually biased a real class A amplifier.
…In a really skilled and top tuned total setup: Room, positioning and playback equipment.
But:
”Amplifier long term Warm up, stabilize, and settle down.”
That It is for sure a real thing for every real deal good sound and not tone deaf dude, who have actually built, actually listened to, and actually biased a real class A amplifier.
…In a really skilled and top tuned total setup: Room, positioning and playback equipment.
Well it certainly looks like it ought to sound great! I think JeyDee makes a very good point.
It seems rather more likely that it's your ears that burn in.
I'd argue that a circuit is flawed if its performance changed significantly as function of temperature or drift.
Tom
Depends on your definition of "long term". Even a large Class A amp shouldn't take more than an hour or two to reach thermal equilibrium. It's not completely unreasonable to expect the circuit performance to change measurably during this time. But any change beyond that would be attributed to component aging and that happens on a much, much, MUCH longer time scale (decades). Whether any these changes would be audible is another matter.
I'd argue that a circuit is flawed if its performance changed significantly as function of temperature or drift.
Tom
In the good old days, when you bought a new car, you had to "run it in" first so that all the mechanical parts were set up correctly.
Your ALR 2 is decades old and without a doubt perfectly mechanically burned in...
A properly designed amplifier does not need a burn-in period
Your ALR 2 is decades old and without a doubt perfectly mechanically burned in...
A properly designed amplifier does not need a burn-in period
Speakers can certainly “loosen up” when new, or after long periods in storage - and class a amps typically need to settle in for an hourish to reach equilibrium or their optimal operating point and thd spectrum. But, past those easily verifiable scenarios I’ve never experienced “burn in” with any other components.
My point is the following: if there is no objective evidence (one way or the other), we will remain in the realm of speculation.
Which however is not entirely a bad thing (IMO) if we think about how different our ears or our brains can be.
So, it is impossible to say a definitive word.
In the meantime, in my opinion, as a temporary word 😛, about burn-in is even obvious that something has to change if only because everything that ages changes, no exceptions allowed.
Whether that change (small or large as it may be) is perceptible to hearing is another matter.
But it cannot be ruled out that someone can perceive it, otherwise we would also have to rule out that no one can perceive it, but no one is able to know this for sure.
I notice break in in a large way with both speakers and phono cartridges. While it may be some way my mind fools itself, but I perceive break in or burn in with every amp I've ever built, just not as large as with speakers and cartridges. With them, there is a physical-mechanical run in, that I can hear huge.
With power amps, I always thought tube amps sounded more "wirey" sounding the first few hours or so. Solid state amps somewhat more subtle. Beginning with improvements in bass, then mid range and in the end, the high end. Pre amps and phono amps not so much, at least solid state. Been too long since I have built a tube pre, so dont recall.
After break in, I notice (with these class A amps) a difference during warm up, which even Pass has commented as well as others, best sound after an hour or so.
With power amps, I always thought tube amps sounded more "wirey" sounding the first few hours or so. Solid state amps somewhat more subtle. Beginning with improvements in bass, then mid range and in the end, the high end. Pre amps and phono amps not so much, at least solid state. Been too long since I have built a tube pre, so dont recall.
After break in, I notice (with these class A amps) a difference during warm up, which even Pass has commented as well as others, best sound after an hour or so.
True, some dont hear differences in positive vs negative phase either...
Yes, this definitely (still not exclusively) can be true.
However, there is no evidence that burn-in of a piece of equipment does not stabilize its performance over time (I'm not talking about the 1 hour time after you turn it on).
Indeed, it seems impossible that it should not happen.
Can you hear the stabilization of the old-age of the electronic components?
I think so, with tubes (just as an example) one can hear it, I guess.
The key question then is whether his M2 sounds like an M2 should or not. In other words: is it improperly built, or just not his cup of tea/an ill fit for his speakers.
Zen Mod always says give it 50 hours or so before final judgement. But if crap from the start, hours won’t help.
I usually consider two things in need of a few hours: power supply caps, and caps in the signal path (may need many). Other than that, just get it up to equilibrium, pour some wine, and chill.
That said, I am a subjectivist with regard to these things. We are not remaking the Super.
Zen Mod always says give it 50 hours or so before final judgement. But if crap from the start, hours won’t help.
I usually consider two things in need of a few hours: power supply caps, and caps in the signal path (may need many). Other than that, just get it up to equilibrium, pour some wine, and chill.
That said, I am a subjectivist with regard to these things. We are not remaking the Super.
