500 Bloat

Not an educated elve (or anything else !) so only a stab-in-the-dark thought......

Perhaps capacitors Or other components)  build up a base-line charge and function more effectively if they are "switched off" and allowed to discharge for a while, thus renewing their "headroom" or dynamic range ??

Good to know that your system sounds great again.

J.N. posted:

My system was sounding great last evening, and had apparently gone of the boil this evening. A bit lumpy, heavy, congested and shouty.

Is it me?

I powered down the 500 for a couple of minutes and re-started it. The magic was back. The sound opened-up, smoothed-out and wasn't fat and lumpy any more.

Gary (DB) told me about the phenomena of '500 bloat' a long time ago and I was sceptical, but it seems that a prolonged period of continuously powered-up Naim power-supplies can result in the sound going 'off'. It's probably just more noticeable with the NAP500 because of its level of resolution and chunky power-supply. Two to three months seems to be the time frame which has an audible effect on my 500.

So; if your Naim kit hasn't been powered down for a while, try a refresher folks. It only takes two minutes.

Any 'Educated Elves of the Electrical Grotto' care to offer up a for why?

John.

 

Hi John, great advice.

So, what have you been up to today 

i havent experienced this (yet?) ... or maybe i'm just cloth-eared. i have two of the monsters and so i would expect the effect to be even more pronounced.

but i seem to recall a similar discussion here sometime ago -- and it was concluded that yes indeed,power cycle (reboot) every ever so often (dont know the freq) has some benefit.

If i have to do it, its not at all a big deal since the system sounds mighty grand right now... and i can definitely see the point of it...

interesting to hear other owners' comments...

enjoy

ken

With my 250s the "bloat" build up over a couple of weeks. Turning the power amps off for 30 second and on again clears the congestion. Takes about 15 minutes for the system to get into its stride. Maybe there's some external influence that accounts for different users different experiences with this effect? Mains here is all on overhead lines and of questionable quality at times, especially milking time, or welding time.

Willy.

It's SOP in this house but i don't need to do it very often. Less often this year because we've been away more and therefore powered down. I don't know how it works but I know it works. I did it with the 300 too.

It's happening to me when I'm thinking about a modest 500 DR.....

If I listen everyday, how often should I turn it off?  Weekly?

My 500PS has a fiddly switch and it does not like to stay on.  It is a small issue if I leave it on.   It would be an easy trip to NANA in Chicago or Indy, but Canada is a world away with an international border.

Bloat is not our friend.  What is the maximum on-off cycle time to minimize bloat?

sc

Try turning it off if it doesn't sound like its usual magical self. If it does, don't. It's not an operating requirement.

Harry posted:

Try turning it off if it doesn't sound like its usual magical self. If it does, don't. It's not an operating requirement.

+1

enjoy

ken

It is funny that this point was raised - so I am not alone. 

I have an active system 2x500 1x300 which I needed to power down for a few days so that I could cover it up during some minor decoration works. I was expecting a cold system to sound rather poor (usually the timing is off). It actually sounded rather good and not too long to warm up. I would say it sounded a bit more balanced and lively. 

Before I was blaming it on the 300 just not being up for the job, but I now think I can soldier on a.bit longer with the wonky setup. 

John

As per our previous conversations this is so right - thanks for reminding me again. I will take a free upgrade any day of the week!

I am curious to hear from some of our expert electrical engineers as I am sure there is some concrete theory behind this. Richard - does Roy have any comments about this?

best

Gregg

Gregg,

I don't know  - I've never asked Roy about this.  

Richard

OK. Any other technical wizards feel free to chime in

Supply Electrolytic capacitors are little chemical factories that can become non-linear if they get a mains spike that pushes them out of their normal operating voltage. One hypothesis is that if that happens you get the so-called 'bloat' effect and turning off and on re-sets them again.

I also get this effect every several weeks and do the reset to clear it.

DB.

Thanks DB

Makes sense to me. 

I need to start doing this on a regular basis. It has been ages since a power down and this was a MAJOR lift to the system. 

