Wear and tear on amplifiers

[CJ14]

Nope! its a bit more complex than that. I did a back-of-fag-packet calculation for those caps working at their full rated voltage and if you keep the ambient temp at around 30 degrees (instead of 85) the expected life is over 80 years. Temperature really is the killer of electrolytic capacitors.

Electrolytic caps rely on chemistry to work and the rate of chemical reactions was discovered by Arrhenius. Basically the rate of a chemical reaction doubles for each 10 degree rise in temp so even without doing any more big complicated sums we can determine that if life at 30 degrees is 80 years then at 40 its 40 years at 50 its 20 years at 60 its 10 years - get the picture?

Cheers,

DV

True but it also depends on internal plate size and current and ESR, lots to consider. Lets all recycled paper and make paper cap in air , how big would 0.5Farad be at 50V? Oh I need 4 in each amp.

 

[James]

The best thing I did for my class A amplifier was to build a platform with a couple of variable speed fans to force air through the perforated base cover. The power transistors are adequately heat-sunk, but the audio board diodes run hot, so I do what I can to keep them coolish.

They are switched on only when I'm listening.

 

[ryder]

The best thing I did for my class A amplifier was to build a platform with a couple of variable speed fans to force air through the perforated base cover. The power transistors are adequately heat-sunk, but the audio board diodes run hot, so I do what I can to keep them coolish.

They are switched on only when I'm listening.

Fans do greatly help with ventilation and keep Class A amps which produce a lot of heat cool.

Similarly all my amps are only switched on when I want to listen to music. Otherwise they are all in standby mode.

 

[CJ14]

The new one I am Designing for Pearl Acoustic has 3 positions, ON cont, OFF for ever and trigger it only turns on when music is played , it looks for 5mV on either balance or RCA when music stops it shuts down in about 60mins, but still leaves a low voltage on the caps a cct, about 10% of the running voltage, so from 40W silent to 200W peak in this mode it takes only 2W.
The circuit board was fun as it is dual mono.
Quickie is making one now.
It has twin mains filter and DC blocking built in, this will tolerate 10VDC nom and 25VDC pk

 

[quickie]

Quickie is making one now.

Made some good progress on the boards yesterday

Busy doing parent duties today though.....

 

[eevo1969]

The best thing I did for my class A amplifier was to build a platform with a couple of variable speed fans to force air through the perforated base cover. The power transistors are adequately heat-sunk, but the audio board diodes run hot, so I do what I can to keep them coolish.

They are switched on only when I'm listening.

Following the advice above I’ve shamelessly just ordered a couple of silent variable speed fans and I’m now thinking about how best to discreetly use them.

Plinths do seem a good idea but I have now promised not to spend money on Hifi for a while so a set of cutouts on the shelving that the amps sit on and mounting the fans from underneath seems very attractive atm.
I’ll make a decision when the fans arrive.

 

[James]

Following the advice above I’ve shamelessly just ordered a couple of silent variable speed fans and I’m now thinking about how best to discreetly use them.

Plinths do seem a good idea but I have now promised not to spend money on Hifi for a while so a set of cutouts on the shelving that the amps sit on and mounting the fans from underneath seems very attractive atm.

The fans I use are less than 1" tall/thick. It was a simple matter of cutting an MDF/ply board to size, figuring out where the feet of the amp will contact the board, and cutting the holes for the fans so they can do their job and not be fouled. I can post photos of my twin-fan platform if it helps.

The only thing I wish I knew how to do is auto-temperature sensing. I set the fan speed manually with a variable voltage wall-wart PSU. During warmer times, I run the fans slightly faster to keep the heat sinks cool enough to touch comfortably.

 

[RoA]

I have been using a near silent fan for my Samsung QLED Connect box for a couple of years. I noticed it getting (very) toasty after a day of using it (no internal fans). It has been running only slightly warm ever since). USB powered from the connect so starts/stops with the device.

I also noticed Sky boxes get rather warm.

 

[Sonny Beauceron]

FWIW, the manual for the EAR 509/II says this on this subject:

"DON'T switch on and off quickly. Normally it is best left to run the whole evening, ie, once on and off per 24 hour period."

 

[James]

Unloaded cooling platform bolted to Mana PSU table:

Loaded with 20kg of class A amplifier:

 

[Chris]

I put much taller feet on my Sugden A21SE which happen to be Maglev. There is now a good 4.5 cms between shelf and amp which I assume, allows better renovation of air. Butt ugly but it’s in a backless cupboard anyway so no-one can see it.

 

[eevo1969]

Unloaded cooling platform bolted to Mana PSU table:

Loaded with 20kg of class A amplifier:

Now that is very smart, nice work!
I think I’ll forget about disfiguring the stand and follow your example now that I can see what’s possible. I’ll drop my meds down for a day or so and have a go myself. I honestly wouldn’t have thought to bolt it down.
Thank you for the pictures, they’re really helpful. I’ll report back when I have something in hand.

 

[James]

Now that is very smart, nice work!
I think I’ll forget about disfiguring the stand and follow your example now that I can see what’s possible. I’ll drop my meds down for a day or so and have a go myself. I honestly wouldn’t have thought to bolt it down.
Thank you for the pictures, they’re really helpful. I’ll report back when I have something in hand.

No worries. You will note that the outlets are round, but the body of the fans is square. To save routing a solid piece of MDF/ply precisely, I glued a 6mm thick MDF with the round holes, to the 18-22mm thick MDF with the square holes. If you look carefully, you can see the delineation. The trick is to line the centres up carefully before committing to the cuts. The rest is mostly about sealing the edges and finishing with satin enamel paint.

 

[mercalia]

Unloaded cooling platform bolted to Mana PSU table:

Loaded with 20kg of class A amplifier:

I am glad to know I am not the only one to worry to this exent. I was thinking of getting a custom top made for my Audiolab 8200cdq with a hole in the top for a fan instead of just placing one resting on the edges as at the moment.

 

[Gervais Cote]

I make these racks to put under class A and A/B and they lower the temperature by 8 Celsius so maybe enough for some :

 

[davidsrsb]

The snag with true Class A is that it runs hottest when you don't play music through it

 

[Robert]

Unloaded cooling platform bolted to Mana PSU table:

Loaded with 20kg of class A amplifier:

Love it, quality solution James!

 

[Tony Lockhart]

I would just have to round off the edges of those holes for improved airflow

 

[James]

I am glad to know I am not the only one to worry to this exent. I was thinking of getting a custom top made for my Audiolab 8200cdq with a hole in the top for a fan instead of just placing one resting on the edges as at the moment.

That would work only in there are perforations on opposing sides of the casework. Otherwise, air just won't flow.

 

[Ian Austen]

I can remember a friend of mine who had a VERY hot running Musical Fidelity class A amp donkey's years ago.

My class A amp runs relatively cool and has lots of space inside due to it having hardly any components