Zaphod Beeblebrox

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ What these two guys said. Bang-on. $200.00 is too much.

Sort of. Trouble with generalisations is that they're not always correct. I recently rebuilt a pair of AR speakers, dating from 1973-ish. They've done a fair bit of work, apparently. Most of the HF drivers are shot and two mids had failed. The small electros on the mids and HF drivers were showing signs of their age, but were still not too bad. The electros on the bass drivers were spot-on. Well within tolerance and ESR was excellent. Very well made electros. I would expect polyprops to remain in spec for several life-times. That said, I have found a few dead ones over the years. Some were of recent manufacture. Sound-wise, polyprops may offer some sonic improvements, depending on various factors.

Any product that is not fitted with the components specified by the design engineer is a product to avoid. Sure, as can many other fine products. Many of those products are built using components specified by the design engineers and not the bean counters. The reason why old computer equipment was not switched off, was because old hard drives lacked automatic 'parking'. Old style 'mini computers' and mainframes use VERY high grade capacitors with typical life-spans of 100,000 hours. Capacitors found in typical audio products are usually less than 10,000 hours. Frequently, they are 2,000 hour components. I've been in more recording studios than I've had hot breakfasts. I've installed equipment in a few and attended a few recording sessions until the wee hours. At the end of what is usually a VERY long day (well past midnight for many), the studio is shut down. The risk of fire is far too great to leave the equipment powered. I ignore nothing. I am very well aware of the limitations of electrolytic capacitors. HEAT is the enemy. And yes, as an electrolytic cap is subject to charge/discharge cycles, it gets warm. This occurs continuously and is why capacitors are rated as XX Amps ripple current. By comparison, the initial switch-on is utterly and completely insignificant. Good manufacturers choose appropriate components to do the job, combined with appropriate attention to proper cooling of those components. Ripple current rating is important. However, the heat generated by nearby components is VERY important too. Really? Got a capacitor manufacturer's cite for that claim? That's what I have been explaining to you. It is the EXTERNAL heat sources that are the most problematical for amplifiers like your Plinius. And yes, under normal operation, electrolytic caps will generate internal heat. An initial switch-on is an insignificant problem. I get that you are scrabbling for excuses to justify leaving your amp on. That's normal human nature. However, your claims of thermal shock, failing solder joints due to thermal shock are just bogus. There are far more important and significant problems. Poor solder joints will certainly suffer under elevated temperatures. Nothing to do with switch on or switch off though. My business is and has been high quality audio servicing for many years. I am well versed in the failure modes of components in amplifiers. Switch-on surges can damage rectifiers, surge resistors, lamps, valves and other components, but NOT electrolytic caps (unless they have been sitting idle for a few years - but that is a completely different mechanism) nor solder joints.

You keep making this claim as if it has any validity. It does not. HEAT is the killer of electrolytic caps. Solder joints stressed by turning an amp on and off? Not in this universe. Stop making this specious claim. HEAT is the enemy of electrolytic caps. Leaving an amp permanently powered will accelerate wear on electrolytic caps. None of which has ever been in dispute. Any manufacturer that specifies that their amplifier, which runs hot (convection cooled), should be left permanently powered, but chooses 85 degree C caps needs a swift kick up the bum.

Sure does. The flammable side cheeks assist in this process too. [ANECDOTE] Back in the 1980s, I sold Sansui. The Sansui rep kept asking me to sell the cheap range, but I refused, explaining that I had repaired a few, so I knew how they were constructed. Anyway, as you probably know, Sansui thoughtfully made it very easy for lazy techs to bypass a failed transformer thermal fuse with a wire link, thus magnifying the fire risk dramatically. The transformers were of particularly poor quality and very large numbers of thermal fuses failed. I know, for my part, that I replaced a large number of thermal fuses in that range back in the day. Anyway, one Saturday morning a mate called by to buy a system, but I was unavailable. Annoyed, he went into the city and purchased a complete Sansui system from DME Hi Fi. When he informed me of his decision, I declined to explain that he had purchased absolute junk, instead telling him that I did not stock that range of Sansui gear. Fast forward 5 years and I happened across Russ at a party. I offered my condolences at the loss of his house in the fire. He then explained that the fire investigators had nominated that the fire started in his Sansui hi fi system and spread rapidly through his timber home. I didn't probe further, but I reckon the amp was probably repaired by a lazy tech, who bypassed the thermal fuse when it failed. The amp then overheated, caught fire and burned his house down.

"Decidedly average"? You're being WAY too generous.

YIKES! Plinius should consider a major re-design.