I was having fun with my initial answer to the question, obviously.
Since we are in this game for fun, there is plenty of room for individual perceptions and experience. I have built quite a few different amps over the last few years. I have noticed a general trend with the Nelson Pass inspired amps and clones thereof. Namely, after the initial warm-up period there is a noticeable change in the character of the sound as the amp is used for a number of hours. Some amps seem to settle in very well at around 20 hours or so. Others have taken 100 hours or more before they really seemed to be fully settled. The perception is difficult to describe, but it occurs regularly and reliably enough that I would not dismiss it.
With amps that use a large DC blocking electrolytic capacitor on the output, there is a justifiable electro-mechanical process at work. Big capacitors are mechanical constructs, as are vacuum tubes, just to a different degree. There is a known process called electric forming with big power supplies used for high power studio strobe lights used for photography. (I have a few of those.) It is not a stretch to imagine that smaller degrees of forming take place with the electrolytics that we use in output stages and even in power supplies. Big film caps are also mechanical constructs, hopefully more constant and stable than electrolytics, but still inescapably mechanical in nature.
Big power Mosfets have noticeable thermal drift in their electrical characteristics. This is documented in many datasheets. Again, I would not consider it a stretch to imagine that permanent alteration of Mosfet characteristics would take place over a number of hours running at temperature. The diffusion of N-type and P-type doping ions (and N++ and P++) will change over time when the devices are run at higher temperatures. The Fets are annealed during manufacturing to achieve initial stability, but this process does not magically stop after the parts are packaged and shipped.
I was a custom ASIC designer in my previous life. I have designed circuits down to the transistor level when it was necessary to do so, I'm also still an enthusiastic amateur photographer.
Since we are in this game for fun, there is plenty of room for individual perceptions and experience. I have built quite a few different amps over the last few years. I have noticed a general trend with the Nelson Pass inspired amps and clones thereof. Namely, after the initial warm-up period there is a noticeable change in the character of the sound as the amp is used for a number of hours. Some amps seem to settle in very well at around 20 hours or so. Others have taken 100 hours or more before they really seemed to be fully settled. The perception is difficult to describe, but it occurs regularly and reliably enough that I would not dismiss it.
With amps that use a large DC blocking electrolytic capacitor on the output, there is a justifiable electro-mechanical process at work. Big capacitors are mechanical constructs, as are vacuum tubes, just to a different degree. There is a known process called electric forming with big power supplies used for high power studio strobe lights used for photography. (I have a few of those.) It is not a stretch to imagine that smaller degrees of forming take place with the electrolytics that we use in output stages and even in power supplies. Big film caps are also mechanical constructs, hopefully more constant and stable than electrolytics, but still inescapably mechanical in nature.
Big power Mosfets have noticeable thermal drift in their electrical characteristics. This is documented in many datasheets. Again, I would not consider it a stretch to imagine that permanent alteration of Mosfet characteristics would take place over a number of hours running at temperature. The diffusion of N-type and P-type doping ions (and N++ and P++) will change over time when the devices are run at higher temperatures. The Fets are annealed during manufacturing to achieve initial stability, but this process does not magically stop after the parts are packaged and shipped.
I was a custom ASIC designer in my previous life. I have designed circuits down to the transistor level when it was necessary to do so, I'm also still an enthusiastic amateur photographer.
I believe in my FryBaby2. It doesn't work on everything in the audio chain and there's a clear limit to the improvements it can deliver, but I (and friends who have borrowed it) am convinced it isn't audio voodoo or a psychoacoustic trick. And that informs me that some components require a break-in period before they can sound their best.
Unless the capacitors in the amp have recently been used elsewhere, it's kind of hard to miss the change in sound after burn-in.
Even brand new caps have been on the shelf for months or years since their manufacture.
And used caps that have sat idle for a long period of time do the same, in my experience.
When I designed my DG300B I certainly noticed that the 300B tubes took a while to break in. The THD of the tubes changed by ~2x from hour 0 to hour 4-or-so. It seemed to settle there. After that it only took a few minutes after power-on to achieve the same "hour 4" performance.
I used the amp for a few years. Then moved to the Modulus-86 instead. The 300B amps sat for a few years until I sold them. I checked the performance of the amps before I shipped them and they performed as well as they did at the "hour 4" mark.
Tom
And exactly what aspect of the capacitor changes after "burn-in" that affects the sound?
That is a different discussion. However, science starts from observations, not theory.