Best

Gregg

I leave my system powered up 24/7 and to my ears it sounds the same everyday. It may be the case that I live in an area that receives a consistent supply of electricity, but this phenomenon should affect any device that contains electrolytic capacitors. I'm wondering why it only seems to affect power amps? Do the 552PS and 555PS also contain these capacitors?

Whenever my system is not song, I reflect on the day that I have had and realise that my mind is often filled with thoughts and emotions that change my perception. I leave my system as is and power myself down to resolve the internal disharmony. When I have destressed and I am no longer preoccupied with excessive thoughts, I'll sit myself down and enjoy some music. However, it is not always possible to restore homeostasis within a few hours and it can sometimes take a few days to understand the root of the emotive force. I would like to consider that my system remains the same: it is me that has changed from the influence of the environment that I inhabit.

There is a phenomenon known as expectation bias, it is subjective and it has a profound influence. It is not technical. It is not educated in engineering. It could be construed as a mechanism to appease the inner voice that yearns for change.

Powering down an amp is free and if it seems to work, I'd say go for it

Minh Nguyen posted:

There is a phenomenon known as expectation bias, it is subjective and it has a profound influence.  

I expect listening to music my system to sound great and to affect my emotions in a good way    - then again I'm biased 

DB, haven't heard that bloat theory before.. the more I thought about it the more I thought nahhh. Yes the mains does have little transients, but the transformer bandwidth is limiting, and so these transients are filtered by the time they are rectified ready for the reservoir electrolytics. These electrolytics always have a max working voltage several/many volts above the quiescent voltage... So I would envisage a peak that exceeded the max voltage here would pop most lights and device fuses in your house..

i think the situation is more to the dynamic stabilisation and feedback that is in most electronic circuitry.. I suspect performance is not linear across all operating conditions... and so power reset'  resets' the circuitry.. Perhaps to a known / recognized more comfortable sweet spot. To my mind this is exactly the same phenomena that occurs when a device starts from cold, and the time it takes to come on song..

Simon

Minh Nguyen posted:

There is a phenomenon known as expectation bias, it is subjective and it has a profound influence. It is not technical. It is not educated in engineering. It could be construed as a mechanism to appease the inner voice that yearns for change.

 

(Italics mine) I find this a very clever statement, and at least as good an explanation of the phenomenon as the more technical ones.

M

If left on for many months the 300 could occasionally start to sound flat and congested, like it needed a good cough. Powering it down and re starting cured this. In the case of the 500 it's what I would describe as overblown bass. These effects tend to creep in. It's not like it suddenly goes bad or even becomes difficult to listen to. It just sounds a bit off. If you do not detect such changes then don't worry about it. Our system has been powered down four times so far this year for holidays and storms. I haven't felt the need for the "reset" this year which may be because it has not so far run continuously for more than three months on 2015.  Or maybe not.

It is not a question of if a power amp at any level or from any manufacturer needs to be occasionally reset.  It is a question of if you, the individual owner, hears a change over time which you consider to be a loss of sound quality. If so try this. If not then don't.

I've had the same experience as John, although not for some time though. 'Bloated' is a good term to describe the sound. 

'SN2 bloat' present and attending over here. Having been powered on for a good couple of months now I turned her off for a few hours yesterday to counter what I suspected to be a bit of 'bloat'. Back on song in a big way today. Thanks for the heads up!

Darke Bear posted:

Supply Electrolytic capacitors are little chemical factories that can become non-linear if they get a mains spike that pushes them out of their normal operating voltage. One hypothesis is that if that happens you get the so-called 'bloat' effect and turning off and on re-sets them again.

I also get this effect every several weeks and do the reset to clear it.

DB.

This is also my dealer explanation, spikes and polluted mains marring capacitors.

A  few minutes reset usually sort this.

Regards

Roberto

I suffer from 500 bloat so much these days that I power it down every evening as it definitely sounds better when I power it up next day (I still leave my NAC, Supercap and Radikal on 24x7).

I have a service planned for this year so we will see if that removes or reduces the bloat effect.

Richard

As we discussed on Friday the 500 service and DR upgrade would seem to be the priority in your system and the amp seems to be asking for it if you need to power down every night.