Stop making this unsubstantiated claim. Heat and time are the big killers of electrolytic capacitors. Switch on is not a problem for electrolytic capacitors in any properly designed product. IF they last 20 years. Operating a 3,000 hour capacitor at constant high temperatures will see compromised performance in far less than 20 years. I have never seen an amplifier manufacturer suggest that their product be left permanently powered. It is not smart design.

Please check the numbers on the fuse carefully and report. T8 suggests an 8 Amp slo blo fuse. Are you certain? That's a big fuse. I assume the amp has a big toroidal transformer fitted.

OK. That is a slo blo (time delay) M205 (20mm X 5mm) fuse. The usual method of designation is 3.15AT or similar: https://au.element14.com/w/c/circuit-protection/fuses-fuse-accessories/fuses/cartridge-fuses?blow-characteristic=slow-blow&fuse-current=3.15a&fuse-size-metric=5mm-x-20mm

I don't know which Rotel you have. Some use 3AG fuses and some use M205 types. M205 is more common: https://au.element14.com/w/c/circuit-protection/fuses-fuse-accessories/fuses/cartridge-fuses?blow-characteristic=fast-acting&fuse-current=5a&fuse-size-metric=5mm-x-20mm

Just buy your fuses from RS Components or Element14. All their fuses meet the basic specs required. I can't promise that your Rotel won't stop blowing fuses (since that is a well known issue), but you'll be secure in the knowledge that the fuses are the best available.

You claimed that the major problem was at switch on. This is incorrect and highly misleading advice. The major problem facing electrolytic capacitors is heat and time. Switching a hot running product off, when not required, will ensure that the electrolytic capacitors last longer. Irrelevant. You made the claim, then failed to support that claim. I supplied the data from the capacitor manufacturer to support my statement. Can you cite where Plinius state that the amp should be left operating 24/7? I supplied two further options: * Arrange for a remote switch to turn the amp on. * Put the amp on a timer. Personally, I regard neither as a particularly good idea, as appliances like your Plinius should not be operated unattended. And I pointed out some better solutions and your error/s.

Well, just to be a pedant, that's not quite true. A 10 Amp fuse will not blow at 10 Amps. Counter-intuitive, I know, but here are the specs of a Littelfuse (Bussmann will be similar): https://www.littelfuse.com/~/media/electronics/datasheets/fuses/littelfuse_fuse_312_318_datasheet.pdf.pdf You'll note that a 10 Amp fuse can pass 10 Amps more or less indefinitely. Not necessarily. Jaycar are not a ISO9000 accredited supplier. I have found, to my cost, that relying on the quality of any products supplied by Jaycar and other non-ISO9000 suppliers, that the results can be unpleasant. I ONLY use Jaycar as a supplier of last resort. That includes fuses. I have found that many unbranded or unknown brand fuses do meet the standards that apply to proper fuse manufacturers, like Littelfuse, Bussmann and others. Well, I am and always have been passionate about quality components. That does not mean silly, 'audiophile' type, gold plated and poorly specified components. FWIW, quality fuses do not have to cost a lot: https://au.element14.com/w/c/circuit-protection/fuses-fuse-accessories/fuses/cartridge-fuses?blow-characteristic=fast-acting&fuse-current=10a&voltage-rating-vac=250v&fuse-size-imperial=1-4-x-1-1-4- Yes, more expensive than Jaycar rubbish, but, in the big scheme of things, cheap as chips. Provided you know the characteristics of the cheapest fuse. I've seen non-ISO9000 components rated at 3.15 Amps, but they blow at around 2 Amps! Naturally, the cheap fuses may blow the wrong way too (IOW: much higher than the rated current).

I am well aware of Mr McGowan and his products. Some of what he states is bang-on and some is nonsense. I have not viewed the particular video you cited. I may do so tomorrow. I do, however, direct you to this specification sheet from a typical, high quality electrolytic capacitor manufacturer: http://www.farnell.com/datasheets/1792286.pdf?_ga=2.114744192.603030959.1547452860-1632355343.1545968869&_gac=1.216868130.1545968869.EAIaIQobChMIqsq_487B3wIVRaSWCh0nwANUEAQYAiABEgIWtPD_BwE Look and read page 3 carefully. Note the life-span of the caps at various temperatures. It perfectly illustrates why it is important to keep electrolytic capacitors cool wherever possible. That means shutting equipment off when not in use. I have no argument with the use of high quality electrolytic capacitors in any products. What I take issue with is your claim that extended high temperature operation is not a major problem. Far from it: It is a BIG problem and capacitor manufacturers know it. They all take care in spelling out the limitations in their spec sheets. Switch on and switch off are simply not a problem. Heat is the enemy of electrolytic caps. As long as you understand that you are needlessly shortening the life of your amp and causing your electricity bill to be higher than it needs to be, then fine. I do not share your view. The heat is a big problem for the electrolytic caps.